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March 29, 2021
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https://www.sciencedaily.com/releases/2021/03/210329085941.htm
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Carried with the wind: Mass migration of Larch Budmoth to the Russian High Arctic
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Arctic habitats have fascinated biologists for centuries. Their species-poor insect faunas, however, provide little reward for entomologists -- scientists who study insects -- to justify spending several weeks or even months in the hostile environments of tundra or polar deserts. As a result, data on insects from the High Arctic islands are often based on occasional collecting and remain scarce.
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Vize Island, located in the northern part of the Kara Sea, is one of the least studied islands of the Russian High Arctic in terms of its biota. Scientists Dr Maria V. Gavrilo of the Arctic and Antarctic Research Institute in Russia and Dr Igor I. Chupin of the Institute of Systematics and Ecology of Animals in Russia visited this ice-free lowland island in the summer of 2020."Our expedition studied the ecology of Ivory Gull," Maria Gavrilo says, "but we also looked for other wildlife." Because of the lack of data, scientists appreciate any observation on insects they can get from the High Arctic.On the island, the team found hundreds of small moths. They were identified by Dr Mikhail V. Kozlov of the University of Turku, Finland, as Larch Budmoths -- the first and only terrestrial invertebrate to ever be observed and collected on Vize Island. Their observations are published in the open-access, peer-reviewed journal The scientists first observed live and freshly dead moths on the sandy banks of a pond near the meteorological station. Then, they saw hundreds of them at the sandy bottom of a river valley with shallow streams. Moths, single or in groups, were mostly found at the water's edge, along with some fine floating debris. Despite extremely low daily temperatures (+2-5°C), flying moths were also spotted on several occasions.The larvae of Larch Budmoth feed on the needles of different coniferous trees. Because Vize Island is located 1000 km north of the tree limit, the scientists can be sure about the migratory origin of the moths observed on Vize Island. They were likely transported there on 12-14 July 2020 by strong winds coming from the continent. The nearest potential source population of Larch Budmoth is located in the northern part of the Krasnoyarsk Region, which means they travelled at least 1200 km.Importantly, some moths remained alive and active for at least 20 days after their arrival, which means that long-distance travel did not critically deplete resources stored in their bodies. The current changes in climate are making it easier for more southerly insects to invade species-poor areas in the High Arctic islands -- provided they can reach them and survive there."The successful arrival of a large number of live moths from continental Siberian forests to Vize Island has once more demonstrated the absence of insurmountable barriers to initial colonisation of High Arctic islands by forest insects," concludes Mikhail Kozlov, who has studied Arctic insects for decades. "The Arctic islands will be colonised by forest insects as soon as changing environmental conditions allow the establishment of local populations."
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Geography
| 2,021 |
March 26, 2021
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https://www.sciencedaily.com/releases/2021/03/210326104723.htm
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Climate change significantly increases population displacement risk
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Every year, millions of people around the world are displaced from their homes due to severe weather caused by climate change. According to the International Red Cross and Red Crescent Movement, 10.3 million people were displaced as a result of climate-related events in the last six months alone -- four times the number displaced by war and conflict in the same period. One of the main causes of displacement is flooding. A recent example is the situation in eastern Australia, where tens of thousands of people are having to flee their homes to seek safety from this hundred-year flood.
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An international research team led by the Weather and Climate Risks Group at ETH Zurich has just published a new study aimed at providing a better understanding of future displacement risks due to flooding from rivers overflowing their banks. Their study also evaluates the influence of climate change as well as demographic and socioeconomic factors on these risks.Using a variety of climate, hydrology and population distribution models, the researchers show that if the population remains stable at its current level, the risk of flood-related displacement increases by more than 50 percent (relative to 2010 levels) for each degree of global warming.However, the world's population is growing. Even if this growth continues towards a more sustainable path, the risk of displacement will still increase significantly: assuming that the world meets the Paris Agreement's goal of limiting global warming to a maximum of 2° Celsius, the globally averaged risk is projected to rise by up to 110 percent by the end of this century.However, under "business as usual" climate-change conditions and if the gap between rich and poor continues to widen, the risk is projected to increase even more dramatically. For this scenario, the researchers calculated that the risk of displacement due to flooding would be up to 350 percent higher.According to the study's authors, it is not yet too late to address and manage the risk of flood displacement through spatial and urban planning measures and protective infrastructure such as dams. "Our findings highlight the need for rapid action on both climate mitigation and adaptation agendas in order to reduce future risks, especially to vulnerable populations," says Pui Man Kam, lead author of the study and doctoral student in ETH Professor David N. Bresch's group. "Floods often affect the most socio-economically vulnerable groups, who tend to live in more hazard-prone areas," she explains.To conduct their study, the researchers used a global climate-, hydrology- and inundation-modelling chain to quantify the effect of global warming on displacement risk for both current and projected future population distributions. The study has just been published in the journal "Because floods are a major driver of displacement and due to the fact that they are influenced by climate change, it is imperative that we have a better understanding of how the risks are changing," Kam says.
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Geography
| 2,021 |
March 26, 2021
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https://www.sciencedaily.com/releases/2021/03/210326104656.htm
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Gray's beaked whales 'resilient' to ecosystem changes
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An elusive whale species in the Southern Ocean could be resilient to near-future ecosystem changes, according to a new study by the universities of Exeter and Copenhagen.
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Gray's beaked whales living in the deep oceans of the Southern Hemisphere are rarely seen alive and their ecology has remained a mystery to scientists until now.The study used genome sequencing of 22 whales washed up on beaches in South Africa, Australia and New Zealand to investigate the history of the population over the past 1.1 million years.Author of the study Dr Kirsten Thompson, of the University of Exeter, said: "The population approximately doubled about 250 thousand years ago, coinciding with a period of increased Southern Ocean productivity, sea surface temperature and a potential expansion of suitable habitat."The current population appears to have high levels of genetic diversity and no "genetic structure" (patterns of genetic similarity in geographical areas), suggesting the whales leave their birth groups and move widely throughout their Southern Hemisphere range.Based on these findings, this perfect match of high genetic diversity, a flexible social system and the rich habitats of Southern Hemisphere mean that Gray's beaked whales could be to be resilient to changing conditions."Human activity is causing rapid ecological change in every habitat on Earth, including the deep oceans," said Dr Thompson."We need to understand how different species might respond to these changes, but we lack detailed knowledge on many animals, particularly deep-sea whales like Gray's beaked whales."Observation data on this species is impossible to obtain -- they are small (five metres), deep-diving whales that spend most of their time below the surface searching and feeding on squid -- whalers nicknamed them "scamperdown whales" due to their elusive behaviour.The study used both mitochondrial DNA to investigate the history of the population, and partial nuclear genomes to estimate population structure."Our findings suggest numbers of Gray's beaked whales have been relatively stable for the last 1.1 million years," Dr Thompson said."The Southern Hemisphere's oceans could potentially support a surprisingly large number of Gray's beaked whales. Good news for one species at least."We show how genomic tools can help to reveal past history, current status and potential near-future changes in animal populations that are enigmatic, rarely observed and beyond the reach of traditional boat surveys."
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Geography
| 2,021 |
March 25, 2021
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https://www.sciencedaily.com/releases/2021/03/210325150151.htm
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Changes in ocean chemistry show how sea level affects global carbon cycle
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A new analysis of strontium isotopes in marine sediments has enabled scientists to reconstruct fluctuations in ocean chemistry related to changing climate conditions over the past 35 million years.
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The results, published March 26 in "Strontium is very similar to calcium, so it gets incorporated into the calcium carbonate shells of marine organisms," explained lead author Adina Paytan, research professor in the Institute of Marine Sciences at UC Santa Cruz.Paytan and her coauthors looked at the ratios of different isotopes of strontium, including radiogenic isotopes (produced by radioactive decay) and stable isotopes, which provide complementary information about geochemical processes. They found that the stable isotope ratio of strontium in the ocean has changed considerably over the past 35 million years, and it is still changing today, implying large changes in seawater strontium concentration."It's not in a steady state, so what's coming into the ocean and what's leaving don't match," Paytan said. "The strontium composition of seawater changes depending on how and where carbonates are deposited, and that is influenced by changes in sea level and climate."The fluctuations in strontium isotope ratios analyzed in this study reflect the combined effect of shifts in the global balance of geologic processes including weathering of rocks on land, hydrothermal activity, and the formation of carbonate sediments in both deep-sea and shallow, nearshore marine environments.Carbonate deposition in the open ocean comes from marine plankton like coccolithophores and foraminifera, which build their shells of the calcium carbonate mineral calcite. In shallow water on the continental shelves, hard corals are more abundant, and they build their skeletons of a different mineral of calcium carbonate, aragonite, which incorporates more strontium than calcite does."When corals form, they remove strontium, and when they are exposed, this strontium washes out and goes back into the ocean," Paytan said. "With changes in sea level, more or less of the continental shelf where corals grow is exposed, so that impacts the strontium composition of seawater."Carbonate deposition also feeds back into the climate system, because the ocean absorbs carbon dioxide from the atmosphere, and carbonate deposition on geological timescales removes carbon from the system. The global carbon cycle and atmospheric carbon dioxide are tightly coupled to climate change, both in the long-term and during the recurring ups and downs of recent ice age cycles."The new type of information we can read from the stable strontium isotopes now allows us to take a close look at the business end of the global carbon cycle, when carbon is removed from the environment and laid down into marine carbonate beds," said coauthor Mathis Hain, assistant professor of Earth and planetary sciences at UCSC."These findings throw open a new window to let us see how the global carbon cycle adjusted to sea level and climate change through geologic time," he added. "We will need these insights in guiding our response to our current climate emergency and to mitigate the worst effects of ocean acidification."The researchers were able to reconstruct a robust and detailed record of strontium isotope variations in seawater based on an analysis of marine barite extracted from deep-sea sediment cores."Records like this are critical to understanding how our earth operates over geologic times," said coauthor Elizabeth Griffith at Ohio State University. "Our international team worked together to both create this unique record and explain its significance through mathematical modeling, so we can reconstruct changes in the past when the climate conditions were different. The hope is to gain insight into how our blue planet might operate in the future."In addition to Paytan, Hain, and Griffith, the coauthors of the paper include Anton Eisenhauer and Klaus Wallmann at the GEOMAR Helmholtz Center for Ocean Research in Germany, and Andrew Ridgwell at UC Riverside. This work was supported by the National Science Foundation.
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Geography
| 2,021 |
March 25, 2021
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https://www.sciencedaily.com/releases/2021/03/210325101215.htm
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New insights into close encounters between albatross and fishing vessels
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A novel analysis of encounters between albatross and commercial fishing vessels across the North Pacific Ocean is giving researchers important new understanding about seabird-vessel interactions that could help reduce harmful encounters.
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The new research method, which combines location data from GPS-tagged albatross and commercial fishing vessels, allows researchers to accurately identify bird-vessel encounters and better understand bird behavior, environmental conditions and the characteristics that influence these encounters."It is hard to conceptualize how often birds encounter vessels in the open ocean, but with this new data, it becomes really apparent," said Rachael Orben, an assistant professor in the Department of Fisheries and Wildlife in Oregon State University's College of Agricultural Sciences and the study's lead author. "Some of these birds are in an environment where they see vessels all the time, while others are in an environment where they rarely encounter vessels."The findings were just published in the Albatross are large, long-lived seabirds that roam widely over the open ocean. Three albatross species are found in the North Pacific: the black-footed albatross, the Laysan albatross and the short-tailed albatross. All three species are of high conservation concern and the short-tailed albatross is listed as endangered under the Endangered Species Act.Fishing activity can offer the birds opportunities for foraging, but not without risks, including threat of bycatch. Bycatch is the term for fish, birds or other animals caught unintentionally and includes interactions with fishing vessels and fishing gear.Researchers have been using biologging, the practice of attaching data recording devices to animals, to track individual bird movements at sea for more than 20 years. But they have not had much access to information about the location of vessels, which is a critical piece to understanding the seabird-fishery interaction puzzle, Torres said.Torres learned that Global Fishing Watch was processing and making available data from the Automatic Identification System, or AIS, an automatic tracking system that uses transceivers on ships. The data includes information about vessel size, movement, fishing method and more. Access to the data was a "game-changer," she said."With their data, you can track individual vessels," Torres said. "You can get precise information about a vessel's location, its size, the type of fishing gear it is using and the flag nation of the ship."Global Fishing Watch's goals include making commercial fishing on the high seas more transparent to the public, improving fisheries regulation and ensuring sustainability of ocean resources."This study represents a new frontier in our ability to understand how fisheries impact marine life," said David Kroodsma, director of research and innovation at Global Fishing Watch. "Vessel tracking data, collected by satellites and processed with machine learning, can be a powerful tool to analyze how biodiversity and fishing vessels interact at sea."Members of the research team had previously collected albatross tracking data from adult black-footed albatross and Laysan albatross breeding in the Papah?naumoku?kea Marine National Monument in the Northwest Hawaiian Islands; Laysan albatross nesting on Oahu, Hawaii; and juvenile short-tailed albatross originating from their colonies in Japan.The researchers were able to marry data on fishing vessels with tracking data from the GPS-tagged albatross during the same periods to identify and locate where bird-vessel interactions occur throughout the North Pacific Ocean.When birds are within 30 kilometers of a vessel, the researchers assumed the albatross was aware of the vessel's presence, Orben said. When the bird was within 3 kilometers of the vessel, researchers assumed a close encounter between the two. The research team then modeled the drivers of these close encounters."With these models, we can start to understand why birds sometimes do and sometimes don't interact with a fishing vessel," Torres said. "This information can help identify how and when efforts should be made to make sure these interactions don't go wrong for the bird. As we start to identify patterns, we can potentially help mitigate these bycatch events.""These results indicate that it may be more important to use bycatch mitigation methods from a fishing vessel in low wind conditions," Torres said. "Things like that can help guide efforts to reduce bycatch of seabirds. The best regulations are those that are the least burdensome to fishermen and the most effective."The analysis framework developed by the researchers could be used to study encounters between fishing vessels and other seabirds or marine mammals. Information gathered through the study of these interactions could help inform fisheries management decisions, as well, the researchers said."Our study is really one of the first to look at the fine-scale overlap between fishing vessels and marine animals on the high seas, in international waters," Torres said. "It opens a whole new understanding of the dynamics between animals and vessels. This work can help the fishing community fish better and help these seabirds survive and thrive."
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Geography
| 2,021 |
March 24, 2021
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https://www.sciencedaily.com/releases/2021/03/210324142842.htm
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Greenland caves: Time travel to a warm Arctic
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An international team of scientists presents an analysis of sediments from a cave in northeast Greenland, that cover a time period between about 588,000 to 549,000 years ago. This interval was warmer and wetter than today, the cave deposits provide an outlook in a possible future warmer world due to climate change.
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A 12-centimetre-thick sample of a deposit from a cave in the northeast of Greenland offers unique insights into the High Arctic's climate more than 500,000 years ago. The geologist and cave scientist Prof. Gina Moseley collected it during an exploratory expedition in 2015 for her palaeoclimatic research in one of the most sensitive areas of the world to climate change. The cave is located at 80° North 35 km from the coast and 60 km from the Greenland Ice Sheet margin. It was part of the Greenland Caves Project, funded by 59 different sponsors including the National Geographic Society. Moseley and her team are interested in the climate and environmental history captured by the unique cave deposit."Mineral deposits formed in caves, collectively called speleothems, include stalagmites and stalactites. In this case we analysed a flowstone, which forms sheet-like deposits from a thin water film," explains Moseley. It is very special to find a deposit of this kind in the High Arctic at all, the geologist continues: "Today this region is a polar desert and the ground is frozen due to permafrost. In order for this flowstone to form, the climate during this period must have been warmer and wetter than today. The period between about 588,000 to 549,000 years before present is generally considered to be globally cool in comparison to the present. The growth of the speleothem at this time, however, shows that the Arctic was surprisingly warm."Gina Moseley therefore highlights the regional heterogeneities that need to be considered when researching climate change especially for future developments in a warmer world. "Our results of a warmer and wetter Arctic support modelling results showing that regional heterogeneities existed and that the Arctic was anomalously warm as a consequence of the Earth's orbital relationship to the sun at the time. Associated with these warmer temperatures was a reduction of the extent of sea ice in the Arctic, thus providing open ice-free waters from which moisture could be evaporated and transported to northeast Greenland," adds the geologist from the University of Innsbruck. The speleothem palaeoclimate record offers the possibility to extend the knowledge of Greenland's past climate and hydrological conditions beyond the 128,000-year-limit of the deep Greenland ice cores. The team used state-of-the-art methods such as uranium-thorium dating which is able to enlarge the timeline much further back. "Since the Greenland ice cores are biased towards the last glacial period and therefore cold climates, the speleothem record provides a nice counter-balance with respect to past warm periods," Moseley says. "The Arctic is warming at more than twice the rate of the global average. Understanding more about how this sensitive part of the world responds in a warmer world is very important."Gina Moseley identified the importance of the caves in northeast Greenland back in 2008 while doing her PhD in Bristol, UK. In 2015, she led a five-person expedition funded by many different sponsors. The expedition was a challenge: The team first tried to fly as far as possible, then crossed a 20-kilometre-wide lake in a rubber boat and then had to hike for three days to get to the caves. This was the first time such climate records had been made from caves in the High Arctic and Gina Moseley was awarded the START Prize from the Austrian Science Fund (FWF) for her research, which enabled her to start a new six-year research project. In July 2019, Moseley and her Greenland Caves Project team returned to northeast Greenland for a three-week expedition.
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Geography
| 2,021 |
March 23, 2021
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https://www.sciencedaily.com/releases/2021/03/210323131253.htm
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The same sea level for everyone
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Maps generally indicate elevation in meters above sea level. But sea level is not the same everywhere. A group of experts headed by the Technical University of Munich (TUM), has developed an International Height Reference System (IHRS) that will unify geodetic measurements worldwide.
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How high is Mount Everest? 8848 meters? 8844 meters? Or 8850 meters? For years, China and Nepal could not agree. In 2019, Nepal sent a team of geodesists to measure the world's highest mountain. A year later a team from China climbed the peak. Last December the two governments jointly announced the outcome of the new measurement: 8848.86 meters.The fact that both China and Nepal recognize this result must be seen as a diplomatic success. It was made possible by the new International Height Reference System (IHRS), used for the first time by the geodetic specialists conducting the new measurement. Scientists from TUM played a leading role in developing the new system. It establishes a generally agreed zero level as a basis for all future measurements. It thus replaces the mean sea level, which has traditionally served as the zero level for surveyors and thus for all topographical maps. A paper in the The standard used until now -- the mean sea level -- was flawed from the outset: There was never a fixed definition. Every country could use arbitrary tide gauges to define its own zero level. As a result, Germany's official sea level is 31 centimeters higher than Italy's, 50 cm higher than that used in Spain and actually 2.33 m higher than in Belgium, where the zero height is based on low water in Ostend.When topographical maps are only used for hiking, no one is bothered by such differences. But for geodetics specialists trying to arrive at a universally agreed height -- for Mount Everest, for example, half in Nepal and half in China -- the inconsistent zero levels are a bigger problem. And it can be very costly when planners of cross-border structures such as bridges and tunnels forget to check the different coordinates used by the teams and convert them as needed. On the Hochrheinbrücke, a bridge connecting Germany and Switzerland, a discrepancy of this kind was noticed just in time."The introduction of an internationally valid height reference system was long overdue," says TUM researcher Dr. Laura Sánchez of the Deutsches Geodätisches Forschungsinstitut (DGFI-TUM), who has headed working groups studying theoretical aspects and implementing the new global height reference system at the International Association of Geodesy for several years.What is needed is obvious: a universally accepted zero level. The new International Height Reference System (IHRS) defines how it can be calculated: It takes into account the shape of the Earth -- which is close to spherical, but flattened at the poles and bulging slightly at the equator due to its rotation -- and the uneven distribution of masses in the interior and on the surface. The resulting irregularities in the gravity field are the basis for calculating the height system because the strength and direction of the force determine the distribution of water in the oceans. If we assume that the Earth's surface is completely covered with water, the height of a hypothetical sea level and thus the zero level for the entire globe can be calculated precisely."It became possible to realize the IHRS only with the availability of global data from satellite missions such as the ESA earth observation satellite GOCE (Gravity field and steady-state Ocean Circulation Explorer)," says Prof. Roland Pail of the TUM Chair of Astronomical and Physical Geodesy (APG). His team played an integral role in analyzing the GOCE measurements and using them to calculate global models of the Earth's gravity field. "The information gained in this way provides the basis to calculate the mean sea level for every point on Earth with the new International Height Reference System, regardless of whether it is on a continent or in an ocean, and thus to compute the internationally accepted zero level," explains Sánchez.Does every map have to be redrawn? "It won't be that dramatic," says Sánchez. "In the industrial countries, where they have been making gravity measurements for decades, the deviations are quite small -- only in the decimeter range." But with construction projects, for example, even small deviations can cause serious troubles. Consequently, the scientist is confident that the new reference system will gain acceptance quickly.
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Geography
| 2,021 |
March 23, 2021
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https://www.sciencedaily.com/releases/2021/03/210323090556.htm
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These baby great white sharks love to hang out near New York
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Uncovering detailed travel patterns and habitat use of sharks along and across shelf territories has been historically challenging -- especially for most pelagic shark species -- which remain offshore for most of their lives. Their vertical diving behavior has been a subject of inquiry for a long time, and for young sharks in particular, has remained elusive.
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Using cutting-edge 3D satellite technology, a study led by Florida Atlantic University's Harbor Branch Oceanographic Institute, in collaboration with NOAA's National Marine Fisheries Service; OCEARCH; The South Fork Natural History Museum and Nature Center; and the Wildlife Conservation Society, is providing a unique look into how young white sharks in the North Atlantic Ocean travel and use their habitats. The study also is the first to provide fine-scale analysis of vertical movement behavior in young-of-year (1 to 2 years) and juvenile white sharks (Carcharodon carcharias) in the New York Bight, the only confirmed white shark nursery area in the entire North Atlantic Ocean.Results published in the journal Data from the study simultaneously address many questions on the ecology, behavior and conservation of a highly mobile marine species that has been challenging to explore, and will inform ongoing preservation strategies for this vulnerable white shark population."We have known about the importance of nurseries for young sharks for some time, however, knowledge of the finer scale use of shelf systems by these animals has been limited. This lack of information impacts our understanding of potential shark 'hotspots' within these large ecosystems," said Rachel Shaw, lead author, and a recent graduate from the Fisheries Ecology and Conservation (FEC) Lab, led by Matt Ajemian, Ph.D., co-author and an assistant research professor at FAU Harbor Branch.Between 2016 and 2019, 21 young-of-year and juvenile white sharks were fitted with satellite and acoustic tags to examine their distribution and habitat selection during late summertime (August to October) in the New York Bight -- the coastal region between Montauk, New York and Cape May, New Jersey. Movement data from the 21 young white sharks were collected (11 males and 10 females ranging in size from 54 to 61 inches in length) and linked to environmental measurements from remote sensing platforms.These data sets produced the first-ever glimpse into the 3D movements for these young white sharks alongside oceanographic features like bathymetry (submarine topography), sea surface temperature, chlorophyll-a levels, and sea surface salinity."Undoubtedly, our research shows that young white sharks traverse variable oceanographic features across the continental shelf in the New York Bight, but they certainly have their habitat preferences," said Shaw.The vertical diving behavior and accompanying measurements showed that sharks encountered several areas across the shelf with thermally stratified water column structure. This was most evident around the Hudson Shelf Valley region where some of the coldest bottom temperatures were recorded during the summertime, and is indicative of the "cold pool" that sets up in this region. Further, young white sharks also selected areas with relatively high levels of productivity (i.e., mesotrophic waters) as reflected by salinity and chlorophyll-a concentration. Tagged individuals selected sea surface salinities slightly less saline than oceanic waters, which are typically associated with coastal areas.Altogether, the research suggests young white sharks prefer nearshore habitats, but can exhibit connectivity between the immediate shoreline and mid-continental shelf region, where they play important ecological roles as apex predators on a variety of species. The study improves characterization of essential habitat for young white sharks and provides new insights into their reliance on this productive continental shelf ecosystem, which may provide them with the resources needed to grow quickly as well as a refuge from predators."While the northwest Atlantic white shark population appears to be recovering from historical overfishing, there is considerable uncertainty in their population dynamics, seasonal habitat preferences, ecological roles, and exposure to environmental impacts," said Ajemian. "Understanding species-habitat relationships is critical for predicting the potential impacts of long-term environmental changes including climate change, which is disproportionately affecting this region."
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Geography
| 2,021 |
March 22, 2021
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https://www.sciencedaily.com/releases/2021/03/210322135221.htm
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Arctic methane release due to melting ice is likely to happen again
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Beneath the cold, dark depths of the Arctic ocean sit vast reserves of methane. These stores rest in a delicate balance, stable as a solid called methane hydrates, at very specific pressures and temperatures. If that balance gets tipped, the methane can get released into the water above and eventually make its way to the atmosphere. In its gaseous form, methane is one of the most potent greenhouse gases, warming the Earth about 30 times more efficiently than carbon dioxide. Understanding possible sources of atmospheric methane is critical for accurately predicting future climate change.
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In the Arctic Ocean today, ice sheets exert pressure on the ground below them. That pressure diffuses all the way to the seafloor, controlling the precarious stability in seafloor sediments. But what happens when the ice sheets melt?New research, published on today in Geology, indicates that during the last two global periods of sea-ice melt, the decrease in pressure triggered methane release from buried reserves. Their results demonstrate that as Arctic ice, such as the Greenland ice sheet, melts, similar methane release is likely and should be included in climate models.Pierre-Antoine Dessandier, a postdoctoral scientist at the Arctic University of Norway, and his co-authors were interested in two periods around 20 thousand years ago (ka), known as the Last Glacial Maximum (LGM), and 130 ka, known as the Eemian deglaciation. Because the Eemian had less ice and was warmer than the LGM, it is more similar to what the Arctic is experiencing today, serving as a good analogue for future climate change."The oldest episode recorded (Eemian) is very important because it was a strong interglacial in the Arctic, with very similar climate characteristics to what is happening today," Dessandier said. "The idea with the Eemian interglacial is to... compare that with what could happen in the future. Seafloor methane emission is important to consider for modeling spatial estimations of future climate."To track past methane release, Dessandier measured isotopes of carbon (carbon molecules with slightly different compositions) in the shells of tiny ocean-dwellers called foraminifera. Because the foraminifera build their shells using ingredients from the water around them, the carbon signal in the shells reflects the chemistry of the ocean while they were alive. After they die, those shells are preserved in seafloor sediments, slowly building a record spanning tens of thousands of years.To reach that record, Dessandier and the team needed to drill a deep core off the western coast of Svalbard, a Norwegian archipelago in the Arctic Ocean. The team collected two cores: a 60-meter reference core, which they used to date and correlate stratigraphy, and a 22-meter core spanning the LGM and the Eemian deglaciations. The site for the 22-meter core was chosen based on its "pockmark" feature, marking where the gas escaped violently in the past, and massive carbonate rocks that form where methane is still leaking out today.Carbon isotopes of microscopic shells in the long core revealed multiple episodes of methane release, which geochemists recognize from their distinct spikes in the record. Because methane is still seeping from the sediments, Dessandier needed to to make sure the signal wasn't from modern interference. He compared the shells' carbon isotope values to measurements his colleagues made on carbonate minerals that formed outside the shells, after the foraminifera had died, when methane emission was at its most intense.The isotopic record showed that as ice melted and pressure on the seafloor lessened, methane was released in violent spurts, slow seeps, or -- most likely -- a combination of both. By the time the ice disappeared completely, some thousands of years later, methane emissions had stabilized.How much methane eventually made it to the atmosphere, which is what would contribute to the greenhouse effect, remains uncertain. Part of the problem in quantifying this is the microbial communities that live on the seafloor and in the water, and that use methane to survive."For the microbes, it's an oasis. It's fantastic," Dessandier said. "So they grow like crazy, and some species produce methane and others consume it." That activity complicates the core's detailed carbon record. In sediments, a bustling community with lots of methane recycling could overprint the original signal; in the water column, where nutrients may be less plentiful, methane could get gobbled up or transformed into carbon dioxide before it reaches the atmosphere.Despite modern complications, the team has pinpointed two methane releases associated with ice retreat, like they hypothesize could happen today. The best part for Dessandier was discovering layers of massive bivalves in the cores which, based on modern observations from remotely operated vehicles, can indicate a methane leak. "It was super interesting for us to observe these same sorts of layers at the LGM and the Eemian," he said. "It confirmed what we thought at the beginning, with a methane-rich seafloor allowing this community to develop... We can say that these events are very similar, with similar processes happening during both periods of warming. So this is something to consider for our current warming. It could happen again."
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Geography
| 2,021 |
March 18, 2021
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https://www.sciencedaily.com/releases/2021/03/210318142440.htm
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How bushfire smoke traveled around the world
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It's not just how hot the fires burn -- it's also where they burn that matters. During the recent extreme fire season in Australia, which began in 2019 and burned into 2020, millions of tons of smoke particles were released into the atmosphere. Most of those particles followed a typical pattern, settling to the ground after a day or week; yet the ones created in fires burning in one corner of the country managed to blanket the entire Southern hemisphere for months. A pair of Israeli scientists managed to track puzzling January and February 2020 spikes in a measure of particle-laden haze to those fires, and then, in a paper recently published in
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Particles reaching the stratosphere -- the upper layer of the atmosphere -- most often get there through volcanic eruptions. The ash emitted in the more extreme eruptions dims the sun and cools the planet, as well as producing spectacular sunsets. Prof. Ilan Koren of the Weizmann Institute of Science's Earth and Planetary Science Department, who conducted the study together with his former student, Dr. Eitan Hirsch, now the Head of the Environmental Sciences Division at the Israel Institute for Biological Research in Ness Tziona, had noticed an extreme increase in a satellite-based measure of particle loading in the atmosphere called AOD -- or aerosol optical depth. In January 2020, those measurements, plotted in standard deviations, showed a deviation three times the normal -- some of the highest readings ever obtained, higher even than those from Mt. Pinatubo in 1991. But the timing did not coincide with any volcanic activity. They wondered if fires might be to blame, even though it is rare for the smoke from fires to escape the lower layer of atmosphere known as the troposphere in significant amounts. The troposphere extends from the ground to a height of several kilometers, and if smoke particles manage to rise that high, they hit an inversion layer called the tropopause that acts as a sort of ceiling between the troposphere and the stratosphere.Working backwards and using data from several satellites, including, in addition to AOD, LIDAR readings that revealed how the particles were distributed vertically in "slices" of atmosphere, the two were able to prove that the source of the spikes was bushfires -- specifically those burning in Southeastern Australia. Further analysis of satellite data revealed the broad band of haze in the stratosphere spreading to cover the Southern hemisphere, peaking from January to March and persisting through July; reaching all the way around and back to Australia's west coast.How did these smoke particles penetrate through the tropopause ceiling and why did they come from these fires and not the others? One clue, says Hirsch, lay in another, distant forest fire that had occurred several years ago in Canada. Then, too, high AOD levels had been recorded. Both of these fires occurred in high latitudes, away from the equator.The height of the troposphere shrinks at these latitudes: Over the tropics its upper ceiling can reach up to 18 km above the surface, while somewhere above the 45th parallel -- North and South, it takes a sudden step down to around 8-10 km in height. So the first element enabling the particles' trans-layer flight was simply having less atmosphere to cross.Pyrocumulus clouds -- clouds fueled by the fires' energy -- were considered as a means of transporting smoke to the stratosphere. However, when inspecting the satellite data, Hirsch and Koren noticed that pyrocumulus clouds formed only over a small fraction of the fires' duration, and they were mostly seen over fires burning on the central part of the coast. In other words, these clouds could not explain the large amounts found to be transported to the stratosphere, and an additional mechanism for lifting smoke downwind from the sources was missing.This brings up the second element: the weather patterns in the strip known as the mid-latitude cyclone belt that runs through the southern end of Australia, one of the stormiest regions on the planet. The smoke was first advected (moved horizontally) by the prevailing winds in the lower atmosphere to the Pacific Ocean, and then some of it converged into the deep convective clouds there and was lifted in the clouds' core into the stratosphere. An interesting feedback mechanism known as "cloud invigoration by aerosols" can further deepen the clouds. In a previous study, the authors had shown that in conditions such as the pristine environment over the Southern Ocean, the convective clouds are "aerosol limited." The elevated smoke levels could thus act as cloud condensation nuclei, allowing the clouds to develop deeper and thus increasing the number of clouds that able to penetrate the tropopause and inject the smoke in the stratosphere.Up in the stratosphere, the particles found themselves in a different world than the one they had just left. If below they were at the mercy of mixing and churning air currents, up on top the air moves in a steady, linear fashion. That is, there was one strong current, and it was moving them eastwards over the ocean to South America and back over the Indian Ocean toward Australia, and slowly settling around the entire hemisphere. "People in Chile were breathing particles from the Australian fires," says Hirsch. By sailing on an endless air current, these particles remained airborne for much longer than lower atmosphere smoke particles."For people on the ground, the air may have just seemed a bit hazier or the sunsets a bit redder. But such a high AOD -- much, much higher than normal -- means sunlight was getting blocked, just as it does after volcanic eruptions," says Koren. "So the ultimate effect of that smoke on the atmosphere was cooling, though we still do not know how much influence that cooling and dimming may have had on the marine environment or weather patterns."There are always fires burning in California, in Australia and in the tropics," he adds. "We might not be able to stop all of the burning, but we do need an understanding that the precise locations of those fires may grant them very different effects on our atmosphere."Prof. Ilan Koren's research is supported by the de Botton Center for Marine Science; the Sussman Family Center for the Study of Environmental Sciences; the Dr. Scholl Foundation Center for Water and Climate Research; the Ben May Center for Chemical Theory and Computation; Scott Eric Jordan; the Yotam Project; the estate of Emile Mimran; and the European Research Council. Prof. Koren is the incumbent of the Beck / Lebovic Chair for Research in Climate Change.Video:
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Geography
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March 18, 2021
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https://www.sciencedaily.com/releases/2021/03/210318142434.htm
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Twice as much carbon flowing from land to ocean than previously thought
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Every year 600-900 million tons of carbon flow through rivers to the ocean either as particles or in dissolved form. Researchers have known for a long time that this does not represent the total amount of carbon that gets transported from the land to the ocean. But the remaining contributors mostly from coastal ecosystems, such as carbon-rich mangrove forests, and from groundwater discharge into the ocean have been notoriously difficult to measure.
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A new study published in the journal By using oceanic observations of δAfter accounting for these effects, the authors were up for a surprise: they found much higher numbers for the land to ocean carbon transfer of 900-1900 million tons per year. Most of non-riverine carbon inputs of about 300-1300 million tons of carbon per year occur mostly along the coastlines of the Indian and Pacific Oceans. "This is consistent with the idea that groundwater discharge and coastal ecosystems, the so-called blue carbon, play a fundamental role in the global carbon cycle" says Dr. Kwon.One of the remaining open questions is which oceanic processes are responsible for carrying the dissolved carbon from the coastal zones to the open ocean, where part of it outgases back to the atmosphere. "This question will be addressed in future with a series of new earth system model simulations that we just conducted on our supercomputer Aleph," says Axel Timmermann, co-author of the study and Director of the IBS Center for Climate Physics.
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Geography
| 2,021 |
March 18, 2021
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https://www.sciencedaily.com/releases/2021/03/210318122527.htm
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What is the probability of ships becoming beset in ice in Arctic waters?
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Statisticians have calculated the probability of ships of different Polar Ship Categories becoming beset in ice along the Northern Sea Route. Their data will help assess the risks of maritime traffic in the Arctic.
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The results of the new study, published recently in the The Northern Sea Route is attracting more tankers and cargo ships travelling from Russia and Asia to Europe, and traffic is expected to increase along the route in tandem with global warming.In the winter, the sea is frozen over, making it inaccessible to ships of a lower Polar Ship Category without the assistance of an icebreaker. Ships can also become beset in ice in the spring and summer, leading to transport delays. At its worst, ice may force a vessel off its course so that it runs aground, with disastrous consequences."This is the first time a comprehensive risk assessment of a besetting event was performed using open data only," says Assistant Professor of Statistics Jarno Vanhatalo, head of the Environmental and Ecological Statistics group and director of the Master's Programme in Life Science Informatics at the University of Helsinki.The researchers used satellite data on ice conditions in Arctic marine areas as well as open data sources on shipping."One of the biggest tasks required the merger of open datasets so that analyses could be conducted. This task was performed by Aalto University. The statistical analyses were carried out at the University of Helsinki, using a traditional generalised linear model, to which a Bayesian approach was applied," Vanhatalo explains."If we know the ice conditions prevailing in a specific area, which can usually be ascertained from satellite images, we can make a prediction for, say, today and for each point along the Northern Sea Route," states Vanhatalo. The prediction indicates the probability of a ship of a particular type becoming beset in ice in a particular area.The Polar Ship Category of a ship has a crucial impact on the probability of besetting. Ships of a lower category are most at risk, and many of them become beset in ice each year.The researchers also analysed the effect of ice concentration on the probability of besetting. Ice concentration indicates the share of the sea covered by ice. In the winter, ice concentration is 100%, whereas in the spring and summer it varies from 0% to 100%, which means that the marine area is a mosaic of ice floes and open water.The probability of a ship becoming beset in ice increases the longer the distance it travels in ice-covered waters and also increases significantly with higher ice concentrations. There are also considerable differences between ships of different Polar Ship Categories. For the best vessels, i.e., Category A ships, the probability of besetting on a journey of 3,000 nautical miles (NM) in 90%-100% ice concentration is just 0.04. Correspondingly, the probability for Category B ships is 7.5 times higher, or 0.3, whereas the probability for Category C ships is 22.5 times higher, or 0.9.The newly published study is part of an international long-term research project funded by the Lloyd's Register Foundation and aimed at improving maritime safety. Launched in 2003, the project will conclude at the end of 2021. Participants in the CEARCTIC and CEPOLAR projects, headed by Aalto University, include not only the University of Helsinki, but also the Norwegian University of Science and Technology (NTNU), the Memorial University of Newfoundland in Canada, and the Hamburg University of Technology in Germany.The University of Helsinki researchers have been responsible for assessing the impact of a potential oil spill on the Arctic environment and biotic communities. Previous publications have focused on species of organisms in the Kara Sea and the effects of an oil spill in the area.Although the research project is coming to a close, before the end of this year it will publish more statistical analyses of uncertainties associated with the modelling."Due to the limited measurement data available from Arctic marine areas, there are major uncertainties concerning shipping, living organisms and the behaviour of oil. Another major uncertainty relates to the natural stochasticity of highly unstable environmental conditions," Vanhatalo adds.Another article currently being written explores the relative significances of factors affecting the overall risk as well as how risk analyses should be carried out and how the conclusions drawn differ depending on what is examined. Does the examination focus solely on the accident risk of vessels or also on the risk they pose to marine biotic communities? The results depend on whether both are examined separately or at the same time.Other upcoming publications include summarising reports on the project as a whole and recommendations based on the research conducted.
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Geography
| 2,021 |
March 18, 2021
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https://www.sciencedaily.com/releases/2021/03/210318085607.htm
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Four lichen species new to science discovered in Kenyan cloud forests
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Researchers from the University of Helsinki's Finnish Museum of Natural History Luomus and the National Museums of Kenya have discovered four lichen species new to science in the rainforests of the Taita Hills in southeast Kenya.
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"Species that belong to the Micarea genus are known all over the world, including Finland. However, the Micarea species recently described from the Taita Hills have not been seen anywhere else. They are not known even in the relatively close islands of Madagascar or Réunion, where species of the genus have been previously studied," Postdoctoral Researcher Annina Kantelinen from the Finnish Museum of Natural History says."The Taita Hills cloud forests are quite an isolated ecosystem, and at least some of the species now discovered may be native to the area or to eastern Africa. Our preliminary findings also suggest that there are more unknown Micarea lichen species there."The Taita Hills are part of the Eastern Arc Mountains that range from south-eastern Kenya to eastern Tanzania. The mountains rise abruptly from the surrounding plain, with the tallest peak reaching over two kilometers. Lush indigenous rainforests are mainly found on the mountaintops, capturing precipitation from clouds and mist developed by the relatively cool air rising from the Indian Ocean.Thanks to ecological isolation and a favourable climate, the area is one of the global hotspots of biodiversity. However, the native cloud forests in the region are shrinking year by year as they are replaced by forest plantations of exotic tree species that are not native to Africa. Compared to 1955, the area of indigenous forests has been diminished to less than half."Planted forests have been found to bind less moisture and be more susceptible to forest fires. Therefore, they can make the local ecosystem drier and result in species becoming endangered. Some lichen species are capable of utilising cultivated forests at least temporarily, but indigenous forests have the greatest biodiversity and biomass," Kantelinen says.The University of Helsinki maintains in the area the Taita Research Station, which is celebrating its tenth anniversary this year.
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Geography
| 2,021 |
March 17, 2021
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https://www.sciencedaily.com/releases/2021/03/210317155151.htm
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Algae growing on dead coral could paint a falsely rosy portrait of reef health
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Algae colonizing dead coral are upending scientists' ability to accurately assess the health of a coral reef community, according to new work from a team of marine science experts led by Carnegie's Manoela Romanó de Orte and Ken Caldeira. Their findings are published in
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Corals are marine invertebrates that build tiny exoskeletons, which accumulate to form giant coral reefs. Widely appreciated for their beauty, these reefs are havens for biodiversity and crucial for the economies of many coastal communities. But they are endangered by ocean warming, seawater acidification, extreme storms, pollution, and overfishing.Coral reefs use calcium carbonate to construct their architecture, a process called calcification. For a reef to be healthy, its coral's building activities must exceed erosion, a natural phenomenon that is exacerbated by all the environmental stresses to which human activity is exposing them."Coral reefs are dealing with so many simultaneous threats, many of which directly inhibit their ability to grow at a sustainable rate," Caldeira explained. "If they can't maintain a slow but steady amount of growth, they could get knocked out by rising sea levels in the coming years."However, Romanó de Orte and Caldeira's research -- with former Carnegie colleagues David Koweek (now at Ocean Visions), Yuichiro Takeshita (now at the Monterey Bay Aquarium Research Institute), and Rebecca Albright (now at the California Academy of Sciences) -- showed that if researchers only make measurements to assess coral health during the daytime, it could lead to false sense of security.Why?Because dead coral is often colonized by algal communities that can also accumulate carbonate minerals during the day. However, most of these deposits dissolve overnight, so the carbonate minerals do not accumulate over time. In contrast, living corals, , which have evolved to build massive carbonate reefs visible from space, can continue to build their skeletons, albeit slowly, even at night."It's long been thought that measuring calcium carbonate production could be linked directly to the health of a coral community," Romanó de Orte said. "But our findings show that as algae increasingly succeed in overgrowing dead coral, it is going to be more difficult to rely on a once tried-and-true method for assessing whether a reef community is thriving."To gain this critical understanding, the research team -- which also included Tyler Cyronak of Nova Southeastern University, Alyssa Griffin of the Scripps Institution of Oceanography, Kennedy Wolfe of the University of Queensland, and Alina Szmant and Robert Whitehead of University of North Carolina Wilmington -- deployed specially designed, state-of-the-art incubator technology to closely monitor both coral and colonizing algae in an area of Australia's Great Barrier Reef that had been heavily damaged by two tropical cyclones in 2014 and 2015. They were able to monitor both calcification and dissolution of carbonate minerals, as well as the organisms' metabolic activity."This amazing tool allowed us to home in on the specific role that each organism has in an ecosystem's total output, which gives us new insights into how reefs are changing" Romanó de Orte explained.
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Geography
| 2,021 |
March 17, 2021
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https://www.sciencedaily.com/releases/2021/03/210317141645.htm
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Ocean areas that, if strongly protected, would help solve climate, food and biodiversity crises
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From climate change and carbon emissions to biodiversity and global hunger, humanity faces so many challenges that tackling them quickly is a daunting task. One solution that potentially addresses multiple issues could provide the impetus society needs to make significant progress.
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An international team of 26 authors, including six at UC Santa Barbara, has just published a study in the prestigious journal The researchers identified specific areas of the ocean that could provide multiple benefits if protected. Safeguarding these regions would protect nearly 80% of marine species, increase fishing catches by more than 8 million metric tons and prevent the release of more than one billion tons of carbon dioxide by protecting the seafloor from bottom trawling, a widespread yet destructive fishing practice.The study is also the first to quantify the potential release of CO"Ocean life has been declining worldwide because of overfishing, habitat destruction and climate change. Yet only 7% of the ocean is currently under some kind of protection," said the study's lead author Enric Sala, an explorer in residence at the National Geographic Society."In this study, we've pioneered a new way to identify the places that -- if protected -- will boost food production and safeguard marine life, all while reducing carbon emissions," Sala said. "It's clear that humanity and the economy will benefit from a healthier ocean. And we can realize those benefits quickly if countries work together to protect at least 30% of the ocean by 2030."To identify the priority areas, the authors -- leading marine biologists, climate experts and economists -- analyzed the world's unprotected ocean waters. They focused on the degree to which they are threatened by human activities that can be reduced by marine protected areas (for example, overfishing and habitat destruction).They then developed an algorithm to identify where protections would deliver the greatest benefits across the three complementary goals of biodiversity protection, seafood production and climate mitigation. They mapped these locations to create a practical "blueprint" that governments can use as they implement their commitments to protect nature."While we consider three key benefits that marine protection is known to confer, this is really just the beginning," said co-author Darcy Bradley(link is external), co-director of the Ocean and Fisheries Program at UC Santa Barbara's Environmental Market Solutions Lab (emLab). "Our approach is a way to bring multiple stakeholders to the table, to show that their interests can be prioritized, and ultimately to demonstrate that solutions that protect large ocean areas and benefit multiple simultaneous objectives exist."The study does not provide a single map for ocean conservation, but it offers a first-in-kind framework for countries to decide which areas to protect depending on their national priorities. However, the analysis supports the claim that 30% is the minimum amount of ocean that the world must protect in order to provide multiple benefits to humanity."There is no single best solution to save marine life and obtain these other benefits. The solution depends on what society -- or a given country -- cares about, and our study provides a new way to integrate these preferences and find effective conservation strategies," said coauthor Juan Mayorga(link is external), a marine scientist at emLab as well as National Geographic Society's Pristine Seas.The study comes ahead of the 15th Conference of the Parties to the United Nations Convention on Biological Diversity, which will gather in May in Kunming, China. The meeting will bring together representatives of 190 countries to finalize an agreement to end the world's biodiversity crisis. The goal of protecting 30% of the planet's land and ocean by 2030 (the "30x30" target) is expected to be a pillar of the treaty. The report follows commitments by the United States, the United Kingdom, Canada, the European Commission and others to achieve this target on national and global scales."Solutions with multiple benefits are attractive to people and leaders alike," said coauthor Jane Lubchenco, a university distinguished professor at Oregon State University. "Our pioneering approach allows them to pinpoint the places that, if protected, will contribute significantly to three big problems at once: food security, climate change, and biodiversity loss. Our breakthrough in methodology can bring multiple benefits to nature and people."The report identifies highly diverse marine areas in which species and ecosystems face the greatest threats from human activities. Establishing marine protected areas with strict regulations in those places would safeguard more than 80% of the ranges of endangered species, up from a current coverage of less than 2%. The authors found that priority locations lie throughout the ocean, with the vast majority of them contained within the 200-mile Exclusive Economic Zones (EEZs) of coastal nations.Additional protection targets are located in the high seas -- those waters governed by international law. These include the Mid-Atlantic Ridge (a massive underwater mountain range); the Mascarene Plateau in the Indian Ocean; the Nazca Ridge off the west coast of South America; and the Southwest Indian Ridge, between Africa and Antarctica."Perhaps the most impressive and encouraging result is the enormous gain we can obtain for biodiversity conservation with only 21% of the ocean being protected, if we carefully chose the location of strictly protected marine areas," said coauthor David Mouillot, a professor at the Université de Montpellier in France. "One notable priority for conservation is Antarctica, which currently has little protection, but is projected to host many vulnerable species in a near future due to climate change."The study finds that wisely placed marine protected areas (MPAs) that ban fishing would actually boost the production of fish at a time when supplies of wild-caught fish are dwindling and demand is rising. In doing so, the study refutes a long-held view that ocean protection harms fisheries. Instead, it opens up new opportunities to revive the industry just as it is suffering from a recession due to overfishing and the impacts of global warming."Some argue that closing areas to fishing hurts fishing interests. But the worst enemy of successful fisheries is overfishing, not protected areas," said lead author Sala. The study finds that protecting the right places could increase the catch of seafood by over 8 million metric tons relative to business as usual."It's simple: When overfishing and other damaging activities cease, marine life bounces back," said co-author Reniel Cabral(link is external), an assistant researcher at UC Santa Barbara's Marine Science Institute and in its Bren School of Environmental Science & Management. "After protections are put in place, the diversity and abundance of marine life increase over time, with measurable recovery within reserves occurring in as little as three years. Target species and large predators come back, and entire ecosystems are restored within MPAs. With time, the ocean can heal itself and again provide services to humankind."The study is also the first to calculate the climate impacts of bottom trawling, a damaging fishing method used worldwide in which boats drag heavy nets across the ocean floor. The researchers found that the amount of CO"The ocean floor is the world's largest carbon storehouse. If we're to succeed in stopping global warming, we must leave the carbon-rich seabed undisturbed," said coauthor Trisha Atwood of Utah State University. "Yet every day, we are trawling the seafloor, depleting its biodiversity and mobilizing millennia-old carbon and thus exacerbating climate change. Our findings about the climate impacts of bottom trawling will make the activities on the ocean's seabed hard to ignore in climate plans going forward."The study finds that countries with large national waters and large industrial bottom trawl fisheries have the highest potential to contribute to climate change mitigation via protection of carbon stocks. The authors estimate that protecting only 4% of the ocean -- mostly within national waters -- would eliminate 90% of the present risk of carbon disturbance due to bottom trawling.The study's range of findings helps to close a gap in our knowledge about the impacts of ocean conservation, which to date had been understudied relative to land-based conservation."The ocean covers 70% of the Earth; yet, until now, its importance for solving the challenges of our time has been overlooked," said coauthor Boris Worm, Killam Research Professor at Dalhousie University in Halifax, Nova Scotia. "Smart ocean protection will help to provide cheap natural climate solutions, make seafood more abundant and safeguard imperiled marine species -- all at the same time."The benefits are clear," he continued. "If we want to solve the three most pressing challenges of our century -- biodiversity loss, climate change and food shortages -- we must protect our ocean."
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Geography
| 2,021 |
March 17, 2021
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https://www.sciencedaily.com/releases/2021/03/210317111738.htm
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Modeling the probability of methane hydrate deposits on the seafloor
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Methane hydrate, an ice-like material made of compressed natural gas, burns when lit and can be found in some regions of the seafloor and in Arctic permafrost.
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Thought to be the world's largest source of natural gas, methane hydrate is a potential fuel source, and if it "melts" and methane gas is released into the atmosphere, it is a potent greenhouse gas. For these reasons, knowing where methane hydrate might be located, and how much is likely there, is important.A team of researchers from Sandia National Laboratories and the U.S. Naval Research Laboratory have developed a new system to model the likelihood of finding methane hydrate and methane gas that was tested in a region of seafloor off the coast of North Carolina.While methane hydrate deposits have been found in a variety of locations, there are significant unknowns in terms of how much methane hydrate exists on the seafloor and where. It is challenging to collect samples from the seafloor to find methane hydrate deposits. This is where Sandia's computer modeling expertise comes in."This is the first time someone has been able to approach methane hydrate distribution in the same way we approach weather forecasting," said Jennifer Frederick, a computational geoscientist and lead researcher on the project. "When you hear a weather forecast for a 60% chance of two inches of rain, you don't necessarily expect exactly two inches. You understand that there is uncertainty in that forecast, but it is still quite useful. In most places on the seafloor we don't have enough information to produce an exact answer, but we still need to know something about methane and its distribution. By using a probabilistic approach, similar to modern weather forecasting, we can provide useful answers."The new system combines Sandia's longstanding expertise in probabilistic modeling with machine learning algorithms from the Naval Research Laboratory. The system was tested and refined by modeling the area around Blake Ridge, a hill on the seafloor 90 to 230 miles southeast of North Carolina's Outer Banks with known deposits of methane hydrate and methane gas.The team shared their model for Blake Ridge and compared it with previous empirical data in a paper published on March 14 in the scientific journal The Naval Research Laboratory's Global Predictive Seafloor Model provides site-specific details on seafloor properties, such as temperature, overall carbon concentration and pressure. If data is missing for a certain region, the Naval Research Laboratory's model uses advanced machine-learning algorithms to estimate the missing value based on information about another area that may be geographically distant but similar geologically.The research team imported the data from the Naval Research Laboratory's model into Sandia software that specializes in statistical sampling and analysis, called Dakota. Using Dakota, they determined the most likely value for influential seafloor properties, as well as the natural variation for the values. Then, in a statistical manner, they inserted a value from this expected range for each property into PFLOTRAN, another software maintained and developed at Sandia. PFLOTRAN models how chemicals react and materials move underground or under the seafloor. The team conducted thousands of methane production simulations of the Blake Ridge region. All the software involved in the system is open source and will be available for other oceanographic researchers to use."One of the biggest things we found is that there is almost no formation of methane hydrates shallower than 500 meters, which is to be expected given the temperature and pressure needed to form methane hydrate," said William Eymold, a postdoctoral fellow at Sandia and primary author of the paper. Solid methane hydrate is known to form in low-temperature, high-pressure environments where molecules of methane are trapped within well-organized water molecules.The team also found methane gas formed closer to shore. They were able to compare their model to methane hydrate values calculated by past studies and samples collected a few decades ago by the National Science Foundation's Ocean Drilling Program, he said. For example, methane hydrate was detected in a seafloor sample collected from a hole drilled on Blake Ridge called Site 997."The fact that we predicted methane hydrate formation in similar amounts to past studies and observations really showed that the system appears to be working pretty well, and we will be able to apply it to other geographic locations that may have less data," Eymold said.The location of methane hydrate deposits and methane gas near the seafloor is important to the Navy."Understanding how sound interacts with the seafloor is really important for any kind of naval operation," said Frederick. "Methane gas affects the acoustics dramatically. Even if only 1% or 2% of the pore space in the seafloor sediment is filled with a gas bubble, the speed of sound decreases a hundredfold, or more. This is a very large effect, and if you don't account for it properly, then you're not going to get precise acoustics."Frederick compared a submarine using sonar to the early arcade game Breakout, where a player moves a paddle horizontally in order to keep a ball bouncing to destroy a wall of bricks. In this analogy, the seafloor serves as the "paddle" to reflect or refract sound waves, or the "ball," in order to get a complete view of obstacles in the ocean. If the paddle started to bounce the ball differently -- or held on to the ball for varying lengths of times -- depending on where the paddle was located, the game would become far more challenging.So far, the team has used their system to create models of a region of the Norwegian Sea between Greenland and Norway and the shallow waters of the Arctic Ocean offshore of the North Slope of Alaska, two areas of interest to the Navy.Frederick has also worked with a large team of international experts to assess the amount of methane and carbon dioxide stored in the shallow Arctic seafloor, and how sensitive those deposits would be to rising temperatures.The team has also created a much coarser model of the whole globe and has started looking at the mid-Atlantic, where methane gas was spotted bubbling out of the seafloor a few years ago."It will be interesting to see if our model is able to predict these regions of methane seeps on the seafloor," Frederick said. "We'd like to see if we can predict the distribution of these methane seeps and whether they are consistent with the thermodynamic properties of methane-hydrate stability. When you see a seep, that means that there is a lot of gas beneath the seafloor. That will significantly impact how sound travels through the seafloor, and thus sonar. Also, these deposits could be a source of natural gas for energy production, will impact the ocean ecology and nutrient cycles, and if that gas reaches the atmosphere, it will have climate change implications."This research was funded by Sandia's Laboratory Directed Research and Development program. Frederick is seeking funding to continue the project with her collaborators at the Naval Research Laboratory.
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Geography
| 2,021 |
March 16, 2021
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https://www.sciencedaily.com/releases/2021/03/210316214636.htm
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Extinct Caribbean bird's closest relatives hail from Africa, South Pacific
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In a genetic surprise, ancient DNA shows the closest family members of an extinct bird known as the Haitian cave-rail are not in the Americas, but Africa and the South Pacific, uncovering an unexpected link between Caribbean bird life and the Old World.
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Like many animals unique to the Caribbean, cave-rails became extinct soon after people settled the islands. The last of three known West Indian species of cave-rails -- flightless, chicken-sized birds -- vanished within the past 1,000 years. Florida Museum of Natural History researchers sought to resolve the group's long-debated ancestry by analyzing DNA from a fossil toe bone of the Haitian cave-rail, Nesotrochis steganinos. But they were unprepared for the results: The genus Nesotrochis is most closely related to the flufftails, flying birds that live in sub-Saharan Africa, Madagascar and New Guinea, and the adzebills, large, extinct, flightless birds native to New Zealand.The study presents the first example of a Caribbean bird whose closest relatives live in the Old World, showcasing the power of ancient DNA to reveal a history erased by humans.The discovery was "just mind-blowing," said study lead author Jessica Oswald, who began the project as a postdoctoral researcher at the Florida Museum."If this study had not happened, we might still be under the assumption that the closest relatives of most things in the Caribbean are on the mainland in the Americas," said Oswald, now a postdoctoral researcher at the University of Nevada, Reno and a Florida Museum research affiliate. "This gives us an understanding of the region's biodiversity that would otherwise be obscured."Many animals evolved unusual forms on islands, often making it difficult to classify extinct species based on their physical characteristics alone. But advancements in extracting viable DNA from fossils now enables scientists like Oswald to answer longstanding questions with ancient genetic evidence. Oswald described her work as similar to a forensic investigation, tracing the evolutionary backstory of extinct animals by piecing together fragmented, degraded genetic material."Understanding where all of these extinct species fit into a larger family tree or evolutionary history gives us insight into what a place looked like before people arrived," she said. "That's why my job is so fun. It's always this whodunit."Oswald was just starting her ancient DNA work at the Florida Museum when David Steadman, curator of ornithology and study co-author, suggested the Haitian cave-rail as a good candidate for analysis.Cave-rails share physical characteristics with several types of modern birds, and scientists have conjectured for decades whether they are most closely related to wood rails, coots or swamphens -- birds that all belong to the rail family, part of a larger group known as the Gruiformes. Oswald and Steadman hoped that studying cave-rail DNA would clarify "what the heck this thing is," Oswald said.When preliminary results indicated the species had a trans-Atlantic connection, Steadman, who has worked in the Caribbean for more than 40 years, was skeptical.The genetics also showed that the cave-rail isn't a rail at all: While flufftails and adzebills are also members of the Gruiformes, they are in separate families from rails."It just didn't seem logical that you'd have to go across the Atlantic to find the closest relative," Steadman said. "But the fact that people had a hard time classifying where Nesotrochis was within the rails -- in hindsight, maybe that should have been a clue. Now I have a much more open mind."One reason the cave-rail was so difficult to classify is that when birds lose the ability to fly, they often converge on a similar body plan, Steadman said. Flightlessness is a common adaptation in island birds, which face far fewer predators in the absence of humans and invasive species such as dogs, cats, rats and pigs."You don't have to outfly or outrun predators, so your flying and running abilities become reduced," Steadman said. "Because island birds spend less energy avoiding predators, they also tend to have a lower metabolic rate and nest on the ground. It's no longer life in the fast lane. They're essentially living in a Corona commercial."While sheltered from the mass extinctions that swept the mainland, cave-rails were helpless once people touched foot on the islands, having lost their defenses and cautiousness."Being flightless and plump was not a great strategy during human colonization of the Caribbean," said study co-author Robert Guralnick, Florida Museum curator of biodiversity informatics.How did cave-rails get to the Caribbean in the first place? Monkeys and capybara-like rodents journeyed from Africa to the New World about 25-36 million years ago, likely by rafting, and cave-rails may also have migrated during that timespan, Steadman said. He and Oswald envision two probable scenarios: The ancestors of cave-rails either made a long-distance flight across an Atlantic Ocean that was not much narrower than today, or the group was once more widespread across the continents, with more relatives remaining to be discovered in the fossil record.Other researchers have recently published findings that corroborate the story told by cave-rail DNA: A study of foot features suggested Nesotrochis could be more closely related to flufftails than rails, and other research showed that adzebills are close relatives of the flufftails. Like cave-rails, adzebills are also an example of a flightless island bird extinguished by human hunters."Humans have meddled so much in the region and caused so many extinctions, we need ancient DNA to help us sort out what's related to what," Oswald said.The findings also underscore the value of museum collections, Steadman said. The toe bone Oswald used in her analysis was collected in 1983 by Charles Woods, then the Florida Museum's curator of mammals. At that time, "nobody was thinking about ancient DNA," Steadman said. "It shows the beauty of keeping things well curated in a museum."Ryan Terrill of Occidental College, the Florida Museum's Brian Stucky and Michelle LeFebvre and Julie Allen of the University of Nevada, Reno, and the University of Illinois Urbana-Champaign also co-authored the study.
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Geography
| 2,021 |
March 16, 2021
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https://www.sciencedaily.com/releases/2021/03/210316164843.htm
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Meandering rivers create 'counter-point bars' no matter underlying geology
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It's not uncommon for crescent-shaped swaths of sand to dot the shorelines of meandering rivers. These swaths usually appear along the inner side of a river bend, where the bank wraps around the sandy patch, forming deposits known as a "point bars."
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When they appear along an outer bank, which curves the opposite way, they form "counter-point" bars, which are usually interpreted by geoscientists as an anomaly: a sign that something -- such as a patch of erosion-resistant rocks -- is interfering with the river's usual manner of sediment deposition.But according to research led by The University of Texas at Austin, counter-point bars are not the oddities they're often made out to be. In fact, they're a perfectly normal part of the meandering process."You don't need a resistant substrate, you can get beautiful [counter-point] bars without it," said Zoltán Sylvester, a research scientist at UT's Bureau of Economic Geology who led the study.The finding suggests that counter-point bars -- and the unique geology and ecology associated with them -- are more common than previously thought. Building awareness around that fact can help geoscientists be on the lookout for counter-point bars in geological formations deposited by rivers in the past, and understand how they may be influencing the flow of hydrocarbons and water passing though them.The research was published in the The co-authors are David Mohrig, a professor at the UT Jackson School of Geosciences; Paul Durkin, a professor at the University of Manitoba; and Stephen Hubbard, a professor at the University of Calgary.Rivers are constantly on the move. For meandering rivers, this means carving out new paths and reactivating old ones as they snake across a landscape over time.The researchers observed this behavior in both an idealized computer model and in nature, using satellite photos of a stretch of Bolivia's Mamoré River, which is known for quickly changing its path. The satellite photos captured how the river changed over 32 years, from 1986 -- 2018.In both the model and the Mamoré, counter-point bars appeared. The researchers found that the appearance was linked directly to short, high curvature bends: little spikes in a river's path.The researchers observed that these spikes frequently form when the river's course is abruptly changed, such as when a new oxbow lake forms through cutoff, or after reconnecting with an old oxbow lake.But the sharp bends don't stay put, they start migrating in the downstream direction. And as they rapidly move downstream, they create the conditions for sediment to accumulate around the bend as a counter-point bar.The study shows a number of instances of this happening in the Mamoré. For example, in 2010, a sharp bend (bend 2 in the image) forms when an ox-bow lake reconnects with a downstream portion of the river. By 2018, the bend has moved about 1.5 miles downstream, with counter-point deposits along the shoreline marking its path.Geomorphologists and engineers knew for some time that long-term change along a river can be described in terms of local and upstream values of curvature (places where the river seems to wrap around a small circle have high curvatures). In the study, the researchers used a formula that uses these curvature values to determine the likelihood of a counter-point bar forming at a particular location.Sylvester said that he was surprised at how well this formula -- and the simplified models used in part to derive it -- worked to explain what was thought to be a complex phenomenon."Natural rivers, they are actually not that far from what these really simple models predict," Sylvester said.This is not the first time that Sylvester's research has revealed that river behavior can be governed by relatively simple rules. In 2019, he led a study published in Geology that described a direct relationship between bend sharpness and river migration.Superficially, point bars and counter-point bars look quite similar and frequently blend into one another. But counter-point bars are distinct environments: compared to point bars, they have finer sediments and lower topography, making them more prone to flooding and hosting lakes. These characteristics create unique ecological niches along rivers. But they are also geologically important, with ancient counter-point bar deposits preserved underground influencing the flow of fluids, such as water and oil and gas.Mathieu Lapôtre, a geoscientist and assistant professor at Stanford University, said that recognizing that counter-point bars can readily form in meandering rivers -- and having a formula for predicting where they will form -- is a significant advancement."Altogether, the results of Sylvester et al. have important implications for a range of scientific and engineering questions," he said.The research was funded by the bureau's Quantitative Clastics Laboratory research consortium.
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Geography
| 2,021 |
March 15, 2021
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https://www.sciencedaily.com/releases/2021/03/210315160722.htm
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Study predicts the oceans will start emitting ozone-depleting CFCs
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The world's oceans are a vast repository for gases including ozone-depleting chlorofluorocarbons, or CFCs. They absorb these gases from the atmosphere and draw them down to the deep, where they can remain sequestered for centuries and more.
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Marine CFCs have long been used as tracers to study ocean currents, but their impact on atmospheric concentrations was assumed to be negligible. Now, MIT researchers have found the oceanic fluxes of at least one type of CFC, known as CFC-11, do in fact affect atmospheric concentrations. In a study appearing today in the The researchers project that by the year 2075, the oceans will emit more CFC-11 back into the atmosphere than they absorb, emitting detectable amounts of the chemical by 2130. Further, with increasing climate change, this shift will occur 10 years earlier. The emissions of CFC-11 from the ocean will effectively extend the chemical's average residence time, causing it to linger five years longer in the atmosphere than it otherwise would. This may impact future estimations of CFC-11 emissions.The new results may help scientists and policymakers better pinpoint future sources of the chemical, which is now banned worldwide under the Montreal Protocol."By the time you get to the first half of the 22nd century, you'll have enough of a flux coming out of the ocean that it might look like someone is cheating on the Montreal Protocol, but instead, it could just be what's coming out of the ocean," says study co-author Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies in MIT's Department of Earth, Atmospheric and Planetary Sciences. "It's an interesting prediction and hopefully will help future researchers avoid getting confused about what's going on."Solomon's co-authors include lead author Peidong Wang, Jeffery Scott, John Marshall, Andrew Babbin, Megan Lickley, and Ronald Prinn from MIT; David Thompson of Colorado State University; Timothy DeVries of the University of California at Santa Barbara; and Qing Liang of the NASA Goddard Space Flight Center.CFC-11 is a chlorofluorocarbon that was commonly used to make refrigerants and insulating foams. When emitted to the atmosphere, the chemical sets off a chain reaction that ultimately destroys ozone, the atmospheric layer that protects the Earth from harmful ultraviolet radiation. Since 2010, the production and use of the chemical has been phased out worldwide under the Montreal Protocol, a global treaty that aims to restore and protect the ozone layer.Since its phaseout, levels of CFC-11 in the atmosphere have been steadily declining, and scientists estimate that the ocean has absorbed about 5 to 10 percent of all manufactured CFC-11 emissions. As concentrations of the chemical continue to fall in the atmosphere, however, it's predicted that CFC-11 will oversaturate in the ocean, pushing it to become a source rather than a sink."For some time, human emissions were so large that what was going into the ocean was considered negligible," Solomon says. "Now, as we try to get rid of human emissions, we find we can't completely ignore what the ocean is doing anymore."In their new paper, the MIT team looked to pinpoint when the ocean would become a source of the chemical, and to what extent the ocean would contribute to CFC-11 concentrations in the atmosphere. They also sought to understand how climate change would impact the ocean's ability to absorb the chemical in the future.The researchers used a hierarchy of models to simulate the mixing within and between the ocean and atmosphere. They began with a simple model of the atmosphere and the upper and lower layers of the ocean, in both the northern and southern hemispheres. They added into this model anthropogenic emissions of CFC-11 that had previously been reported through the years, then ran the model forward in time, from 1930 to 2300, to observe changes in the chemical's flux between the ocean and the atmosphere.They then replaced the ocean layers of this simple model with the MIT general circulation model, or MITgcm, a more sophisticated representation of ocean dynamics, and ran similar simulations of CFC-11 over the same time period.Both models produced atmospheric levels of CFC-11 through the present day that matched with recorded measurements, giving the team confidence in their approach. When they looked at the models' future projections, they observed that the ocean began to emit more of the chemical than it absorbed, beginning around 2075. By 2145, the ocean would emit CFC-11 in amounts that would be detectable by current monitoring standards.The ocean's uptake in the 20th century and outgassing in the future also affects the chemical's effective residence time in the atmosphere, decreasing it by several years during uptake and increasing it by up to 5 years by the end of 2200.Climate change will speed up this process. The team used the models to simulate a future with global warming of about 5 degrees Celsius by the year 2100, and found that climate change will advance the ocean's shift to a source by 10 years and produce detectable levels of CFC-11 by 2140."Generally, a colder ocean will absorb more CFCs," Wang explains. "When climate change warms the ocean, it becomes a weaker reservoir and will also outgas a little faster.""Even if there were no climate change, as CFCs decay in the atmosphere, eventually the ocean has too much relative to the atmosphere, and it will come back out," Solomon adds. "Climate change, we think, will make that happen even sooner. But the switch is not dependent on climate change."Their simulations show that the ocean's shift will occur slightly faster in the Northern Hemisphere, where large-scale ocean circulation patterns are expected to slow down, leaving more gases in the shallow ocean to escape back to the atmosphere. However, knowing the exact drivers of the ocean's reversal will require more detailed models, which the researchers intend to explore."Some of the next steps would be to do this with higher-resolution models and focus on patterns of change," says Scott. "For now, we've opened up some great new questions and given an idea of what one might see."This research was supported, in part, by the VoLo Foundation, the Simons Foundation, and the National Science Foundation.
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Geography
| 2,021 |
March 15, 2021
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https://www.sciencedaily.com/releases/2021/03/210315141801.htm
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Melting glaciers could speed up carbon emissions into the atmosphere
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The loss of glaciers worldwide enhances the breakdown of complex carbon molecules in rivers, potentially contributing further to climate change.
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An international research team led by the University of Leeds has for the first time linked glacier-fed mountain rivers with higher rates of plant material decomposition, a major process in the global carbon cycle.As mountain glaciers melt, water is channelled into rivers downstream. But with global warming accelerating the loss of glaciers, rivers have warmer water temperatures and are less prone to variable water flow and sediment movement. These conditions are then much more favourable for fungi to establish and grow.Fungi living in these rivers decompose organic matter such as plant leaves and wood, eventually leading to the release of carbon dioxide into the air. The process -- a key part of global river carbon cycling -- has now been measured in 57 rivers in six mountain ranges across the world, in Austria, Ecuador, France, New Zealand, Norway and the United States.The findings, funded mainly by the Natural Environment Research Council, are published today (15 March) in the journal Lead author Sarah Fell, of Leeds' School of Geography and water@leeds, said similar patterns and processes were discovered worldwide."We found increases in the rate of organic matter decomposition in mountain rivers, which can then be expected to lead to more carbon release to the atmosphere."This is an unexpected form of climate feedback, whereby warming drives glacier loss, which in turn rapidly recycles carbon in rivers before it is returned to the atmosphere."The retreat of mountain glaciers is accelerating at an unprecedented rate in many parts of the world, with climate change predicted to drive continued ice loss throughout the 21st century.However, the response of river ecosystem processes (such as nutrient and carbon cycling) to decreasing glacier cover, and the role of fungal biodiversity in driving these, remains poorly understood.The research team used artists' canvas fabric to mimic plant materials such as leaves and grass that accumulate naturally in rivers. This was possible because the canvas is made from cotton, predominantly composed of a compound called cellulose -- the world's most abundant organic polymer which is found in plant leaves that accumulate in rivers naturally.The canvas strips were left in the rivers for approximately one month, then retrieved and tested to determine how easily they could be ripped. The strips ripped more easily as aquatic fungi colonised them, showing that decomposition of the carbon molecules proceeded more quickly in rivers which were warmer because they had less water flowing from glaciers.The study's co-author, Professor Lee Brown, also of Leeds' School of Geography and water@leeds, explained: "Our finding of similar patterns of cellulose breakdown at sites all around the world is really exciting because it suggests that there might be a universal rule for how these river ecosystems will develop as mountains continue to lose ice. If so, we will be in much improved position to make forecasts about how river ecosystems will change in future.Co-author Professor Alex Dumbrell, whose team at the University of Essex analysed the fungi from the river samples, added: "Our work showed that measuring a specific gene that underpins the activity of the cellulose-degrading enzyme (Cellobiohydrolase I) meant we could predict cotton strip decomposition better than using information about the abundance of fungal species themselves, which is the more commonly used approach. This opens up new routes for research to improve our predictions about changes in carbon cycling."As algal and plant growth in glacier-fed rivers is minimised by low water temperature, unstable channels and high levels of fine sediment, plant matter breakdown can be an important fuel source to these aquatic ecosystems. In some parts of the world, such as Alaska and New Zealand, glacier-fed rivers also extend into forests that provide greater amounts of leaf litter to river food chains.In addition, because glacier loss means less water flows through the rivers and they are less prone to changing course, it is expected that bankside plants and trees will grow more in these habitats in future, meaning even more leaf litter will accumulate in rivers. This is likely to accelerate the fungal processing of carbon in mountain rivers worldwide even more than at present.
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Geography
| 2,021 |
March 15, 2021
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https://www.sciencedaily.com/releases/2021/03/210315132141.htm
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European summer droughts since 2015 unprecedented in past two millennia
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Recent summer droughts in Europe are far more severe than anything in the past 2,100 years, according to a new study.
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An international team, led by the University of Cambridge, studied the chemical fingerprints in European oak trees to reconstruct summer climate over 2,110 years. They found that after a long-term drying trend, drought conditions since 2015 suddenly intensified, beyond anything in the past two thousand years.This anomaly is likely the result of human-caused climate change and associated shifts in the jet stream. The results are reported in the journal Recent summer droughts and heatwaves in Europe have had devastating ecological and economic consequences, which will worsen as the global climate continues to warm."We're all aware of the cluster of exceptionally hot and dry summers we've had over the past few years, but we needed precise reconstructions of historical conditions to see how these recent extremes compare to previous years," said first author Professor Ulf Büntgen from Cambridge's Department of Geography, who is also affiliated with CzechGlobe Centre in Brno, Czech Republic. "Our results show that what we have experienced over the past five summers is extraordinary for central Europe, in terms of how dry it has been consecutively."Most studies attempting to reconstruct past climates are restricted to temperature, but stable isotopes in tree rings can provide annually-resolved and absolutely-dated information about hydroclimatic changes over long periods of time.Büntgen and his colleagues from the Czech Republic, Germany and Switzerland studied more than 27,000 measurements of carbon and oxygen isotopic ratios from 147 living and dead European oak trees, covering a period of 2,110 years. The samples came from archaeological remains, subfossil materials, historical constructions and living trees from what is now the Czech Republic and parts of south-eastern Bavaria."Generally, our understanding is worse the further back we go back in time, as datasets looking at past drought conditions are rare," said Büntgen, who is a specialist in dendrochronology, the study of data from tree-ring growth. "However, insights before medieval times are particularly vital, because they enable us to get a more complete picture of past drought variations, which were essential for the functioning and productivity of ecosystems and societies."For each ring in each tree, researchers extracted and analysed carbon and oxygen isotopes independently, enabling them to build the largest and most detailed dataset of summer hydroclimate conditions in central Europe from Roman times to the present."These tree-ring stable isotopes give us a far more accurate archive to reconstruct hydroclimate conditions in temperate areas, where conventional tree-ring studies often fail," said co-author Professor Jan Esper from the University of Mainz, Germany.Stable tree-ring isotopes differ from the usual tree-ring measures of ring width and wood density, as they reflect physical conditions and tree responses rather than net stem growth. "While carbon values depend on the photosynthetic activity, oxygen values are affected by the source water. Together, they closely correlate with the conditions of the growing season," said co-author Professor Paolo Cherubini from the Federal Research Institute WSL in Birmensdorf, Switzerland.Over the 2,110-year period, the tree-ring isotope data showed there were very wet summers, such as 200, 720 and 1100 CE, and very dry summers, such as 40, 590, 950 and 1510 CE. Despite these 'out of the ordinary years', the results show that for the past two millennia, Europe has been slowly getting drier.The samples from 2015-2018, however, show that drought conditions in recent summers far exceed anything in the 2,110 years: "We've seen a sharp drop following centuries of a slow, significant decline, which is particularly alarming for agriculture and forestry," said co-author Professor Mirek Trnka from the CzechGlobe Research Centre in Brno, Czech Republic. "Unprecedented forest dieback across much of central Europe corroborates our results."The researchers say that the recent cluster of abnormally dry summers is most likely the result of anthropogenic climate warming, and the associated changes in the jet stream position. "Climate change does not mean that it will get drier everywhere: some places may get wetter or colder, but extreme conditions will become more frequent, which could be devastating for agriculture, ecosystems and societies as a whole," said Büntgen.
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Geography
| 2,021 |
March 15, 2021
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https://www.sciencedaily.com/releases/2021/03/210315132125.htm
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Important forests and wetlands are disappearing in Belize
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Using NASA satellite images and machine learning, researchers with The University of Texas at Austin have mapped changes in the landscape of northwestern Belize over a span of four decades, finding significant losses of forest and wetlands, but also successful regrowth of forest in established conservation zones that protect surviving structures of the ancient Maya.
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The research serves as a case study for other rapidly developing and tropical regions of the globe, especially in places struggling to balance forest and wetland conservation with agricultural needs and food security."Broad-scale global studies show that tropical deforestation and wetland destruction is occurring rapidly, which contributes to climate change in multiple ways such as through greenhouses gas increases," said Timothy Beach, the study's co-author and professor in the Department of Geography and the Environment at UT Austin. "These also lead to more runoff and water pollution in much of the Global South. Belize has served as our long-term environmental research laboratory for this global dilemma."In a study published in The Landsat program, which has been recording images of Earth since 1972, is currently on its eighth satellite. To study such broad periods, the authors used images from Landsat 8 and earlier satellites and employed a multitemporal approach, creating composite images from wet and dry seasons over several years for each period. They then trained an algorithm to identify eight distinct land types, including several varieties of forest and wetlands. From this, they generated maps illustrating the LULC for each of the three periods.During the first period (1984-1987), deforestation was limited to small patches resulting from milpa farming -- a system of rotating crops and allowing previous plots to lie fallow in between use to maximize yields.Several protected areas were established in the late 1980s and early 1990s. By the second period examined (1999-2001), forests in these protected areas had regrown but losses to wetlands continued, as did the conversion of nonprotected land to agriculture.The third period mapped (2014-2016) followed a shift to industrial agriculture in the 2000s and showed "alarming" losses to both forest (7.5% loss) and wetlands (28.2% loss) outside of protected areas, said co-author Sheryl Luzzadder-Beach, the founding director of the university's Water Quality & Environmental Hydrology Lab.Population growth contributed to the increase in land used for agriculture. However, it was a greater factor between the first and second periods, when the population nearly doubled, than between the second and third periods, when population grew more slowly, indicating that changes in farming practices had a greater impact on land use.The maps also revealed the importance of conservation efforts in maintaining forests. Of the remaining forest in the study area, 76% is estimated to be on protected lands. These habitats are crucial in housing native flora and fauna and also contain structures from the Maya civilization important to the region's cultural heritage."These ecosystems provide many services such as aiding in the water cycle and preventing flooding," Doyle said. "The conversion of forest to pastureland and industrial agriculture is also a major contributor to increasing greenhouse gas emissions across the tropics."
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Geography
| 2,021 |
March 15, 2021
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https://www.sciencedaily.com/releases/2021/03/210315115027.htm
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Global river flow contingent upon climate change
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More often than ever before, water available in rivers is at the mercy of climate change, international researchers collaborating on a worldwide study with Michigan State University have revealed. The finding could profoundly affect future water and food security around the world.
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Yadu Pokhrel, associate professor of civil and environmental engineering in the MSU College of Engineering and a co-author of the study, said climate is the key driver in the current changes to global river flow."It's a noteworthy finding because as climate change impacts extreme flows, it could be worsening flooding or increasing water scarcity during dry seasons," Pokhrel explained.Details of the new study, "Globally observed trends in mean and extreme river flow attributed to climate change," have been published in the journal, Pokhrel said flows in rivers and streams can alter year by year, but they don't change direction over long-time scales without serious influence -- from changing climate or human actions."Previous research has shown that river flows have been changing over time globally but the causes were not known. This study shows that the change in stream flow annually or during droughts was primarily caused by climate change during the past 30 years," Pokhrel said."This suggests that we are on course to lose more and more water in rivers as climate change continues, which could seriously undermine our ability to maintain water supplies for drinking, industries, power generation, and food production."The study used measurements of streamflow at 7,250 locations globally and computer simulations from nine global hydrological models to examine how humanmade climate change affected river flows across the global from 1971 to 2010. It found that climate change affected long-term average river flow as well as the flow during dry seasons."It highlights that it is critical to incorporate climate change impacts on water resource planning and management," Pokhrel added.Lukas Gudmundsson at ETH Zurich, Switzerland, led the research."This study was possible thanks to the great collaboration between researchers and institutions from 12 countries," Gudmundsson said.
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Geography
| 2,021 |
March 15, 2021
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https://www.sciencedaily.com/releases/2021/03/210315110229.htm
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Antarctic peninsula likely to warm over next two decades
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An analysis of historic and projected simulations from 19 global climate models shows that, because of climate change, the temperature in the Antarctic peninsula will increase by 0.5 to 1.5 degrees Celsius by 2044.
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The projections also showed that precipitation -- a threat to ice if it manifests as rain -- will likely increase on the peninsula by about 5% to 10% over that same time period.The estimates were published recently in the journal "We are concerned about these findings. We've been seeing overall quite big changes on the peninsula, generally getting warmer and ice shelves and glaciers discharging into the ocean," said David Bromwich, a leading author of the study and a research professor at The Ohio State University Byrd Polar and Climate Research Center and department of geography.The peninsula sticks up like a tail off the northwest side of Antarctica, curving near the southernmost part of South America and Chile.Since the 1950s, the peninsula, along with the rest of the western part of Antarctica, has been one of the fastest-warming regions on Earth. And because it is covered in mountains -- the highest peak is just over 10,600 feet -- standard climate models overlook some of the nuances of how climate change affects the peninsula, Bromwich said."The issue for the Antarctic peninsula is that it's this narrow but high mountain range, and these big models spanning the whole continent don't take that into account. Our goal was to provide more detail in those projections," he said.The analysis found that the greatest increases in temperature -- about 2 degrees Celsius -- were likely to happen in the Antarctic fall and winter, but warmer temperatures projected for summer would cause the most trouble.That could create a double threat to the ice on the peninsula, Bromwich said: Warmer temperatures also mean that some precipitation that might have previously fallen as snow will likely fall as rain.More rain means less snow on top of the ice, which protects ice from the sun's rays by reflecting them back into the sky."But now, if you have bare ice, or ice that's a little bit melting, and the sun beats down on it, a good fraction of that energy goes into melting," Bromwich said. "And we've seen this in the past with other ice shelves -- it's like a hammer, it just shatters."The study's authors also found that, to truly predict what might happen on the peninsula, better, more nuanced climate models are needed.Big climate models -- those that cover the surface of the Earth -- often do not consider other factors specific to smaller regions. In the Antarctic peninsula, Bromwich said, an overlooked factor is the modification of the westerlies, winds that blow from west to east near either pole. The westerlies blow directly over the Antarctic peninsula, creating a sort of micro-climate that big climate models often miss.Those nuances are especially important in the Antarctic peninsula, which has since the late 1970s been considered an important vanguard of what might happen throughout the rest of Antarctica. The peninsula, climate scientists have come to understand, is more susceptible to the effects of climate change. The first person to predict that changes throughout Antarctica would first be seen on the peninsula was another Ohio State researcher, John Mercer, who was known around the world for his work on climate change in Antarctica.
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Geography
| 2,021 |
March 12, 2021
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https://www.sciencedaily.com/releases/2021/03/210312181148.htm
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Oil in the ocean photooxidizes within hours to days, new study finds
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A new study lead by scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science demonstrates that under realistic environmental conditions oil drifting in the ocean after the DWH oil spill photooxidized into persistent compounds within hours to days, instead over long periods of time as was thought during the 2010 Deepwater Horizon oil spill. This is the first model results to support the new paradigm of photooxidation that emerged from laboratory research.
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After an oil spill, oil droplets on the ocean surface can be transformed by a weathering process known as photooxidation, which results in the degradation of crude oil from exposure to light and oxygen into new by-products over time. Tar, a by-product of this weathering process, can remain in coastal areas for decades after a spill. Despite the significant consequences of this weathering pathway, photooxidation was not taken into account in oil spill models or the oil budget calculations during the Deepwater Horizon spill.The UM Rosenstiel School research team developed the first oil-spill model algorithm that tracks the dose of solar radiation oil droplets receive as they rise from the deep sea and are transported at the ocean surface. The authors found that the weathering of oil droplets by solar light occurred within hours to days, and that roughly 75 percent of the photooxidation during the Deepwater Horizon oil spill occurred on the same areas where chemical dispersants were sprayed from aircraft. Photooxidized oil is known to reduce the effectiveness of aerial dispersants."Understanding the timing and location of this weathering process is highly consequential. said Claire Paris, a UM Rosenstiel School faculty and senior author of the study. "It helps directing efforts and resources on fresh oil while avoiding stressing the environment with chemical dispersants on oil that cannot be dispersed.""Photooxidized compounds like tar persist longer in the environment, so modeling the likelihood of photooxidation is critically important not only for guiding first response decisions during an oil spill and restoration efforts afterwards, but it also needs to be taken into account on risk assessments before exploration activities" added Ana Carolina Vaz, assistant scientist at UM's Cooperative Institute for Marine and Atmospheric Studies and lead author of the study.
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Geography
| 2,021 |
March 12, 2021
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https://www.sciencedaily.com/releases/2021/03/210312155454.htm
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Traces of Earth's early magma ocean identified in Greenland rocks
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New research led by the University of Cambridge has found rare evidence -- preserved in the chemistry of ancient rocks from Greenland -- which tells of a time when Earth was almost entirely molten.
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The study, published in the journal It is the gradual cooling and crystallisation of this 'magma ocean' that set the chemistry of Earth's interior -- a defining stage in the assembly of our planet's structure and the formation of our early atmosphere.Scientists know that catastrophic impacts during the formation of the Earth and Moon would have generated enough energy to melt our planet's interior. But we don't know much about this distant and fiery phase of Earth's history because tectonic processes have recycled almost all rocks older than 4 billion years.Now researchers have found the chemical remnants of the magma ocean in 3.6-billion-year-old rocks from southwestern Greenland.The findings support the long-held theory that Earth was once almost entirely molten and provide a window into a time when the planet started to solidify and develop the chemistry that now governs its internal structure. The research suggests that other rocks on Earth's surface may also preserve evidence of ancient magma oceans."There are few opportunities to get geological constraints on the events in the first billion years of Earth's history. It's astonishing that we can even hold these rocks in our hands -- let alone get so much detail about the early history of our planet," said lead author Dr Helen Williams, from Cambridge's Department of Earth Sciences.The study brings forensic chemical analysis together with thermodynamic modelling in search of the primeval origins of the Greenland rocks, and how they got to the surface.At first glance, the rocks that make up Greenland's Isua supracrustal belt look just like any modern basalt you'd find on the sea floor. But this outcrop, which was first described in the 1960s, is the oldest exposure of rocks on Earth. It is known to contain the earliest evidence of microbial life and plate tectonics.The new research shows that the Isua rocks also preserve rare evidence which even predates plate tectonics -- the residues of some of the crystals left behind as that magma ocean cooled."It was a combination of some new chemical analyses we did and the previously published data that flagged to us that the Isua rocks might contain traces of ancient material. The hafnium and neodymium isotopes were really tantalizing, because those isotope systems are very hard to modify -- so we had to look at their chemistry in more detail," said co-author Dr Hanika Rizo, from Carleton University.Iron isotopic systematics confirmed to Williams and the team that the Isua rocks were derived from parts of the Earth's interior that formed as a consequence of magma ocean crystallisation.Most of this primeval rock has been mixed up by convection in the mantle, but scientists think that some isolated zones deep at the mantle-core boundary -- ancient crystal graveyards -- may have remained undisturbed for billions of years.It's the relics of these crystal graveyards that Williams and her colleagues observed in the Isua rock chemistry. "Those samples with the iron fingerprint also have a tungsten anomaly -- a signature of Earth's formation -- which makes us think that their origin can be traced back to these primeval crystals," said Williams.But how did these signals from the deep mantle find their way up to the surface? Their isotopic makeup shows they were not just funnelled up from melting at the core-mantle boundary. Their journey was more circuitous, involving several stages of crystallization and remelting -- a kind of distillation process. The mix of ancient crystals and magma would have first migrated to the upper mantle, where it was churned up to create a 'marble cake' of rocks from different depths. Later melting of that hybrid of rocks is what produced the magma which fed this part of Greenland.The team's findings suggest that modern hotspot volcanoes, which are thought to have formed relatively recently, may actually be influenced by ancient processes."The geochemical signals we report in the Greenland rocks bear similarities to rocks erupted from hotspot volcanoes like Hawaii -- something we are interested in is whether they might also be tapping into the depths and accessing regions of the interior usually beyond our reach," said Dr Oliver Shorttle, who is jointly based at Cambridge's Department of Earth Sciences and Institute of Astronomy.The team's findings came out of a project funded by Deep Volatiles, a NERC-funded 5-year research programme. They now plan to continue their quest to understand the magma ocean by widening their search for clues in ancient rocks and experimentally modelling isotopic fractionation in the lower mantle."We've been able to unpick what one part of our planet's interior was doing billions of years ago, but to fill in the picture further we must keep searching for more chemical clues in ancient rocks," said co-author Dr Simon Matthews from the University of Iceland.Scientists have often been reluctant to look for chemical evidence of these ancient events. "The evidence is often altered by the course of time. But the fact we found what we did suggests that the chemistry of other ancient rocks may yield further insights into the Earth's formation and evolution -- and that's immensely exciting," said Williams.
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Geography
| 2,021 |
March 11, 2021
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https://www.sciencedaily.com/releases/2021/03/210311123513.htm
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Study of Redoubt and other volcanoes improves unrest detection
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Volcanologists do what they can to provide the public enough warning about impending eruptions, but volcanoes are notoriously unpredictable. Alerts are sometimes given with little time for people to react.
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That may soon change.Work led by research assistant professor Társilo Girona, with the University of Alaska Fairbanks Geophysical Institute, has revealed a method by which scientists -- and the public -- can have perhaps years of advance warning about a potential eruption.The solution lies in regular and widespread monitoring of the radiant temperature of a volcano's flanks before the appearance of any of the usual warning signs, such as glacier melting, sulfur odors, increased gas emissions, quaking and deformation.Girona is the lead author of a paper published today in the journal "This is showing that very large areas in the volcanoes are increasing the release of heat," Girona said. "It's a process which is going on in, we cannot say in the whole volcano itself, but in very large areas in the volcano. It's a large-scale process."Girona also works with the Alaska Volcano Observatory, which is evaluating how best to integrate the research findings into its monitoring of Alaska volcanoes. The AVO is a cooperative organization among UAF, the U.S. Geological Survey and the Alaska Division of Geological and Geophysical Surveys.David Fee, AVO coordinating scientist at UAF, said the findings can bolster volcano monitoring. That's important for the airline industry, particularly in Alaska and especially near Anchorage and other communities potentially in the path of an ash cloud."These results might provide critical information on how best to supplement existing monitoring networks, especially for difficult-to-monitor volcanoes in remote parts of Alaska," he said. "Any advance information on eruptions is helpful."The research focused on five volcanoes that erupted or exploded in the past 20 years, that displayed a wide range of behaviors and characteristics, and that are considered representative of volcanoes worldwide: Mount Redoubt in Alaska, Mount Ontake in Japan, Mount Ruapehu in New Zealand, Calbuco in Chile and Pico do Fogo in Cabo Verde, an island nation off the west coast of Africa.The researchers analyzed 16 ½ years of thermal infrared radiance data collected by NASA's Terra and Aqua satellites.The satellite data had never been analyzed with an eye toward long-term early awareness of potential volcanic activity.Girona, Realmuto and Lundgren wanted to answer this question: Does volcanic activity underground produce a noticeable increase in radiant temperature at the surface long before an eruption?The data provided the answer for all five of the studied volcanoes: A clear "yes."The researchers wrote that volcanoes can experience thermal unrest "for several years before eruption" and that the unrest "is dominated by a large-scale phenomenon operating over extensive areas of volcanic edifices." They also found that the heat increased regardless of the type of eruption.Mount Redoubt, for example, had an increase of 0.85 degrees Fahrenheit, plus or minus 0.31 degrees (0.47 degrees Celsius, plus or minus 0.17), from mid-2006 to its major eruption of March 2009. Notably, the radiant temperature began increasing approximately one year earlier than the onset of other warning signs. Redoubt's radiant temperature began dropping quickly a year after the eruption and has remained low since 2014.The researchers said their findings will allow scientists to anticipate eruptions that are difficult to forecast through other geophysical and geochemical methods."This is especially relevant for phreatic eruptions (volcanic gas explosions), such as the one at Ontake, Japan, in 2014," Girona said. "Phreatic eruptions are generally very difficult to anticipate with traditional methods."The research, which Girona began at JPL and continued after moving to the Geophysical Institute, also provides insights into the interaction between a volcano's magmatic gases and its subsurface system of superheated water.Lundgren said the new approach, combined with such tools as GPS or satellite radar measurements of surface displacements, can reveal even more about volcano processes.For example, the team integrated surface heat emissions with surface displacements in another recent publication to better understand the behavior of Domuyo, a newly discovered deforming volcano in Argentina.
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Geography
| 2,021 |
March 9, 2021
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https://www.sciencedaily.com/releases/2021/03/210309185701.htm
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Spawning preferences of mahi-mahi
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In the Florida Straits at night, and under a new moon is the preference for spawning mahi-mahi, according to a new study by scientists at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science.
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These new details on the daily life of the highly sought-after migratory fish can help better manage their populations and provide scientists with new information to understand the impacts to the animal from changing environmental conditions.To uncover these important details about the behaviors of mahi-mahi, or dolphinfish, the research team tagged captive spawning fish located at the UM Experimental Hatchery to build predictive spawning models and then used the models with data collected from mahi-mahi tagged in the wild. The study is the first to use acceleration data from remotely transmitting pop-up satellite tags to predict the spawning habitat of a wild marine fish. The UM Experimental Hatchery is the only place in the country where spawning mahi-mahi are kept in captivity.To build the predictive models, the research team tagged five spawning mahi-mahi (Coryphaena hippurus) at the UM Hatchery and waited overnight to record the timing of when they spawned. In total, 40 individual spawning events were tracked in captivity. Then, they paired the acceleration data collected from the tags with the exact time of spawning to estimate when the animals would spawn in the wild.To test the models' capability to estimate where and when the fish spawned in the wild, the researchers tagged 17 wild mahi-mahi off the coast of Miami and two in the Gulf of Mexico.From an analysis of the satellite tag data, the researchers found that wild mahi-mahi spawn at night, primarily during a new moon at depths greater than they would normally be. The Florida Straits appeared to be an important spawning habitat for mahi-mahi, although the models suggest that some limited spawning takes place further north.They found that mahi-mahi typically go deeper in the water column at night and are more surface oriented during the day. However, the phase of the moon had an effect on their nighttime depth distribution with a full moon bringing mahi-mahi closer to the surface at night.They also found that mahi-mahi use behavioral thermoregulation to stay between a relatively narrow temperature window of about 27-28 degrees Celsius (80 -- 82 degrees Fahrenheit). When surface waters are warmer, they move deeper and swim northward with the Gulf Stream to regulate their temperature, while fish tagged in cooler months stayed primarily in surface waters and migrated east and west between Florida and the Bahamas, rather than swimming north. They were also found to be the most active at cooler temperatures and in warm waters during a full moon at night."Mahi-mahi are highly sought after by recreational and commercial fisheries and are economically important," said Lela Schlenker, an alumna of the UM Rosenstiel school and lead author of the study. "It is critical to understand their migrations and the frequency, timing, and location of where they reproduce as well as how changing environmental conditions -- like warmer oceans -- might affect them to manage their populations sustainably now and in the future."The team also found from the satellite tag data that the wild mahi-mahi travel long distances -- up to 107 kilometers (105 miles) per day and dive to depths of 250 meters (820 feet)."Together these findings suggest that as climate change continues to warm ocean waters, mahi-mahi will likely continue to shift northward and deeper throughout their migrations," said Martin Grosell," professor and chair of the Department of Marine Biology and Ecology at the UM Rosenstiel School. "This is important for recreational and commercial landings of mahi-mahi and the ecology of pelagic ecosystems. A fruitful collaboration between scientists from three departments at the Rosenstiel School, as well as colleagues from University of Massachusetts, Dartmouth and access to healthy spawning mahi-mahi in captivity revealed new information about these valuable fish," said Grosell.
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Geography
| 2,021 |
March 9, 2021
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https://www.sciencedaily.com/releases/2021/03/210309132543.htm
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Deforestation's effects on malaria rates vary by time and distance
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Deforestation may cause an initial increase in malaria infections across Southeast Asia before leading to later decreases, a study published today in
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The results may help malaria control programs in the region develop better strategies for eliminating malaria infections and educating residents on how to protect themselves from infection.Mosquitos spread the malaria parasite to humans causing infections that can be severe and sometimes deadly. In the area along the Mekong river in Southeast Asia, many residents hunt or harvest wood in the surrounding forests, which can increase their risk of infection. Yet recent outbreaks of malaria in the region have also been linked to deforestation."As countries in the region focus their malaria control and elimination efforts on reducing forest-related transmission, understanding the impact of deforestation on malaria rates is essential," says first author Francois Rerolle, Graduate Student Researcher at the University of California San Francisco (UCSF), US, who works within the UCSF Malaria Elimination Initiative.To better understand the effects of deforestation on malaria transmission, Rerolle and colleagues examined both forest cover data and village-level malaria incidence data from 2013-2016 in two regions within the Greater Mekong Sub-region.They found that in the first two years following deforestation activities, malaria infections increased in villages in the area, but then decreased in later years. This trend was mostly driven by infections with the malaria parasite Plasmodium falciparum. Deforestation in the immediate 1-10-kilometer radius surrounding villages did not affect malaria rates, but deforestation in a wider 30-kilometer radius around the villages did. The authors say this is likely due to the effect that wider deforestation can have on human behaviour. "We suspect that people making longer and deeper trips into the forest results in increased exposure to mosquitoes, putting forest-goers at risk," Rerolle explains.Previously, studies on the Amazon in South America have found increased malaria infections in the first 6-8 years after deforestation, after which malaria rates fall. The difference in timing may be due to regional differences. The previous studies in the Amazon looked at deforestation driven by non-indigenous people moving deeper into the forest, while communities in the current study have long lived at the forest edges and rely on subsistence agriculture."Our work provides a more complete picture of the nuanced effects of deforestation on malaria infections," says senior author Adam Bennett, Program Lead at the UCSF Malaria Elimination Initiative. "It may encourage more in-depth studies on the environmental and behavioural drivers of malaria to help inform strategies for disease elimination."
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Geography
| 2,021 |
March 9, 2021
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https://www.sciencedaily.com/releases/2021/03/210309100140.htm
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Antarctic Peninsula warming up due to heat in Tasman sea
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The melting of the Earth's ice cover intensified in the 20th century, with glaciers and sea ice in the Arctic and Antarctic regions melting at alarming speeds. In fact, The Antarctic Peninsula (AP), which is the only landmass of Antarctica extending out past the Antarctic Circle, was found to be one of the most rapidly warming regions on the planet during the second half of the 20th century. This rapid change in climate has raised serious concerns of rising sea levels the world over.
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Multiple factors have been associated with the melting of the ice cover: the primary factor being the greenhouse gas emissions from human activities that cause warming up of the atmosphere and the oceans and the consequent ice melting. Apart from this, atmospheric variations, ocean currents, and wind patterns also play a significant role. Now, a collaborative group of scientists from Japan and Australia -- led by Assistant Professor Kazutoshi Sato from Kitami Institute of Technology and Associate Professor Jun Inoue from National Institute of Polar Research in Japan -- has focused efforts on understanding how fluctuations in these climatic factors affect the warming of the Antarctic. They have documented their findings in a brand-new article published in Previous studies have examined the relationship between the wind dynamics over the Southern Ocean (also called SO; located north of Antarctica) and climate variability in tropical oceans. It was found that heating in tropical regions generates atmospheric waves called "Rossby wave trains" from the tropics to the Antarctic region via the SO, which causes heating of the West Antarctic region. Interestingly, Rossby waves are an attempt of nature to balance heat in the atmosphere as they transfer heat from the tropics to the poles and cold air towards the tropics.On the path of understanding the warming of AP, Dr. Sato points out, Dr. Sato and his team analyzed the temperature data from six stations in AP and the wind and cyclone patterns over the Tasman sea and the SO from 1979 to 2019. They found that even without unusual heating in the tropics, only the heating in the Tasman Sea modifies the wind patterns over the SO and forces the Rossby waves to move even deeper into the Amundsen sea low, a low-pressure area lying to the west of the AP. This larger pressure gradient causes stronger colder winds towards the poles. The meandering wind stream moves towards the AP, resulting in the warming of this region. Additionally, this effect was found to be prominent in the winter months when the cyclones are more active. The ever-increasing warming of the AP -- rather, the whole of Antarctica at large -- is a major concern plaguing climatologists all over the world. Commenting on the serious implications of this rapid rise in temperature and sea levels and the importance of the findings of their study, Dr. Inoue says, Dr. Sato and his team concludes by stating that the findings of their study can also aid the future forecast of ice sheet melting in Antarctica and consequent global sea level rise.
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Geography
| 2,021 |
March 8, 2021
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https://www.sciencedaily.com/releases/2021/03/210308152458.htm
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Sea otters maintain remnants of healthy kelp forest amid sea urchin barrens
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Sea otters have long been recognized as a classic example of a keystone species, a dominant predator that maintains the balance of kelp forest ecosystems by controlling populations of sea urchins, which are voracious kelp grazers.
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Since 2014, however, California's kelp forests have declined dramatically, and vast areas of the coast where kelp once thrived are now "urchin barrens," the seafloor carpeted with purple sea urchins and little else. This has occurred even in Monterey Bay, which hosts a large population of sea otters.In 2017, UC Santa Cruz graduate student Joshua Smith set out to understand why. "Here in Monterey Bay, we now have a patchy mosaic, with urchin barrens devoid of kelp directly adjacent to patches of kelp forest that seem pretty healthy," Smith said. "We wanted to know how did this sea urchin outbreak happen where there are so many otters, how did the otters respond, and what does that mean for the fate of kelp forests here on the Central Coast?"Working with a team of sea otter researchers at UCSC, the U.S. Geological Survey, and the Monterey Bay Aquarium, Smith conducted intensive underwater surveys along the Monterey Peninsula over a span of three years. The study built on decades of long-term monitoring of sea otter populations and kelp forest ecosystems along the California coast.Smith's findings, published March 8 in It began in 2013 with the outbreak of a mysterious disease called sea star wasting syndrome, which decimated sea stars all along the West Coast. Among the hardest hit species was the sunflower sea star (Pycnopodia helianthoides), a major sea urchin predator. But according to Smith, that was just one factor leading to a massive outbreak of sea urchins."We believe several factors initiated the urchin outbreak," he said. "The loss of a major urchin predator was soon followed by a decline in kelp productivity due to climatic stressors."In kelp forests, sea urchins mostly occupy crevices in rocky reefs on the seafloor where they are protected from predators. Pieces of kelp drift down onto the reef like falling leaves in a forest, delivering food directly to the urchins in their shelters.Kelp thrives where cold, nutrient-rich water wells up along the coast from the ocean depths, and giant kelp (the dominant species on the Central Coast) can grow more than a foot per day in good conditions. In 2014, however, an unprecedented marine heatwave hit the Northeast Pacific. Known as "the blob," it spread over the West Coast from Alaska to Central California. Around the same time, a major El Niño event brought warm water up the coast from the south.With all that warm water bathing the coast, kelp growth rates dropped dramatically. That meant less kelp detritus drifting into the crevices of the reefs, and sea urchins began to emerge in search of food. With no sea stars around to attack them, the urchins mowed down the living kelp fronds, turning kelp forests into urchin barrens."It happened so fast, before we knew it we had lost over 80 percent of the historic kelp forest cover in Northern California," Smith said. "We also had an urchin outbreak on the Central Coast, but not to the same extent as in the areas north of San Francisco."Smith and his colleagues found that sea otters on the Central Coast responded to the urchin outbreak by increasing their urchin consumption dramatically, eating about three times as many sea urchins as they had prior to 2014. Thanks to an abundance of prey (including an increase in mussels as well as urchins), the sea otter population increased substantially after 2014, from about 270 to about 432 sea otters in the Monterey region at the southern end of Monterey Bay.Yet the urchin barrens remained. A close look at sea otter foraging behavior explained why. Smith's team found that the otters were feeding on urchins in the remaining patches of kelp forest, but not in the urchin barrens."It's easy to see from shore where they are diving repeatedly and coming up with sea urchins," he said.The dive team surveyed those places, as well as areas not being targeted by otters, and collected urchins to examine in the lab. The researchers found that urchins from the kelp beds had much higher nutritional value than those from the urchin barrens, with large, energy-rich gonads. In the barrens, however, the urchins are starved and not worth the effort to a hungry otter."Some people call them zombie urchins," Smith said. "You open them up, and they're empty. So the otters are ignoring the urchin barrens and going after the nutritionally profitable urchins in the kelp forest."By doing this, the sea otters are helping to maintain those patches of healthy kelp forest, which are now crucially important for the persistence of giant kelp along the coast. Spores produced from those remaining patches could eventually reseed the barren areas and restore the kelp beds.Sea otters alone, however, won't disrupt the urchin barrens. Some other factor is needed to clear enough urchins from the barrens to enable new kelp plants to grow there. Smith said another predator could help knock down the urchin population, or a disease, or even a major storm bringing large, bottom-scouring waves. Some groups are even exploring human interventions, sending teams of volunteer divers out to remove sea urchins in an effort to restore the kelp forests.Mark Carr, professor and chair of ecology and evolutionary biology at UC Santa Cruz, said the differences between kelp forests on the southern, central, and northern coasts of California are striking. Carr, who is Smith's adviser but not a coauthor of the PNAS paper, has been studying kelp forests all along the West Coast for years. He said Southern California's kelp beds did not decline to the extent seen on the central and northern coasts."The difference in Southern California is that even though they lost the sea stars, they have other predators like the spiny lobster and California sheephead that are able to control urchin populations and allow the kelp forests to persist," Carr said.Northern California's kelp beds, in contrast, have fared much worse. The absence of sea otters north of San Francisco may be a factor, but it's hard to say because the dominant species of canopy-forming kelp is different, with bull kelp (Nereocystis leutkeana) dominant in the north and giant kelp (Macrocystis pyrifera) dominant on the central and southern coasts."It is possible that the presence of a healthy sea otter population in the north might have made those kelp forests more resilient, but it's hard to speculate," Carr said. "The role of a predator can be very different depending on where you are."The pioneering studies of sea otters and kelp forests conducted in the Aleutian Islands by James Estes, now a professor emeritus of ecology and evolutionary biology at UCSC, showed that as the sea otter population in the Aleutians recovered from near extinction, the otters transformed urchin barrens into kelp forests as they recolonized islands. But those interactions are playing out differently on the Central Coast, and could have yet another outcome in Northern California."This study not only fine tunes our understanding of the role of sea otters in kelp forests, it also emphasizes the importance of animal behavior," Smith said. "So much of this is driven by behavior -- the urchins shifting their behavior to active foraging, and the otters choosing to prey on healthy urchins in the kelp forest -- and these behavioral interactions have implications for the overall fate of the ecosystem."In addition to Smith, the coauthors of the paper include Joseph Tomoleoni and Sophia Lyon at the USGS Western Ecological Research Center, Michelle Staedler and Jessica Fujii at the Monterey Bay Aquarium, and Tim Tinker at UC Santa Cruz. This research was supported by the National Science Foundation.
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Geography
| 2,021 |
March 8, 2021
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https://www.sciencedaily.com/releases/2021/03/210308140740.htm
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Rise of marine predators reshaped ocean life as dramatically as sudden mass extinctions
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Evolutionary arms races between marine animals overhauled ocean ecosystems on scales similar to the mass extinctions triggered by global disasters, a new study shows.
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Scientists at Umeå University in Sweden and the Florida Museum of Natural History used paleontological databases to build a multilayered computer model of the history of marine life over the last 500 million years. Their analysis of the fossil record closely echoed a seminal 1981 study by paleontologist J. John Sepkoski -- with one key difference.Sepkoski's ground-breaking statistical work showed abrupt ocean-wide changes in biodiversity about 490 and 250 million years ago, corresponding to two mass extinction events. These events divided marine life into what he called "three great evolutionary faunas," each dominated by a unique set of animals.But the new model reveals a fourth.The fierce fight for survival that played out between predatory marine animals and their prey about 250 to 66 million years ago may have been an equally powerful force, reshaping ocean diversity into what we see today. This third grand transition was much more gradual than its predecessors and driven by organisms, rather than external processes."What we learned is that not all major shifts in animal life have been related to mass extinction events," said study lead author Alexis Rojas, who earned his Ph.D. at the University of Florida. Rojas is now a postdoctoral researcher at the Integrated Science Lab, a hub dedicated to interdisciplinary research at Umeå University.Many scientists have long held the view that external factors such as volcanic activity, asteroid impacts or changes in climate are the primary drivers of major shifts in the Earth's biosphere, said study co-author Michal Kowalewski, Rojas' doctoral adviser and the Florida Museum Thompson Chair of Invertebrate Paleontology."The fossil record tells us that some of the key transitions in the history of life were rapid changes triggered by abrupt external factors. But this study shows that some of those major transitions were more gradual and may have been driven by biological interactions between organisms," he said.One reason Sepkoski's work was so revolutionary was that he took a mathematical approach to a practical problem: The fossil record is too big and complex for one person to be able to discern life's underlying patterns by looking at specimens alone."When its components are examined individually or in small groups, the complexity of their form, function, interaction, and history often seems overwhelming, and almost infinite," he wrote in the introduction to his 1981 study.Organizing these components into a hierarchy of systems, he argued, presented a more complete view. Sepkoski's modelling divided 500 million years of ocean life into three great dynasties, each separated by a mass extinction that cleared the way for new groups to flourish and dominate. After the reign of trilobites, clamlike animals known as brachiopods and certain ancient corals and ammonites rose to prominence. After the cataclysmic end-Permian extinction, sometimes known as the "Great Dying," they were in turn replaced by snails, clams, crustaceans, modern corals and various kinds of bony fishes.Sepkoski's hypothesis fundamentally changed how scientists thought about the history of life, Kowalewski said. It offered an organized way of understanding the history of marine ecosystems -- the overarching storyline and plot twists.But as our knowledge of the fossil record grows, so does Sepkoski's dilemma of how to analyze such vast and complex information, said Kowalewski."With millions of fossil specimens now documented, there is simply no feasible way for our brains to process such massive archives of paleontological data," he said. "Fortunately, analytical methods continue to improve, giving us better ways to extract and examine information hidden inside these immensely complex data."Rojas took on this challenge by using the latest advancements in data modelling. Specifically, he was interested in using complex network tools to create a better representation of the fossil record. Unlike other approaches in paleobiology, complex networks use a linked structure of nodes representing physical and abstract variables to uncover underlying patterns in a given system. Network approaches can be applied to social phenomena -- for example, showing a Facebook user's patterns of interactions with friends on the platform -- but they can also be applied to complex natural systems. Like Sepkoski, Rojas is a classically trained paleontologist looking for a fresh perspective on the fossil record."There are many processes happening at the same time at multiple scales: in your neighborhood, your country and across the entire planet. Now imagine the processes that occur in one day, one year or 500 years. What we are doing is trying to understand all these things across time," he said.A simple network might consist of a single layer -- all records of animal life and where they lived. But Rojas and his colleagues' network incorporates different intervals of time as individual layers, a feature lacking in previous research on macroevolution. The result is what Rojas described as a new, abstracted fossil record, a complement to the physical fossil record represented by the specimens in museum collections."It's important because the questions we are asking, the processes we are studying, occur at different scales in time and space," Rojas said. "We've taken some steps back so we can look at the entire fossil record. By doing that, we can explore all sorts of questions."Think of it like navigating a Google Earth that represents the oceans over the last 500 million years. When and where would you go?"Our interactive map of marine life shows smaller groups of animals and their interactions within each evolutionary fauna," Rojas said. "At the most basic levels, this map shows ocean regions with particular animals. The building blocks of our study are the individual animals themselves."This complex network shows what Sepkoski's model could not capture: a gradual transition in ocean life coincident with the Mesozoic Marine Revolution, which started about 150 million years ago during the Mesozoic Era. First hypothesized in the 1970s, this revolution was caused by the rapid increase of marine predators such as bony fish, crustaceans and snails, which have dominated oceans ever since. Their proliferation drove prey to become more mobile, hide beneath the ocean floor or enhance their defenses by thickening their armor, developing spines or improving their ability to regenerate body parts.Sepkoski knew about the Mesozoic Marine Revolution, but his model, limited by the methods and data available at the time, was unable to delineate the ocean ecosystems preceding and following this gradual transition. The study by Rojas and his colleagues demonstrates that both physical and biological processes play key roles in shaping ocean life at the highest levels."We are integrating the two hypotheses -- the Mesozoic Marine Revolution and the three great evolutionary faunas into a single story," Rojas said. "Instead of three phases of life, the model shows four."Joaquin Calatayud, Magnus Neuman and Martin Rosvall of Umeå University also co-authored the study.
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Geography
| 2,021 |
March 8, 2021
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https://www.sciencedaily.com/releases/2021/03/210308111957.htm
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Oceans were stressed preceding abrupt, prehistoric global warming
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Microscopic fossilized shells are helping geologists reconstruct Earth's climate during the Paleocene-Eocene Thermal Maximum (PETM), a period of abrupt global warming and ocean acidification that occurred 56 million years ago. Clues from these ancient shells can help scientists better predict future warming and ocean acidification driven by human-caused carbon dioxide emissions.
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Led by Northwestern University, the researchers analyzed shells from foraminifera, an ocean-dwelling unicellular organism with an external shell made of calcium carbonate. After analyzing the calcium isotope composition of the fossils, the researchers concluded that massive volcanic activity injected large amounts of carbon dioxide into the Earth system, causing global warming and ocean acidification.They also found that global warming and ocean acidification did not just passively affect foraminifera. The organisms also actively responded by reducing calcification rates when building their shells. As calcification slowed, the foraminifera consumed less alkalinity from seawater, which helped buffer increasing ocean acidity."The formation and dissolution of calcium carbonate help regulate the acidity and alkalinity of seawater," said Northwestern's Andrew Jacobson, a senior author of the study. "Our calcium isotope data indicate that reduced foraminiferal calcification worked to dampen ocean acidification before and across the PETM.""This is a pretty new concept in the field," added Gabriella Kitch, the study's first author. "Previously, people thought that only the dissolution of carbonates at the sea floor could increase alkalinity of the ocean and buffer the effects of ocean acidification. But we are adding to existing studies that show decreased carbonate production has the same buffering effect."The research was published online last week (March 4) in the journal Jacobson is a professor of Earth and planetary sciences at Northwestern's Weinberg College of Arts and Sciences. Kitch is a Ph.D. candidate and National Science Foundation Graduate Research Fellow in Jacobson's laboratory. Northwestern Earth science professors Bradley Sageman and Matthew Hurtgen, as well as collaborators from the University of California-Santa Cruz (UCSC) and the University of Kansas, coauthored the paper with Jacobson and Kitch.To study oceanic conditions during the PETM, the researchers examined the calcium isotope composition of foraminiferal fossils collected from two sites -- one in the southeast Atlantic Ocean and one in the Pacific Ocean -- by the Ocean Drilling Program.Because each fossilized shell is about the size of a single grain of sand, UCSC researchers physically collected the tiny specimens by first identifying them under a microscope. After sorting the shells from bulk sediments, the Northwestern team dissolved the samples and analyzed their calcium isotope composition using a thermal ionization mass spectrometer."The work is very challenging," Jacobson said. "To manipulate these tiny materials, you have to pick them up, one by one, with a wet paintbrush tip under a microscope."As the shells formed more than 56 million years ago, they responded to oceanic conditions. By examining these shells, the Northwestern team found that calcium isotope ratios increased prior to the onset of the PETM."We are looking at one group of organisms that built their shells in one part of the ocean, recording the seawater chemistry surrounding them," Kitch said. "We think the calcium isotope data reveal potential stress prior to the well-known boundary."Other archives indicate that the atmosphere-ocean system experienced a massive carbon dioxide release immediately before the PETM. When atmospheric carbon dioxide dissolves in seawater, it forms a weak acid that can inhibit calcium carbonate formation. Although it is still undetermined, Earth scientists believe the carbon release most likely came from volcanic activity or cascading effects, such as a release of methane hydrates from the seafloor as a result of ocean warming."My suspicion is that it's both of these factors or some sort of combination," Sageman said. "Most big events in Earth's history represent a confluence of many actors coming together at the same time."This is the third study led by Jacobson to find that ocean acidification precedes major environmental catastrophes that correlate with large igneous province eruptions. Last month, Jacobson's team published results finding that volcanic activity triggered a biocalcification crisis prior to an ocean anoxic event that occurred 120 million years ago. Just over a year ago, Jacobson's team published another study finding ocean acidification preceded the asteroid impact leading to the Cretaceous-Paleogene mass extinction event 66 million years ago, which included the demise of dinosaurs.In all three studies, Jacobson's team used sophisticated tools in his laboratory to analyze the calcium isotope composition of calcium carbonate fossils and sediment. Jacobson said a clear pattern is emerging. Influxes of carbon dioxide led to global warming and ocean acidification and, ultimately, to massive environmental changes."In all of our studies, we consistently see an increase in calcium isotope ratios before the onset of major events or extinction horizons," Jacobson said. "This seems to point to similar drivers and common responses.""Perhaps the calcium isotope system has a sensitivity to the earliest phases of these events," Sageman added.Many researchers study the PETM because it provides the best analog for current-day, human-caused global warming. The carbon influx during the PETM is similar to the amount of carbon released during the past two centuries. The timescales, however, differ significantly. Temperatures during the PETM increased by 5 to 8 degrees Celsius over 170,000 years. With human-caused climate change, the same level of warming is projected to occur in less than 200 years, if carbon dioxide emissions remain unabated.Frighteningly, terrestrial and ocean stress, including a major decrease in foraminiferal calcification, accompanied the PETM."The PETM is a model for what happens during major large carbon cycle perturbations," Jacobson said. "A lot of predictions for Earth's future climate rely on understanding what happened during the PETM."
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Geography
| 2,021 |
March 8, 2021
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https://www.sciencedaily.com/releases/2021/03/210308111915.htm
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Sea level rise up to four times global average for coastal communities
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Coastal populations are experiencing relative sea-level rise up to four times faster than the global average -- according to new research from the University of East Anglia.
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A new study published today in The impact of subsidence combined with sea-level rise has until now been considered a local issue rather than a global one.But the new study shows that coastal inhabitants are living with an average sea level rise of 7.8 mm -- 9.9 mm per year over the past twenty years, compared with a global average rise of 2.6mm a year.And the impacts are far larger than the global numbers reported by the Intergovernmental Panel on Climate Change (IPCC).Lead researcher Prof Robert Nicholls, Director of the UK's Tyndall Centre for Climate Change Research and Chair of Climate Adaptation at the University of East Anglia, said: "Climate induced sea-level rise is caused by melting glaciers and thermal expansion of water due to rising global temperatures."Rapid rates of subsidence in deltas and especially cities on deltas are also human-caused, mostly due to groundwater pumping, also oil and gas extraction, and sediment resupply prevented by upstream dams, flood defences, sand extraction or mining."About 58 per cent of the world's coastal population lives on deltas where land is subsiding. Less than 1 per cent of global coastal population lives where land is uplifting."We wanted to look at the big picture globally, to better understand the impact of global sea-level rise combined with measurements of sinking land."We found that coastal populations live with sea-level rise at three and four times the global average and that the impacts of sea-level rise being experienced today are much larger than the global numbers being reported by the Intergovernmental Panel on Climate Change (IPCC)."Addressing human-induced subsidence is important in the short term, as it is an essential coastal adaptation to protect people and economies," he added.The research team assessed four components of relative sea-level change -- climate induced sea-level change, the effects of glacier weight removal causing land uplift or sinking, estimates of river delta subsidence and subsidence in cities.Sea-level measurements were taken from satellite data. The team then weighted their results by population to show their importance to people.The overall analysis used the Dynamic Interactive Vulnerability Assessment (DIVA) model which is designed for understanding coastal management needs.They found that high rates of relative sea-level rise are most urgent in South, South East and East Asia as the area has many subsiding deltas and coastal flood plains, growing coastal megacities and more than 70 per cent of the world's coastal population.They also found that over the 20th Century, the city of Tokyo experienced net subsidence of 4m, while Shanghai, Bangkok, New Orleans, and Jakarta, have experienced between 2m and 3m subsidence.In Tokyo, Shanghai and Bangkok the subsidence has been stopped or greatly reduced by reduced groundwater extraction, while in other cities there has been little direct response to reduce subsidence.Prof Robert Nicholls said: "One of the main reasons that Jakarta, the capital city of Indonesia, is being moved to Borneo is because the city is sinking due to groundwater extraction from shallow wells."We hope that our analysis improves the understanding of how sea-level rise and subsidence are hand-in hand for science and coastal management policy worldwide. Jakarta might be just the beginning."The research was led by the University of East Anglia (UK) in collaboration with the Global Climate Forum, Berlin (Germany), Humboldt-University, Berlin (Germany), Bournemouth University (UK), Kiel University (Germany), Université de Toulouse (France), the University of Southampton (UK) and East China Normal University, Shanghai (China).It was funded by the EC Horizon 2020 Framework Programme, IDRCEC Seventh Framework Programme, and EC Seventh Framework Programme.
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Geography
| 2,021 |
March 8, 2021
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https://www.sciencedaily.com/releases/2021/03/210308084230.htm
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Irrigation management key for bioenergy production to mitigate climate change
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To avoid a substantial increase in water scarcity, biomass plantations for energy production need sustainable water management, a new study shows. Bioenergy is frequently considered one of the options to reduce greenhouse gases for achieving the Paris climate goals, especially if combined with capturing the CO
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"Irrigation of future biomass plantations for energy production without sustainable water management, combined with population growth, could double both the global area and the number of people experiencing severe water stress by the end of the century, according to our computer simulations," says lead author Fabian Stenzel from the Potsdam Institute for Climate Impact Research (PIK) who developed the research idea in the Young Scientists Summer Program of the International Institute for Applied Systems Analysis (IIASA). "However, sustainable water management could almost halve the additional water stress compared to another analyzed scenario of strong climate change unmitigated by bioenergy production.""Sustainable water management means both political regulation -- such as pricing or water allocation schemes -- to reduce the amounts of water taken from rivers as well as on-farm improvements to make more efficient use of the water," says co-author Sylvia Tramberend from IIASA. This could include cisterns for rainwater collection or mulching to reduce evaporation. "Moreover, sustainable water management includes the preservation of reliable river flows to ensure undisturbed ecosystems in and alongside rivers. Up- and downstream river management may in fact require international cooperation calling for more transboundary river management as well as between different water users -- that's the challenge ahead for integrated water resource management."Largely unmitigated global warming together with population growth would increase the number of people under water stress by about 80% in the simulations. Enhanced use of bioenergy with carbon capture and storage could limit climate change: When plants grow, they take up COIn many scenarios, these are seen as necessary for meeting ambitious climate mitigation targets if direct emission reductions proceed too slowly, and to balance any remaining greenhouse gas emissions that are difficult or impossible to reduce, for instance potentially in aviation, certain types of industry or in livestock production."According to existing scenarios, biomass plantations could increase by up to 6 million square kilometers if global warming is to be limited to 1.5 degrees Celsius by the end of the century, the more ambitious of the two temperature targets of the Paris Agreement," says co-author Dieter Gerten from PIK. "We use these scenario inputs to run simulations in our high-resolution global vegetation and water balance model to explore the freshwater implications. While substantial irrigation implied in a bioenergy plus CCS scenario including population growth suggests a 100% increase in the number of people facing water stress, combining it with sustainable water management brings the number down to 60%. This, of course, is still an increase, so challenging tradeoffs are on the table."Regions that already suffer from water stress today would be most affected in the climate change scenario, like the Mediterranean, the Middle East, northeastern China, South-East and southern West Africa. In the bioenergy plus CCS scenario without sustainable water management, high water stress extends to some otherwise unaffected regions, like the East of Brazil and large parts of Sub-Saharan Africa. Here, large biomass plantation areas in need of irrigation are assumed in the scenario analyzed.Climate mitigation is one of the Sustainable Development Goals (SDGs) the world has agreed to achieve. The water-energy-environment nexus studied in this research highlights that pathways to sustainability must consider all affected SDGs."The numbers show that either way, sustainable water management is a challenge urgently to be addressed," says co-author Wolfgang Lucht, head of PIK's Earth System Analysis research department. "This new study confirms that measures currently considered to stabilize our climate, in this case bioenergy plus CCS, must take into account a number of further dimensions of our Earth system -- water cycles are one of them. Risks and tradeoffs have to be carefully considered before launching large-scale policies that establish biomass markets and infrastructure. The concept of Planetary Boundaries considers the whole Earth system, including but not limited to climate. Particularly the integrity of our biosphere must be acknowledged to protect a safe operating space for humanity."
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Geography
| 2,021 |
March 5, 2021
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https://www.sciencedaily.com/releases/2021/03/210305113513.htm
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What can stream quality tell us about quality of life?
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As the source of most of the water we drink and a place where we often go to recreate and enjoy nature, streams represent a crucial point-of-contact between human beings and the environment.
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Now researchers in the College of Natural Resources and Environment and the Department of Biological Systems Engineering are using stream quality data to find new insights into the interactions between the health of our natural spaces and human well-being.Their findings, published in the journal "We started off wanting to explore the general, intuitive relationship between human well-being and ecosystem health," explained Paul Angermeier, professor in the Department of Fish and Wildlife Conservation and assistant unit leader of the Virginia Cooperative Fish and Wildlife Research Unit for the U.S. Geological Survey. "Many of us intuit that healthy ecosystems produce benefits that accrue to people, but that outcome isn't well documented in a quantitative way."To document that relationship, the research team had to break from the environmental quality management processes that too often separate the natural world from human experiences."When we consider natural resources, we tend to think about whether we're managing an environment for nonhuman considerations or human ones," said Associate Professor Leigh-Anne Krometis, of the Department of Biological Systems Engineering, which is in both the College of Engineering and the College of Agriculture and Life Sciences. "For instance, at the state level we have a department of environmental quality and a department of health, which both deal with the subject of water quality, but in different ways. What we wanted to see was how those two perspectives converge."To find correlations across the state, the researchers used two key data sets: water quality measurements provided by the Virginia Department of Environmental Quality and county-level demographics data from the U.S. Census Bureau. They considered 13 indicators of human well-being, four demographic metrics, and two indicators of stream health."We had large data sets that we had to organize and process," explained Professor Marc Stern of the Department of Forest Resources and Environmental Conservation. "Our expectations on finding meaningful relationships between stream health and human factors weren't that high. The fact that they showed up so distinctly was a surprise."What the researchers found is that there is a strong correlation between ecosystem health and human demographics, particularly along the lines of race. Stream conditions were found to be better in counties with higher percentages of white residents. More polluted streams were correlated with higher degrees of overall mortality."The term environmental justice is important to bring into our discussion," noted Stern, a senior fellow in the Center for Leadership in Global Sustainability. "These findings relate to the broader issue of systemic prejudices and the reality that our institutions and social systems do not favor marginalized communities. They get caught up in a cycle of being left behind, and while it's not impossible to break that pattern, it's going to take work."Virginia is a suitable microcosm for revealing such dimensions: the state has high-density urban cities, suburban and rural areas, coastal and mountain geographies, and a broad socio-economic diversity that make it a useful starting point for broader research into the subject of human-environment interactions.A crucial next step for the researchers is understanding how people are interacting with natural environments."We still don't have hard data on how people are interacting with nature," said Angermeier, who, along with Krometis, is an affiliate of Virginia Tech's Global Change Center housed in the Fralin Life Sciences Institute. "For instance, we found that mortality rates for people are correlated with contamination levels in fish. What does that mean? Are people eating contaminated fish, are they merely sharing a polluted water source, or is it something else? A better understanding of the mechanisms by which people are interacting with water will help us draw clearer conclusions about health outcomes."The project was funded by Virginia Tech's Global Change Center, the Institute for Society, Culture, and the Environment, and the Fralin Life Sciences Institute. The contributing faculty members aim to expand their research by looking to see if similar correlations between environment health and human well-being extend across the Mid-Atlantic and the U.S. as a whole.
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Geography
| 2,021 |
March 5, 2021
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https://www.sciencedaily.com/releases/2021/03/210305080129.htm
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Antarctic seals reveal worrying threats to disappearing glaciers
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More Antarctic meltwater is surfacing than was previously known, modifying the climate, preventing sea ice from forming and boosting marine productivity- according to new research from the University of East Anglia (UEA).
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For the first time, researchers have been able to obtain full-depth glacial meltwater observations in winter, using instruments attached to the heads of seals living near the Pine Island Glacier, in the remote Amundsen Sea in the west of Antarctica.The harsh environmental conditions in the Antarctic limit the use of most traditional observation systems, such as ships and airplanes, especially in winter. But oceanographers working with biologists used data collected by tagged seals to measure water temperature and salinity.The paper, 'Winter seal-based observations reveal glacial meltwater surfacing in the southeastern Amundsen Sea', is published in today the journal The researchers found a highly variable meltwater distribution with two meltwater-rich layers -- one in the upper 250 metres and another at around 450 metres deep -- connected by scattered meltwater-rich columns. The hydrographic signature of meltwater is clearest in winter, when its presence can be unambiguously mapped; this analysis is only possible in winter.The surfacing meltwater provides near-surface heat that helps to maintain areas of open seawater surrounded by sea ice, close to glaciers, and may change the melting rate of these fragile ice shelves. These findings offer important clues to better predicting the future climate system and sea level rise.Pine Island Glacier is rapidly melting, exporting the glacial meltwater into the ocean. Glacial meltwater is thought to play a role in hydrography and sea ice distribution, but until now little has been known about it.Yixi Zheng, a postgraduate researcher in UEA's School of Environmental Sciences, is the lead author of the study. She said: "The temperature and salinity of water change everywhere glacial meltwater exists. Just like looking for a 'fingerprint' of glacial meltwater, we use temperature and salinity data to track the glacial meltwater."The glacial meltwater distribution is very patchy. It doesn't mix well with the ambient water, instead flowing along two meltwater-rich layers in the upper 250 metres and at around 450 metres, connected by meltwater-rich columns."As the glacial meltwater is warmer and fresher than the ambient water, it is lighter than the ambient water and more likely to rise up. It brings heat and nutrients such as iron to the near surface, which may melt the sea ice near glaciers and increase the nutrient level near the surface. This enhances the air-sea interactions, and the meltwater-related nutrient may boost the growth of marine planktons like algae."The winter processes revealed by the study are likely important for bringing nutrients to the near-surface layer prior to the spring bloom, and for bringing heat to the surface to prevent sea ice from forming. This action helps to maintain the open water areas, called polynyas, in front of glaciers.Many glaciers around Antarctica are thinning rapidly, due primarily to basal melting (i.e. melting that occurs at the interface between the ocean and the ice shelf glacier). The strongest melt has been reported in west Antarctic glaciers such as the Pine Island Glacier, where the research took place.The volume of meltwater produced is small in comparison with the volumes of Antarctic shelf seas, but it is believed to exert a disproportionate influence on regional circulation and climate.The heat from the meltwater is likely to prevent sea ice formation, allowing melting of sea ice and thus increasing the extent of open water areas in front of glaciers.The strong offshore wind near the glacier front may also transport warm near-surface water further and expand the meltwater-influenced region. These enlarged polynyas (open-water areas surrounded by ice) can then lead to enhanced air-sea fluxes and have further impacts on iceberg calving and glacier melting.Seven southern elephant seals (Mirounga leonina) and seven Weddell seals (Leptonychotes weddellii) were captured and tagged with CTD-Satellite Relayed Data Loggers around the Amundsen Sea in February 2014. The data were gathered by Marine Mammals Exploring the Oceans Pole to Pole (MEOP). Researchers from the universities of Gothenburg and Rhode Island also contributed.The scientists say further research is required. The study was based on one year of seal-tag data from the Pine Island Glacier, so it can't be used to calculate trends over time or take into account interannual variability such as the El Nino-Southern Oscillation, which may affect the global water temperature.
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Geography
| 2,021 |
March 5, 2021
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https://www.sciencedaily.com/releases/2021/03/210305080126.htm
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The collapse of Northern California kelp forests will be hard to reverse
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Satellite imagery shows that the area covered by kelp forests off the coast of Northern California has dropped by more than 95 percent, with just a few small, isolated patches of bull kelp remaining. Species-rich kelp forests have been replaced by "urchin barrens," where purple sea urchins cover a seafloor devoid of kelp and other algae.
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A new study led by researchers at UC Santa Cruz documents this dramatic shift in the coastal ecosystem and analyzes the events that caused it. This was not a gradual decline, but an abrupt collapse of the kelp forest ecosystem in the aftermath of unusual ocean warming along the West Coast starting in 2014, part of a series of events that combined to decimate the kelp forests.Published March 5 in "There were a lot of disruptions at one time that led to this collapse, and the system now persists in this altered state," said first author Meredith McPherson, a graduate student in ocean science at UC Santa Cruz. "It's a naturally dynamic system that has been really resilient to extreme events in the past, but the die-off of sunflower stars caused the resilience of the ecosystem to plummet. As a result, the kelp forests were not able to withstand the effects of the marine heatwave and El Niño event combined with an insurgence of sea urchins."The researchers used satellite imagery from the U.S. Geological Survey's Landsat missions going back to 1985 to assess historical changes in kelp forest canopy cover.Bull kelp is the dominant canopy-forming kelp species north of San Francisco Bay, while giant kelp is dominant to the south. Both species thrive when strong upwelling of cold, deep water brings nutrients to the surface along the coast. Marine heatwaves and El Niño events suppress coastal upwelling, resulting in warm water and low nutrient conditions in which kelp grows poorly."There have been big changes before, when a strong El Niño has reduced the kelp canopy dramatically, but in the past it's always come back," said coauthor Raphael Kudela, professor and chair of ocean science at UC Santa Cruz. "The loss of resiliency is what made this time different -- the combination of ocean warming and the loss of the sea stars allowed the urchins to take over."Sea star wasting disease first appeared in 2013, affecting all types of sea stars along the West Coast. The sunflower sea star was among the hardest hit species and was recently was listed as critically endangered by the International Union for Conservation of Nature.Late 2014 saw the advent of an unusual marine heatwave in the Northeast Pacific which became known as "the blob" as it spread down the West Coast in 2015. A strong El Niño event began to develop around the same time, bringing warm water up the coast from the south. The warm water coincided with an increase in sea urchin populations along the North Coast."The alignment of all of those events resulted in an incredibly dramatic loss of kelp," Kudela said.Kelp forests declined all along the California coast, but not to the same extent as in Northern California. Bull kelp is an annual species that regrows each year, which may make it more sensitive to these stressors than giant kelp. But another critical difference in Northern California is the absence of other urchin predators such as sea otters, which have enabled patches of healthy kelp forest to persist in Monterey Bay, for example."Sea otters haven't been seen on the North Coast since the 1800s," McPherson said. "From what we observed in the satellite data from the last 35 years, the kelp had been doing well without sea otters as long as we still had sunflower stars. Once they were gone, there were no urchin predators left in the system."What that means for the future, she said, is that the prospects for recovery of the Northern California kelp forests are poor unless sunflower sea stars or some other urchin predator returns to the system. Even if temperature and nutrient conditions are good for kelp growth, new kelp plants will have a hard time getting established in the midst of the urchin barrens.There have been some efforts to have divers manually remove urchins from selected areas and see if that can help the kelp to recover, led by the Reef Check California Program (which contributed subtidal survey data for the study). An outbreak of sea urchin disease could also potentially lead to mass mortality of urchins and give the kelp a chance to recover. In the absence of some mechanism to reduce the urchin populations, however, it will be hard to restore and maintain the kelp forests, according to McPherson."There's a lot of research and discussion now about the best management strategies for the future," she said. "It's important to understand and monitor the whole system. If we're going to undertake restoration efforts, we need to make sure to do it when the temperature and nutrient conditions are right for the kelp."Kudela said ocean temperatures are beginning to cool down along the coast, after remaining above normal since 2014. "This year we are finally seeing ocean temperatures starting to cool off, so we're hoping that it reverses naturally and the kelp is able to take off again," he said. "There's really not much we can do except to keep monitoring it. Of course, the long-term solution is to reduce our carbon emissions so we don't have these extreme events."
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Geography
| 2,021 |
March 4, 2021
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https://www.sciencedaily.com/releases/2021/03/210304125353.htm
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Female gannets go the extra mile to feed chicks
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Female gannets travel further than male gannets to find fish for their chicks in some years but not others, new research shows.
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Scientists tracked breeding gannets from Grassholm Island in Wales over 11 years with tiny GPS devices and by measuring isotopic signatures in their blood.Male gannets flew an average of 220km to forage for their chicks, while females averaged 260km. Some birds travelled 1,000km on a single trip.The scientists also found that the two sexes selected different habitats and foraged at different times of day, but some years they were more in sync.Dr Bethany Clark worked on the research during her PhD at the University of Exeter's Environmental and Sustainability Institute, and now works at BirdLife International."Our study used GPS tracking to investigate behaviour and stable isotopes revealed information about their diet," she said."The foraging differences we found might indicate that males and females respond differently to changes in environmental conditions, such as how windy it is."Their dietary preferences were more consistent over the years: males tended to eat larger fish from closer to shore than females."Our results highlight the importance of long-term studies."Stephen Votier, Professor of Seabird Ecology at the Lyell Centre, Heriot-Watt University, in Edinburgh said: "These birds are true ocean wanderers -- travelling thousands of miles at sea throughout their lives to find food. It must be a pretty challenging four and half months raising their chicks each year."The sexes are virtually identical so differences are not due to size. Instead, we think males stay close to home because they establish and maintain the nest and perhaps because of subtle differences in taste."
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Geography
| 2,021 |
March 4, 2021
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https://www.sciencedaily.com/releases/2021/03/210304125333.htm
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NASA's ICESat-2 satellite reveals shape, depth of Antarctic ice shelf fractures
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When a block of ice the size of Houston, Texas, broke off from East Antarctica's Amery Ice Shelf in 2019, scientists had anticipated the calving event, but not exactly where it would happen. Now, satellite data can help scientists measure the depth and shape of ice shelf fractures to better predict when and where calving events will occur, according to researchers.
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Ice shelves make up nearly 75% of Antarctica's coastline and buttress -- or hold back -- the larger glaciers on land, said Shujie Wang, assistant professor of geography at Penn State. If the ice shelves were to collapse and Antarctica's glaciers fell or melted into the ocean, sea levels would rise by up to 200 feet."When we try to predict the future contribution of Antarctica to sea-level rise, the biggest uncertainty is ice shelf stability," said Wang, who also holds an appointment in the Earth and Environmental Systems Institute. "There's no easy way to map the depth of fractures in the field over a regional scale. We found that satellite data can capture the depth and surface morphology of ice shelf fractures and thereby allow us to consistently monitor this information over a large range."Wang and her colleagues examined high-resolution data collected by the Ice, Cloud and Land Elevation Satellite (ICESat-2) over the Amery Ice Shelf, which is about the size of West Virginia, between October 2018 and November 2019. The satellite shoots green laser pulses to the land surface and uses reflected photons to determine surface height. Whereas other satellites have a resolution of several thousands of feet, ICESat-2 has a resolution of approximately 56 feet, enabling it to see smaller fractures and the fracture morphology.The researchers then ran the ICESat-2 data through an algorithm that identifies surface depression features to locate and characterize fractures in the ice. They reported their results in the journal The researchers identified three types of fractures -- U-shaped, parabolic-shaped and V-shaped fractures -- up to 164 feet deep in the ice shelf. They also realized that this surface information provides insights into what is happening hundreds of feet below the surface of the ice.Basal fracture morphology -- the shape and size of fractures at the base of the ice shelf -- is proportional to the surface depressions, according to Wang. As the glacier that the ice sheet is buttressing accumulates more snow and ice, the parabolic-shaped fractures flow toward the edges of the ice shelf. Once they cross a certain boundary, those surface fractures have a greater potential to penetrate deeper into the ice as the basal fractures extend upward. These fractures can then become V-shaped, potentially signaling that a rift -- a fracture that penetrates the entire thickness of the ice sheet -- has formed. These rifts are more likely to cause calving events."Incorporating satellite-based vertical information can improve future ice shelf models," Wang said. "It can help us actually predict calving fronts and where an ice shelf is vulnerable to these events."Other contributors to this study included Patrick Alexander and Marco Tedesco, Lamont-Doherty Earth Observatory at Columbia University and NASA Goddard Institute for Space Studies; Qiusheng Wu, University of Tennessee; and Song Shu, Appalachian State University.The National Science Foundation and NASA supported this study.
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Geography
| 2,021 |
March 4, 2021
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https://www.sciencedaily.com/releases/2021/03/210304100338.htm
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High-resolution ocean model provides insight into sea turtles' lost years
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An exquisitely detailed global ocean model simulation from the National Center for Atmospheric Research (NCAR) has given scientists rare insight into where baby sea turtles may go in their "lost years" after they scramble off the sandy beaches where they are born and swim into the open ocean.
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This look at a critically important period in the life cycle of endangered loggerhead turtles could help inform more comprehensive conservation efforts that encompass regions of the open ocean where young turtles grow, and not just the nesting beaches. It also pinpoints regions of the ocean that are important to study to better understand how to protect sea turtles."To understand where sea turtle hatchlings are being swept to when they enter the open ocean -- and how favorable that habitat is to turtle survival -- we need to simulate smaller scale ocean features, the jets and eddies that transport these younglings," said Cheryl Harrison, a researcher at the University of Texas Rio Grande Valley, who led the study. "The models typically used to simulate global ocean movement are too coarse for us to resolve these important features. The really exciting thing about this study is we were able to use a high-resolution, eddy-resolving model to track where turtles are traveling."The ocean simulation used for the new study, published in the journal The research was funded by the National Science Foundation, which is NCAR's sponsor, NASA, and the U.S. Department of Energy. Harrison began work on the study as a postdoctoral researcher at NCAR, working with oceanographer Matthew Long, who co-authored the study. Harrison is now an assistant professor at the University of Texas Rio Grande Valley.Loggerhead turtles nest on specific beaches scattered around the globe, often where strong currents come close to land. After hatching, the baby turtles head for the ocean, where they spend the next several years as they mature. Once they reach sexual maturity decades later, the turtles eventually return to the beach where they were born to mate and lay their own eggs before the cycle begins again.For the new study, Harrison and her colleagues studied how hatchlings are likely to disperse during the first year of their lives from nesting sites on the coasts of Japan, Florida, Cape Verde, Oman, west Australia, east Australia, Brazil, and South Africa. Because the baby sea turtles must stay near the surface of the ocean to breathe -- and because they are not yet able to swim for significant periods -- the researchers were able to emulate their possible journeys using a method known as particle tracking, which follows how particles "released" into the model move with simulated water trajectories over time.The results show that at many of the nesting sites, strong nearby currents -- including the Kuroshio, Gulf Stream, Brazil, and Agulhas currents -- sweep the turtles poleward to a region of ocean where two circular ocean currents (known as gyres) come together. This boundary between the subpolar and subtropical gyres is warm enough for the hatchlings to survive and also rich with zooplankton and other food that turtles depend on to survive.The study results help demarcate the regions where turtles from each beach are going in their "lost years" when ecologists cannot easily keep tabs on them. For example, turtles born in southeastern Florida travel with the Gulf Stream all the way to the Azores, a productive and warm ocean habitat perfect for nurturing them.At other nesting sites, such as the one on the coast of Oman, the hatchlings do not hitch a ride on a strong current to far-off ocean habitats. Instead, they use a local current that disperses them relatively nearby because the area waters are already suitable for the young turtles. This understanding of where the turtles go allows scientists to better understand what threats the turtles may be facing."Sea turtle hatchlings are very difficult to track and observe as they have high mortality rates and grow out of tags quickly," Harrison said. "Modelling studies help us close this observational gap and predict where they are going in the 'lost years.' Identifying ocean habitat helps us understand what factors are important for their survival in this life stage."
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Geography
| 2,021 |
March 4, 2021
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https://www.sciencedaily.com/releases/2021/03/210304100406.htm
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Limiting invasive species may be a better goal than eliminating them
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Managing invasive species -- not eliminating them altogether -- is a better use of time and conservation resources in many cases, according to a study led by a University of Alberta biologist.
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Every year, hundreds of introduced species cause billions of dollars in damage to ecosystems, agriculture and infrastructure in North America alone. The research, led by Stephanie Green, makes a case for working smarter, not harder, to temper the impact of destructive and widespread invasive species using a strategy called functional eradication."Rather than trying to completely eliminate invasive species that have spread over large areas, which is very challenging, functional eradication aims to limit their abundances below levels that damage the ecosystem in priority locations. Resources that might otherwise be wasted on attempting complete eradication can be spread to other areas, protecting more places from impacts," explained Green, assistant professor in the Department of Biological Sciences and Canada Research Chair in Aquatic Global Change Ecology and Conservation.Green partnered with Edwin Grosholz, an ecologist in the Department of Environmental Science and Policy at the University of California, Davis, to survey 232 natural resource managers and invasive species specialists in Canada and the United States."More than 90 per cent of these folks said the most destructive invaders in their regions were spread beyond a scale at which they could eradicate them, and instead local teams were engaged in a long-term battle to suppress or contain the species," explained Green.However, only two per cent said they had identified targets for when they had done enough to manage a species."This points to a major gap between the needs of the people who must make decisions about invasive species, and the information scientists and monitoring programs are collecting," said Grosholz.Managing widespread invasive species is a long-term endeavour, but not one without hope, Green explained."Involving local communities in the functional eradication process is essential for maintaining the capacity needed to continually suppress these invaders."An example of functional eradication at work is invasive lionfish. The beautiful Indo-Pacific fish, which are popular in aquariums, have spread throughout the Caribbean Sea and the Atlantic Ocean, where they prey on many native species. They are now caught and consumed as food, and used in local art. The financial incentives for catching lionfish are also serving to reduce their population below levels that affect native species in the area.Similar strategies can be applied to the European green crab, an invasive species found along the Pacific and Atlantic coasts in Canada and the United States, as well as Prussian carp, which is spreading throughout central Canada, including in Alberta's Bow River."Our study shows that ecologically damaging and widespread invasive species are prime candidates for functional eradication. To effectively keep populations down in priority areas, targets need to be based on how many of the invasive species it takes to cause major changes in the ecosystem," said Green.
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Geography
| 2,021 |
March 3, 2021
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https://www.sciencedaily.com/releases/2021/03/210303142520.htm
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Humans control majority of freshwater ebb and flow on Earth
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Humans have made a remarkable impact on the planet, from clearing forests for agriculture and urbanization to altering the chemistry of the atmosphere with fossil fuels. Now, a new study in the journal Nature reveals for the first time the extent of human impact on the global water cycle.
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The study used NASA's Ice, Cloud and Land Elevation Satellite (ICESat-2) to assemble the largest ever dataset of seasonal water levels in more than 227,000 lakes, ponds and reservoirs worldwide. The data reveal that even though human-managed reservoirs comprise only a small percentage of all water bodies, they account for 57% of the total seasonal water storage changes globally."We tend to think of the water cycle as a purely natural system: Rain and snowmelt run into rivers, which run to the ocean where evaporation starts the whole cycle again," said Sarah Cooley, a postdoctoral researcher at Stanford University who launched the research project while a graduate student at Brown University. "But humans are actually intervening substantially in that cycle. Our work demonstrates that humans are responsible for a majority of the seasonal surface water storage variability on Earth."Cooley led the work with Laurence Smith, a professor of environmental sciences at Brown, and Johnny Ryan, a postdoctoral researcher at the Institute at Brown for Environment and Society.The researchers say the study provides a critical baseline for tracking the global hydrological cycle as climate change and population growth put new stresses on freshwater resources.Launched into orbit in 2018, ICESat-2's primary mission is to track changes in the thickness and elevation of ice sheets around the world. It does so with a laser altimeter, which uses pulses of light to measure elevation to an accuracy of 25 millimeters. Cooley, who has experience using satellites to study water levels in Arctic lakes, was interested in bringing the satellite's precise measurement capacity to bear on lake levels worldwide.Cooley says that ICESat-2's laser altimeter has far greater resolution than instruments used to measure water levels in the past. That made it possible to gather a large, precise dataset that included small ponds and reservoirs."With older satellites, you have to average results over a large area, which limits observations to only the world's largest lakes," Cooley said. "ICESat has a small footprint, so we can get levels for small lakes that we couldn't get close to before. That was important for understanding global water dynamics, since most lakes and reservoirs are pretty small."From October 2018 to July 2020, the satellite measured water levels in 227,386 bodies of water, ranging in size from the American Great Lakes to ponds with areas less than one tenth of a square mile. Each water body was observed at different times of year to track changes in water levels. The researchers cross-referenced the water bodies they observed with a database of reservoirs worldwide to identify which water bodies were human-controlled and which were natural.While countries like the U.S. and Canada gauge reservoir levels and make that information publicly available, many countries don't publish such data. And very few non-reservoir lakes and ponds are gauged at all. So there was no way to do this analysis without the precise satellite observations, the researchers said.The study found that while natural lakes and ponds varied seasonally by an average of .22 meters, human-managed reservoirs varied by .86 meters. Added together, the much larger variation in reservoirs compared to natural lakes means that reservoirs account for 57% of the total variation. In some places, however, human influence was even stronger than that. For example, in arid regions like the Middle East, American West, India and Southern Africa, variability attributed to human control surges to 90% and above."Of all the volume changes in freshwater bodies around the planet -- all the floods, droughts and snowmelt that push lake levels up and down -- humans have commandeered almost 60% of that variability," Smith said. "That's a tremendous influence on the water cycle. In terms of human impact on the planet, this is right up there with impacts on land cover and atmospheric chemistry."As the first global quantification of human impacts on the water cycle, the results will provide a crucial baseline for future research on how the impacts affect ecosystems around the world, the researchers say.In a separate study published recently in Geophysical Research Letters, the research team was able to use ICESat-2 data to shed light on how reservoir water is being used. The study showed that in places like the Middle East, reservoir levels tend to be lower in summer and higher in the winter. That suggests that water is being released in the dry season for irrigation and drinking water. In contrast, the trend in places like Scandinavia was the opposite. There, water is released in the winter to make hydroelectric power for heating."This was an exploratory analysis to see if we can use remote sensing to understand how reservoirs are being used at a global scale," Ryan said.Smith says he expects satellites to play an increasing role in study of the Earth's water cycle. For the past few years, he has been working with NASA on the Surface Water and Ocean Topography mission, which will be dedicated entirely to this kind of research."I think within the next three years we are going to see an explosion of high-quality satellite hydrology data, and we're going to have a much better idea of what's going on with water all over the planet," Smith said. "That will have implications for security, trans-boundary water agreements, forecasting crop futures and more. We're right on the edge of a new understanding of our planet's hydrology."The research was supported by the NASA Studies with ICESat-2 Program (80NSSC20K0963) and the NASA Surface Water and Ocean Topography mission (80NSSC20K1144S).
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Geography
| 2,021 |
March 3, 2021
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https://www.sciencedaily.com/releases/2021/03/210303142501.htm
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Reconstructing historical typhoons from a 142-year record
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A team of scientists has, for the first time, identified landfalls of tropical cyclones (TCs) in Japan for the period from 1877 to 2019; this knowledge will help prepare for future TC disasters.
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In recent years strong TCs have been making landfalls in Japan, such as Typhoon Jebi in 2018, which severely hit the Kinki region, and Typhoon Hagibis in 2019, which severely hit eastern Japan. While Japan has suffered from a number of TC impacts throughout its history, meteorological data for these events has been sparse.The team, including Specially Appointed Associate Professor Hisayuki Kubota of the Faculty of Science, Hokkaido University, investigated TC activity over the western North Pacific and TC landfalls in Japan by analyzing a combination of TC tracking and meteorological data observed at weather stations and lighthouses, including rescued and recovered historical observations.The team has collected and recovered TC track and landfall data and meteorological observations in the mid-19th century and later through an approach that rescues, collects and digitizes weather data across the world that has been stored away and often forgotten. To give the data useful consistency, the team developed a new, unified definition for TCs, based on minimum pressure.According to their analysis, TC landfall locations tend to shift to the northeast and then southwest regions of Japan at roughly 100-year intervals. The analysis also shows that annual TC landfall numbers and their intensities have been increasing in recent years, while noting that these increases may be part of an oscillated fluctuation operating on interdecadal time scales.The landfall numbers were relatively small in the late 20th century, and larger at other times. The Tohoku and Hokkaido regions, which experienced small numbers of TC landfalls in the late 20th century, may experience more landfalls in the future.Japan's first official meteorological observation was conducted in Hakodate, Hokkaido, in 1872. There is very little earlier meteorological data obtained by meteorological instruments at terrestrial stations, which makes it difficult to perform long-term meteorological variability analyses. In a new approach, the team focused on foreign ship log weather records from the mid-19th century made with meteorological instruments on vessels sailing through East- and Southeast Asian waters.The team used records from the US Navy expedition fleet to Japan led by Commodore Matthew C. Perry and from British Navy ships that also sailed to Japan to accurately identify the track of a TC moving over the ocean around the Okinawa Islands from 21 to 25 July 1853, and the track of a TC moving north over the East China Sea from 15 to 16 August 1863.The results of the study show for the first time the usefulness of such marine data in identifying weather patterns after the mid-19th century in Asia, where there is much less meteorological data for that time period compared with Western countries. "It is projected that stronger TCs will hit Japan in the future due to global warming. The long-term data from our research is indispensable for knowing the variabilities of TC activities in the past and to prepare for future TCs," says Hisayuki Kubota.
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Geography
| 2,021 |
March 3, 2021
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https://www.sciencedaily.com/releases/2021/03/210303142423.htm
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Diversity of fish species supply endangered killer whale diet throughout the year
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Endangered Southern Resident killer whales prey on a diversity of Chinook and other salmon. The stocks come from an enormous geographic range as far north as Alaska and as far south as California's Central Valley, a new analysis shows.
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The diverse salmon stocks each have their own migration patterns and timing. They combine to provide the whales with a "portfolio" of prey that supports them across the entire year. The catch is that many of the salmon stocks are at risk themselves."If returns to the Fraser River are in trouble, and Columbia River returns are strong, then prey availability to the whales potentially balances out as the whales have evolved to move rapidly throughout their range," said NOAA Fisheries wildlife biologist Brad Hanson, lead author of the new research. "But if most of the stocks throughout their range are reduced then this could spell trouble for the whales."The researchers examined more than 150 prey and fecal samples collected from the whales from 2004 to 2017. This produced the most comprehensive picture yet of Southern Resident prey over the course of the year."When so many prey species are endangered, then they lose some of that diversity," Hanson said. "The question for managers is how do you support and improve this diverse portfolio of species and stocks."The analysis also revealed that the whales prey almost exclusively on Chinook salmon when they are available in the summer. However, they diversify their diet the rest of the year to include species such as skates, halibut, and lingcod, as well as steelhead, chum, and coho salmon. Most of the salmon the whales consume in winter and spring come from three large river systems: the Columbia, Sacramento, and rivers entering Puget Sound.The researchers note that increased production of hatchery fish could help support the 75 remaining whales, but that this strategy is not without risks.Many hatchery fish are already available at certain times of the year, said Robin Baird, a research biologist at Cascadia Research Collective and a coauthor of the study. Increasing the diversity of hatchery stocks to include stocks that inhabit the whales' range in winter, when they appear to have less food, may be most helpful."We don't need more cookie-cutter fish that all come back during the time when Chinook are most abundant; we need to diversify and increase availability at other times of the year," Baird said.Additional funding was provided through the federal Pacific Salmon Commission and the Washington State Legislature. The funding paid for the release of more than 11.6 million additional hatchery-origin Chinook salmon in 2020, compared to previous years. It will also pay for more than 18.3 million additional fish in 2021.In line with the findings, the hatchery production will help maintain the portfolio of stocks, including those that overlap with the killer whales during the lean times of winter. Biologists also manage the production to avoid risk to naturally produced salmon.The Southern Residents have historically spent much of the summer in the inland waters of the Salish Sea. There they feed almost exclusively on Chinook salmon from the Fraser River and the Skagit, Snohomish, and other rivers entering Puget Sound. In the late summer, fall and early winter, they also turn to coho and chum salmon as Chinook decline in number.Two of the three pods -- K and L pods -- typically move to the outer coast in fall and winter. There they spend much of their time feeding off the Washington coast, with forays south as far as Monterey Bay in California. They likely concentrate near the Columbia River area because of the large number of returning salmon, heavily supplemented by hatchery fish, the scientists said.They also diversify their diet with salmon from potentially as far away as the Taku River in Alaska and other species. Those fish comprise a larger share of the whales' diet than scientists first thought based on observations of the whales feeding at the surface. Biologists collected fecal samples from the whales while tracking them along the coast. The samples revealed the more complete picture, including the ocean species they consume underwater and out of sight.The third pod, J pod, spends more time in inland waters while also traveling along the west coast of Vancouver Island. There they access a mix of salmon traveling a kind of superhighway south to West Coast rivers.The research also explores the Southern Residents' potential competition for prey with Northern Resident killer whales. These whales are a separate population that primarily frequents Canadian waters off Vancouver Island and north. The Northern Residents have increased in number to about 300 as the Southern Residents have declined. These opposing trends may reflect the Northern Residents' greater access to prey.Salmon returning south from waters off Alaska and British Columbia to West Coast rivers pass through Northern Residents' range before reaching the Southern Residents. In comparing their data to results from an earlier Canadian study of Northern Residents, the researchers found that the Northern Residents consumed larger and older salmon. The largest and oldest class of salmon consumed by the Northern Residents were absent from the Southern Residents' diet.The Southern Resident J-pod that forages to the north of the other two pods may also benefit from the same earlier access. J-pod has had a greater reproductive rate than the other pods, the study notes.Chinook salmon are also shrinking over time along the entire West Coast, and other predators may also play a role."The net result is that the consistent consumption of these smaller fish, which have a lower caloric value, may pose an additional challenge to the [Southern Resident killer whale] population's ability to meet their energetic needs," the scientists wrote.NOAA Fisheries has designated the Southern Residents one of nine national Species in the Spotlight. These species are highly endangered and can benefit from focused recovery efforts, including conservation of their prey. NOAA Fisheries West Coast Region has already applied the prey study findings in its proposal to expand critical habitat for the Southern Residents along the West Coast."Knowing what these whales eat throughout the year and across their various habitats helps us focus recovery efforts for both the Southern Residents and the salmon they rely on," says Lynne Barre, Recovery Coordinator for the Southern Residents at NOAA Fisheries West Coast Region.
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Geography
| 2,021 |
March 2, 2021
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https://www.sciencedaily.com/releases/2021/03/210302104825.htm
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Detection dogs help generate important data for research and conservation
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The lists of Earth's endangered animals and plants are getting increasingly longer. But in order to stop this trend, we require more information. It is often difficult to find out exactly where the individual species can be found and how their populations are developing. According to a new overview study published in
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How many otters are there still in Germany? What habitats do threatened crested newts use on land? And do urban hedgehogs have to deal with different problems than their rural conspecifics? Anyone wishing to effectively protect a species should be able to answer such questions. But this is by no means easy. Many animals remain in hiding -- even their droppings can be difficult to find. Thus, it is often difficult to know exactly whether and at what rate their stocks are shrinking or where the remaining survivors are. "We urgently need to know more about these species," says Dr Annegret Grimm-Seyfarth of the UFZ. "But first we must find them."Remote sensing with aerial and satellite images is useful for mapping open landscapes or detecting larger animals. But when it comes to densely overgrown areas and smaller, hidden species, experts often carry out the search themselves or work with cameras, hair traps, and similar tricks. Other techniques (e.g. analysing trace amounts of DNA) have also been attracting increasing interest worldwide. The use of specially trained detection dogs can also be particularly useful. After all, a dog's sense of smell is virtually predestined to find the smallest traces of the target species. While humans have about six million olfactory receptors, a herding dog has more than 200 million -- and a beagle even 300 million. This means that dogs can perceive an extremely wide range of odours, often in the tiniest concentrations. For example, they can easily find animal droppings in a forest or plants, mushrooms, and animals underground.At the UFZ, the detection dogs have already proven their abilities in several research projects. "In order to be able to better assess their potential, we wanted to know how detection dogs have previously been used around the world," says Grimm-Seyfarth. Together with UFZ employee Wiebke Harms and Dr Anne Berger from the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin, she has evaluated 1220 publications documenting the use of such search dogs in more than 60 countries. "We were particularly interested in which breeds of dogs were used, which species they were supposed to track down, and how well they performed," explains the researcher.The longest experience with the detection dogs is in New Zealand, where dogs have been tracking threatened birds since around 1890. Since then, the idea has been implemented in many other regions, especially in North America and Europe. The studies analysed focused mainly on finding animals as well as their habitats and tracks. Dogs have been used to find more than 400 different animal species -- most commonly mammals from the cat, dog, bear, and marten families. They have also been used to find birds and insects as well as 42 different plant species, 26 fungal species, and 6 bacterial species. These are not always endangered species. The dogs sometimes also sniff out pests such as bark beetles or invasive plants such as knotgrass and ragweed."In principle, you can train all dog breeds for such tasks," says Grimm-Seyfarth. "But some of them may require more work than others." Pinschers and Schnauzers, for example, are now more likely to be bred as companion dogs and are therefore less motivated to track down species. And terriers tend to immediately snatch their targets -- which is, of course, not desirable.Pointers and setters, on the other hand, have been specially bred to find and point out game -- but not to hunt it. This is why these breeds are often used in research and conservation projects in North America, Great Britain, and Scandinavia in order to detect ground-breeding birds such as ptarmigans and wood grouse. Retrievers and herding dogs also have qualities that make them good at tracking species. They are eager to learn, easy to motivate, enjoy working with people, and generally do not have a strong hunting instinct. That is why Labrador Retrievers, Border Collies, and German Shepherds are among the most popular detection dogs worldwide.Grimm-Seyfarth's Border Collie Zammy, for example, learned as a puppy how to track down the droppings of otters. This is a valuable contribution to research because the droppings can be genetically analysed to find out which individual it comes from, how it is related to other conspecifics, and what it has eaten. However, even for experienced experts, these revealing traces are not so easy to find. Especially small and dark coloured droppings are easy to overlook. Dogs, on the other hand, sniff even the most unremarkable droppings without distinction. In an earlier UFZ study, they found four times as many droppings as human investigators alone. And the fact that Zammy is now also looking for crested newts makes his efforts even more rewarding.According to the overview study, many other teams around the world have had similarly good experiences. In almost 90% of cases, the dogs worked much more effectively than other detection methods. Compared with camera traps, for example, they detected between 3.7 and 4.7 fold more black bears, pied martens, and bobcats. They are also often reach their destination particularly quickly. "They can find a single plant on a football field in a very short time," says Grimm-Seyfarth. They are even able to discover underground parts of plants.However, there are also cases where the use of detection dogs is not the method of choice. Rhinos, for example, leave their large piles of excrement clearly visible on paths so that humans can easily find them on their own. And animal species that know feral dogs as enemies are more likely to find (and fight) the detection dogs than to be found."However, in most cases where the dogs did not perform so well, poor training is to blame," says Grimm-Seyfarth. She believes that good training of the animal is the most important recipe for success for detection dogs. "If you select the right dog, know enough about the target species, and design the study accordingly, this can be an excellent detection method." She and her colleagues are already planning further applications for the useful detection dogs. A new project that involves tracking down invasive plant species will soon be launched.
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Geography
| 2,021 |
March 2, 2021
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https://www.sciencedaily.com/releases/2021/03/210302094050.htm
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Largest carbon stores found in Australian World Heritage Sites
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Australia's marine World Heritage Sites are among the world's largest stores of carbon dioxide according to a new report from the United Nations, co-authored by an ECU marine science expert.
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The UNESCO report found Australia's six marine World Heritage Sites hold 40 per cent of the estimated 5 billion tons of carbon dioxide stored in mangrove, seagrass and tidal marsh ecosystems within UNESCO sites.The report quantifies the enormous amounts of so-called blue carbon absorbed and stored by those ecosystems across the world's 50 UNESCO marine World Heritage Sites.Despite covering less than 1 per cent of the world's surface, blue carbon ecosystems are responsible for around half of the carbon dioxide absorbed by the world's oceans while it is estimated they absorb carbon dioxide at a rate about 30 times faster than rainforests.Report author and ECU Research Fellow Dr Oscar Serrano said Australia's Great Barrier Reef, Ningaloo Coast and Shark Bay World Heritage areas contained the vast majority of Australia's blue carbon ecosystems."We know Australia contains some of the world's largest stores of blue carbon due to the enormous size and diversity of our marine ecosystems," he said."However here in Australia and around the world, these ecosystems are under threat from human development and climate change."While they're healthy, blue carbon ecosystems are excellent stores of carbon dioxide, but if they are damaged, they can release huge amounts of carbon dioxide stored over millennia back into the atmosphere."In 2011 seagrass meadows in the Shark Bay World Heritage Site in Western Australia released up to nine million tons of stored carbon dioxide after a marine heatwave devastated more than 1000sqkm of seagrass meadows.The UNESCO Report's authors have outlined the potential for the countries including Australia to use the global carbon trading market to fund conservation and restoration efforts at marine World Heritage Sites including here in Australia.Dr Serrano said both Shark Bay and the Great Barrier Reef ecosystems are at risk due to climate change and human development."There are significant opportunities for both the Great Barrier Reef and Shark Bay to be protected and restored to ensure they survive and thrive in the future," he said."Australia also has plenty of marine ecosystems in need of protection not contained within a World Heritage Site which are worthy of our attention.Dr Serrano's previous research has highlighted the millions of dollars in potential conservation and restoration projects of blue carbon ecosystems while also helping Australia and other countries achieve their commitments to the Paris Climate Agreement.The report was led by Professor Carlos Duarte and a team of collaborators from Australia, Saudi Arabia, Denmark, the United States, Kenya and the United Kingdom.The UNESCO Marine World Heritage report is titled 'Custodians of the globes' blue carbon assets' and can be accessed at the UNESCO webpage.
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Geography
| 2,021 |
March 1, 2021
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https://www.sciencedaily.com/releases/2021/03/210301211625.htm
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Neanderthal and early modern human stone tool culture co-existed for over 100,000 years
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Research from the University of Kent's School of Anthropology and Conservation has discovered that one of the earliest stone tool cultures, known as the Acheulean, likely persisted for tens of thousands of years longer than previously thought.
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The Acheulean was estimated to have died out around 200,000 years ago but the new findings suggest it may have persisted for much longer, creating over 100,000 years of overlap with more advanced technologies produced by Neanderthals and early modern humans.The research team, led by Dr Alastair Key (Kent) alongside Dr David Roberts (Kent) and Dr Ivan Jaric (Biology Centre of the Czech Academy of Sciences), made the discovery whilst studying stone tool records from different regions across the world. Using statistical techniques new to archaeological science, the archaeologists and conservation experts were able to reconstruct the end of the Acheulean period and re-map the archaeological record.Previously, a more rapid shift between the earlier Acheulean stone tool designs often associated with Homo heidelbergensis -- the common ancestor of modern humans and Neanderthals -- and more advanced 'Levallois' technologies created by early modern humans and Neanderthals, was assumed. However, the study has shed new light on the transition between these two technologies, suggesting substantial overlap between the two.Acheulean stone tool technologies are the longest-lived cultural tradition practiced by early humans. Originating in East Africa 1.75 million years ago, handaxes and cleavers -- the stone tool types which characterise the period -- went on to be used across Africa, Europe and Asia by several different species of early human. Prior to this discovery, it was widely assumed that the Acheulean period ended between 300-150,000 year ago. However, the record was lacking in specific dates, and the timing of its demise has been heavily debated. The Kent and Czech team discovered that the tradition likely ended at different times around the world, varying from as early as 170,000 years ago in Sub-Saharan Africa through to as late as 57,000 years ago in Asia.To understand when the Acheulean ended, the team collected information on different archaeological sites from around the world to find the latest known stone tool assemblages. A statistical technique known as optimal linear estimation -- commonly used in conservation studies to estimate species extinctions -- was used to predict how much longer the stone tool tradition continued after the most recent known sites. In effect, the technique was able to model the portion of the archaeological record yet to be discovered.Dr Alastair Key, a Palaeolithic Archaeologist and the lead author of the study, said: "The earliest archaeological record will always be an incomplete picture of early human behaviour, so we know that the youngest known Acheulean sites are unlikely to actually represent the final instances of these technologies being produced. By allowing us to reconstruct these missing portions of the archaeological record, this technique not only gives us a more accurate understanding of when the tradition ended, but it gives us an indication of where we can expect to find new archaeological discoveries in the future."Dr Roberts added: "This technique was originally developed by myself and a colleague to date extinctions, as the last sighting of a species is unlikely to be the date when it actually became extinct. It is exciting to see it applied in a new context."Their research paper 'Modelling the end of the Acheulean at global and continental levels suggests widespread persistence into the Middle Palaeolithic' is published by
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Geography
| 2,021 |
March 1, 2021
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https://www.sciencedaily.com/releases/2021/03/210301112349.htm
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Half a trillion corals: Coral count prompts rethink of extinction risks
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For the first time, scientists have assessed how many corals there are in the Pacific Ocean -- and evaluated their risk of extinction.
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While the answer to "how many coral species are there?" is 'Googleable', until now scientists didn't know how many individual coral colonies there are in the world."In the Pacific, we estimate there are roughly half a trillion corals," said the study lead author, Dr Andy Dietzel from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE at JCU)."This is about the same number of trees in the Amazon, or birds in the world."The results are crucial for the research and conservation of corals and coral reefs as they decline across the world due to the effects of climate change."We need to know the abundance of a species to assess its risk of extinction," Dr Dietzel said. "However, there is very little data on most of Earth's wild animal and plant species -- not just corals."Dr Dietzel said the eight most common coral species in the region each have a population size greater than the 7.8 billion people on Earth.The findings suggest that while a local loss of coral can be devastating to coral reefs, the global extinction risk of most coral species is lower than previously estimated.Extinctions could instead unfold over a much longer timeframe because of the broad geographic ranges and huge population sizes of many coral species.Co-author Professor Sean Connolly, from Coral CoE at JCU and the Smithsonian Tropical Research Institute, said the study's new analysis of the 80 species considered by the IUCN to have an elevated extinction risk shows that 12 of those species have estimated population sizes of more than one billion colonies."As an example, the finger-coral, Porites nigrescens, ranks amongst the ten most abundant species we examined. It's also not considered to be highly susceptible to coral bleaching -- yet it is currently listed by IUCN as vulnerable to global extinction," Prof Connolly said.Co-author Professor Michael Bode from Coral CoE at JCU and the Queensland University of Technology said, "One third of the rarest species in our analysis -- covering the bottom ten percent of species abundances -- are nonetheless listed by the IUCN as being of Least Concern."The study measured the population sizes of more than 300 individual coral species on reefs across the Pacific Ocean, from Indonesia to French Polynesia. The scientists used a combination of coral reef habitat maps and counts of coral colonies to estimate species abundances.Co-author Professor Terry Hughes from Coral CoE at JCU said the study results have major implications for managing and restoring coral reefs."We counted an average of 30 corals per square metre of reef habitat. This translates into tens of billions of corals on the Great Barrier Reef -- even after recent losses from climate extremes," Prof Hughes said."Coral restoration is not the solution to climate change. You would have to grow about 250 million adult corals to increase coral cover on the Great Barrier Reef by just one percent."He said the study highlights the opportunity for action to mitigate the threats to reef species -- and well before climate change causes global extinctions -- to make an eventual recovery of reef coral assemblages possible."The challenge now is to protect wild populations of corals, because we could never replace more than a tiny percentage of them. Prevention is better than cure," Prof Hughes said."Given the huge size of these coral populations, it is very unlikely that they face imminent extinction. There is still time to protect them from anthropogenic heating, but only if we act quickly on reducing greenhouse gas emissions."
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Geography
| 2,021 |
March 1, 2021
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https://www.sciencedaily.com/releases/2021/03/210301093546.htm
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Wrasses dazzle: How fairy wrasses got their flamboyant colors
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With their exuberant colours, fiery personalities and captivating courtship displays, the fairy wrasses are one of the most beloved coral reef fish. Despite this, the evolutionary history of its genus was not well understood -- until now.
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Fairy wrasses diverged in form and colour after repeated sea level rises and falls during the last ice age, finds a new study. Published in top journal Lead author, ichthyologist and PhD candidate at the University of Sydney, Mr Yi-Kai (Kai) Tea, says that the fish's divergence occurred rapidly and over a short amount of time."Although the fairy wrasses split from their most common ancestor some 12 million years ago, it was only within the last 2-5 million years ago that much of their divergences took place, in the Pliocene/Pleistocene epoch," said Mr Tea, a researcher in the School of Life and Environmental Sciences."They developed distinct colours and forms in a sort of evolutionary arms race, putting on dazzling displays in an effort to court females and chase off rival males. Also, sea level changes caused groups to become isolated, and therefore evolve separately. The repeated rise and fall of sea levels acted like a 'species pump', propelling fish into the Indian Ocean and even as far as the Red Sea. Most of this movement, however, occurred in the Pacific Ocean, in particular, around the Indo-Australian Archipelago."Mr Tea completed the work under the supervision of Professors of Molecular Evolution, Simon Ho and Nathan Lo.Despite the vast variation in colour and form, many species of fairy wrasses have highly conserved, or similar, regions of their genome. This poses a challenge in trying to reconstruct their evolutionary history.The current study used an approach that had not been previously attempted on fairy wrasses: by combining genome-wide ultra-conserved elements with mitochondrial DNA, the researchers reconstructed a robust evolutionary tree. Using that, they began to tease apart the reason behind the fish's diversification.In addition to sea level fluctuations, male fairy wrasses (as with many animals, the more colourful sex) developed their bright colours and individual forms to court females."They do a little dance, and they are capable of changing colours, sometimes temporarily flashing bright, iridescent colours. They also do this to ward off rival males," said Mr Tea. "In a reef where multiple species often occur, there is increased pressure for males to attract not only a female's attention, but also the female of the correct species.""We have only just begun scratching the surface of this exciting group, and more work still needs to be done in order to fully understand the drivers of species diversification," he continued.That work, and the present study, might be germane to reef conservation and management, too. For example, the finless 'mutant wrasse', an Australian endemic species restricted to a narrow distribution of reefs in far northwest Western Australia, is listed as vulnerable on the International Union for Conservation of Nature Red List of threatened species. The species has been placed in its own genus, with a single species. However, Mr Tea's study finds strong evidence that this species is simply a derived fairy wrasse, and that its loss of fins likely resulted from it being 'bottlenecked' in a narrow area.Fairy wrasse facts
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Geography
| 2,021 |
February 25, 2021
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https://www.sciencedaily.com/releases/2021/02/210225113357.htm
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Gulf Stream System at its weakest in over a millennium
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Never before in over 1000 years the Atlantic Meridional Overturning Circulation (AMOC), also known as Gulf Stream System, has been as weak as in the last decades. This is the result of a new study by scientists from Ireland, Britain and Germany. The researchers compiled so-called proxy data, taken mainly from natural archives like ocean sediments or ice cores, reaching back many hundreds of years to reconstruct the flow history of the AMOC. They found consistent evidence that its slowdown in the 20th century is unprecedented in the past millennium; it is likely linked to human-caused climate change. The giant ocean circulation is relevant for weather patterns in Europe and regional sea-levels in the US; its slowdown is also associated with an observed cold blob in the northern Atlantic.
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"The Gulf Stream System works like a giant conveyor belt, carrying warm surface water from the equator up north, and sending cold, low-salinity deep water back down south. It moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow," explains Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research PIK, initiator of the study to be published in Nature Geoscience. Previous studies by Rahmstorf and colleagues showed a slowdown of the ocean current of about 15 percent since the mid-20th century, linking this to human-caused global warming, but a robust picture about its long-term development has up to now been missing: This is what the researchers provide with their review of results of proxy data studies."For the first time, we have combined a range of previous studies and found they provide a consistent picture of the AMOC evolution over the past 1600 years," says Rahmstorf. "The study results suggest that it has been relatively stable until the late 19th century. With the end of the little ice age in about 1850, the ocean currents began to decline, with a second, more drastic decline following since the mid-20th century." Already the 2019 special report on the oceans of the Intergovernmental Panel on Climate Change (IPCC) concluded with medium confidence "that the Atlantic Meridional Overturning Circulation (AMOC) has weakened relative to 1850-1900." "The new study provides further independent evidence for this conclusion and puts it into a longer-term paleoclimatic context," Rahmstorf adds.Because ongoing direct AMOC measurements only started in 2004, the researchers applied an indirect approach, using so-called proxy data, to find out more about the long-term perspective of its decline. Proxy data, as witnesses of the past, consist of information gathered from natural environmental archives such as tree rings, ice cores, ocean sediments, and corals, as well as from historical data, for instance from ship logs."We used a combination of three different types of data to obtain information about the ocean currents: temperature patterns in the Atlantic Ocean, subsurface water mass properties and deep-sea sediment grain sizes, dating back from 100 to ca. 1600 years. While the individual proxy data is imperfect in representing the AMOC evolution, the combination of them revealed a robust picture of the overturning circulation," explains Levke Caesar, part of the Irish Climate Analysis and Research Unit at Maynooth University and guest scientist at PIK.As proxy records in general are subject to uncertainties, statistician Niamh Cahill from Maynooth University in Ireland tested the robustness of the results in consideration of these. She found that in 9 of the 11 data sets considered, the modern AMOC weakness is statistically significant. "Assuming that the processes measured in proxy records reflect changes in AMOC, they provide a consistent picture, despite the different locations and time scales represented in the data. The AMOC has weakened unprecedentedly in over 1000 years," she says.An AMOC slowdown has long been predicted by climate models as a response to global warming caused by greenhouse gases. According to a number of studies, this is likely the reason for the observed weakening. The Atlantic overturning is driven by what the scientists call deep convection, triggered by the differences in the density of the ocean water: Warm and salty water moves from the south to the north where it cools down and thus gets denser. When it is heavy enough the water sinks to deeper ocean layers and flows back to the south. Global warming disturbs this mechanism: Increased rainfall and enhanced melting of the Greenland Ice Sheet add fresh water to the surface ocean. This reduces the salinity and thus the density of the water, inhibiting the sinking and thus weakening the flow of the AMOC.Its weakening has also been linked to a unique substantial cooling of the northern Atlantic over the past hundred years. This so-called cold blob was predicted by climate models as a result of a weakening AMOC, which transports less heat into this region.The consequences of the AMOC slowdown could be manifold for people living on both sides of the Atlantic as Levke Caesar explains: "The northward surface flow of the AMOC leads to a deflection of water masses to the right, away from the US east coast. This is due to Earth's rotation that diverts moving objects such as currents to the right in the northern hemisphere and to the left in the southern hemisphere. As the current slows down, this effect weakens and more water can pile up at the US east coast, leading to an enhanced sea level rise." In Europe, a further slowdown of the AMOC could imply more extreme weather events like a change of the winter storm track coming off the Atlantic, possibly intensifying them. Other studies found possible consequences being extreme heat waves or a decrease in summer rainfall. Exactly what the further consequences are is the subject of current research; scientists also aim to resolve which components and pathways of the AMOC have changed how and for what reasons."If we continue to drive global warming, the Gulf Stream System will weaken further -- by 34 to 45 percent by 2100 according to the latest generation of climate models," concludes Rahmstorf. This could bring us dangerously close to the tipping point at which the flow becomes unstable.
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Geography
| 2,021 |
February 24, 2021
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https://www.sciencedaily.com/releases/2021/02/210223113319.htm
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An underestimated source of marine microplastic pollution
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Shipping traffic can be a major source of tiny plastic particles floating in the sea, especially out in the open ocean. In a paper published in the scientific journal
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The scientists found that most of the plastic particles in water samples taken from the German Bight, an area in the south-eastern corner of the North Sea which encompasses some of the world's busiest shipping lanes, originate from binders used in marine paints. "Our hypothesis is that ships leave a kind of 'skid mark' in the water which is of similar significance as a source of microplastics as tyre wear particles from cars are on land," Scholz-Böttcher says.In the autumn of 2016 and 2017, the Oldenburg team took water samples from various locations in the German Bight with the research vessel "Heincke." Scholz-Böttcher and her two colleagues Christopher Dibke and Marten Fischer used stainless steel sieves to filter plastic particles of much less than one millimetre in diameter out of the seawater and then analysed the chemical composition of the collected particles. They used a special analytical method in which the plastic molecules were first heated to temperatures of almost 600 degrees Celsius to break them down into smaller, characteristic fragments, and then separated and assigned to different polymer groups based on their mass and chemical properties. With this method the researchers were also able to quantify the mass of each plastic type. "Previous studies have only measured particle numbers for the North Sea. We, for the first time, also determined the mass distribution, and thus obtained a more comprehensive picture of the emergence of the different plastic types," Scholz-Böttcher stresses.The team was surprised by the results: the samples contained above all indicators for polyvinyl chloride (PVC), polymers known as acrylates, and polycarbonates. Their mass accounted for about two-thirds of the total microplastic content in the mean and up to 80 percent in certain samples. Packaging plastics such as polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET), which were previously estimated to make up the bulk of microplastics in the sea, accounted for a much smaller percentage. "We weren't expecting this distribution pattern," says Scholz-Böttcher.When the researchers conducted a more detailed analysis of the results they observed that PE, PP and PET plastics were found mainly near the coastline, whereas in the open North Sea and in the Elbe estuary -- particularly in the proximity of major shipping routes -- the other types of plastic were predominant. "We believe that these particles originate from ship coatings, where these plastics are used as binders in acrylic paints or epoxy resins, for example," Scholz-Böttcher explains. These results suggest that far larger quantities of microplastics are produced directly at sea than previously thought.According to the team, literature studies show that in the European Union alone, several thousand tonnes of paint end up in the marine environment every year. With potentially harmful consequences for the environment: coatings and paints used on ships contain heavy metals and other additives that are toxic to many organisms. These antifouling components are used to protect ships' hulls from barnacles and other subaquatic organisms and are constantly rubbed off by the wind and waves. The team is currently conducting further studies, for example in river estuaries and in sediments, to gain more insights into how these microplastics enter the environment.
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Geography
| 2,021 |
February 23, 2021
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https://www.sciencedaily.com/releases/2021/02/210223150834.htm
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Dingo effects on ecosystem visible from space
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The environmental impacts of removing dingoes from the landscape are visible from space, a new UNSW Sydney study shows.
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The study, recently published in The researchers found that vegetation inside the fence -- that is, areas without dingoes -- had poorer long-term growth than vegetation in areas with dingoes."Dingoes indirectly affect vegetation by controlling numbers of kangaroos and small mammals," says Professor Mike Letnic, senior author of the study and researcher at UNSW's Centre for Ecosystem Science."When dingoes are removed, kangaroo numbers increase, which can lead to overgrazing. This has follow-on effects to the entire ecosystem."The Dingo Fence, which spans across parts of Queensland, NSW and South Australia, was erected in the 1880s to keep dingoes away from livestock. At 5600 kilometres long, it's one of the longest structures in the world.Up until now, most dingo research has been site-based or conducted using drone imagery. But NASA and United States Geological Survey's Landsat program -- which has been taking continuous images of the area since 1988 -- has made landscape-wide analysis possible."The differences in grazing pressure on each side of the fence were so pronounced they could be seen from space," says Prof. Letnic.The satellite images were processed and analysed by Dr Adrian Fisher, a remote sensing specialist at UNSW Science and lead author of the study. He says the vegetation's response to rainfall is one of the key differences between areas with, and without, dingoes."Vegetation only grows after rainfall, which is sporadic in the desert," says Dr Fisher."While rainfall caused vegetation to grow on both sides of the fence, we found that vegetation in areas without dingoes didn't grow as much -- or cover as much land -- as areas outside the fence."Apex predators play an important role in maintaining the biodiversity of an ecosystem.Removing them from an area can trigger a domino effect for the rest of the ecosystem -- a process called trophic cascade.For example, an increase in kangaroo populations can lead to overgrazing, which in turn reduces vegetation and damages the quality of the soil. Less vegetation can hinder the survival of smaller animals, like the critically endangered Plains Wanderer.Changes to vegetation triggered by the removal of dingoes have also been shown to reshape the desert landscape by altering wind flow and sand movement."The removal of apex predators can have far-reaching effects on ecosystems that manifest across very large areas," says Prof. Letnic. "These effects have often gone unnoticed because large predators were removed from many places a long time ago."The Australian dingo fence -- which is a sharp divide between dingo and non-dingo areas -- is a rare opportunity to observe the indirect role of an apex predator."Satellite imagery traditionally only looks at photosynthesizing vegetation -- that is, plants, trees and grass that are visibly green.But the researchers used a model to factor in non-green vegetation, like shrubs, dry grasses, twigs, branches and leaf litter."Non-photosynthesizing vegetation has a different reflectance spectrum to photosynthesizing vegetation," says Dr Fisher."By using the satellite image and a calibrated scientific model, we were able to estimate the non-green vegetation cover -- which is especially important when studying a desert landscape." The model was developed by the Joint Remote Sensing Research Program, a collaborative group that includes UNSW.While there are other contributing factors to the difference in vegetation -- for example, differing rainfall patterns and land use -- the satellite imagery and site analysis showed dingoes played a central role."There were clear differences in landscape on either side of the dingo fence," says Dr Fisher. "Dingoes may not be the whole explanation, but they are a key part of it."Satellite image technology is a powerful tool for assessing large-scale role of not only dingoes, but all kinds of environmental change.In 2019, researchers from UNSW Engineering used powerful satellite radar imaging technology to map severe floods in near real-time -- intelligence that could help emergency services make tactical decisions during extreme weather events.Dr Fisher hopes to next use Landsat imagery -- which is freely available to download -- to study how different amounts of vegetation can influence bushfire frequency."Our study is an example of how satellite technology can be used in big picture environmental research," says Dr Fisher."With over three decades' worth of data, this technology has opened up so many research possibilities."
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Geography
| 2,021 |
February 23, 2021
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https://www.sciencedaily.com/releases/2021/02/210223110705.htm
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'Missing ice problem' finally solved
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During glacial periods, the sea level falls, because vast quantities of water are stored in the massive inland glaciers. To date, however, computer models have been unable to reconcile sea-level height with the thickness of the glaciers. Using innovative new calculations, a team of climate researchers led by the Alfred Wegener Institute has now managed to explain this discrepancy. The study, which was recently published in the journal
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During transitions from glacials to interglacials, the glaciers on Greenland and in North America and Europe wax and wane over tens of thousands of years. The more water that is stored in the mighty glaciers, the less there is in the oceans -- and the lower the sea level is. Climate researchers are now investigating to what extent the glaciers could melt in the coming centuries due to anthropogenic climate change, and how much the sea level would rise as a result. To do so, they're look back into the past. If they can understand the ice growth and melting during past glacials and interglacials, they'll be able to draw valuable conclusions about the future.However, reconstructing the distant past is no mean feat, because the glaciers' thickness and sea level can't be measured directly. Accordingly, climate researchers have to painstakingly gather evidence that they can then use to form a picture of the past. The problem: different pictures emerge, depending on the types of evidence collected. We can't say with absolute certainty what the situation was actually like ten thousand years ago. This 'missing ice problem' remained unsolved for many years. It describes the incongruity of two different scientific approaches that sought to reconcile sea-level height and glacier thickness at the peak of the last glacial, ca. 20,000 years ago. A team of climate experts led by Evan Gowan from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in Bremerhaven has now solved the problem using a new method. "It looks like we've found a new way to reconstruct the past as far back as 80,000 years," says Dr Gowan, who has been investigating the problem for roughly a decade. These findings have now been published in the journal The 'missing ice problem' is based, on the one hand, on an analysis of sediments from core samples collected from the seafloor in the tropics. These contain traces of corals that can still tell us today to what extent the sea level rose or fell over the millennia. Why? Because corals only live in well-lit waters near the ocean's surface. The sediment cores indicate that 20,000 years ago, the sea level in the tropics implied that sea level was roughly 130 metres lower than it is today. On the other hand, previous models have suggested that the glacial masses weren't large enough 20,000 years ago to explain such a low sea level. To be more precise, for the sea level to be that low, on a global scale an additional volume of water with twice the mass of the Greenland Ice Sheet would have to have been frozen; hence the 'missing ice problem'.With his new method, Gowan has now reconciled sea level and glacier mass: according to his calculations, the sea level at the time was ca. 116 metres lower than it is today. Based on his approach, there is no discrepancy in terms of glacier mass. Unlike the previous global model, Gowan closely examined the geological conditions in the glaciated regions: how steep was the ice surface? Where did glaciers flow? How much did the rocks and sediment at the base of the ice resist ice flow? His model considers all of these aspects. It also takes into account to what extent the ice sheet pressed down on the Earth's crust in the respective areas. "That depends on how viscous the underlying mantle was," Gowan explains. "We base our calculations on different mantle viscosities, and therefore arrive at different ice masses." The resulting ice masses can now be reconciled with the sea level without any discrepancy.The recent article by Gowan and his team critically re-examines the long-established scientific method used to estimate glacier masses: the oxygen isotope method. Isotopes are atoms of the same element that have different numbers of neutrons and therefore different masses. Oxygen, for example, has a lighter 16O isotope, and a heavier 18O isotope. According to conventional theory, the lighter 16O evaporates from the oceans, while the heavier 18O remains in the water. Accordingly, during glacials, when large inland glaciers form and the volume of water in the oceans decreases, the 18O concentration in the oceans should increase. However, as has been shown, this established model produces discrepancies when it comes to reconciling sea-level height and glacier masses for the period 20,000 years ago and earlier. "For many years, the isotope model has been frequently used to determine the ice volume of glaciers up to several million years ago. Our study calls into question the reliability of this method," says Gowan. His aim is to now use his new method to improve the traditional oxygen isotope method.
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Geography
| 2,021 |
February 23, 2021
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https://www.sciencedaily.com/releases/2021/02/210223110449.htm
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Glaciers accelerate in the Getz region of West Antarctica
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Glaciers in West Antarctica are moving more quickly from land into the ocean, contributing to rising global sea levels. A 25-year record of satellite observations has been used to show widespread increases in ice speed across the Getz sector for the first time, with some ice accelerating into the ocean by nearly 50%.
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The new study, led by the University of Leeds, reports that 14 glaciers in the Getz region are thinning and flowing more quickly into the ocean. Between 1994 and 2018, 315 gigatonnes of ice has been lost, adding 0.9 mm to global mean sea level -- equivalent to 126 million Olympic swimming pools of water.The results published today (19/02/2021) in the journal Heather Selley, lead author of the study and a glaciologist at the Centre for Polar Observation and Modelling at the University of Leeds, said: "The Getz region of Antarctica is so remote that humans have never set foot on most of this part of the continent. Satellite radar altimetry records have shown substantial thinning of the ice sheet."However, the high rates of increased glacier speed -- coupled with ice thinning -- now confirms the Getz basin is in 'dynamic imbalance', meaning that it is losing more ice than it gains through snowfall."Using a combination of observations and modelling, we show highly localised patterns of acceleration. For instance, we observe the greatest change in the central region of Getz, with one glacier flowing 391 m/year faster in 2018 than in 1994. This is a substantial change as it is now flowing at a rate of 669 m/year, a 59% increase in just two and a half decades."The research, funded by the Natural Environment Research Council (NERC) and the European Space Agency (ESA), reports how the widely reported thinning and acceleration observed in the neighbouring Amundsen Sea glaciers, now extends over 1,000 km along the West Antarctic coastline into Getz.Dr Anna Hogg, study co-author and climate researcher in Leeds' School of Earth and Environment said: "The pattern of glacier acceleration shows the highly localised response to ocean dynamics."High-resolution satellite observations from satellites such as ESA's Sentinel-1, which collects a new image every six-days, means we can measure localized speed changes with ever greater detail."Consistent and extensive sampling of both ice speed and ocean temperature are needed to further our understanding of the dynamic ice loss, which now accounts for 98.8 % of the Antarctica's sea level contribution."By examining 25 years of ocean measurements, the research team were able to show complex and annual variations in ocean temperatures. These results suggest that the "dynamic imbalance" is mainly caused by longer-term ocean forcing, where increased heat content in the ocean is interacting with the ice and enhancing melt.Pierre Dutrieux, study co-author and climate researcher at British Antarctic Survey, said: "We know that warmer ocean waters are eroding many of West Antarctica's glaciers, and these new observations demonstrate the impact this is having on the Getz region."This new data will provide a new perspective of the processes taking place so we can predict future change with more certainty."
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Geography
| 2,021 |
February 22, 2021
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https://www.sciencedaily.com/releases/2021/02/210222192830.htm
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Effects of past ice ages more widespread than previously thought
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Cold temperatures, prevalent during glacial periods, had a significant impact on past and modern unglaciated landscapes across much of North America, according to a recent study by University of Arkansas geologist Jill A. Marshall.
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Marshall, assistant professor of geosciences, is the first author of the study, published in the journal The findings help shape understanding of the earth's "Critical Zone," the relatively thin layer of the planet that extends from where vegetation meets the atmosphere to the lowermost extent of weathered bedrock. "Climate and ecosystems determine how quickly bedrock weathers, how soil is produced, how sediment moves on land and in rivers and other factors that shape the landscape," the authors wrote.In cold lands, such as Alaska today, frost can crack or weather rock that is at or near the surface of the earth -- making it more porous and turning solid rock into sediment. By applying a frost-weathering model to North America paleoclimate simulations tracking temperatures during the Last Glacial Maximum approximately 21,000 years ago, Marshall and her team determined that a large swath of North America, from Oregon to Georgia and as far south as Texas and Arkansas, were likely affected by such periglacial processes.While permafrost landscapes like the modern Arctic experience frozen ground for two years or more, periglacial landscapes, though not permanently frozen, experience below-freezing temperature for much of the year. Though the evidence of past periglacial processes is easily hidden by vegetation and/or erased by subsequent geological processes, the teams' results suggest that frost weathering (and by extent other periglacial processes) covered an area about 3.5 times larger than the mapped extent of permafrost during the Last Glacial Maximum. This predicted influence of past cold climates on below ground weathering may significantly influence modern landscape attributes that we depend on such as soil thickness and water storage."Based on the widespread occurrence of glacial-period frost weathering over meter-scale depths, we suggest that past cold climates have had a significant impact on modern landscapes, both through lingering impact on subsurface pathways for water and thus chemical weathering, and the rock damage that contributes to the rate at which rock disaggregates into sediment and potential instability due to non-steady rates of hillslope and river processes," the paper states.
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Geography
| 2,021 |
February 21, 2021
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https://www.sciencedaily.com/releases/2021/02/210221154616.htm
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Colorful connection found in coral's ability to survive higher temperatures
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Anyone who visits the Great Barrier Reef in Australia, Southeast Asia's coral triangle, or the reefs of Central America, will surely speak of how stunning and vibrant these environments are. Indeed, coral reefs are believed to house more biodiversity than any other ecosystem on the planet, with the coral providing protection and shelter for hundreds of species of fish and crustaceans.
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But these ecosystems are under threat. Global pressures, such as rising ocean temperatures, are causing coral to turn ghostly white, a phenomenon called bleaching, and die. One family of coral -- "Coral reefs are very beautiful and have a whole variety of different colors," said Professor Noriyuki Satoh, who leads the Marine Genomics Unit at the Okinawa Institute of Science and Technology Graduate University (OIST). "When we started looking at the different color morphs of The Unit worked with several individuals from the Okinawan community, including Koji Kinjo from Sea Seed, who directs a private aquarium where the different color morphs have been grown for around 20 years. This aquarium was instrumental for the researchers to observe the coral over the last two decades and to determine how resilient this species is to climate change, and the underlying causes.In 2020, Professor Satoh and his collaborators decoded the genome of "At first, we thought the difference in resilience might be linked to the corals housing different kinds of symbiotic algae, which photosynthesize for the coral and thus provide the coral with energy. Previous research has shown that some symbiotic algae are more resilient to climate change than others. But when we looked at the three-color morphs, we found that they all housed very similar algae," explained Professor Satoh.With this in mind, the research group instead focused the expression levels of the proteins that are thought responsible for the coral's color. There are four different groups of these proteins -- green fluorescent proteins (GFP), red fluorescent proteins (RFP), cyan fluorescent proteins (CFP), and non-fluorescent blue/purple chromoproteins (ChrP). The researchers looked at the gene expression levels of five types of GFP, three types of RFP, two types of CFP and seven types of ChrP in several coral in each morph.As can be expected, they found that the green morph expressed high quantities of FGPs, but the researchers found that two of the five were expressed at particularly high levels. More surprising was that these two proteins were expressed at even higher levels during summer, which indicates that they help the coral to withstand warmer temperatures. Specifically, these proteins seemed to protect the symbiotic algae, which meant that this color morph experienced very little bleaching.In contrast, the corals with the brown color morph, which express much lower quantities of these two proteins, bleached by around 50% over July and August 2017.The purple morph was different again. It expressed very little of any of the fluorescent proteins, but much higher levels of Chrp. The corals with this color morph bleached at levels in between that seen in corals with the brown morph and that seen in corals with the green morph."Coral reefs are so important for biodiversity," concluded Professor Satoh. "Finding out more about them will help us to conserve them. Right now, we cannot help so much about the coral reef situation but gathering this fundamental knowledge, understanding how corals work, is very important for long-term conservation."This research has showcased that the color morphology of coral is very much involved in its response to high temperatures. The underlying reasons behind this, such as exactly how the green fluorescent protein protects the symbiosis, will no doubt be the topic of research in the future.Professor Satoh and his Unit worked with people from Umino-Tane Co. LTD, IDEA Consultants, Inc., and Okinawa Environmental Research Co., Ltd., as well as researchers from the University of Tokyo. In addition, OIST's DNA Sequencing Section and Imaging Section were also involved in this project.
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Geography
| 2,021 |
February 23, 2021
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https://www.sciencedaily.com/releases/2021/02/210223164448.htm
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Conservation paradox - the pros and cons of recreational hunting
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Recreational hunting -- especially hunting of charismatic species for their trophies -- raises ethical and moral concerns. Yet recreational hunting is frequently suggested as a way to conserve nature and support local people's livelihoods.
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In a new article published in the journal Co-lead author University of Helsinki Associate Professor Enrico Di Minin says while it might seem counterintuitive, there is evidence to suggest some recreational hunting can deliver environmental and social benefits.University of Helsinki colleague and co-lead author Dr Hayley Clements says more analysis is needed to understand how and why recreational hunting can work for good, and those areas where it can be detrimental.Flinders University Professor Corey Bradshaw says it's a paradox that goes to the heart of the pros and cons of recreational hunting."We determined the geographic spread and diversity of species hunted around the globe, and investigated and summarized the main topics surrounding recreational hunting to consider both the positive and negative implications of recreational hunting for nature conservation and the livelihoods and well-being of people" says Professor Bradshaw, who leads Flinders' Global Ecology Lab."On the one hand, recreational hunting can reduce the number of individual animals in a population, whereas on the other, diverting land from agricultural or other types of development to priority hunting areas can in fact benefit entire ecosystems," he says.Hunting research has focused mainly on the behaviour and population dynamics of large mammals in North America, Europe and Africa.Dr Clements says evidence is still lacking, however, to answer the pressing questions of why hunting contributes to sustainable conservation of biodiversity in some places and not others."Two-thirds of the hunting research is focussed on mammals. Red deer, white-tailed deer, wild boar, moose and lion are the most well-studied. Of these species, only the lion is of conservation concern, with many recommendations on how hunting can be made sustainable through quotas or seasonal limits," says Dr Clements."Far less research has tried to examine the broader impacts of hunting on ecosystem integrity and function, and how it affects the livelihoods of local people, or to document local people's perceptions about hunting," she continues.For example, approximately 1,394,000 kmAssociate Professor Di Minin, who leads the Helsinki Lab of Interdisciplinary Conservation Science contends future research should focus on the contribution of recreational hunting towards meeting both biodiversity and social objectives."We have outlined a research agenda to assess the role of recreational hunting in diverse social-ecological systems, and to consider local people's values and needs.The need for such evidence is urgent given declining numbers of recreational hunters in some regions and increasing opposition to trophy hunting in others," says Associate Professor Di Minin."We should also expand research beyond charismatic and common species to assess the impact of recreational hunting on threatened and less charismatic species," he concludes
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Geography
| 2,021 |
February 19, 2021
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https://www.sciencedaily.com/releases/2021/02/210219124233.htm
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Sweet marine particles resist hungry bacteria
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A major pathway for carbon sequestration in the ocean is the growth, aggregation and sinking of phytoplankton -- unicellular microalgae like diatoms. Just like plants on land, phytoplankton sequester carbon from atmospheric carbon dioxide. When algae cells aggregate, they sink and take the sequestered carbon with them to the ocean floor. This so called biological carbon pump accounts for about 70 per cent of the annual global carbon export to the deep ocean. Estimated 25 to 40 per cent of carbon dioxide from fossil fuel burning emitted by humans may have been transported by this process from the atmosphere to depths below 1000 meter, where carbon can be stored for millennia.
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Yet, even it is very important, it is still poorly understood how the carbon pump process works at the molecular level. Scientists of the research group Marine Glycobiology, which is located at the Max Planck Institute for Marine Microbiology and the MARUM -- Center for Marine Environmental Sciences at the University of Bremen, investigate in this context marine polysaccharides -- meaning compounds made of multiple sugar units -- which are produced by microalgae. These marine sugars are very different on a structural level and belong to the most complex biomolecules found in nature. One single bacterium is not capable to process this complex sugar-mix. Therefore a whole bunch of metabolic pathways and enzymes is needed. In nature, this is achieved by a community of different bacteria that work closely and very efficiently together -- a perfect coordinated team. This bacterial community works so well that the major part of microalgal sugars are degraded before they aggregate and start to sink. A large amount of the sequestered carbon therefore is released back into the atmosphere.But, how is it possible that nevertheless a lot of carbon is still transported to the deep-sea? The scientists of the group Marine Glycobiology now revealed a component that may be involved in this process and published their results in the journal A crucial part of the finding is that this microbial resistant sugar formed particles. During growth and upon death unicellular diatoms release a large amount of unknown, sticky long-chained sugars. With increasing concentration, these sugar chains stick together and form molecular networks. Other components attach to these small sugar flakes, such as other sugar pieces, diatom cells or minerals. This makes the aggregates larger and heavier and thus they sink faster than single diatom cells. These particles need about ten days to reach a depth of 1000 meters -- often much longer. This means that the sticky sugar core has to resist biodegradation for at least so long to hold the particle together. But this is very difficult as the sugar-eating bacteria are very active and always hungry.In order to unravel the structures of microalgae polysaccharides and identify resistant sticky sugars, the scientists of the research group Marine Glycobiology are testing new methods. This is necessary because marine sugars are found within complex organic matter mixtures. In the case of this study, they used a method which originates from medical and plant research. It combines the high-throughput capacity of microarrays with the specificity of monoclonal antibody probes. This means, that the scientists extracted the sugar-molecules out of the seawater samples and inserted them into a machine that works like a printer, which doesn't use ink but molecules. The molecules are separately "printed" onto nitrocellulose paper, in form of a microarray. A microarray is like a microchip, small like a fingernail, but can contain hundreds of samples. Once the extracted molecules are printed onto the array it is possible to analyse the sugars present on them. This is achieved by using the monoclonal antibody probes. Single antibodies are added to the arrays and as they react only with one specific sugar the scientists can see, which sugars are present in the samples."The novel application of this technology enabled us to simultaneously monitor the fate of multiple complex sugar molecules during an algal bloom," says Silvia Vidal-Melgosa. "It allowed us to find the accumulation of the sugar FCSP, while many other detected polysaccharides were degraded and did not store carbon." This study proves the new application of this method. "Notably, complex carbohydrates have not been measured in the environment before at this high molecular resolution," says Jan-Hendrik Hehemann, leader of the group Marine Glycobiology and senior author of the study. "Consequently, this is the first environmental glycomics dataset and therefore the reference for future studies about microbial carbohydrate degradation."The discovery of FCSP in diatoms, with demonstrated stability and adhesive properties, provides a previously uncharacterised polysaccharide that contributes to particle formation and potentially therefore to carbon sequestration in the ocean. One of the next steps in the research is "to find out, if the particles of this sugar exist in the deep ocean," says Hehemann. "That would indicate that the sugar is stable and constitutes an important player of the biological carbon pump." Furthermore, the observed stability against bacterial degradation, and the structure and physicochemical behaviour of diatom FCSP point towards specific biological functions. "Given its stability against degradation, FCSP, which coats the diatom cells, may function as a barrier protecting the cell wall against microbes and their digestive enzymes," says Hehemann. And last but not least, another open question to be solved: These sugar particles were found in the North Sea near the island of Helgoland. Do they also exist in the sea of other regions in the world?
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Geography
| 2,021 |
February 18, 2021
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https://www.sciencedaily.com/releases/2021/02/210218140141.htm
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New piece of the puzzle increases understanding of speciation
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Speciation is important because it increases biodiversity. A thesis from the University of Gothenburg examines the speciation process in multiple marine species where different populations of the same species might evolve into two completely new species.
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When two populations of a species become isolated, their genes no longer intermix and over time, the two populations become increasingly different from each other. What is known as a reproduction barrier has then been formed because the two different populations no longer mate with each other even if they would meet again.For a long time, researchers proposed that new species could be formed only if two populations were separated by a physical barrier over a very long period of time, for hundreds of thousands of generations or more.Today, there are many examples of species being formed without isolation, such as during ongoing genetic exchange. This exchange should prevent two populations to become different and so, understanding how reproductive barriers can still develop is an intriguing question for speciation researchers.Samuel Perini, researcher at the Department of Marine Sciences and author of the new thesis, has studied what happens in species with populations that are genetically different and meet at a contact zone, a boundary area between the two populations."I have investigated reproductive barriers that exist between two different forms of Littorina saxatilis, an intertidal marine snail, and I have analyzed data on reproductive barriers found in several marine species around the mouth of the Baltic Sea," says Perini.In a review of reproductive barriers in 23 different species, including cod, herring and plaice, Samuel Perini found large genetic differences between the Baltic Sea populations and the North Sea populations."These differences are maintained partly because the populations survive differently in different salinities and partly because their reproduction is separated in time or space, or both."For the Littorina saxatilis snail, which is common in the Atlantic along the coasts of both Europe and North America, two different populations or ecotypes have formed under ongoing genetic exchange, according to previous research. One population is known as the "Crab" ecotype and the other population is known as the "Wave" ecotype.Crab snails live in and are adapted to portions of the rocky shore with large stones and crabs, while Wave snails live on portions of the rocky shore with rock slabs exposed to waves. Crab snails and Wave snails meet at the boundary of these two habitats but genetic and phenotypic differences are still maintained between the two populations. Adaptations to the Crab and Wave habitat is strongly driven by natural selection and survival in the non-native environment is low. Hence, natural selection reduces genetic exchange between Crab and Wave snail populations because it decreases the opportunity for a Crab snail to survive and reproduce in the Wave habitat with a Wave snail of the opposite sex (and vice versa).The size of the intertidal marine snail is important for adaptation to the different environments. Large snails are selected for in environments where there are crabs, and small snails are favoured in environments exposed to waves."My studies show that the size of intertidal marine snails is important not only for survival but also for mating. I show in my thesis that mating is more common between snails of similar sizes and that small males have more matings. Both of these factors help to counteract gene exchange between the large Crab snails and the smaller Wave snails when they meet both inside and outside the contact zones."
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Geography
| 2,021 |
February 18, 2021
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https://www.sciencedaily.com/releases/2021/02/210218140115.htm
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Pandemic got you down? A little nature could help
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Having trouble coping with COVID?
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Go take a hike. Literally.Researchers have long been aware of the positive impact of a connection with nature on psychological health and, according to a new study published in the journal "Thinking about the natural world in an interconnected and harmonious way corresponds to improved psychological health, no matter where you are," says Brian W. Haas, the lead author of the new study and an associate professor in the Behavioral and Brain Sciences Program at the University of Georgia.Haas and his collaborators -- Fumiko Hoeft, a professor of psychological sciences at UConn and director of UConn's Brain Imaging Research Center; and Kazufumi Omura, faculty of Education, Art and Science at Yamagata University in Japan -- used a survey in America and Japan to measure worldviews on nature as well as how much the pandemic impacted people's lives, and their current psychological health.The survey sought to gauge whether the participants had a worldview in harmony with nature -- being in tune or connected with the natural world, or a worldview of mastery over nature -- the belief that people have the ability to control the natural world. They also reported on their stress levels and were asked if the COVID-19 pandemic has affected them personally or impacted their employment or finances.The researchers found that, while participants in general report greater stress levels during the pandemic, individuals with a harmony-with-nature worldview were coping better regardless of whether they lived in Japan or in the United States."Clearly there's great need for study as relates to the pandemic, not just now during COVID, but also of previous pandemics and for possible future pandemics," says Hoeft. "I feel like this is a really great lesson, and a moment for us to really appreciate that things like our relationship with nature do matter and make an impact on more tangible things, like our mental health, which we often forget."The researchers found that the difference between the two cultures, however, became apparent when looking at individuals with a mastery-over-nature worldview."We found that the Americans who believed that humans are, and should be, the masters of the natural world did not tend to cope well during the pandemic," Haas says. "While this was not the case in Japan."Rather, in Japan, having a mastery-over-nature worldview was not correlated with poor coping. The researchers suggest the difference might be rooted in the concept of naïve dialecticism -- the acceptance or tolerance of contradiction."In other cultures outside of the United States, people tend to be more comfortable with contradiction; in other cultures, it is generally more accepted to possess conflicting ideas within your mind at the same time," Haas says. "But in the United States, it's not. We can apply this concept to nature and the current global pandemic. For instance, if I hold a view that I am the master of the natural world, and then a global pandemic happens, this is a clear natural disaster. If I believe that I am the master of the natural world, then surely I would never allow a natural disaster to happen. These concepts are inconsistent with one another, and a consequence of inconsistency is often negative mood."While the study offers only a snapshot view of just two cultures, Haas believes other cultures would likely demonstrate a similar positive association with a harmony-with-nature worldviews, predicting that "it's likely a universal phenomenon."Both Haas and Hoeft say that, in an increasingly virtual and technology driven world, taking a moment to appreciate nature has clear benefits regardless of where you live."In Japanese, there's this word called 'forest-bathing,'" Hoeft says. "It's basically when you go out into nature, and enjoy being surrounded by trees. It's usually for forests, but you go walking and it's supposed to refresh you. People often talk about how they went out 'forest bathing.' I love thinking about these kinds of old phrases -- do they have some real impact or real scientific background in the end? And I think this is one of them where this really does have a connection. There is some scientific truth behind this.""Think about taking a step away from Zoom for a moment and taking a walk and listening to the birds chirp," Haas says. "I mean, just the benefit of that, and understanding that we have a role in this natural world, and we're part of it. I think that's really intuitive and it's obvious, but I think it's also really, really important. We're showing very convincingly with empirical data that, during a very difficult time like we are in now, that it's important to do these things to maintain your psychological health."This study was supported with funding from a Global Research Collaboration Grant from the University of Georgia and a National Science Foundation grant, NSF #202937.
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Geography
| 2,021 |
February 17, 2021
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https://www.sciencedaily.com/releases/2021/02/210217151042.htm
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How sessile seahorses managed to speciate and disperse across the world's oceans
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The international research collaboration involving the research team led by evolutionary biologist Professor Axel Meyer at the University of Konstanz and researchers from China and Singapore was able to identify factors that led to the success of the seahorse from a developmental biology perspective: its quickness to adapt by, for example, repeatedly evolving spines in the skin and its fast genetic rates of evolution. The results will be published on 17 February 2021 in
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Seahorses of the genus Hippocampus emerged about 25 million years ago in the Indo-Pacific region from pipefish, their closest relatives. And while the latter usually swim fairly well, seahorses lack their pelvic and tail fins and evolved a prehensile tail instead that can be used, for example, to hold on to seaweed or corals. Early on, they split into two main groups. "One group stayed mainly in the same place, while the other spread all over the world," says Dr Ralf Schneider, who is now a postdoc-toral researcher at the GEOMAR Helmholtz Centre for Ocean Research Kiel, and participated in the study while working as a doctoral researcher in Axel Meyer's re-search team. In their original home waters of the Indo-Pacific, the remaining species diversified in a unique island environment, while the other group made its way into the Pacific Ocean via Africa, Europe and the Americas.The particularly large amount of data collected for the study enabled the research team to create an especially reliable seahorse tree showing the relationships be-tween species and the global dispersal routes of the seahorse. Evolutionary biologist, Dr Schneider, says: "If you compare the relationships between the species to the ocean currents, you notice that seahorses were transported across the oceans." If, for example, they were carried out to sea during storms, they used their grasping tail to hold on to anything they could find, like a piece of algae or a tree trunk. These are places where the animals could survive for a long time. The currents often swept these "rafts" hundreds of kilometres across the ocean before they landed someplace where the seahorses could hop off and find a new home.Since seahorses have been around for more than 25 million years, it was important to factor in that ocean currents have changed over time as tectonic plates have shift-ed. For example, about 15 million years ago, the Tethys Ocean was almost as large as today's Mediterranean Sea. On the west side, where the Strait of Gibraltar is lo-cated today, it connected to the Atlantic Ocean. On the east side, where the Arabian Peninsula is today, it led to the Indian Ocean.The researchers were able to underscore, for example, that the seahorses were able to colonize the Tethys Ocean via the Arabian Sea just before the tectonic plates shifted and sealed off the eastern connection. The resulting current flowing westward towards the Atlantic Ocean brought seahorses to North America. A few million years later, this western connection also closed and the entire Tethys Ocean dried out. Ralf Schneider: "Until now it was unclear whether seahorses in the Atlantic all traced their lineage to species from the Arabian Sea that had travelled south along the east coast of Africa, around the Cape of Good Hope and across the southern Atlantic Ocean to reach South America. We found out that a second lineage of seahorses had done just that, albeit later."Since the research team gathered 20 animal samples from each habitat, it was also possible to measure the genetic variation between individuals. And this generally revealed: The greater the variation, the larger the population. "We can reconstruct the age of a variation based on its type. This makes it possible to calculate the size of the population at different points in time," the evolutionary biologist explains. This calculation reveals that the population that crossed the Atlantic Ocean to North America was very small, supporting the hypothesis that it have come from just a few animals brought there by the ocean's currents while holding on to a raft. The same data also showed that, even today, seahorses from Africa cross the southern Atlantic Ocean and introduce their genetic material into the South American population.Seahorses not only spread around the world by travelling with the ocean currents, but they were also surprisingly good at settling in new habitats. Seahorses have greatly modified genomes and, throughout their evolution, they have lost many genes, emerged with new ones or gained duplicates. This means: Seahorses change very quickly in comparison to other fish. This is probably why different types of "bony spines" evolved quickly and independently of each other that protect seahorses from predation in some habitats.Some of the genes have been identified that exhibit particular modifications for cer-tain species, but they are not the same for all species. Multiple fast and independent selections led to the development of spines, and although the same genes play a role in this development, different mutations were responsible. This shows that the slower, sessile seahorses were particularly able to adapt quickly to their environments. This is one of the main reasons the research team gives for seahorses being so successful in colonizing new habitats.
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Geography
| 2,021 |
February 17, 2021
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https://www.sciencedaily.com/releases/2021/02/210217114416.htm
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World's oldest DNA reveals how mammoths evolved
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An international team led by researchers at the Centre for Palaeogenetics in Stockholm has sequenced DNA recovered from mammoth remains that are up to 1.2 million years old. The analyses show that the Columbian mammoth that inhabited North America during the last ice age was a hybrid between the woolly mammoth and a previously unknown genetic lineage of mammoth. In addition, the study provides new insights into when and how fast mammoths became adapted to cold climate. These findings are published today in
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Around one million years ago there were no woolly or Columbian mammoths, as they had not yet evolved. This was the time of their predecessor, the ancient steppe mammoth. Researchers have now managed to analyse the genomes from three ancient mammoths, using DNA recovered from mammoth teeth that had been buried for 0.7-1.2 million years in the Siberian permafrost.This is the first time that DNA has been sequenced and authenticated from million-year-old specimens, and extracting the DNA from the samples was challenging. The scientists found that only minute amounts of DNA remained in the samples and that the DNA was degraded into very small fragments."This DNA is incredibly old. The samples are a thousand times older than Viking remains, and even pre-date the existence of humans and Neanderthals," says senior author Love Dalén, a Professor of evolutionary genetics at the Centre for Palaeogenetics in Stockholm.The age of the specimens was determined using both geological data and the molecular clock. Both these types of analyses showed that two of the specimens are more than one million years old, whereas the third is roughly 700 thousand years old and represents one of the earliest known woolly mammoths.Analyses of the genomes showed that the oldest specimen, which was approximately 1.2 million years old, belonged to a previously unknown genetic lineage of mammoth. The researchers refer to this as the Krestovka mammoth, based on the locality where it was found. The results show that the Krestovka mammoth diverged from other Siberian mammoths more than two million years ago."This came as a complete surprise to us. All previous studies have indicated that there was only one species of mammoth in Siberia at that point in time, called the steppe mammoth. But our DNA analyses now show that there were two different genetic lineages, which we here refer to as the Adycha mammoth and the Krestovka mammoth. We can't say for sure yet, but we think these may represent two different species," says the study's lead author Tom van der Valk.The researchers also suggest that it was mammoths that belonged to the Krestovka lineage that colonised North America some 1.5 million years ago. In addition, the analyses show that the Columbian mammoth that inhabited North America during the last ice age, was a hybrid. Roughly half of its genome came from the Krestovka lineage and the other half from the woolly mammoth."This is an important discovery. It appears that the Columbian mammoth, one of the most iconic Ice Age species of North America, evolved through a hybridisation that took place approximately 420 thousand years ago," says co-lead author Patrícia Pec?nerova?.The second million-year-old genome, from the Adycha mammoth, appears to have been ancestral to the woolly mammoth. The researchers could therefore compare its genome with the genome from one of the earliest known woolly mammoths that lived 0.7 million years ago, as well as with mammoth genomes that are only a few thousand years old. This made it possible to investigate how mammoths became adapted to a life in cold environments and to what extent these adaptations evolved during the speciation process.The analyses showed that gene variants associated with life in the Arctic, such as hair growth, thermoregulation, fat deposits, cold tolerance and circadian rhythms, were already present in the million-year-old mammoth, long before the origin of the woolly mammoth. These results indicate that most adaptations in the mammoth lineage happened slowly and gradually over time."To be able to trace genetic changes across a speciation event is unique. Our analyses show that most cold adaptations were present already in the ancestor of the woolly mammoth, and we find no evidence that natural selection was faster during the speciation process," says co-lead author David Di?ez-del-Molino.The new results open the door for a broad array of future studies on other species. About one million years ago was a period when many species expanded across the globe. This was also a time period of major changes in climate and sea levels, as well as the last time that Earth's magnetic poles changed places. Because of this, the researchers think that genetic analyses on this time scale have great potential to explore a wide range of scientific questions."One of the big questions now is how far back in time we can go. We haven't reached the limit yet. An educated guess would be that we could recover DNA that is two million years old, and possibly go even as far back as 2.6 million. Before that, there was no permafrost where ancient DNA could have been preserved," says Anders Götherström, a professor in molecular archaeology and joint research leader at the Centre for Palaeogenetics.
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Geography
| 2,021 |
February 16, 2021
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https://www.sciencedaily.com/releases/2021/02/210216083056.htm
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Groundwater recharge rates mapped for Africa
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Effective governance and investment decisions need to be informed by reliable data, not only about where groundwater exists, but also the rate at which groundwater is replenished. For the first time using ground measurements, a recent study has quantified groundwater recharge rates across the whole of Africa -- averaged over a fifty-year period -- which will help to identify the sustainability of water resources for African nations.
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The study, led by the British Geological Survey and involving an international team from the UK, South Africa, France, Nigeria, and America, developed a dataset of 134 existing recharge studies for Africa for the period from 1970 to 2019 to create a valuable resource providing an overview of the recharge pattern across the continent. Long-term average recharge values were evaluated, and each data source was critically reviewed. The recharge data were then analysed using a linear model, to map across Africa. The resulting dataset provides the first such ground-based approximation of the renewability of groundwater storage in Africa. The results have been published today in the IOP Publishing journal Lead author of the paper, BGS Hydrogeologist Professor Alan MacDonald explains the need for this research: "In many parts of the world, rapid increases in groundwater pumping have led to unsustainable conditions, characterised by falling water tables and problems with water quality. Consequently, quantifying the scale of groundwater recharge is critical to characterise the resilience of groundwater supplies to both increased use and climate change."Estimating groundwater recharge is difficult, as the authors outline: "There is no one method that can directly quantify the volume of rainwater that reaches the water-table, so the focus of the research has been to combine many different methods, each appropriate to the different environments in Africa and then aggregate them using statistical techniques."The results show that at a continental scale, long-term average rainfall predicts groundwater recharge but there are differences at a local scale due to soil and landcover and from year to year, due to the variability in the intensity of rainfall. Approximately 2% of all groundwater storage is replenished in Africa every decade and recharge can occur even in semi-arid areas. This research turns around some widely held perceptions and provides hope for the continent as it rapidly grows in population and infrastructure development.The new groundwater maps show an interesting pattern for Africa. Most African countries with little groundwater storage (such as Liberia, Guinea and Burundi) have high rainfall and therefore regular recharge and, conversely, many north African countries with negligible rainfall, usually considered as water insecure, have considerable groundwater storage.It is hoped that the groundwater recharge maps will help show where there is potential to sustainably develop more groundwater and where it could be wise to invest effort in monitoring groundwater that may be at risk of depletion or susceptible to drought. The research could also help countries locate where new more detailed studies should be focused and how to design these studies, identifying which methods may be the best to use.Professor MacDonald adds: "The maps of groundwater recharge and storage help uncover the hidden water security situation in Africa. For several countries with high groundwater storage, particularly in North Africa, groundwater pumping can increase current water security but, ultimately, at the expense of future generations. Countries with low groundwater storage are common in Africa because of the geology -- however for most of these countries this groundwater storage is replenished regularly and is a reliable source of water. Only if people pump out too much (for example for large scale irrigation) will the groundwater be in danger of drying up during droughts."Professor Seifu Kebede from the University of KwaZulu Natal, a co-author of the paper adds: "This effort brought together extensive African knowledge with expertise from other countries to provide information to sustainably develop water resources and overcome some of the most pressing issues countries often face, such as drought, deprivation, and starvation."This research was funded by the UPGro research programme, co-funded by the Natural Environment Research Council, UK Foreign, Commonwealth & Development Office and the Economic and Social Research Council.The maps and data will be added to the online groundwater Atlas, a gateway for groundwater information for African countries
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Geography
| 2,021 |
February 15, 2021
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https://www.sciencedaily.com/releases/2021/02/210215160442.htm
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In predicting shallow but dangerous landslides, size matters
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The threat of landslides is again in the news as torrential winter storms in California threaten to undermine fire-scarred hillsides and bring deadly debris flows crashing into homes and inundating roads.
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But it doesn't take wildfires to reveal the landslide danger, University of California, Berkeley, researchers say. Aerial surveys using airborne laser mapping -- LiDAR (light detection and ranging) -- can provide very detailed information on the topography and vegetation that allow scientists to identify which landslide-prone areas could give way during an expected rainstorm. This is especially important for predicting where shallow landslides -- those just involving the soil mantle -- may mobilize and transform as they travel downslope into destructive debris flows.The catch, they say, is that such information cannot yet help predict how large and potentially hazardous the landslides will be, meaning that evacuations may target lots more people than are really endangered by big slides and debris flows.In a new paper appearing this week in the journal Yet, while the model is better at identifying areas prone to larger and potentially more dangerous landslides, the researchers discovered factors affecting landslide size that can't easily be determined from aerial data and must be assessed from the ground -- a daunting task, if one is concerned about the entire state of California.The key unknowns are what the subsurface soil and underlying bedrock are like and the influence of past landslides on ground conditions."Our studies highlight the problem of overprediction: We have models that successfully predict the location of slides that did occur, but they end up predicting lots of places that didn't occur because of our ignorance about the subsurface," said Dietrich, UC Berkeley professor of earth and planetary science. "Our new findings point out specifically that the spatial structure of the hillslope material -- soil depth, root strength, permeability and variabilities across the slope -- play a role in the size and distribution and, therefore, the hazard itself. We are hitting a wall -- if we want to get further with landslide prediction that attempts to specify where, when and how big a landslide will be, we have to have knowledge that is really hard to get, but matters."Decades of studies by Dietrich and others have led to predictive models of where and under what rainfall conditions slopes will fail, and such models are used worldwide in conjunction with weather prediction models to pinpoint areas that could suffer slides in an oncoming storm and warn residents. But these models, triggered by a so-called "empirical rainfall thresholds," are conservative, and government agencies often end up issuing evacuation warnings for large areas to protect lives and property.Dietrich, who directs the Eel River Critical Zone Observatory -- a decade-long project to analyze how water moves all the way from the tree canopy through the soil and bedrock and into streams -- is trying to improve landslide size prediction models based on the physics of slopes. Airborne laser imaging using LiDAR can provide submeter-scale detail, not only of vegetation, but also of the ground under the vegetation, allowing precise measurements of slopes and a good estimate of the types of vegetation on the slopes.Slopes fail during rainstorms, he said, because the water pressure in the soil -- the pore pressure -- pushes soil particles apart, making them buoyant. The buoyancy reduces the friction holding the soil particles against gravity, and once the mass of the slide is enough to snap the roots holding the soil in place, the slope slumps. Shallow slides may involve only the top portion of the soil, or scour down to bedrock and push everything below it downslope, creating deadly debris flows that can travel several meters per second.Each wet year along the Pacific Coast, homes are swept away and lives lost from large landslides, though the threat is worldwide. As illustrated by a landslide in Sausalito exactly two years ago, landslides can originate just a short distance upslope and mobilize as a debris flow traveling meters per second before striking a house. The size of the initial landslide will influence the depth and speed of the flow and the distance it can travel downslope into canyons, Dietrich said.With earlier computer models, Dietrich and his colleagues were able to pinpoint more precisely the places on hillslopes that would suffer landslides. In 2015, for example, Bellugi and Dietrich used their computer model to predict shallow landslides on a well-studied hillslope in Coos Bay, Oregon, during a sequence of landslide-triggering rainstorms, based solely on these physical measures. Those models employed LiDAR data to calculate steepness and how water would flow downslope and affect pore pressure inside the slope; the seasonal history of rainfall in the area, which helps assess how much groundwater is present; and estimates of the soil and root strength.In the new paper, Bellugi and David Milledge of Newcastle University in Newcastle upon Tyne in the United Kingdom tested the landslide prediction model on two very different landscapes: a very steep, deeply etched and forested hillside in Oregon, and a smooth, grassy, gently sloped glacial valley in England's storied Lake District.Surprisingly, they found that the distribution of small and large shallow landslides were quite similar across both landscapes and could be predicted if they took into account one extra piece of information: the variability of hillslope strength across these hillsides. They discovered that small slides can turn into major slides if the conditions -- soil strength, root strength and pore pressure -- do not vary sufficiently over short distances. Essentially, small slides can propagate across the slope and become larger by connecting isolated slide-prone areas, even if they're separated by more solid slope."These areas that are susceptible to shallow landslides, even though you may be able to define them, may coalesce, if close enough to each other. Then you can have a big landslide that encompasses some of these little patches of low strength," Bellugi said. "These patches of low strength may be separated by areas that are strong -- they may be densely forested or less steep or drier -- but if they are not well separated, then those areas can coalesce and make a giant landslide.""On hillsides, there are trees and topography, and we can see them and quantify them," Dietrich added. "But starting from the surface and going down into the ground, there is a lot that we need in models that we can't now quantify over large areas: the spatial variation in soil depth and root strength and the influence of groundwater flow, which can emerge from the underlying bedrock and influence soil pore pressure."Getting such detailed information across an entire slope is a herculean effort, Dietrich said. On the Oregon and Lake District slopes, researchers walked or scanned the entire area to map vegetation, soil composition and depth, and past slides meter by meter, and then painstakingly estimated root strength, all of which is impractical for most slopes."What this says is that to predict the size of a landslide and a size distribution, we have a significant barrier that is going to be hard to cross -- but we need to -- which is to be able to characterize the subsurface material properties," Dietrich said. "Dino's paper says that the spatial structure of the subsurface matters."The researchers' previous field studies found, for example, that fractured bedrock can allow localized subsurface water flow and undermine otherwise stable slopes, something not observable -- yet -- by aerial surveys.They urge more intensive research on steep hillsides to be able to predict these subsurface features. This could include more drilling, installing hydrologic monitoring equipment and application of other geophysical tools, including cone penetrometers, which can be used to map soil susceptible to failure.Other co-authors of the paper are Lauren Larsen and Kurt Cuffey, UC Berkeley professors of geography.The work was supported by a Gordon and Betty Moore Foundation Data Driven Discovery Investigator Award to Bellugi and Larsen. Dietrich is supported by a National Science Foundation grant for the Eel River Critical Zone Observatory (EAR-1331940). Cuffey was supported by the Martin Family Foundation.
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Geography
| 2,021 |
February 11, 2021
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https://www.sciencedaily.com/releases/2021/02/210211114002.htm
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Study finds even the common house sparrow is declining
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The European House Sparrow has a story to tell about survival in the modern world. In parts of its native range in Europe, House Sparrow numbers are down by nearly 60%. Their fate in the U.S. and Canada is less well known. A new study by Cornell Lab of Ornithology scientists aims to clarify the status of this non-native species, using 21 years of citizen science data from the Cornell Lab's Project FeederWatch. The results are published in the
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"We wanted to find out where and how much House Sparrows might be declining here," explains lead author Liam Berigan, who did this work while at the Cornell Lab and who is now a Ph.D. student at the University of Maine. "We also explored whether the declines would match up with an increase in hawk populations, as is true in European studies. Surprisingly, they didn't."FeederWatchers record observations during the non-breeding season when House Sparrows gather in flocks. Reports from nearly 12,500 sites were used and cross-referenced with the National Land Cover database to determine whether the U.S. sightings came from rural or urban locations.Findings for the U.S. and Canada:House Sparrows were introduced in Brooklyn in 1851. They expanded rapidly to become one of the most common species in the U.S. and Canada. Latest estimates peg the population at 82 million individuals. The global breeding population is estimated at 740 million (Partners in Flight)."When even a bird as common as the House Sparrow is experiencing population declines, this is probably a reflection on the state of the environment," says Berigan. "In Europe, a lack of urban green space and nesting sites are threats. It's likely some of those same factors are at work in North America and contribute to House Sparrow declines here."
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Geography
| 2,021 |
February 10, 2021
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https://www.sciencedaily.com/releases/2021/02/210210165959.htm
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Sawfish face global extinction unless overfishing is curbed
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Sawfish have disappeared from half of the world's coastal waters and the distinctive shark-like rays face complete extinction due to overfishing, according to a new study by Simon Fraser University researchers, published in
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Sawfish, named after their unique long, narrow noses lined by teeth, called rostra, that resemble a sawblade, were once found along the coastlines of 90 countries but they are now among the world's most threatened family of marine fishes, presumed extinct from 46 of those nations. There are 18 countries where at least one species of sawfish is missing, and 28 more where two species have disappeared.According to SFU researchers Helen Yan and Nick Dulvy, three of the five species of sawfish are critically endangered, according to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, and the other two are endangered.Their teeth on their rostra are easily caught in fishing nets. Sawfish fins are among the most valuable in the global shark fin trade and rostra are also sold for novelty, medicine and as spurs for cockfighting.The current presence of all sawfishes world-wide is unknown, but Dulvy warns complete extinction is possible if nothing is done to curb overfishing and to protect threatened habitats, such as mangroves, where sawfish can thrive."Through the plight of sawfish, we are documenting the first cases of a wide-ranging marine fish being driven to local extinction by overfishing," Dulvy says. "We've known for a while that the dramatic expansion of fishing is the primary threat to ocean biodiversity, but robust population assessment is difficult for low priority fishes whose catches have been poorly monitored over time. With this study, we tackle a fundamental challenge for tracking biodiversity change: discerning severe population declines from local extinction."The study recommends that international conservation efforts focus on eight countries (Cuba, Tanzania, Columbia, Madagascar, Panama, Brazil, Mexico and Sri Lanka) where conservation efforts and adequate fishing protections could save the species. It also found Australia and the United States, where adequate protections already exist and some sawfish are still present, should be considered as "lifeboat" nations."While the situation is dire, we hope to offset the bad news by highlighting our informed identification of these priority nations with hope for saving sawfish in their waters," says Yan. "We also underscore our finding that it's actually still possible to restore sawfish to more than 70 per cent of their historical range, if we act now."
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Geography
| 2,021 |
February 10, 2021
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https://www.sciencedaily.com/releases/2021/02/210210091204.htm
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Genetic markers show Pacific albacore tuna intermingle across equator
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Analyzing thousands of genetic markers in albacore tuna from the Pacific Ocean, researchers at Oregon State University have learned that just seven dozen of those markers are needed to determine which side of the equator a fish comes from.
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The scientists also discovered that fish from different hemispheres intermingle and sometimes breed with each other.Published Tuesday in Albacore in the North and South Pacific Oceans are currently managed as separate stocks. The OSU study affirms this approach while also opening the door to more research into overlap and interbreeding that can be used to refine management strategies throughout the Pacific."Albacore support one of the world's largest and most valuable fisheries and one that is particularly important on the west coast of North America," said Kathleen O'Malley, an associate professor in the OSU College of Agricultural Sciences. "There's been a lot of work done to understand stock structure of the albacore globally, but research in the Pacific hasn't been very fine-tuned and has tended to generate as many questions as answers."O'Malley, who is also the fisheries geneticist for the state of Oregon, noted that previous research involving tagged fish has revealed no movement of albacore from one side of the equator to the other. At the same time, previous genetic data have yielded no way to tell if a fish was from the North Pacific or South Pacific -- hence the lack of understanding regarding the connectivity between the two populations.O'Malley and postdoctoral research associate Felix Vaux, who led the study, looked at DNA from 308 fish from 12 locales around the Pacific. They identified nearly 13,000 genetic markers -- DNA sequences with known physical locations on chromosomes -- and learned that fewer than 100 of those markers told the tale of what part of the ocean a fish came from."We identified 12,872 markers and were able to discriminate between North and South Pacific albacore by using only 84 of them," Vaux said.Those 84, he added, appear to be "under selection" and may reflect adaptive differences between the two albacore stocks. In any population, individuals with locally adapted traits tend to be the most successful reproductively, meaning that over time selection will increase the prevalence of those traits. With continuing, intense selection, adaptive traits become universal or close to it in a population or species."There is no complete genome for albacore to compare our data against, so we weren't able to determine which genes underlie these likely adaptive differences," O'Malley said. "In addition, we found that some fish have mixed genetic backgrounds -- indicating that albacore from the North and South Pacific sometimes spawn at the same time and place and breed together. Also, we detected albacore with South Pacific genetic profiles in the North Pacific, providing evidence for migration across the equator that had earlier gone undetected via physical tagging data."Future studies, she added, will use these genetic markers to more deeply investigate interbreeding between North and South Pacific albacore as well as migration between hemispheres.O'Malley, who directs the State Fisheries Genomics Lab at OSU's Hatfield Marine Science Center, says that both genetic and demographic connectivity, while important for effective management and conservation strategies, are not well understood in most marine species.Genetic diversity is an important tool for populations trying to adapt to climate change and other environmental perturbances, she said. With more variation, it is more likely that some individuals in a population will be suited to withstand the changes and produce offspring that are also able to thrive in the modified environment.
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Geography
| 2,021 |
February 4, 2021
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https://www.sciencedaily.com/releases/2021/02/210204101646.htm
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Ocean surface slicks are pelagic nurseries for diverse fishes
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To survive the open ocean, tiny fish larvae, freshly hatched from eggs, must find food, avoid predators, and navigate ocean currents to their adult habitats. But what the larvae of most marine species experience during these great ocean odysseys has long been a mystery, until now.
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A team of scientists from NOAA's Pacific Islands Fisheries Science Center, the University of Hawai'i (UH) at Manoa, Arizona State University and elsewhere have discovered that a diverse array of marine animals find refuge in so-called 'surface slicks' in Hawai'i. These ocean features create a superhighway of nursery habitat for more than 100 species of commercially and ecologically important fishes, such as mahi-mahi, jacks, and billfish. Their findings were published today in the journal Surface slicks are meandering lines of smooth surface water formed by the convergence of ocean currents, tides, and variations in the seafloor and have long been recognized as an important part of the seascape. The traditional Hawaiian mele (song) Kona Kai `?pua describes slicks as Ke kai ma`oki`oki, or "the streaked sea" in the peaceful seas of Kona. Despite this historical knowledge and scientists' belief that slicks are important for fish, the tiny marine life that slicks contain has remained elusive.To unravel the slicks' secrets, the research team conducted more than 130 plankton net tows inside the surface slicks and surrounding waters along the leeward coast of Hawai'i Island, while studying ocean properties. In these areas, they searched for larvae and other plankton that live close to the surface. They then combined those in-water surveys with a new technique to remotely sense slick footprints using satellites.Though the slicks only covered around 8% of the ocean surface in the 380-square-mile-study area, they contained an astounding 39% of the study area's surface-dwelling larval fish; more than 25% of its zooplankton, which the larval fish eat; and 75% of its floating organic debris such as feathers and leaves.Larval fish densities in surface slicks off West Hawai?i were, on average, over 7 times higher than densities in the surrounding waters.The study showed that surface slicks function as a nursery habitat for marine larvae of at least 112 species of commercially and ecologically important fishes, as well as many other animals. These include coral reef fishes, such as jacks, triggerfish and goatfish; pelagic predators, for example mahi-mahi; deep-water fishes, such as lanternfish; and various invertebrates, such as snails, crabs, and shrimp.The remarkable diversity of fishes found in slick nurseries represents nearly 10% of all fish species recorded in Hawai?i. The total number of taxa in the slicks was twice that found in the surrounding surface waters, and many fish taxa were between 10 and 100 times more abundant in slicks."We were shocked to find larvae of so many species, and even entire families of fishes, that were only found in surface slicks," said lead author Dr. Jonathan Whitney, marine ecologist at NOAA, former postdoctoral fellow at the Joint Institute for Marine and Atmospheric Research (JIMAR) in UH Manoa's School of Ocean and Earth Science and Technology (SOEST). "This suggests they are dependent on these essential habitats.""These 'bioslicks' form an interconnected superhighway of rich nursery habitat that accumulate and attract tons of young fishes, along with dense concentrations of food and shelter," said Whitney. "The fact that surface slicks host such a large proportion of larvae, along with the resources they need to survive, tells us they are critical for the replenishment of adult fish populations."In addition to providing crucial nursing habitat for various species and helping maintain healthy and resilient coral reefs, slicks create foraging hotspots for larval fish predators and form a bridge between coral reef and pelagic ecosystems.What's more, the slicks host larvae and juvenile stages of many forage fishes like flying fishes that are critical to pelagic food webs."These hotspots provide more food at the base of the food chain that amplifies energy up to top predators," said study co-author Dr. Jamison Gove, a research oceanographer for NOAA. "This ultimately enhances fisheries and ecosystem productivity."While slicks may seem like havens for all tiny marine animals, there's a hidden hazard lurking in these ocean oases: plastic debris. Within the study area, 95% of the plastic debris collected into slicks, compared with 75% of the floating organic debris. Larvae may get some shelter from plastic debris, but it comes at the cost of chemical exposure and incidental ingestion."Until we stop plastics from entering the ocean," Whitney said, "the accumulation of hazardous plastic debris in these nursery habitats remains a serious threat to the biodiversity hosted here."In certain areas, slicks can be dominant surface features, and the new research shows these conspicuous phenomena hold more ecological value than meets the eye."Our work illustrates how these oceanic features (and animals' behavioral attraction to them) impact the entire surface community, with implications for the replenishment of adults that are important to humans for fisheries, recreation, and other ecosystem services," said Dr. Margaret McManus, co-author, Professor and Chair of the Department of Oceanography at UH Manoa. "These findings will have a broad impact, changing the way we think about oceanic features as pelagic nurseries for ocean fishes and invertebrates."
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Geography
| 2,021 |
February 1, 2021
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https://www.sciencedaily.com/releases/2021/02/210201101520.htm
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Are plastics and microplastics in the Ocean on the increase?
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That is the question that Prof. Alan Deidun, resident academic within the Department of Geosciences of the Faculty of Science, along with a cohort of high-profile co-authors, posed within a study recently published in the
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The study, whose lead author is litter researcher Dr Francois Galgani from IFREMER, concludes that, despite the well-known increase in the volume of plastics making their way to the marine domain from land, most studies indicate constant amounts of litter in coastal marine systems in recent years until 2019. For instance, collections of marine litter by Continuous Plankton Recorders showed relatively unchanged amounts trapped annually in the North East Atlantic since the year 2000, following a steady increase since the 1950s. For some components of marine litter, such as industrial pellets, policy-making seems to be effective given that measures taken to reduce their use in industrial practices seem to have translated into smaller volumes of this component being detected within the marine domain.Although a prima facie a surprising find, this 'steady state' scenario could be indicative of:a transfer of plastic litter to remote areas of the global ocean, where human monitoring programmes are non-existent or subdued, such that the same litter does not feature in statistics and/orthe degradation into smaller fragments (micro- and nanoplastics) of the same litter which can go undetected due to its small size (e.g. fibres within microplastic nets) or since they are within marine biota.The published study emanated from Chapter 12 of the UN's Second World Ocean Assessment, which is imminently set to be released by the UN in the coming months. Prof. Deidun features as a co-author within two different chapters in such an Assessment, including the ones on marine alien species and on benthic invertebrates. The same study concludes by soliciting, within the current UN Decade for Ocean Sciences, a greater research effort to be invested in identifying the sources of the marine litter as well as in the degradation pathways for different components of the same litter, as otherwise our capacity to identify temporal trends in marine litter will not progress further.Statistics related to marine plastic litter make for sobering reading. For instance, according to the Ocean Conservancy, an estimated 8 million tons of plastic enter seas worldwide each year, on top of the 150 million plastic tons already roaming the same seas. A staggering 380 million tons of plastic are produced annually, of which an estimated 50% is Single-Use Plastic (SUP), including the 500 billion plastic bags sold worldwide each year and which, on average, have a lifetime of just 15 minutes.
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Geography
| 2,021 |
January 26, 2021
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https://www.sciencedaily.com/releases/2021/01/210126140039.htm
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Scientists identify flank instability at a volcano with history of collapse
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Landslides caused by the collapse of unstable volcanoes are one of the major dangers of volcanic eruptions. A method to detect long-term movements of these mountains using satellite images could help identify previously overlooked instability at some volcanoes, according to Penn State scientists.
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"Whenever there is a large volcanic eruption, there is a chance that if a flank of the volcano is unstable there could be a collapse," said Judit Gonzalez-Santana, a doctoral student in the Department of Geosciences. "To better explore this hazard, we applied an increasingly popular and more sensitive time-series method to look at these movements, or surface deformation, over longer time periods."Using the time-series technique, the scientists found surface deformation related to flank motion had occurred at Pacaya, an active volcano in Guatemala, from 2011 to 2013 when the volcano was largely quiet, and increased leading up to an eruption in 2014. Previous work had not identified flank motion during this time, the scientists said."People have looked at that volcano with satellite remote sensing but did not detect this long-term flank motion or creep," said Christelle Wauthier, associate professor of geosciences. "Because the surface deformation changes are pretty small per year, it can easily be below the detection limits of conventional methods, but still within the limits of Judit's work using a time-series approach."Scientists track surface deformation using radar satellites sensitive enough to spot changes of just a few inches on the ground. Comparing two of these images using the conventional Interferometric Synthetic Aperture Radar (InSAR) technique creates an interferogram, essentially a map of surface movement. But the quality of the InSAR results decreases with the time separating two images and can be affected by even small changes, like from vegetation growth or a buildup of ash spewed from a volcano, the scientists said.The team instead conducted an InSAR time-series analysis using hundreds of satellite images taken over years and identifying surface deformation between each."You can use many of these short-term surface movement maps to give you information of surface displacement over a long time period," Gonzalez-Santana said. "Then you can look at the surface deformation maps and see how much each pixel has been moving since the date the first image was acquired, for example."The results, published in the "This kind of creep is not uncommon and not particularly dangerous on its own, but if you have extra forcings like from magma being pressurized and pushing against the wall of the chamber or intrusion, it can trigger a catastrophic collapse," Wauthier said. "To be able to understand the behavior of the instability and potentially detect changes in rates of motion is very critical for monitoring that potential collapse."The method shows promise for identifying deformation particularly at volcanoes that lack expensive real-time monitoring networks and those located in tropical areas with thick vegetation that create problems for traditional InSAR, the scientists said.Flank instability is often studied at oceanic volcanoes, where a collapse could trigger a deadly tsunami, according to the scientists. But collapses also happen inland, including prominently at Mount St. Helens in 1980.Pacaya itself experienced a collapse sometime around 1,000 years ago, creating a debris avalanche that traveled more than 15 miles, and leaving a prominent scar on the volcano. Subsequent eruptions have built the volcano back up and it could someday again collapse, the scientists said."More than 10,000 people live within about three miles of the volcano," Gonzalez-Santana said. "If you take into consideration the last avalanche traveled 15 miles away, anyone living in the valleys around the volcano could be at risk."A NASA Earth Surface and Interior grant, a Future Investigators in NASA Earth and Space Science and Technology grant, and an Institute for Computational and Data Sciences seed grant funded this research.
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Geography
| 2,021 |
January 25, 2021
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https://www.sciencedaily.com/releases/2021/01/210125144548.htm
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Diverse cephalopod fauna in the canary current large marine ecosystem
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An extensive review of cephalopod fauna from the Northwest African Atlantic coast was performed by researchers from the University of Vigo (Spain) and the Spanish Institute of Oceanography (IEO). The study was based on the collections gathered in 1,247 bottom trawl stations carried out during ten multidisciplinary surveys in the Canary Current Large Marine Ecosystem (CCLME).
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The surveys were conducted by the IEO and the FAO -- in the framework of their EAF-Nansen and CCLME projects -- along the continental shelf and slope off Morocco, Western Sahara, Mauritania, Senegal, The Gambia, Guinea-Bissau, Guinea, and Cabo Verde, between 2004 and 2012. In all these surveys, the EcoAfrik research team (UVIGO-IEO) led the development of a program focused on benthos intensive sampling. During these surveys a huge amount of quantitative biological data, environmental parameters of the water column and seabed, and important collections of benthic invertebrates were obtained.After several years devoted to taxonomic study and the exhaustive review of the existing literature, an updated checklist of 138 cephalopods species was generated for the whole CCLME area. Besides, the known geographical distributions of several species have been expanded, as some deep-sea octopuses (such as Muusoctopus januarii, Bathypolypus valdiviae or Cirrothauma murrayi) and many oceanic squids (such as Abralia siedleckyi, Magnoteuthis magna or Chtenopteryx sicula), some recorded for the first time in the area.The CCLME hosts one of the four major marine upwelling systems and is the third concerning primary productivity worldwide, supporting the largest fisheries of the Atlantic African coast, with an annual production of approximately 2-3 million tonnes. Among the main target commercial species are included some cephalopod groups as squids, cuttlefishes and octopuses.Although most of the cephalopod species with commercial value in the region have been well-studied, many aspects of the systematic, distribution, biogeography and ecology of other cephalopods are practically unknown.The EcoAfrik collections represent an exceptional source of information that will provide a global view on the biodiversity, composition and distribution of cephalopods from Northwest Africa.
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Geography
| 2,021 |
January 21, 2021
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https://www.sciencedaily.com/releases/2021/01/210121131837.htm
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Fish sex organs boosted under high-CO2
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Research from the University of Adelaide has found that some species of fish will have higher reproductive capacity because of larger sex organs, under the more acidic oceans of the future.
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Published in "The warming oceans absorb about one-third of the additional CO"We know that many species are negatively affected in their behaviour and physiology by ocean acidification. But we found that in this species of temperate fish -- the common triplefin -- both males and females had larger gonads under conditions of ocean acidification. This meant increased egg and sperm production and therefore more offspring."The team used natural volcanic COThey found that there were no negative effects of ocean acidification for the triplefins. The larger gonads did not come at a physiological cost."We found males were eating more. They showed intensified foraging on more abundant prey -- which was more abundant because of the increased biomass of algae that grows under the elevated CO"The females, on the other hand, did not eat more. They instead reduced their activity levels to preserve energy and then invested this in larger ovaries."We also found there were more mature males under elevated COThe researchers found that other, less dominant, fish species did not show such an effect of reproductive output, perhaps due to their less competitive nature."We think it likely that the triplefin and similar species will do very well under increased ocean acidification," says co-author Professor Sean Connell. "The study shows that some, more dominant, species will be able to capitalise on changes to ecosystems under ocean acidification, increasing their population."
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Geography
| 2,021 |
January 21, 2021
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https://www.sciencedaily.com/releases/2021/01/210121131715.htm
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Burial practices point to an interconnected early Medieval Europe
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Early Medieval Europe is frequently viewed as a time of cultural stagnation, often given the misnomer of the 'Dark Ages'. However, analysis has revealed new ideas could spread rapidly as communities were interconnected, creating a surprisingly unified culture in Europe.
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Dr Emma Brownlee, Department of Archaeology, University of Cambridge, examined how a key change in Western European burial practices spread across the continent faster than previously believed -- between the 6th -- 8th centuries AD, burying people with regionally specific grave goods was largely abandoned in favour of a more standardised, unfurnished burial."Almost everyone from the eighth century onwards is buried very simply in a plain grave, with no accompanying objects, and this is a change that has been observed right across western Europe," said Dr Brownlee.To explore this change, Emma examined over 33,000 graves from this period in one of the largest studies of its kind. Statistical analysis was used to create a 'heat map' of the practice, tracking how it changed in frequency over time.The results of this analysis, published in the journal "The most important finding is that the change from burial with grave goods to burial without them was contemporary across western Europe," said Dr Brownlee. "Although we knew this was a widespread change before, no one has previously been able to show just how closely aligned the change was in areas that are geographically very far apart."Crucially, this contemporary transition provides strong evidence that early Medieval Europe was a well-connected place, with regular contact and exchange of ideas across vast areas.Evidence of increasing long-distance trade is seen around this period, which may have been how these connections were facilitated. As the idea spread between communities, social pressure drove more people to adopt it. As more people did, this pressure grew -- explaining why the spread of unfurnished funerals appeared to accelerate over time.With people sharing more similarities, this likely reinforced the connections themselves as well."The change in burial practice will have further reinforced those connections; with everyone burying their dead in the same manner, a medieval traveller could have gone anywhere in Europe and seen practices they were familiar with," said Dr Brownlee.An interconnected Europe with long-distance trade and travel facilitating the spread of new ideas to create a shared culture may sound modern, but in reality, Europe has been 'global' for over a millennium.
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Geography
| 2,021 |
January 21, 2021
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https://www.sciencedaily.com/releases/2021/01/210121132037.htm
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European eels - one gene pool fits all
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European eels spawn in the subtropical Sargasso Sea but spend most of their adult life in a range of fresh- and brackish waters, across Europe and Northern Africa. How eels adapt to such diverse environments has long puzzled biologists. Using whole-genome analysis, a team of scientists led from Uppsala University provides conclusive evidence that all European eels belong to a single panmictic population irrespective of where they spend their adult life, an extraordinary finding for a species living under such variable environmental conditions. The study is published in
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How species adapt to the environment is of fundamental importance in biology. Genetic changes that facilitate survival in individuals occupying new or variable environments provides the foundation for evolutionary change. These changes can be revealed as differences in the frequency of gene variants between subgroups within species. Alternatively, individuals may respond to changing environments through physiological change without genetic change, a process known as phenotypic plasticity. For example, eels adjust their osmoregulation when migrating from marine waters to freshwater."Eels have a truly fascinating life history and go through several stages of metamorphosis," explains Dr. Håkan Wickström, from the Swedish University of Agricultural Sciences and one of the co-authors. "Spawning takes place in the Sargasso Sea, then offspring drift as leptocephali larvae until they reach the European or African continent where they metamorphose into glass eels. Glass eels become yellow eels after entering into brackish or freshwater and later develop into reproductively mature silver eels before returning to the Sargasso Sea for spawning, completing a second crossing of the Atlantic. After that they all die.""To the best of our knowledge all eels spawn in the Sargasso Sea, but that did not exclude the possible existence of subpopulations," explains Dr. Mats Pettersson, Uppsala University, one of the shared first authors. "For instance, northern eels may spawn in a different region, or at a different depth, or during a different period than southern eels, or they may simply have the ability to recognise conspecifics from the same climatic region. In this study, we wanted to provide the ultimate answer to the important question whether European eels belong to a single panmictic population or not. We have done that after sequencing the entire genomes of eels collected across Europe and North Africa.""When comparing the DNA sequences of eels from different parts of Europe and North-Africa we do not find any significant differences in the frequency of gene variants," states Mats Pettersson. "We therefore conclude that European eels belong to a single panmictic population and that their ability to inhabit such a wide range of environments must be due to phenotypic plasticity.""Eels are an enigmatic species that have long captured the imagination of society. Modern genomic analysis allows us to track the evolutionary history of eels, and it is rather impressive that adult eels can inhabit such a range of environments without becoming isolated into genetic subpopulations. It is amazing to think that even with millions of genetic variants we cannot distinguish an eel in a lake in Sweden from an eel in a North-African river. This provides just another clue in a long history of uncovering the life history of this fascinating species," said Dr. Erik Enbody, Uppsala University, and shared first author. "An important implication of these findings is that preventing eel population declines requires international cooperation, as this species constitutes a single breeding population."In many other marine fish species, subpopulations living in different environments undergo genetic changes associated with local adaptation to that environment. Recent research from the same group in December on the Atlantic herring revealed extensive local adaptation related to, for instance, salinity and water temperature at spawning. European eels are exposed to a much broader range of environmental conditions than the Atlantic herring, but do not have the associated genetic changes. How is this lack of genetic adaptation in eels possible?"Our hypothesis is that this striking difference between Atlantic herring and Europeans eels is explained by the fact that all eels are spawning under near identical conditions in the Sargasso Sea. Atlantic herring, on the other hand, are spawning in different geographic areas under diverse environmental conditions, with regard to salinity, temperature and season. These conditions require local genetic adaptations because fertilization and early larval development is the most sensitive period during the life of a fish," explains Professor Leif Andersson, Uppsala University and Texas A&M University, who led the study."An important topic for future studies is to explore how eels are able to cope with such diverse environmental conditions. It is likely that eels for millions of years have had a life history where spawning takes place under very similar conditions whereas most part of the lifecycle takes place under diverse environmental conditions. Mechanisms for handling this challenge may thus have evolved by natural selection," Leif Andersson ends.
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Geography
| 2,021 |
January 21, 2021
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https://www.sciencedaily.com/releases/2021/01/210121131913.htm
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This Great Lakes fish may have evolved to see like its ocean ancestors did
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In the dark waters of Lake Superior, a fish species adapted to regain a genetic trait that may have helped its ancient ancestors see in the ocean, a study finds.
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The research focuses on kiyis, which inhabit Lake Superior at depths of about 80 to over 200 meters deep. These fish, known to scientists as "Coregonus kiyi," belong to a group of closely related salmonids known as ciscoes.In contrast to three other Lake Superior ciscoes that dwell and feed in shallower regions of water, the kiyis are far more likely to carry a version of the rhodopsin gene that probably improves vision in dim "blue-shifted" waters, the study concludes. Every one of 21 kiyis the team examined from this deep-water population carried only this variant of the gene.The adaptation appears to mark a return to an ancient state: Some 175 million years ago, the kiyis' ocean-dwelling forebears likely harbored the same genetic variant, according to a reconstruction of the species' evolutionary history.Then, as ancestral fish populations moved from blue-shifted marine waters into shallower, "red-shifted" streams and lakes, a form of rhodopsin that's beneficial in those habitats became more common, scientists say. Finally, the kiyis, reaching the deep waters of Lake Superior, adapted again to the "blue-shifted" color of the waters they now inhabit.The study was published online Nov. 28 in the journal "Evolution is often thought of as a one-way process, at least over deep time, but in this example, over 175 million years, we have this reversal back to a much earlier ancestral state," says Trevor Krabbenhoft, PhD, assistant professor of biological sciences in the UB College of Arts and Sciences and a faculty member in the UB RENEW Institute. Krabbenhoft led the research with first author Katherine Eaton."Fishery biologists are trying to restore native fish populations in the Great Lakes, so it's important to understand the adaptations that species have," says Eaton, a PhD student at Auburn University who completed the study at UB as an undergraduate in biological sciences. "Knowledge of a species' adaptations can help us restore them in environments that are better suited to their biology."It's unclear whether the kiyis' ancestors completely lost the blue-shifted gene variant before re-evolving it, or if the variant simply became less frequent in this fish lineage before re-emerging to become more prolific again.Either way, today, "There is a really clear distinction between the deep-water and shallow-water species," Eaton says.Whereas all of the kiyis studied had the blue-shifted form of rhodopsin, the shallower water ciscoes sampled -- Coregonus artedi, Coregonus hoyi and Coregonus zenithicus -- primarily had the version of the gene that may be helpful in red-shifted waters.Eaton notes that the same blue-shifted variant of rhodopsin is present in a number of other fish that live in the sea or deep lake water. This repeated "parallel" evolution can indicate that an adaptation has an important function: in this case, probably helping fish see in different environments, she says.These insights are important because light in the Great Lakes is changing, Krabbenhoft says. For example, invasive zebra and quagga mussels, which filter organic matter from lakes, are increasing the clarity of the water in places.The knowledge is also valuable as scientists look to restore native fish populations. In addition to the rhodopsin research, Krabbenhoft is a co-author of a study examining the genetics, morphology and ecology of ciscoes more broadly. That work, also funded by the Great Lakes Fishery Commission, was led by Moisés Bernal, PhD, now an assistant professor of biological sciences at Auburn University. The study results were posted on Dec. 16 to the preprint server bioRxiv, and have not yet been published in a peer-reviewed journal."Collectively, these projects have implications for restoring the native biodiversity in the Great Lakes toward a healthy ecosystem," Krabbenhoft says. "Ciscoes were once much more abundant and diverse across the five Great Lakes, but some species went extinct due to overfishing, sea lamprey invasion and pollution. Our data are informing restoration strategies as these fish are being re-established in places where they were lost or highly reduced in number, such as in Lake Ontario.""Ciscoes were once the dominant native prey species in the Great Lakes, supporting top predators such as lake trout and walleye. They remain an important component of the tribal, commercial and recreational fisheries, which are valued at more than $7 billion annually," says Bill Taylor, PhD, Commissioner for the Great Lakes Fishery Commission and a University Distinguished Professor in Global Fisheries Systems at Michigan State University. "Research to better understand their biology and morphology is critical to designing successful restoration efforts in the future."
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Geography
| 2,021 |
January 19, 2021
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https://www.sciencedaily.com/releases/2021/01/210119140200.htm
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Counting elephants from space
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For the first time, scientists have successfully used satellite cameras coupled with deep learning to count animals in complex geographical landscapes, taking conservationists an important step forward in monitoring populations of endangered species.
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For this research, the satellite Worldview 3 used high-resolution imagery to capture African elephants moving through forests and grasslands. The automated system detected animals with the same accuracy as humans are able to achieve.The algorithm that enabled the detection process was created by Dr Olga Isupova, a computer scientist at the University of Bath in the UK. The project was a collaboration with the UK's University of Oxford and the University of Twente in the Netherlands.Dr Isupova said the new surveying technique allows vast areas of land to be scanned in a matter of minutes, offering a much-needed alternative to human observers counting individual animals from low-flying airplanes. As it sweeps across the land, a satellite can collect over 5,000 km² of imagery every few minutes, eliminating the risk of double counting. Where necessary (for instance, when there is cloud coverage), the process can be repeated the next day, on the satellite's next revolution of Earth.The population of African elephants has nose-dived over the past century, mainly due to poaching and habitat fragmentation. With approximately 415,000 African savannah elephants left in the wild, the species is classified as endangered."Accurate monitoring is essential if we're to save the species," said Dr Isupova. "We need to know where the animals are and how many there are."Satellite monitoring eliminates the risk of disturbing animals during data collection and ensures humans are not hurt in the counting process. It also makes it simpler to count animals moving from country to country, as satellites can orbit the planet without regard for border controls or conflict.This study was not the first to use satellite imagery and algorithms to monitor species, but it was the first to reliably monitor animals moving through a heterogeneous landscape -- that is, a backdrop that includes areas of open grassland, woodland and partial coverage."This type of work has been done before with whales, but of course the ocean is all blue, so counting is a lot less challenging," said Dr Isupova. "As you can imagine, a heterogeneous landscape makes it much hard to identify animals."The researchers believe their work demonstrates the potential of technology to support conservationists in their plight to protect biodiversity and to slow the progress of the sixth mass extinction -- the ongoing extinction event triggered by human activity."We need to find new state-of-the-art systems to help researchers gather the data they need to save species under threat," said Dr Isupova.African elephants were chosen for this study for good reason -- they are the largest land animal and therefore the easiest to spot. However, Dr Isupova is hopeful that it will soon be possible to detect far smaller species from space."Satellite imagery resolution increases every couple of years, and with every increase we will be able to see smaller things in greater detail," she said, adding: "Other researchers have managed to detect black albatross nests against snow. No doubt the contrast of black and white made it easier, but that doesn't change the fact that an albatross nest is one-eleventh the size of an elephant."The researchers involved in this project were Dr Olga Isupova from the University of Bath, Isla Duporge, Dr Steven Reece, and Professor David W. Macdonald from the University of Oxford, and Dr Tiejun Wang from the University of Twente.
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Geography
| 2,021 |
January 15, 2021
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https://www.sciencedaily.com/releases/2021/01/210115091335.htm
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Are partially protected areas the 'red herrings' of marine conservation?
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Partially protected areas -- marine reserves that allow some forms of fishing -- are no more effective socially or ecologically than open marine areas in Australia's Great Southern Reef, a new UNSW study has concluded.
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The research, published in The UNSW study discovered partially protected areas in southern Australia had no more fish, invertebrates or algae and no difference in the mix of users -- and they were not valued any more highly by users than areas outside reserves (open areas).The social and ecological researchers found fully protected areas (no-take or sanctuary zones), by comparison, had more fish, higher biodiversity of marine life and were an attraction to many coastal users both for their ecological and protection values.Lead author John Turnbull, UNSW Science researcher, said partially protected areas appear to be the "red herrings" of marine conservation as they distract us from achieving more effective protection."Marine protected areas are the umbrella term for managed marine areas and can be fully or partially protected. They are a primary tool for the stewardship, conservation and restoration of marine ecosystems but globally, 69 per cent of marine protected areas are open to some form of fishing," Mr Turnbull said."This is a surprise to many people -- almost half of the people we surveyed in partially protected areas (42 per cent) mistakenly thought they were in a reserve that protected fish."Just 12 per cent of people knew they were in a partially protected area, compared to 79 per cent of people in fully protected areas who correctly identified they were in one."This is not a small issue; three-quarters of Australia's marine protected area is open to fishing. Most partially protected areas in Australia even allow commercial fishing, which, on an industrial scale, is contrary to international ("IUCN" -- International Union for Conservation of Nature) guidelines."The UNSW study spanned 7000km of coast and five states. The authors assessed 19 fully protected areas, 18 partially protected areas and 19 open areas. They each had different rules and marine communities but they all had broadly stated goals, such as the conservation of biodiversity and ecosystem integrity.The researchers conducted 439 interviews and 190 observation surveys to gauge the social impact of each area (human use, perceptions and values), and analysed existing data from 625 underwater visual census Reef Life Surveys to determine the ecological impact of protection on marine communities (fish, invertebrates and algae).Mr Turnbull said the research team found no social or ecological benefits for partially protected areas relative to open areas. For example, the ecological data revealed that fish species richness and biomass were higher in fully protected areas, but not in partially protected areas. There were 1.3x more fish species, 2.5x more fish biomass and 3.5x more large (20+ cm) fish biomass in fully protected areas compared to open areas.Mr Turnbull said: "Global studies support our findings: there is a lot of research that shows a reduced, if any, impact of partial protection and it depends on the strength of that partial protection."Despite this, fully protected areas are often a very small percentage of a marine park; for example, Sydney's recently proposed marine park had less than three per cent designated as fully protected sanctuary zone, meaning 97 per cent of the area would be open to fishing if the park was approved. This is the degree of 'red herring' we are experiencing."Mr Turnbull said their research also busted the myth that fully protected areas were unpopular."On the contrary, 92 per cent of people we surveyed said they supported protected areas that restrict fishing. We believe our research reflects the general views of coastal users, because we designed our sampling to represent all the different types of user at each site; people swimming, walking, diving, fishing and so on."And there was virtually no difference in support for protected areas between people who fish and people who don't -- just one per cent."Mr Turnbull said the researchers also found most people were passionate about their local coastal areas."People want to see their area looked after and properly protected, especially with sanctuary zones. Often, people specifically visited these because they knew the area was fully protected, and they had personally observed the improvement in marine life" he said."In fully protected areas, we found a higher number of certain types of users; twice as many divers and over three times as many snorkelers. This showed people were directly experiencing the values of fully protected areas and acknowledged them and were attracted to them. This was not the case for partially protected areas; the mix and number of users in these areas were no different to open areas."Study co-author and UNSW Dean of Science Professor Emma Johnston said if governments were going to allocate conservation resources to protect marine areas, they needed to be sure the "investment" was paying off."The current trend towards downgrading fully protected areas to partially protected areas in many parts of the world, including Australia, may be wasting precious conservation resources. Partially protected areas could still be useful but only for specific purposes; for example, to support traditional management practices, protect a particular threatened species, or to create a buffer zone for a fully protected area," Prof. Johnston said."But the results of our substantial study suggest that partially protected areas may be overused and represent a distraction from true conservation measures. The public are confused by partially protected areas and the general biodiversity is no better off."Prof. Johnston said she hoped the researchers' findings would encourage decisionmakers to consider whether their conservation approach was fit for purpose."If we are going to truly protect our planet, partially protected areas must be monitored regularly and the results made public, because if they are failing to provide social or ecological returns, those areas should be upgraded to the level of protection that we know works," she said.
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Geography
| 2,021 |
January 14, 2021
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https://www.sciencedaily.com/releases/2021/01/210114130151.htm
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Posidonia marine seagrass can catch and remove plastics from the sea
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<em>Posidonia oceanica</em>
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The study describes for the first time the outstanding role of the Posidonia as a filter and trap for plastics in the coastal areas, and it is pioneer in the description of a natural mechanism to take and remove these materials from the sea. Other authors of the study are the experts Miquel Canals, William P. de Haan and Marta Veny, from the Research Group on Marine Geosciences of the UB, and Javier Romero, from the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the UB.The According to the analyses, she continues, the trapped microplastics in the prairies of the This marine phanerogam has a vegetative structure made by a modified stem with a rhizome shape from which the roots and leaves appear. When the leaves fall, its bases (pods) are added to rhizomes and give them a feather-like appearance. "As a result of the mechanical erosion in the marine environment, those pods under the seafloors are progressively releasing lignocellulosic fibres which are slowly added and intertwined until they make agglomerates in a ball-shape, known as The polluting footprint of plastics that come from human activity is a serious environmental problem affecting coastal and ocean ecosystems worldwide. Since plastics were created massively in the 20th century fifties, these materials have been left and accumulated at the sea -- seafloors act as a sink for microplastics -- and are transported by ocean currents, wind and waves. "The plastics we find floating in the sea are only a small percentage of everything we have thrown onto the marine environment," warns Anna Sànchez-Vidal.The paper published in the journal "This is why we need to protect and preserve these vulnerable ecosystems. However, the best environmental protection strategy to keep oceans free of plastic is to reduce landfills, an action that requires to limit its use by the population," conclude the experts.
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Geography
| 2,021 |
January 12, 2021
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https://www.sciencedaily.com/releases/2021/01/210112160146.htm
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New study reveals how fences hinder migratory wildlife in Western US
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Each year, thousands of migratory mule deer and pronghorn antelope journey northwest from their winter homes in the Green River Basin, a grassland valley in western Wyoming, to their summer homes in the mountainous landscape near Grand Teton National Park.
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But to reach their destination, these ungulates must successfully navigate the more than 6,000 kilometers (3,728 miles) of fencing that crisscrosses the region. That's enough distance to span nearly twice the length of the U.S.-Mexico border.In a new study, wildlife biologists at the University of California, Berkeley, combined GPS location data of tagged mule deer and pronghorn with satellite imagery of fences to find out just how often these animals encounter fences, and what happens when they do. The results, published on Jan. 7 in the Along with the study, the team is also publishing a software package that will help wildlife managers around the world quickly analyze GPS tracking data to identify fences and other barriers that might be impeding the vital movements of animals."We need fences -- they help keep livestock safe, can help keep livestock and wildlife separate, and mark property boundaries," said Arthur Middleton, an assistant professor of wildlife management and policy at UC Berkeley and senior author of the paper. "So, the question becomes, how do you identify which fences are really important, and which are problematic from a wildlife standpoint, and then seek some way to mitigate the impacts?"Fences don't always pose an insurmountable barrier to wildlife, and different species find different ways to get around them. Mule deer are willing to jump over fences that are low enough. Pronghorn antelope, however, are reluctant to jump over fences and instead must seek out areas where they can move underneath.Wenjing Xu, a Ph.D. student at UC Berkeley and lead author of the paper, took these different behaviors into account when creating the software package that compares animal tracking data with fence maps. The program can categorize different types of behaviors that animals might engage in when they encounter a fence, such as quickly crossing over the fence, pacing back and forth along the fence, or turning around and walking away from the fence.To understand how fences are impacting mule deer and pronghorn, Xu started by painstakingly comparing fencing maps from the federal Bureau of Land Management and the U.S. Forest Service with satellite imagery, adding in fences that were not included in the government surveys. When all the fences were accounted for, Xu was surprised at the sheer amount of fencing in the region."The total length of fences is really, really striking, especially with what we know about the different types of wide-ranging animals that live in that area," Xu said.Xu then compared these maps to GPS tracking data that collected locations every two hours for 24 tagged female mule deer and 24 pronghorn antelope.Each year, mule deer encountered fences an average of 119 times, Xu found. Pronghorn antelope encountered fences at more than twice that rate, about 248 times per year. About 40% of these fence encounters resulted in a change in the animals' behavior."Anybody who's spent time in the West knows you'll find a lot of fences. But, seeing such frequent encounters, 40% of which result in a failure to cross, is kind of mind-blowing -- especially when you multiply those numbers across whole populations and landscapes," Middleton said.Some of these fences are currently being used by ranchers to protect livestock or mark property lines. Others are relics of a bygone era when sheep farming was popular in the state, Middleton said.The best way to mitigate the impact of these fences on animal migration is to remove them, or to replace them with more "wildlife-friendly" fences that mule deer can jump over or that pronghorn can duck under. However, both of these options require money and labor. According to Xu, a recent fencing modification project in Wyoming spent more than $10,000 per mile of fencing to make the fences more permeable to pronghorn.The software package developed by Xu is able to create maps that highlight the fences that pose the greatest impediment to animal movement, helping to prioritize fences to be modified or removed."There is such a strong need for this kind of data," Xu said. "Modifying fences is really, really expensive, and the amount of fencing that might need to be fixed is just so large. [Wildlife managers] really want to find ways to prioritize their resources."Brandon Scurlock, a wildlife management coordinator for the Pinedale region of the Wyoming Game and Fish Department, is working to designate a protected migration "corridor" that connects the summer and winter ranges of pronghorn antelope in western Wyoming. Similar migration corridors for mule deer were established by the state earlier this year.Scurlock's team is already using the study results to identify fences that might create barriers along these routes, and prioritize those for modification."It's been interesting noticing the characteristics of some of these fences that this study has pointed out as being not very permeable for Pronghorn," said Scurlock, who was not a member of the study team. "We recommend the bottom wire of a fence be at least 18 inches above the ground. And, when looking at some of the particularly bad fences that that these methods highlight, we almost invariably see that they have barbed wires that are too close to the ground."One option for offsetting the cost of fence mitigation throughout this region, which is part of the Greater Yellowstone Ecosystem, could consist of imposing a small "conservation fee" on visitors to the area's parks, which include the extremely popular Yellowstone National Park and Grand Teton National Park. Middleton and co-authors, including Berkeley Law professor Holly Doremus, explored the feasibility of this approach in a study published last month in the journal "Fine-scale movement data has helped us see much further into animals' lives, including the challenges we've imposed," Middleton said. "I hope this work helps open people's eyes to the scale of fence effects. Our next steps are to better understand the actual biological cost that all these fence-related behavioral changes have on wildlife populations, and find ways to mitigate those effects at a really large scale."
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Geography
| 2,021 |
January 9, 2021
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https://www.sciencedaily.com/releases/2021/01/210109152432.htm
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Scientists discover slimy microbes that may help keep coral reefs healthy
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Corals have evolved over millennia to live, and even thrive, in waters with few nutrients. In healthy reefs, the water is often exceptionally clear, mainly because corals have found ways to make optimal use of the few resources around them. Any change to these conditions can throw a coral's health off balance.
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Now, researchers at MIT and the Woods Hole Oceanographic Institution (WHOI), in collaboration with oceanographers and marine biologists in Cuba, have identified microbes living within the slimy biofilms of some coral species that may help protect the coral against certain nutrient imbalances.The team found these microbes can take up and "scrub out" nitrogen from a coral's surroundings. At low concentrations, nitrogen can be an essential nutrient for corals, providing energy for them to grow. But an overabundance of nitrogen, for instance from the leaching of nitrogen-rich fertilizers into the ocean, can trigger mats of algae to bloom. The algae can outcompete coral for resources, leaving the reefs stressed and bleached of color.By taking up excess nitrogen, the newly identified microbes may prevent algal competition, thereby serving as tiny protectors of the coral they inhabit. While corals around the world are experiencing widespread stress and bleaching from global warming, it seems that some species have found ways to protect themselves from other, nitrogen-related sources of stress."One of the aspects of finding these organisms in association with corals is, there's a natural way that corals are able to combat anthropogenic influence, at least in terms of nitrogen availability, and that's a very good thing," says Andrew Babbin, the Doherty Assistant Professor in Ocean Utilization in MIT's Department of Earth, Atmospheric and Planetary Sciences. "This could be a very natural way that reefs can protect themselves, at least to some extent."Babbin and his colleagues have reported their findings in the the Babbin's group studies how marine communities in the ocean cycle nitrogen, a key element for life. Nitrogen in the ocean can take various forms, such as ammonia, nitrite, and nitrate. Babbin has been especially interested in studying how nitrogen cycles, or is taken up, in anoxic environments -- low-oxygen regions of the ocean, also known as "dead zones," where fish are rarely found and microbial life can thrive."Locations without enough oxygen for fish are where bacteria start doing something different, which is exciting to us," Babbin says. "For instance, they can start to consume nitrate, which has then an impact on how productive a specific part of the water can be."Dead zones are not the only anoxic regions of the ocean where bacteria exhibit nitrogen-feasting behavior. Low-oxygen environments can be found at smaller scales, such as within biofilms, the microbe-rich slime that covers marine surfaces from shipwrecked hulls to coral reefs."We have biofilms inside us that allow different anaerobic processes to happen," Babbin notes. "The same is true of corals, which can generate a ton of mucus, which acts as this retardation barrier for oxygen."Despite the fact that corals are close to the surface and within reach of oxygen, Babbin wondered whether coral slime would serve to promote "anoxic pockets," or concentrated regions of low oxygen, where nitrate-consuming bacteria might thrive.He broached the idea to WHOI marine microbiologist Amy Apprill, and in 2017, the researchers set off with a science team on a cruise to Cuba, where Apprill had planned a study of corals in the protected national park, Jardines de la Reina, or Gardens of the Queen."This protected area is one of the last refuges for healthy Caribbean corals," Babbin says. "Our hope was to study one of these less impacted areas to get a baseline for what kind of nitrogen cycle dynamics are associated with the corals themselves, which would allow us to understand what an anthropogenic perturbation would do to that system."In exploring the reefs, the scientists took small samples from coral species that were abundant in the area. Onboard the ship, they incubated each coral specimen in its own seawater, along with a tracer of nitrogen -- a slightly heavier version of the molecules found naturally in seawater.They brought the samples back to Cambridge and analyzed them with a mass spectrometer to measure how the balance of nitrogen molecules changed over time. Depending on the type of molecule that was consumed or produced in the sample, the researchers could estimate the rate at which nitrogen was reduced and essentially denitrified, or increased through other metabolic processes.In almost every coral sample, they observed rates of denitrification were higher than most other processes; something on the coral itself was likely taking up the molecule.The researchers swabbed the surface of each coral and grew the slimy specimens on Petri dishes, which they examined for specific bacteria that are known to metabolize nitrogen. This analysis revealed multiple nitrogen-scrubbing bacteria, which lived in most coral samples."Our results would imply that these organisms, living in association with the corals, have a way to clean up the very local environment," Babbin says. "There are some coral species, like this brain coral Diploria, that exhibit extremely rapid nitrogen cycling and happen to be quite hardy, even through an anthropogenic change, whereas Acropora, which is in rough shape throughout the Caribbean, exhibits very little nitrogen cycling. "Whether nitrogen-scrubbing microbes directly contribute to a coral's health is still unclear. The team's results are the first evidence of such a connection. Going forward, Babbin plans to explore other parts of the ocean, such as the tropical Pacific, to see whether similar microbes exist on other corals, and to what extent the bacteria help to preserve their hosts. His guess is that their role is similar to the microbes in our own systems."The more we look at the human microbiome, the more we realize the organisms that are living in association with us do drive our health," Babbin says. "The exact same thing is true of coral reefs. It's the coral microbiome that defines the health of the coral system. And what we're trying to do is reveal just what metabolisms are part of this microbial network within the coral system."This research was supported, in part, by MIT Sea Grant, the Simons Foundation, the MIT Montrym, Ferry, and mTerra funds, and by Bruce Heflinger '69, SM '71, PhD '80.
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Geography
| 2,021 |
December 22, 2020
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https://www.sciencedaily.com/releases/2020/12/201222141524.htm
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Environmental effects of purchasing, consuming mislabeled fish
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Perhaps that sauteed snapper you enjoyed last evening at your neighborhood restaurant was not snapper at all. Perhaps it was Pacific Ocean perch, cloaked in a wine sauce to disguise its true identity. The same goes for that grouper you paid a handsome price for at your local fishmonger's and cooked up at home. Instead, you may have been feasting on a plateful of whitefin weakfish and been none the wiser.
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Seafood is the world's most highly traded food commodity, and reports of seafood mislabeling have increased over the past decade. However, proof of the environmental effects of mislabeled seafood has been scant as has research. So, Arizona State University researcher Kailin Kroetz and her colleagues analyzed the impact of seafood mislabeling on marine population health, fishery management effectiveness, and habitats and ecosystems in the United States, the world's largest seafood importer.The results of the study were published in the The study found that approximately 190,000 to 250,000 tons of mislabeled seafood are sold in the United States each year, or 3.4% to 4.3% of consumed seafood. What's more, the substituted seafood was 28% more likely to be imported from other countries, which may have weaker environmental laws than the United States."In the United States, we're actually very good at managing our fisheries," said Kroetz, assistant professor in ASU's School of Sustainability. "We assess the stock so we know what's out there. We set a catch limit. We have strong monitoring and enforcement capabilities to support fishers adhering to the limit. But many countries we import from do not have the same management capacity."The authors used the Monterey Bay Aquarium Seafood Watch scores for wild-caught product pairs to assess marine population health and fishery management effectiveness."Although we would like to do a global assessment in the longer run, we focused on the U.S. first because Seafood Watch assesses about 85% of U.S. seafood consumed," Kroetz explained. "The data we were able to access in the U.S. were much more detailed than what we could access on the global scale."The study found that substitute species came from fisheries that performed worse in terms of population impacts 86% of the time. The population impact metric accounted for fish abundance, fishing mortality, bycatch and discards -- that is, fish thrown back to sea after being caught. In addition, 78% of the time the substituted seafood fared worse than the expected products listed on the label when it came to fishery management effectiveness.Prior studies have focused on the rates at which specific seafood is mislabeled. But it's the quantity of substituted fish consumed that is key to determining environmental impacts."The rates themselves don't tell us the full story about the impact of mislabeling," Kroetz said. That's because some fish that have high rates of substitution have low levels of consumption and vice versa. In fact, the majority of pairs have relatively low rates of substitution and low consumption.Good examples are shrimp and snapper. The researchers found that giant tiger prawns are substituted for white leg shrimp more than any other seafood product -- and Americans eat more shrimp than any other type of seafood, opening the door to potentially substantial environmental impacts. Meanwhile, snapper has a higher rate of mislabeling, but Americans consume much less of it than shrimp.At the very minimum, mislabeling fish undermines good population management, and in turn, sustainable fisheries.Mislabeling can shake consumer confidence in their quest to eat only sustainable, local seafood. That's because substituted fish is more likely to be imported and come from poorly managed fisheries, thereby creating a market for fish that shouldn't be liberally consumed.For example, you might think you're getting this wonderful local blue crab, supporting local fisheries, and experiencing local cuisine, but in reality, you could be eating something that was imported from Indonesia. Learning about mislabeling might reduce the amount you'd pay for blue crab in the future or result in you not consuming it at all."The expected species is often really well managed," Kroetz said. "Consuming fish from a fishery shouldn't have a negative impact in terms of the population now or in the future if the management is good. But if you're consuming fish from poorly managed fisheries, that's not sustainable."This study was funded by the Paul M. Angell Family Foundation and Resources for the Future. The work was also supported by the National Socio-Environmental Synthesis Center under funding received from the U.S. National Science Foundation.
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Geography
| 2,020 |
December 22, 2020
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https://www.sciencedaily.com/releases/2020/12/201222132044.htm
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Ancient DNA sheds light on the peopling of the Mariana Islands
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To reach the Mariana Islands in the Western Pacific, humans crossed more than 2,000 kilometres of open ocean, and around 2,000 years earlier than any other sea travel over an equally long distance. They settled in the Marianas around 3,500 years ago, slightly earlier than the initial settlement of Polynesia.
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"We know more about the settlement of Polynesia than we do about the settlement of the Mariana Islands," says first author Irina Pugach, a researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The researchers wanted to find out where people came from to get to the Marianas and how the ancestors of the present Mariana Islanders, the Chamorro, might be related to Polynesians.To address these questions the researchers obtained ancient DNA data from two skeletons from the Ritidian Beach Cave site in northern Guam, dating to around 2,200 years ago. "We found that the ancestry of these ancient skeletons is linked to the Philippines," says Pugach. "These findings strengthen the picture that has emerged from linguistic and archaeological studies, pointing to an Island Southeast Asia origin for the first settlers of the Marianas," says co-author Mike T. Carson, an archaeologist at the Micronesian Area Research Center at the University of Guam."We also find a close link between the ancient Guam skeletons and early Lapita individuals from Vanuatu and Tonga in the Western Pacific region," adds Pugach. "This suggests that the Marianas and Polynesia may have been colonized from the same source population, and raises the possibility that the Marianas played a role in the eventual settlement of Polynesia."The researchers point out that while the new results provide interesting new insights, they are based on only two skeletons that date from around 1,400 years after the first human settlement in Guam. "The peopling of Guam and the settlement of such remote archipelagos in Oceania needs further investigation," says senior author Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology.
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Geography
| 2,020 |
December 21, 2020
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https://www.sciencedaily.com/releases/2020/12/201221155935.htm
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New population of blue whales discovered in the western Indian ocean
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An international team of researchers has discovered what it believes to be a new population of blue whales in the western Indian Ocean.
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Blue whales are the largest animals that have ever lived on our planet, and they are found around the globe in all oceans. All blue whales sing very low-pitched and recognizable songs, and conveniently for researchers, every population has its own unique song. In a recently published paper in the journal Dr. Salvatore Cerchio, Director of the African Aquatic Conservation Fund's Cetacean Program and Visiting Scientist at the New England Aquarium, led the analysis of recordings of the whale from three locations in the western Indian Ocean. Dr. Cerchio first recorded the novel song in 2017, during research focused on Omura's whales in the Mozambique Channel off Madagascar, and he recognized it as a blue whale song that had never been described. Cerchio was also working with a team of scientists collecting acoustic recordings off the coast of Oman in the Arabian Sea. This is part of a research effort focused on the highly endangered Arabian Sea humpback whale, an ongoing collaboration between the Environment Society of Oman, Five Oceans Environmental Services LLC, Oman's Environment Authority and Oman's Ministry of Agriculture, Fisheries and Water Resources.While analyzing the Oman acoustic data, the team recognized the same unusual song. This novel blue whale song was recorded even more prevalently off Oman than Madagascar, and it became clear to the researchers that they had found what was likely a previously unrecognized population of blue whales in the western Indian Ocean."It was quite remarkable," said Cerchio, "to find a whale song in your data that was completely unique, never before reported, and recognize it as a blue whale." Blue whale song has been extensively studied globally, and several blue whale populations have been identified based on their distinct songs throughout the Indian Ocean."With all that work on blue whale songs, to think there was a population out there that no one knew about until 2017, well, it kind of blows your mind," Cerchio said.In 2018, the team reported their findings to the Scientific Committee of the International Whaling Commission (IWC), which was in the process of evaluating the status of blue whale populations in the Indian Ocean. The finding created quite a bit of excitement at the meeting, and raised many new questions about blue whale population movements and structure in the Indian Ocean. Emmanuelle Leroy and Tracey Rogers of the University of New South Wales, in Sydney, Australia, were also conducting acoustic research on blue whales in the Indian Ocean. Upon reading the IWC report on the new song, Leroy recognized that they also had recorded the same song off the Chagos Archipelago in the central Indian Ocean."Shortly after we made the first report at IWC," said Cerchio, "I received an email from Emmanuelle saying, 'Hey Sal, I think we have that Oman song off the Chagos!'"The collaborative team grew, and analysis of data from all three sites suggested that the population may spend most of its time in the northwestern Indian Ocean, in the Arabian Sea and to the west of the Chagos. It has long been recognized that a unique population of blue whales resides in the Northern Indian Ocean, but it was assumed that whales in the Arabian Sea belonged to the same population that has been studied off Sri Lanka and ranges into the southcentral Indian Ocean. However, the songs tell a different story."Before our recording effort off Oman, there were no acoustic data from the Arabian Sea, and so the identity of that population of blue whales was initially just a guess," said Andrew Willson from Five Oceans Environmental Services LLC, who led the deployment of the recording units. "Our work shows that there is a lot more to learn about these animals, and this is an urgent requirement in light of the wide range of threats to large whales related to expanding maritime industries in the region."Blue whales were hunted to near extinction around the globe during the 20th century, and populations have only started to recover very slowly over the past several decades following the global moratorium on commercial whaling. The Arabian Sea was targeted by illegal Soviet whaling in the 1960's, an activity that nearly eradicated what were already likely to be small populations of humpback whales, blue whales, sperm whales, and Bryde's whales.Some researchers consider both the northern Indian Ocean blue whales and Arabian Sea humpback whales to comprise unique subspecies, not simply populations, making them particularly special and important to biodiversity."These populations appear to be unique among baleen whales, in the case of the Arabian Sea humpback whales because of their year-round residency in the region without the same long-range migration of other populations," Willson points out."For 20 years we have focused work on the highly endangered Arabian Sea humpback whale, for which we believe only about 100 animals remain off the coast of Oman," says Suaad Al Harthi, Executive Director of the Environment Society of Oman. "Now, we are just beginning to learn more about another equally special, and likely equally endangered, population of blue whale."
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Geography
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December 21, 2020
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https://www.sciencedaily.com/releases/2020/12/201221121723.htm
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Discovery of 66 new Roman Army sites shows more clues about one of the empire
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The discovery of dozens of new Roman Army sites thanks to remote sensing technology has revealed more about one of the empire's most infamous conflicts.
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Analysis of the 66 camps shows the Roman army had a larger presence in the region than previously thought during the 200-year battle to conquer the Iberian Peninsula.The discovery of camps of different sizes -- used for training and shelter -- has allowed experts to map how soldiers attacked indigenous groups from different directions and to learn more about the footprint of the Roman military presence in the northern fringe of the River Duero basin -- the León, Palencia, Burgos and Cantabria provinces.Experts analysed aerial photography and satellite images, created three-dimensional models of the terrain from LiDAR data and used drones to create detailed maps of the sites. This included resources from the Spanish National Geographic Institute (IGN) and geoportals such as Google Earth or Bing Maps. Pinpointing locations allowed fieldwork to then take place.These temporary occupations usually left fragile and subtle traces on the surface. The ditches or the earth and stone ramparts protecting these fortifications have been filled in and flattened. Combining different remote sensing images and fieldwork shows the perimeter shape of the temporary Roman military camps, often a rectangle like a playing card.These new sites are located at the foothills of the Cantabrian Mountains, where the conflict between Romans and natives was focused at the end of the 1st century BC. This suggests soldiers crossed between lowlands and uplands, using ridges in the mountains to stay out of site and give themselves more protection.The fact there were so many army camps in the region shows the immense logistical support which allowed soldiers to conquer the area. Sites were used to aid movement to remote locations and to help soldiers stay in the area over the cold winter months. Some of the camps may have housed soldiers for weeks or months, and overs overnight.The aim of the occupation was to expand the empire and to be able to exploit natural resources such as tin and gold.The research, published in the journal Dr Fonte said: "We have identified so many sites because we used different types of remote sensing. Airborne laser scanning gave good results for some sites in more remote places because it showed earthworks really well. Aerial photography worked better in lowland areas for the detection of cropmarks.""The remains are of the temporary camps that the Roman army set up when moving through hostile territory or when carrying out manoeuveres around their permanent bases. They reveal the intense Roman activity at the entrance to the Cantabrian Mountains during the last phase of the Roman conquest of Hispania."There is an important concentration of 25 sites along the valleys of northern Palencia and Burgos, as well as southern Cantabria. In the province of León, as many as 41 sites have been documented in different valleys. These range from small forts of a few hundred square meters to large fortified enclosures of 15 hectares.Most of these Roman military sites were located in close proximity of later important Roman towns. Sasamón, a village in Burgos that was probably where nearby the Emperor Augusto established his camp during his presence in the front.The research will continue so experts can examine the relationships the Romans established with indigenous communities, named Vaccaei, Turmogi, Cantabri, Astures and Callaeci, according to the Greek and Latin sources.The team is currently developing a project to catalogue and document all the Roman camps in the province of León by means of drones, in order to gain a better understanding of their structures or the evolution of their state of conservation. Work is also continuing in Burgos and in Sasamón, including a study of the Cerro de Castarreño settlement and its conquest in the 1st century BC.
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Geography
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December 18, 2020
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https://www.sciencedaily.com/releases/2020/12/201218112540.htm
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Satellite data identifies companies fishing in high seas
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A team of researchers, using satellite data and other analytical tools, has identified companies fishing in high seas -- waters that lie outside of national jurisdiction where fishing has raised fears about environmental and labor violations. The study, which appears in the journal
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"There is a lot of concern about companies that operate on the high seas, simply because there they are beyond the reach of any nation's laws and regulations," says Jennifer Jacquet, an associate professor in NYU's Department of Environmental Studies and lead author of the peer-reviewed study. "By connecting those boats with specific companies, this study takes a first step in enhancing transparency -- we now know a lot more about who is profiting from fish catches in the global commons."The findings illuminate a significant element of commercial fishing. Previously, researchers could only identify which countries reported catching fish on the high seas, which account for 60 percent of the world's oceans and therefore represent a substantial proportion of waters that lie beyond the reach of national jurisdiction."We also have a much better sense of what we don't know," adds first author Gabrielle Carmine, a doctoral candidate at Duke University's Nicholas School of the Environment who worked with Jacquet as an NYU undergraduate. "The corporate actors we know vary by fishing gear type and by location in the high seas. For example, we know far more about the trawling fleet than the longline fleet and more about the Atlantic Ocean than the Western Tropical Pacific."Species caught on the high seas are fished by industrial fleets and destined mainly for high-end markets in the U.S and Europe. Past assessments of high seas fish populations show that fishing in these waters has led to extraordinary declines in the abundance of many open-ocean species, including several species of tuna, swordfish, and marlin. While fish catches are reported by nations, many companies catch and profit from fish in the global ocean, where fishing is subject to few regulations because the high seas lie beyond national jurisdiction.Combining data that detects fishing vessels made available from Global Fishing Watch with other public databases, such as regional fisheries management organizations and shareholder information, the team's analysis showed 1,120 corporations owned nearly 2,500 high seas fishing vessels in 2018 -- or approximately two-thirds of the total detected fishing effort in these waters.However, high seas fishing is notably concentrated among a small number of entities. The Korean companies Sajo Group and Dongwon, which owns the U.S. subsidiary Starkist, were in the top 10 of the most active corporations on the high seas, along with a handful of Chinese corporations and one U.S. corporation based in Hawaii. Approximately 100 companies, based in the United States, the United Kingdom, China, Taiwan, Russia, Spain, the Netherlands, and South Korea, among other nations, accounted for more than one-third of high seas fishing during the studied period."These results provide a unique lens through which to view accountability for the use and protection of global ocean biodiversity," observes Jacquet.These results come in advance of the fourth United Nations Intergovernmental Conference on Marine Biodiversity of Areas Beyond National Jurisdiction, which was postponed and is expected sometime in 2021.
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Geography
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December 16, 2020
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https://www.sciencedaily.com/releases/2020/12/201216134715.htm
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Effects of organohalogen pollution are coded in gene expression profiles of Baltic salmon
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Researchers of Ehime University and the University of Helsinki measured hepatic organohalogen (OHC) concentrations and gene expression profiles in Atlantic salmon collected from three areas in the Baltic Sea. The results showed that OHCs and gene expression profiles were individually grouped in three areas and the covariation of the two datasets provided by a multivariate method was significantly similar. This suggests that the gene expression profiles in salmon are affected by OHC contamination.
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Hatchery-reared Atlantic salmon (Salmo salar) have been released to support the wild salmon stocks in the Baltic Sea for decades. During their feeding migration, salmon are exposed to organohalogen compounds (OHCs). Here, we investigated the OHC levels and transcriptome profiles in the liver of wild and hatchery-reared salmon collected from the Baltic main basin, the Bothnian Sea, and the Gulf of Finland and examined whether salmon origin and OHC levels contributed to the hepatic transcriptome profiles.There were no differences in the OHC concentrations and transcriptome profiles between wild and hatchery-reared fish but there were large differences among the areas.Several transcript levels were associated with polychlorinated biphenyls, chlordanes, and dichlorodiphenyltrichloroethane in a concentration-dependent manner. When comparing the different areas, lipid metabolism, environmental stress, cell growth and death-related pathways were enriched in the liver transcriptome. Coinertia analysis, a multivariate method, showed that the covariation in the OHC levels and the transcriptome were significantly similar.These results suggest that the hepatic transcriptomes in wild and hatchery-reared salmon are more affected by the OHC level than the salmon's origin. This paper was published in an American Chemical Society Journal,
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Geography
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December 15, 2020
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https://www.sciencedaily.com/releases/2020/12/201215082048.htm
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Mummified baboons shine new light on the lost land of Punt
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Ancient Punt was a major trading partner of Egyptians for at least 1,100 years. It was an important source of luxury goods, including incense, gold, leopard skins, and living baboons. Located somewhere in the southern Red Sea region in either Africa or Arabia, scholars have debated its geographic location for more than 150 years. A new study tracing the geographic origins of Egyptian mummified baboons finds that they were sourced from an area that includes the modern-day countries of Ethiopia, Eritrea, Dijbouti, Somalia, and Yemen, providing new insight into Punt's location. Published in
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"Long-distance seafaring between Egypt and Punt, two sovereign entities, was a major milestone in human history because it drove the evolution of maritime technology. Trade in exotic luxury goods, including baboons, was the engine behind early nautical innovations," explains lead author Nathaniel J. Dominy, the Charles Hansen Professor of Anthropology at Dartmouth College."Many scholars view trade between Egypt and Punt as the first long maritime step in a trade network known as the spice route, which would go on to shape geopolitical fortunes for millennia. Other scholars put it more simply, describing the Egypt-Punt relationship as the beginning of economic globalization," he added. "Baboons were central to this commerce, so determining the location of Punt is important. For over 150 years, Punt has been a geographic mystery. Our analysis is the first to show how mummified baboons can be used to inform this enduring debate."Ancient Egyptians revered baboons throughout their history, with the earliest evidence dating from 3,000 B.C. Baboons were even deified, entering the pantheon of gods as manifestations of Thoth, a god associated with the moon and wisdom. One species, Papio hamadryas (the sacred baboon), was often depicted in wall paintings and other works, as a male, in a seated position with its tail curled to the right of its body. The species was among the types of baboons that were mummified in this very position with the linens carefully wrapped around its limbs and tail. Another species, Papio anubis (the olive baboon), was also mummified but it was typically wrapped in one big cocoon in a manner reflecting far less care. Baboons have never however, existed naturally in the Egyptian landscape and were a product of foreign trade in the region.The study focused on mummified baboons from the New Kingdom period (1550-1069 B.C.) available in the British Museum and specimens from the Ptolemaic period (305-30 B.C.) available in the Petrie Museum of Egyptian Archaeology at University College London. In addition, the authors examined tissues from 155 baboons from 77 locations across eastern Africa and southern Arabia, encompassing every hypothesized location for Punt. The team measured oxygen and strontium isotope compositions and used a method called isotopic mapping to estimate the geographic origins of specimens recovered from the New Kingdom and Ptolemaic sites in Egypt.Strontium is a chemical element that is found in bedrock, which is specific to a geographic location. As strontium erodes, its composition is absorbed into the soil and water and enters the food web. As animals drink the water and eat the plants, their teeth, and hair and bones, obtain a geographic signature reflecting where they have lived in the past and most recently, respectively.Baboons must drink water every day and are considered obligate drinkers. Their bodies reflect the oxygen composition of water in the landscape. The enamel of an animal's adult teeth reflect the unique strontium composition of its environment when the teeth formed in early life. In contrast, hair and bone have isotope signatures that reflect the preceding months (hair) or years (bone) of dietary behavior. Similar to strontium, oxygen compositions (specifically, isotopes) of water can also vary by geographic location but the researchers found data from the specimens in this category were inconclusive, and only reflected values specific to Egypt.The findings demonstrate that the two mummified P. hamadryas baboons from the New Kingdom period, EA6738 and EA6736, were born outside of Egypt. They had most likely come from a location in Eritrea, Ethiopia or Somalia, which narrows down the location of Punt.The data suggest that EA6736, a P. hamadryas baboon, must have died shortly, day or months, after arriving in Egypt, as results indicate that its enamel and hair did not have sufficient time to convert to the local oxygen signature of drinking water.Five species of mummified P. anubis from the Ptolemaic period reflected strontium levels that are consistent with an Egyptian origin, which provides tantalizing hints of a captive breeding program for baboons at this time, probably in Memphis, an ancient capital in Lower Egypt, northwest of the Red Sea.As the researchers explain in the study, their estimated location of Punt is still provisional but the role that baboons played in the Red Sea trade network and their geographic distribution is one that is integral to understanding the historic origins of international maritime commerce.The study was co-authored by Salima Ikram at American University in Cairo; Gillian L. Moritz at Dartmouth; Patrick V. Wheatley at Lawrence Berkeley National Laboratory; Jonathan W. Chipman at Dartmouth; and Paul L. Koch at the University of California in Santa Cruz.
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Geography
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December 9, 2020
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https://www.sciencedaily.com/releases/2020/12/201209170631.htm
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First-known fossil iguana burrow found in the Bahamas
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The discovery of the first known fossil iguana nesting burrow, on an outer island of the Bahamas, fills in a gap of scientific knowledge for a prehistoric behavior of an iconic lizard.
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The fossilized burrow dates back to the Late Pleistocene Epoch, about 115,000 years ago, and is located on the island of San Salvador -- best known as the likely spot where Christopher Columbus made his first landfall in his 1492 voyage."San Salvador is one of the outer-most islands in the Bahamas chain and really isolated," says Anthony Martin, a professor in Emory's Department of Environmental Sciences and senior author of the Martin's specialty is ichnology -- the study of traces of life, such as tracks, nests and burrows. He documents modern-day traces to help him identify trace fossils from the deep past to learn about prehistoric animal behaviors.The current discovery was made during a class field trip to San Salvador as part of the course "Modern and Ancient Tropical Environments," co-taught by Martin and Melissa Hage, an assistant professor of environmental science at Emory's Oxford College and a co-author of the paper. Co-authors also include two former undergraduates from the class: Dottie Stearns (now in medical school at the University of Colorado) and Meredith Whitten (who now works in fisheries management for the state of North Carolina)."No matter how much you read about things in a textbook, a lot of concepts in geology just don't click until you see them in real life," Hage says. "It sparks a lot of excitement in students when they experience the process of scientific discovery in the field.""Students get to actually see the connections of the past and the present," Martin adds. "On the north point of San Salvador, for instance, the undulating landscape consists of ancient sand dunes that turned into rock. We can walk across these ancient dunes to look at the rock record and get an idea of how the island changed over time."During a stop on the shoreline road on the south end of the island, Martin happened to notice what looked like the trace of a fossil iguana burrow on a limestone outcrop exposed by a roadcut.The fossil record for iguanas goes back to the Late Cretaceous in South America. Today iguanas are found in tropical areas of Mexico, Central America, South America, the Caribbean and the Bahamas.Iguanas can grow up to six feet in length, including their tails. Despite their large size, formidable claws and fierce-looking spikes arrayed on their backs, iguanas are mostly herbivores.The now endangered San Salvador rock iguana, Cyclura riyeli riyeli, and other Cyclura species were plentiful throughout the Bahamas before 1492, when European ships began introducing rats, pigs and other invasive species that feed on the lizards' eggs."One of the cool things about iguanas is that they are survivors," Martin says. "And one of the main ways that they survive is through burrowing. Digging burrows has helped them survive hurricanes, droughts and other bad things that might be in their environment, like most predators. But burrows are not as helpful when it comes to rats and pigs."After further investigation, Martin and his co-authors determined that the trace fossil he noticed on the limestone outcrop was that of a nesting iguana burrow. Ample evidence, including a nearby fossil land-crab burrow discovered by Hage, showed that the outcrop was a former inland sand dune, where iguanas prefer to lay their eggs.The iguana trace revealed the distinctive pattern of a female creating a nest. "Iguanas have evolved a behavior where a female actually buries herself alive in sand, lays her eggs, and then 'swims' out, packing the loose sand behind her as she leaves the burrow to hide the eggs from predators," Martin says.This backfilling technique created compaction zones that weathered out over time from the surrounding limestone because they were more durable. "It's like when you pack sand to build a sandcastle at the beach," Martin explains. "It's a similar principle but, in the case of the iguana burrow, it happens underground."The lack of burrows from hatchlings digging their way to the surface, however, suggests that the nest failed and that the eggs never produced young.The researchers were able to date the iguana trace to about 115,000 years ago due to tell-tale red paleosols, or fossilized soils. "The red indicates oxidized iron minerals and there are no native iron minerals in that area," Martin explains. "But whenever there is a drop in sea level, the Sahara expands in size creating big dust storms. The trade winds take this red dust across the Atlantic and deposit it in the Caribbean."The oldest iguana skeletons found on San Salvador only date back less than 12,000 years, in the Holocene Epoch, so the discovery of the iguana trace pushes their presence on the islands back significantly.Most of the Bahamian islands sit on a relatively shallow platform, making it easy to imagine how iguanas might have migrated there during sea-level lows. San Salvador, however, is a small, isolated island surrounded by deep ocean, setting up the mystery for how the first iguanas arrived there at least 115,000 years ago."We're hoping researchers who study iguana evolution will be inspired by our paper to dig deeper into this question," Martin says.The researchers also hope that the paper draws attention to the plight of modern-day San Salvador rock iguanas. "When it comes to species preservation, many people think of panda bears and other cuddly mammals," Hage says. "Making the connection between how long iguanas have been on the island and how the modern-day San Salvador rock iguanas are endangered may help more people understand why they are worth preserving."Additional authors on the paper include Michael Page, a geographer in the Emory Department of Environmental Sciences and the Emory Center for Digital Scholarship; and Arya Basu; a visual information specialist and research scientist in the Emory Center for Digital Scholarship.
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Geography
| 2,020 |
December 9, 2020
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https://www.sciencedaily.com/releases/2020/12/201209140338.htm
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Silky sharks find hope in Atlantic, remain targets in Indo-Pacific
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p>New research shows that conservation efforts in the Atlantic Ocean may be working for one of the most popular -- and endangered -- species that ends up in the global shark fin trade.
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Diego Cardeñosa -- an FIU postdoctoral researcher in the Institute of Environment -- led a new study in collaboration with scientists in Hong Kong that uses DNA analysis to track where fins in the global shark fin trade originate. They focused on silky sharks (Testing revealed 99.8 percent of the fins sampled from retail markets in Hong Kong and China originated from the Indo-Pacific Ocean. Virtually none came from the Atlantic Ocean, which provides the first evidence that conservation efforts could be making an impact.According to FIU research, around 100 million sharks are killed every year. Nearly one-third of the shark species in the global shark fin trade are at risk of extinction.Open ocean sharks, like silky sharks, face a considerable risk of overexploitation because they get caught in nets and longlines set by fishing fleets targeting tuna. High demand for shark fins in Asia means that although they are considered accidental by-catch, they are by-catch worth keeping.Silky sharks are protected under Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) -- an international agreement protecting animals and plants from overexploitation in international trade. Listed in Appendix II, all trade of these sharks requires permits certifying they were legally caught, catch is sustainable, and traceable through the supply chain.The Regional Fisheries Management Organizations oversees fishing regulations and shark management decisions. In 2011, one of these organizations -- the International Commission for the Conservation of Atlantic Tuna (ICCAT) -- prohibited the fishing, retention and transshipment of silky sharks by all fisheries operating under its jurisdiction. Only developing nations are allowed to fish for these sharks as a source of food."This study shows that there is good news for ICCAT and the Atlantic silkies," said Cardeñosa, who was recently named a Distinguished Postdoctoral Scholar in the College of Arts, Sciences & Education. "While it doesn't necessarily mean that the Atlantic population is recovering or that fishing mortality is decreasing, it's a good assessment that there's high compliance with the retention and export ban by ICCAT parties."The long-term goal of Cardeñosa's research is to provide information about where shark fins originate in order to better direct more concentrated shark conservation efforts and fisheries management. This study emphasizes the need for increased monitoring, as well as better implementation of CITES regulations. The reality is illegal, unreported trade continues to happen.In fact, earlier this year Hong Kong customs officials intercepted an illegal shipment lacking proper CITES documentation from Ecuador that included silky and pelagic thresher shark fins. The secret tool behind this historic seizure of shark fins was a DNA testing kit co-developed by Cardeñosa and Demian Chapman, an FIU marine scientist in the Institute of Environment. Created with funding from the Paul G. Allen Family Foundation, the tool is being used in airports and shipping ports to help customs officials identify protected shark species."Understanding which species are most prevalent in the shark fin trade can help identify the species in need of conservation intervention," Cardeñosa said. "Tracing the populations of origin can help identify the key management jurisdictions that can lead proper interventions."The research is supported by the Pew Charitable Trusts and the Pew Fellowship Program. The findings were published in
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Geography
| 2,020 |
December 9, 2020
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https://www.sciencedaily.com/releases/2020/12/201209094256.htm
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Charles Darwin was right about why insects are losing the ability to fly
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Most insects can fly.
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Yet scores of species have lost that extraordinary ability, particularly on islands.On the small islands that lie halfway between Antarctica and continents like Australia, almost all the insects have done so.Flies walk, moths crawl."Of course, Charles Darwin knew about this wing loss habit of island insects," says PhD candidate Rachel Leihy, from the Monash University School of Biological Sciences."He and the famous botanist Joseph Hooker had a substantial argument about why this happens. Darwin's position was deceptively simple. If you fly, you get blown out to sea. Those left on land to produce the next generation are those most reluctant to fly, and eventually evolution does the rest. Voilà."But since Hooker expressed his doubt, many other scientists have too.In short, they have simply said Darwin got it wrong.Yet almost all of these discussions have ignored the place that is the epitome of flight loss -- those 'sub-Antarctic' islands. Lying in the 'roaring forties' and 'furious fifties', they're some of the windiest places on Earth."If Darwin really got it wrong, then wind would not in any way explain why so many insects have lost their ability to fly on these islands," said Rachel.Using a large, new dataset on insects from sub-Antarctic and Arctic islands, Monash University researchers examined every idea proposed to account for flight loss in insects, including Darwin's wind idea.Reporting today in Windy conditions make insect flight more difficult and energetically costly. Thus, insects stop investing in flight and its expensive underlying machinery (wings, wing muscles) and redirect the resources to reproduction."It's remarkable that after 160 years, Darwin's ideas continue to bring insight to ecology," said Rachel, the lead author of the paper.Professor Steven Chown, also from the School of Biological Sciences, added that the Antarctic region is an extraordinary laboratory in which to resolve some of the world's most enduring mysteries and test some of its most important ideas.
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Geography
| 2,020 |
December 9, 2020
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https://www.sciencedaily.com/releases/2020/12/201209094227.htm
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Can sting rays and electric rays help us map the ocean floor?
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Researchers at the RIKEN Center for Biosystems Dynamics Research (BDR) in Japan have completed a feasibility study indicating that electric rays and sting rays equipped with pingers will be able to map the seabed through natural exploration
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The ocean is a big place full of natural resources including fossil fuels, minerals, and of course, fish. The problem is that many of these resources are on the ocean floor in places we have yet to find. Ocean exploration is therefore necessary, and currently automated vehicles, sonar, and satellites are all used with varying advantages and disadvantages. At RIKEN BDR, scientists led by Yo Tanaka are developing a completely different system that relies on the natural swimming behavior of electric rays and sting rays."Electric rays and sting rays are benthic animals, meaning that they spend most of their time swimming around the ocean floor in deep places," explains Tanaka. "By combining simple pinger technology and digital cameras with this natural behavior, we think we can use rays to map the ocean floor, and at the same time collect meaningful data about ocean wildlife, biota, and resources." Additionally, this method could be much more cost effective as Tanaka and his team have already shown that electric rays can use their own electricity to power the small pingers.A pinger is a device that emits and ultrasonic sound. When a pinger's sound is picked up by several receivers, the position of the receivers and the time when the sound is detected can be used to calculate the position of the pinger. By placing cameras on rays and linking the timing of the recorded video to the timing and locations determined by the pingers, the researchers believe they can create accurate maps of the ocean floor. In their proof-of-concept study, the team conducted two experiments that showed that their idea to use rays is feasible.The first study took place in a large water tank. A setup with cameras in three planes -- front, side, and top -- verified that both types of ray swam near the bottom of the tank. The images taken by the camera allowed 3-D reconstruction of movements over time. They also verified that a camera could be attached the rays to record video of their exploration. With these positive results, the team was ready to test their system out in the real world -- an area off the coast of Okinawa in Japan. As this was a proof-of-concept experiment, they chose an area with a relatively flat seabed.They attached pingers to both sting rays and electric rays and lowered them into the ocean from a large boat along with four ultrasound receivers. The depth of the ocean was about 20 m (60 ft) and the rays were allowed to swim about 40 m (120 ft) out from the boat. The researchers recorded the pinger-derived positions as the rays swam near the boat for about two hours. Afterward, they compared the data with a seabed map of the area that already exists and confirmed that the rays' positions were within about 10 cm of those in the public map. Similar results from both types of ray were important because rays are seasonal animals"In our ocean experiment, in addition to the pinger positioning, we were able to confirm that electric rays actually move around the seabed," says Tanaka. "In the near future we will test the system for long-term monitoring." Long-term monitoring will require pingers that the electric rays can self-charge as well as wearable battery packs for the sting rays. The next test will also monitor an area with a more varied seabed with complex geometry.
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Geography
| 2,020 |
December 2, 2020
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https://www.sciencedaily.com/releases/2020/12/201202114536.htm
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Continents prone to destruction in their infancy, study finds
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Monash University geologists have shed new light on the early history of the Earth through their discovery that continents were weak and prone to destruction in their infancy.
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Their research, which relies on mathematical modelling, is published today in The Earth is our home and over its 4,500,000,000 (4.5 billion) year history has evolved to form the environment we live in and the resources on which we depend.However, the early history of Earth, covering its first 1.5 billion years remains almost unknown and, consequently, poorly understood."This was the time of formation of the first continents, the emergence of land, the development of the early atmosphere, and the appearance of primordial life -- all of which are the result of the dynamics of our planet's interiors," said lead study author ARC Future Fellow Dr Fabio Capitanio from the Monash University School of Earth, Atmosphere and Environment."Reproducing the conditions of the early Earth in computer-generated numerical models, we show that the release of internal primordial heat, three to four times that of the present-day, caused large melting in the shallow mantle, which was then extruded as magma (molten rock) onto the Earth's surface," he said.According to the researchers, the shallow mantle left behind by this process was dehydrated and rigid and formed the keels of the first continents."Our results explain that continents remained weak and prone to destruction in their infancy, ~4.5 to ~4.0 billion years ago, and then progressively differentiated and became rigid over the next billion years to form the core of our modern continents," Dr Capitanio said."The emergence of these rigid early continents resulted in their weathering and erosion, changing the composition of the atmosphere and providing nutrients to the ocean seeding the development of life."Dr Capitanio specialises in investigating the dynamics of the Earth's tectonics and plate motions to better understand the mechanisms that force single plates or whole-Earth changes.The work adds to the knowledge on supercontinent formation and its fragmentation into the present-day continents.The quantitative model used in the study explains the enigmatic melt degrees and layered structures observed in most cratons on Earth.The process shows that continents remain weak and prone to destruction in their infancy, then progressively melt and differentiate to become stable continents.This accounts for the transition from the Hadean, covering the first 500 million years of Earth history, in which crust was completely recycled, to the Archean (four to three billion years ago), when rigid continental keels built up and remain preserved through time."The geological record suggests that the very early continents did not survive and were recycled in the planet's interiors, yet this trend dramatically inverted approximately four billion years ago, when the most enduring piece of continents, cratons, appeared," Dr Capitanio said.Only tiny crystals remain from Earth's earliest continental crust, formed more than 4 billion years ago. The mysterious disappearance of this crust can now be explained. The very process that formed new crust, replacing the old one, is critically related to how the continents became stable. By extracting melt from the Earth's interior, rigid rafts in the mantle form beneath the new crust, shielding it from further destruction. The crust formed in this way is still preserved in the core of today's continents, the cratons.The cratons keep record of early life on our planet and are currently a very small fraction of the surface.Australia hosts three cratons, the Yilgarn, the Pilbara, and the Gawler cratons.
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Geography
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November 30, 2020
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https://www.sciencedaily.com/releases/2020/11/201130131529.htm
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Report assesses promises and pitfalls of private investment in conservation
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The Ecological Society of America (ESA) today released a report entitled "Innovative Finance for Conservation: Roles for Ecologists and Practitioners" that offers guidelines for developing standardized, ethical and effective conservation finance projects.
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Public and philanthropic sources currently supply most of the funds for protecting and conserving species and ecosystems. However, the private sector is now driving demand for market-based mechanisms that support conservation projects with positive environmental, social and financial returns. Examples of projects that can support this triple bottom line include green infrastructure for stormwater management, clean transport projects and sustainable production of food and fiber products."The reality is that public and philanthropic funds are insufficient to meet the challenge to conserve the world's biodiversity," said Garvin Professor and Senior Director of Conservation Science at Cornell University Amanda Rodewald, the report's lead author. "Private investments represent a new path forward both because of their enormous growth potential and their ability to be flexibly adapted to a wide variety of social and ecological contexts."Today's report examines the legal, social and ethical issues associated with innovative conservation finance and offers resources and guidelines for increasing private capital commitments to conservation. It also identifies priority actions that individuals and organizations working in conservation finance will need to adopt in order to "mainstream" the field.One priority action is to standardize the metrics that allow practitioners to compare and evaluate projects. While the financial services and investment sectors regularly employ standardized indicators of financial risk and return, it is more difficult to apply such indicators to conservation projects. Under certain conservation financing models, for example, returns on investment are partially determined by whether the conservation project is successful -- but "success" can be difficult to quantify when it is defined by complex social or environmental changes, such as whether a bird species is more or less at risk of going extinct as a result of a conservation project.Another priority action is to establish safeguards and ethical standards for involving local stakeholders, including Indigenous communities. In the absence of robust accountability and transparency measures, mobilizing private capital in conservation can result in unjust land grabs or in unscrupulous investments where profits flow disproportionately to wealthy or powerful figures. The report offers guidelines for ensuring that conservation financing improves the prosperity of local communities.According to co-author Peter Arcese, a professor at the University of British Columbia and adjunct professor at Cornell University, opportunities in conservation finance are growing for patient investors who are interested in generating modest returns while simultaneously supporting sustainable development."Almost all landowners I've worked with in Africa and North and South America share a deep desire to maintain or enhance the environmental, cultural and aesthetic values of the ecosystems their land supports," Arcese said. "By creating markets and stimulating investment in climate mitigation, and forest, water and biodiversity conservation projects, we can offer landowners alternative income sources and measurably slow habitat loss and degradation."Rodewald sees a similar landscape of interest and opportunity. "No matter the system -- be it a coffee plantation in the Andes, a timber harvest in the Pacific Northwest, or a farm in the Great Plains -- I am reminded again and again that conservation is most successful when we safeguard the health and well-being of local communities. Private investments can be powerful tools to do just that," said Rodewald.Report: Amanda Rodewald,
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Geography
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November 25, 2020
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https://www.sciencedaily.com/releases/2020/11/201125135134.htm
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Community conservation reserves protect fish diversity in tropical rivers
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Prohibiting fishing in conservation reserves is a common strategy for protecting ocean ecosystems and enhancing fisheries management. However, such dedicated reserves are rare in freshwater ecosystems, where conservation efforts generally piggyback on the protection of terrestrial habitats and species.
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Now, a collaboration between researchers from Cornell University and the University of Wisconsin-Madison has found that small, community-based reserves in Thailand's Salween River Basin are serving as critical refuges for fish diversity in a region whose subsistence fisheries have suffered from decades of overharvesting.The team's paper, "A Network of Grassroots Reserves Protects Tropical River Fish Diversity," published Nov. 25 in The lead author is Aaron Koning, a former postdoctoral fellow with the Cornell Atkinson Center for Sustainability who is currently a postdoctoral researcher at the University of Nevada, Reno. The project was overseen by Pete McIntyre, the Dwight Webster Sesquicentennial Faculty Fellow and associate professor of natural resources and environment at Cornell University.Freshwater ecosystems across the world have experienced rapid species declines compared to ecosystems on land or in the ocean. One of the leading causes is overfishing, particularly in regions where fish are a vital source of human nutrition.Koning launched his work in Thailand as a doctoral student with McIntyre at the University of Wisconsin-Madison, with the goal of testing whether the benefits documented from marine conservation reserves might also apply to freshwater systems. Both researchers came to Cornell in 2018 and continued to work on the project with their collaborators at UW-Madison.They focused on the Mae Ngao River along Thailand's border with Myanmar, because Southeast Asia has an unusually long history of freshwater conservation reserves. In 2012, Koning began documenting more than 50 reserves spread over 1,000 square kilometers of the river valley. Each of these reserves had been created by a local community to support its own nearby fishing grounds."It was really striking to see this largely uncoordinated effort of grassroots actors who pursued this fascinating conservation strategy of their own volition, and they keep doing it because they can see the benefits in their catches," Koning said. "That really motivated me to ask the questions: Why does this work and could it work elsewhere?"The researchers surveyed fish communities in 23 separate reserves that ranged in length from 300 meters to 2 kilometers. Compared to adjacent areas where fishing is unrestricted and intense, the grassroots reserves contained on average 27% more fish species and 124% higher fish density, with a more than twentyfold increase in overall biomass."Generally, we think of rivers as systems where things flow through and fish move around constantly, so what effect could a small reserve possibly have?" Koning said. "But just having a few hundred meters where people aren't fishing, while they're fishing like crazy everywhere else, can consistently produce these big changes."One of the key characteristics for successful reserves was location. When reserves are placed within view of local villages, the community members can enforce conservation rules and deter poachers."Residents can literally see the large fish from their homes -- it's pretty compelling," McIntyre said.Fish longer than 20 centimeters (approximately 8 inches) were almost entirely restricted to the reserves, and larger reserves saw the biggest bump in fish diversity and size. Community members reported that having the reserves over time helped them to catch larger fish. This indicates the reserves not only protect biodiversity but can also bolster the food security of local populations, especially during the dry season when farmers have collected their crops and turn to subsistence fishing to supplement their families' diets."As if the local benefits were not amazing enough, we were fascinated to see a further benefit of having other reserves nearby. These fish populations appear to be linked, yielding synergistic gains when the ad hoc network of reserves allows exchange among protected areas," McIntyre said.The team's findings aligned with the theoretical predictions made by marine conservation models, which led the researchers to suspect the grassroots reserves could be a successful strategy for other regions that have been overharvested, such as in the Mekong, Amazon and Congo rivers, where intensive fisheries feed millions of people."This is a great example of communities engaging in conservation on their own, and being successful," Koning said. "If we can take that reality, mix it with what we already know from marine systems, then maybe we can marry these things and design a system of small reserves that maximize conservation benefits while improving fishery benefits for communities, too."Koning is now working with Zeb Hogan, an aquatic ecologist at the University of Nevada-Reno who hosts the National Geographic network program "Monster Fish," to study this conservation approach at larger scales in the Mekong River basin.The research was supported by the National Science Foundation, the Mustard Seed Foundation, and the David and Lucile Packard Foundation, in addition to the Cornell Atkinson Center for Sustainability.
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Geography
| 2,020 |
November 24, 2020
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https://www.sciencedaily.com/releases/2020/11/201124111325.htm
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Decoding gigantic insect genome could help tackle devastating locust crises
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A 'game changing' study deciphering the genetic material of the desert locust by researchers at the University of Leicester, could help combat the crop-ravaging behaviour of the notorious insect pest which currently exacerbates a hunger crisis across many developing countries.
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It is hoped that the study will provide the basis for developing 'intelligent pesticides', that act with surgical precision by tapping into locust-specific signals in the nervous system, to either kill or disable their swarming behaviour, without harming other organisms.The full set of genetic information for the desert locust could have major international implications for countries such as East Africa, the Arabian Peninsula and South-West Asia, which this year have been suffering the most devastating desert locust crises in decades despite wide-spread control operations that are still ongoing.According to the Food and Agricultural Organisation (FAO), a swarm of locusts can contain around 40 million insects per square kilometre, which each day can eat the same amount of food as 35,000 people. The FAO estimates that 42 million people are currently facing severe food insecurity caused specifically by the desert locust.Dr Tom Matheson said:"The incredible devastation that these voracious insects can cause to food crops and pastures affects the livelihoods of hundreds of thousands of farmers and exacerbates the risks of starvation for the wider population in already vulnerable regions."The desert locust genome provides key information that could be a complete game-changer for the developing world, and a huge economic step forward for countries struggling to feed their populations."Tackling locust infestations and controlling swarms will never be easy because of the challenging conditions across the huge areas affected, but with the right information and research at hand, we hope that future approaches can become more effective."He added:"If climate change causes locust plagues to become the 'new normal', we will need all hands on deck by way of in-depth research and improved technology to help in the fight to control swarms."Desert locust swarms are a major economic issue in more than 65 countries, across more than 20 per centof the world's total land surface. Authorities in affected countries have been carrying out aerial spraying of pesticides, but the scale of the infestation is often beyond local capacity as desert locusts can travel up to 150km (95 miles) in a day, crossing national borders and rugged terrain in regions with little road infrastructure.While locust swarms are infamous for the great damage they inflict to agriculture, their genetic material ('genome') is famed amongst researchers for its enormous size. At more than 8.8 billion base pairs of DNA (8.8 'giga-bases'), the desert locust genome is the largest insect genome sequenced to date and over 2.8 times larger than the human genome.Dr Swidbert Ott added:"We do not yet understand the genetic instructions that make locusts behave so differently from ordinary grasshoppers, and to such damaging effect. Until now, a major stumbling block has been the lack of the desert locust genome sequence that holds the answer to what makes a grasshopper a locust."We hope that our data can facilitate the development of novel, more sustainable methods of managing swarm outbreaks. With the information in our research now available, there is a unique opportunity for innovators to create an intelligent pesticide that targets locusts, but not other insects crucial to the ecosystem, such as pollinators."
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Geography
| 2,020 |
November 23, 2020
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https://www.sciencedaily.com/releases/2020/11/201123161025.htm
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Largest aggregation of fishes in abyssal deep sea
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The largest aggregation of fishes ever recorded in the abyssal deep sea was discovered by a team of oceanographers from the University of Hawai'i at Manoa (UH, USA), Monterey Bay Aquarium Research Institute (MBARI, USA) and the National Oceanography Centre (NOC, UK). Their findings were published recently in Deep-Sea Research.
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"Our observations truly surprised us," said Astrid Leitner, lead author on the study, who conducted this work as graduate researcher in the UH Manoa School of Ocean and Earth Science and Technology (SOEST). "We had never seen reports of such high numbers of fishes in the sparsely-populated, food-limited deep-sea."The researchers, including Leitner, Jennifer Durden (NOC) and professors Jeffrey Drazen (Leitner's doctoral research advisor) and Craig Smith, made the observation on an expedition to the Clarion Clipperton Zone (CCZ). The CCZ is a large region stretching nearly from Hawai'i to Mexico, which is being explored for deep sea mining of nodules containing metals such as copper, cobalt, zinc and manganese.Abyssal seamounts, deep underwater mountains whose summits are 9,800 ft (3,000 m) below the sea surface, dot the deep seascape and are some of the least explored habitats on the planet. During the expedition, the research team sampled three of these seamounts and their surrounding plains as part of an effort to establish an ecological baseline prior to extraction activities.On the summit of one of the three previously unmapped and completely unexplored seamounts, the team captured on video a swarm of 115 cutthroat eels (Family Synaphobranchidae) at a small bait package containing about two pounds (1 kg) of mackerel. A few eels were caught in a baited trap and identified to be of the species Ilyophis arx, a poorly known species with fewer than 10 specimens in fish collections worldwide.These eels were observed at the top of all of the seamounts, but not on the surrounding abyssal plain. The findings provide evidence for an abyssal seamount effect (where these mountains can support much higher numbers of animals than other surrounding habitats), and also indicate these eels are likely to be seamount specialists.After returning from the expedition, the team determined they had documented the highest number of fishes ever been recorded at one time in the abyssal ocean -- almost double the previous record."If this phenomenon is not just isolated to these two seamounts in the CCZ, the implications on deep sea ecology could be widespread," said Leitner, who is now a postdoctoral researcher at the Monterey Bay Aquarium Research Institute. "Our findings highlight how much there is still left to discover in the deep sea, and how much we all might lose if we do not manage mining appropriately."
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Geography
| 2,020 |
November 19, 2020
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https://www.sciencedaily.com/releases/2020/11/201119141736.htm
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First map of bee species around the globe
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There are over 20,000 species of bee, but accurate data about how these species are spread across the globe are sparse. However, researchers reporting in the journal
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"People think of bees as just honey bees, bumble bees, and maybe a few others, but there are more species of bees than of birds and mammals combined," says senior author John Ascher, an assistant professor of biological sciences at the National University of Singapore. "The United States has by far the most species of bees, but there are also vast areas of the African continent and the Middle East which have high levels of undiscovered diversity, more than in tropical areas."Many plants and animals follow a pattern, known as a latitudinal gradient, where diversity increases toward the tropics and decreases toward the poles. Bees are an exception to this rule, having more species concentrated away from the poles and fewer near the equator, a pattern known as a bimodal latitudinal gradient. There are far fewer bee species in forests and jungles than in arid desert environments because trees tend to provide fewer sources of food for bees than low-lying plants and flowers."When it rains in the desert, there are these unpredictable mass blooms that can literally carpet the entire area," says first author Michael Orr, a postdoctoral fellow at the Institute of Zoology, Chinese Academy of Sciences. "There's a much higher turnover in the desert because of how patchy the resources are year after year. So there's a lot of potential for new species there."To create their maps, Ascher, Orr, Hughes, and colleagues compared data about the occurrence of individual bee species with a massive checklist of over 20,000 species compiled by Dr. Ascher and accessible online at the biodiversity portal DiscoverLife.org. Cross-referencing multiple datasets with complementary coverage resulted in a much clearer picture of how the many species of bees are distributed in different geographic areas. This is an important first step in assessing the distribution and potential declines of bee populations."We're extremely interested in abundance of bees, but that's something that has to be done in relation to a baseline," says Ascher, "We're trying to establish that baseline. We really can't interpret abundance until we understand species richness and geographic patterns."While some of these patterns had been hypothesized by previous researchers such as Charles Michener, they were difficult to prove because of inaccurate, incomplete, or difficult-to-access data. "Cleaning" these data was a major hurdle for the researchers."I was surprised how terrible most of the prior global data really was about bee diversity," says Alice Hughes (@AliceCHughes), an associate professor of conservation biology at Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences and another author on the paper. "A lot of the data were just too patchy or too concentrated on a small number of countries that have prioritized data sharing to be able to use these resources for any large-scale analysis."While there remains a lot to learn about what drives bee diversity, the research team hopes their work will help in the conservation of bees as global pollinators."Many crops, especially in developing countries, rely on native bee species, not honey bees," says Hughes. "There isn't nearly enough data out there about them, and providing a sensible baseline and analyzing it in a sensible way is essential if we're going to maintain both biodiversity and also the services these species provide in the future."The authors view this research as an important first step towards a more comprehensive understanding of global bee diversity and an important baseline for future, more detailed bee research.
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Geography
| 2,020 |
November 19, 2020
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https://www.sciencedaily.com/releases/2020/11/201119103058.htm
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Blue whales return to sub-Antarctic island of South Georgia after near local extinction
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An international research team led by UK scientists has revealed the return of critically endangered Antarctic blue whales to the sub-Antarctic island of South Georgia, 50 years after whaling all but wiped them out. The new study follows recent research that humpback whales are also returning to the region.
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The discovery, based on analysis of 30 years' worth of sightings, photographs and underwater sound recordings, is crucial evidence in learning how the species is recovering following a ban on commercial whaling in the 1960s. The findings are published today (19 November) in the journal Blue whales were abundant off South Georgia before early 20th century industrial whaling between 1904 and 1971 killed 42,698 of them there. Most of these were killed before the mid-1930s.The species all but vanished from the region -- dedicated whale surveys from ships off South Georgia resulted in only a single blue whale sighting between 1998 and 2018 -- but more recent surveys suggest blue whales are making a comeback.A 2020 survey in February resulted in 58 blue whale sightings, and numerous acoustic detections.Lead author Susannah Calderan of the Scottish Association for Marine Science (SAMS), Oban said: "The continued absence of blue whales at South Georgia has been seen as an iconic example of a population that was locally exploited beyond the point where it could recover."But over the past few years we've been working at South Georgia, we have become quite optimistic about the numbers of blue whales seen and heard around the island, which hadn't been happening until very recently. This year was particularly exciting, with more blue whale sightings than we ever could have hoped for."As well as looking for whales, the researchers used listening devices, which can detect the loud, low frequency calls of whales over long distances and can also work in rough weather. The team also had records of whale sightings reported to the South Georgia Museum by mariners and tourist ship passengers, and photographs of blue whales, which enable individual animals to be identified.In total, 41 blue whales have been photo-identified from South Georgia between 2011 and 2020, although none of these matched the 517 whales in the current Antarctic blue whale photographic catalogue.Susannah Calderan added: "We don't quite know why it has taken the blue whales so long to come back. It may be that so many of them were killed at South Georgia that there was a loss of cultural memory in the population that the area was a foraging ground, and that it is only now being rediscovered."There are limited opportunities for dedicated whale surveys in the region, known for its harsh weather and inaccessibility but such surveys are crucial to the future management of South Georgia's seas.Co-author and whale ecologist Dr Jennifer Jackson of British Antarctic Survey, who led the 2020 whale expedition, said: "This is an exciting discovery and a really positive step forward for conservation of the Antarctic blue whale."With South Georgia waters designated as a Marine Protected Area by the Government of South Georgia and the South Sandwich Islands, we hope that these increased numbers of blue whales are a sign of things to come and that our research can continue to contribute to effective management of the area."The team's analysis was funded by South Georgia Heritage Trust and Friends of South Georgia Island, who also funded the collection of some of the data used. Acoustic and sightings data come from expeditions led by British Antarctic Survey, with funding from the Darwin Initiative and EU BEST; from the Swiss Polar Institute Antarctic Circumnavigation Expedition (funded by the ACE Foundation, Ferring Pharmaceuticals and the Australian Antarctic Division), and Government of South Georgia and South Sandwich Islands.This international collaboration includes scientists from the SAMS, BAS, Australian Antarctic Division, US NOAA, International Fund for Animal Welfare, Government of South Georgia and South Sandwich Islands, South Georgia Heritage Trust, University of Washington, Texas A&M University at Galveston, Woods Hole Oceanographic Institution.South Georgia blue whales five decades after the end of whaling by Susannah V. Calderan, Andy Black, Trevor A. Branch, Martin A. Collins, Natalie Kelly, Russell Leaper, Sarah Lurcock, Brian S. Miller, Michael Moore, Paula A. Olson, Ana Širovi?, Andrew G. Wood, Jennifer A. Jackson is published in the journal Video: * Antarctic blue whales are currently classified as Critically Endangered under the IUCN Red List
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Geography
| 2,020 |
November 18, 2020
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https://www.sciencedaily.com/releases/2020/11/201118141825.htm
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Vertebrate biodiversity: A glimmer of hope
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Vertebrate populations -- from birds and fish to antelope -- are not, in general, declining. Despite what has previously been thought and said.
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A McGill University-led team of biologists found, in an article published today in (Populations are groups of individuals of the same species living in a particular area, and therefore decreases in population size will precede loss of species.)It all comes down to math, modeling and different approaches to calculating averages.It has typically been estimated that vertebrate populations have declined on average by more than 50% since 1970, based on historical wildlife monitoring data. "However, given previous mathematical methods used to model vertebrate populations, this estimate could arise from two very different scenarios: widespread systematic declines, or a few extreme declines," explains Brian Leung a McGill ecologist, the UNESCO Chair in Dialogues for Sustainability, and the senior author on the study. In this paper the researchers approached the question differently.Using a dataset of over 14,000 vertebrate populations from around the globe collated in the Living Planet Database, the researchers identified about 1% of vertebrate populations which have suffered extreme population declines since 1970 (such as reptiles in tropical areas of North, Central and South America, and birds in the Indo-Pacific region). When this extreme 1% was accounted for, the researchers found the remaining vertebrate populations were neither generally increasing nor decreasing, when grouped all together."The variation in this global aggregate is also important. Some populations really are in trouble and regions such as the Indo-Pacific are showing widespread systematic declines. However, the image of a global 'biodiversity desert' is not supported by the evidence." says Leung. "This is good, as it would be very discouraging if all of our conservation efforts over the last five decades had little effect.""We were surprised by how strong the effect of these extreme populations was in driving the previous estimate of average global decline," adds co-author Anna Hargreaves, a professor in the Biology Department at McGill. "Our results identify regions that need urgent action to ameliorate widespread biodiversity declines, but also reason to hope that our actions can make a difference."
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Geography
| 2,020 |
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