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November 17, 2020
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https://www.sciencedaily.com/releases/2020/11/201117192550.htm
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Large predatory fish thrive on WWII shipwrecks off North Carolina coast
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During a 2016 National Oceanic and Atmospheric Administration (NOAA) expedition to explore a pair of World War II shipwrecks that lie off the North Carolina coast, marine scientists ensconced within glass-domed submersibles navigated to the Atlantic Ocean seafloor in the hope of profiling the fish communities residing on the wrecks. Some of the findings of this joint ecological-archaeological undertaking were published this week in the Ecological Society of America's journal
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The two ships, a German U-boat and a Nicaraguan freighterJohnson, who grew up spending summers on a small Connecticut island only accessible by boat, jumped at the opportunity to join the research team analyzing the data gathered during the 2016 joint mission, even though she was not able to participate in the mission herself. The expedition team -- led by the paper's other coauthors -- had fitted the manned submersibles with advanced video and laser scanning equipment, which elicited high-definition three-dimensional imagery requiring extensive processing and analyzing. The project lent itself well to Johnson's long-standing interest in the underwater world, and she, like the rest of the team, was surprised by the extent of fish life thriving on the wrecks.According to Avery Paxton, Ph.D., a co-author on the study and a research associate at the NOAA National Centers for Coastal Ocean Science (NCCOS) in Beaufort, N.C., the findings raise questions about how fish find these remote sites in the first place. "Since the shipwrecks are such small islands of habitat on the sandy seafloor, it was surprising to see so many large-bodied groupers, like snowy and Warsaw grouper, occupying the shipwrecks," Paxton said. "This phenomenon warrants further study to determine how common this may be in other deep habitats."The researchers used lasers to acquire 3D snapshots of fish to a millimeter level of precision. For instance, the detailed photos allowed the team to measure the size of a grouper hovering beside the rivet of the U-boat's hull or to document the position of a wreckfish beside the barrel of the deck gun.For fish community ecologists, these kinds of details are essential. They can explain why fish populations decide to call a shipwreck home rather than a rocky reef, for example, and whether the thousands of shipwrecks and other submerged human-made structures scattered on the ocean floor could serve as a significant source of fish habitat in the future."Seeing so many large predators on such a relatively small habitat begs the question of how and whether they are feeding on these sites," said Chris Taylor, Ph.D., a research ecologist at NCCOS and a co-author of the study. "We know some related species aggregate in very large numbers to spawn, and some species like Goliath grouper tend to aggregate on artificial habitats. But we don't think that's happening here."The success of the joint archaeological-ecological mission has opened the door to additional collaborative ventures, which could potentially be carried out by unmanned underwater vehicles in the future.
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Geography
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November 17, 2020
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https://www.sciencedaily.com/releases/2020/11/201117113059.htm
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Extremely rare parasitic crustacean discovered in museum shark collection
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Scientists have discovered an extremely rare species of cymothoid from the mouth of a museum specimen of a deep-sea shark caught from the East China Sea, suggesting its wide distribution around the globe.
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Cymothoids are a family of isopods (a type of crustacean) that are ectoparasites of fish. Some species in this family are also known as tongue-biter or tongue-eating louse (e.g., Assistant Professor Ryota Kawanishi and Dr. Shinpei Ohashi from Hokkaido University have reported the discovery of an extremely rare species of cymothoid, Cymothoids are a diverse family of more than 300 species of parasites, and parasitize a wide variety of fish, from freshwater to the deep sea. A recent study into the genetics of the family has shown that it is highly likely that they evolved in the deep sea and diversified. A number of deep sea cymothoids, however, are poorly studied, primarily due to the difficulty of deep sea sampling.In the current study, the scientists discovered the specimen of This discovery is important as it shows the distribution of This study indicates that there is much that remains to be investigated when it comes to deep sea cymothoids. The scientists also propose using existing specimens of fish in museums across the world to reveal the distribution of cymothoids; from a broader perspective, this work suggests the hidden value of museum natural history collections in studying parasites.
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Geography
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November 17, 2020
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https://www.sciencedaily.com/releases/2020/11/201117113043.htm
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Some sport fish are caught repeatedly, which may throw off population count
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A new study reports that, for several species of oceanic sport fish, individual fish that are caught, released and recaught are more likely to be caught again than scientists anticipated. The findings raise some interesting questions for policy makers tasked with preserving sustainable fisheries.
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The study makes use of data from tagging programs, in which researchers tag fish and release them into the wild. When those fish are caught, and the tag information is returned to the researchers, it can give scientists information that informs fishery policies."Fisheries researchers who work in tagging programs have long noticed that certain fish seem to get caught repeatedly, and we set out to determine the implications of this phenomenon," says Jeff Buckel, co-author of the study and a professor of applied ecology at North Carolina State University.To that end, researchers examined decades' worth of Atlantic coast tagging datasets on four fish species: black sea bass (Centropristis striata), gray triggerfish (Balistes capriscus), red grouper (Epinephelus morio), and Warsaw grouper (Hyporthodus nigritus). Using a computational model, the researchers determined that -- for the black sea bass and both types of grouper -- survival was significantly higher after the second, third, and fourth release as compared to the first release."Think of it this way," says Brendan Runde, first author of the study and a Ph.D. student at NC State. "Let's say you tagged 1,000 fish and recaptured 100 of them for a first time. After re-releasing those 100 fish, you would only expect to recapture 10 of them a second time. But that's not what we're seeing. We're seeing much higher numbers of fish getting recaptured after the second time."Our hypothesis is that this increase in catch rate stems from selection for robust individuals," Runde says.In other words, because some fish don't survive the first release, and you can't catch a dead fish, the fish that were robust enough to survive their first encounter were more likely to survive following catch-and-release events.The finding could have a significant impact on stock assessments, which inform fishery policies."One might assume that every catch and release in a recreational fishery is a unique fish," Buckel says. "So that if 5 million black sea bass were caught and released in a given year, that would mean there were at least 5 million black sea bass in a fishery. For these three species of fish and likely many others, that's just not true. At least some of those 5 million catches were the same fish getting caught over and over again.""Reliable estimates of how many unique fish are released are critical to accurately assessing the health of the population," says Kyle Shertzer, a co-author of the study and stock assessment scientist at NOAA Fisheries."On the positive side, the study also suggests that for many species fish mortality from being released appears lower than we thought," Buckel says. "For those species, if a fish survives its first release, it has an even better chance of surviving subsequent releases.""We think that the issues raised by our findings are likely relevant for many marine fish stock assessments that rely on catch-and-release data -- though this will vary based on the species and the details of how each stock assessment is performed," Runde says.The work was done with support from NOAA, under grants NA14NMF4540061, NA09NMF4720265 and NA09NMF4540140; and from North Carolina Sea Grant Fishery Resource Grant projects 07-FEG-01 and 11-FEG-04.
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Geography
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November 16, 2020
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https://www.sciencedaily.com/releases/2020/11/201116184438.htm
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Henderson island fossils reveal new Polynesian sandpiper species
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Fossil bones collected in the early 1990s on Henderson Island, part of the Pitcairn Group, have revealed a new species of Polynesian sandpiper.
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The Henderson Sandpiper, a small wading bird that has been extinct for centuries, is described in an article in the The newly-described bird is formally named Prosobonia sauli after Cook Islands-based ornithologist and conservationist Edward K Saul.A team of researchers from New Zealand, Australia, Denmark, Switzerland, the Netherlands and China, led by Canterbury Museum Research Curator Natural History Dr Vanesa De Pietri, described the Henderson Sandpiper from 61 fossilised bones cared for by the Natural History Museum at Tring in England.Canterbury Museum Visiting Researcher Dr Graham Wragg collected the bones from caves and overhangs on Henderson Island in 1991 and 1992 during the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands.Prosobonia sauli is the fifth known species of Polynesian sandpiper. All but one of the species, the endangered Tuamotu Sandpiper (Prosobonia parvirostris), are extinct."We think Prosobonia sauli probably went extinct soon after humans arrived on Henderson Island, which archaeologists estimate happened no earlier than the eleventh century," says Dr De Pietri."It's possible these humans brought with them the Polynesian rat, which Polynesian sandpiper populations are very vulnerable to."DNA of the living Tuamotu Sandpiper and the extinct Tahiti Sandpiper (Prosobonia leucoptera), which is known only from a skin in the Naturalis Biodiversity Center in the Netherlands, was used to determine how Polynesian sandpipers are related to other wading birds."We found that Polynesian sandpipers are early-diverging members of a group that includes calidrine sandpipers and turnstones. They are unlike other sandpipers in that they are restricted to islands of the Pacific and do not migrate," says Dr De Pietri.Comparisons with the other two extinct Polynesian sandpiper species, the Kiritimati Sandpiper (Prosobonia cancellata) and the Mo'orea Sandpiper (Prosobonia ellisi), are complicated. These birds are known only from illustrations primarily by William Wade Ellis, an artist and Surgeon's Mate on Captain James Cook's third expedition, who probably saw the birds alive in the 1770s.Compared to the Tuamotu Sandpiper, its geographically closest cousin, the Henderson Sandpiper had longer legs and a wider, straighter bill, indicating how it foraged for food. It probably adapted to the habitats available on Henderson Island, which are different to those on other islands where Polynesian sandpipers were found.Henderson Island is the largest island in the Pitcairn Group, in the middle of the South Pacific Ocean. It has been uninhabited since around the fifteenth century and was designated a World Heritage Site by the United Nations in 1988.Dr Paul Scofield, Canterbury Museum Senior Curator Natural History and one of the study's co-authors, says Henderson Island is home to a number of unique species, a handful of which are landbirds like the Henderson Sandpiper."The island is really quite remarkable because every landbird species that lives there, or that we know used to live there, is not found anywhere else," he says.Dr De Pietri says the study shows the need to protect the one remaining Polynesian sandpiper species, the Tuamotu Sandpiper."We know that just a few centuries ago there were at least five Polynesian sandpiper species scattered around the Pacific. Now there's only one, and its numbers are declining, so we need to ensure we look after the remaining populations."This research was supported by a grant from the Marsden Fund Council, managed by the Royal Society Te Ap?rangi, as well as the R S Allan Fund managed by Canterbury Museum.
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Geography
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November 10, 2020
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https://www.sciencedaily.com/releases/2020/11/201110081553.htm
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New research identifies 'triple trouble' for mangrove coasts
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Some of the world's most valuable ecosystems are facing a "triple threat" to their long-term durability and survival, new research shows.
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The study found that mangrove forests, their large biodiversity and the coastal protection they provide are under pressure from three distinct threats -- sea-level rise, lack of mud and squeezed habitats.The research, conducted by an international team of experts including Dr Barend van Maanen from the University of Exeter, identifies not only how these coastal forests get pushed against their shores, but also what causes the loss of their diversity.It shows the negative effects of river dams that decrease the supply of mud that could otherwise raise mangrove soils, while buildings and seawalls largely occupy the space that mangroves require for survival.The study is published in Coastal mangrove forests are valuable, highly biodiverse ecosystems that protect coastal communities against storms.Mangroves withstand flooding by tides and capture mud to raise their soils. But as the mangrove trees cannot survive if they are under water for too long, the combination of sea-level rise and decreasing mud supply from rivers poses a serious threat.New computer simulations show how coastal forests retreat landward under sea-level rise, especially in coastal areas where mud in the water is declining. The simulations include interactions among tides, mud transport and, for the first time, multiple mangrove species.Dr van Maanen, senior lecturer at the University of Exeter and supervisor of the project, said: "Both mangrove coverage loss and diversity loss go hand in hand when that landward retreat is limited by expanding cities, agriculture or flood protection works."The model also shows that mangrove trees with dense roots trap mud more effectively and can stop it from reaching forest areas further inland.Danghan Xie, PhD researcher at Utrecht University and lead author of the study said: "This makes the more landward-located trees flood for longer periods of time, an effect that is intensified by sea-level rise."Increasing landward flooding then seriously reduces biodiversity."Human land use prevents the mangroves 'escaping' flooding by migrating inland, narrowing the mangrove zone and further endangering biodiversity."A narrow mangrove zone is much less effective in protecting the coast against storms, or in the worst case loses its protective properties altogether.Co-author Dr Christian Schwarz, environmental scientist at the University of Delaware, added: "The loss of mangrove species will have dramatic ecological and economic implications, but fortunately there are ways to help safeguarding these ecosystems."It is essential to secure or restore mud delivery to coasts to counter negative effects of sea-level rise."For coasts where mud supply remains limited, removal of barriers that obstruct inland migration is of utmost importance to avoid loss of mangrove forests and biodiversity."The publication Mangrove diversity loss under sea-level rise triggered by bio-morphodynamic feedbacks and anthropogenic pressures is published in
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Geography
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November 4, 2020
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https://www.sciencedaily.com/releases/2020/11/201104102213.htm
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The dangers of collecting drinking water
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Collecting drinking water in low and middle income countries can cause serious injury, particularly for women, according to new research from the University of East Anglia.
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A new international study published in BMJ Global Health reveals dangers including falls, traffic accidents, animal attacks, and fights, which can result in broken bones, spinal injuries, lacerations, and other physical injuries.And women are most likely to sustain such injuries -- highlighting the social the social and gender inequities of a hidden global health challenge.Dr Jo-Anne Geere, from UEA's School of Health Sciences, said: "Millions of people don't have the luxury of clean drinking water at their home, and they face many dangers before the water even touches their lips."Global research on water has largely focused on scarcity and health issues related to what is in the water, but the burden and risks of how water is retrieved and carried has been overlooked until now."We wanted to better understand the true burden of water insecurity."The new study was led by Northwestern University in the US, in collaboration with UEA, the University of Miamii and the Household Water Insecurity Experiences Research Coordination Network (HWISE RCN).The research team used a large global dataset to understand what factors might predict water-fetching injuries. The work draws on a survey of 6,291 randomly selected households across 24 sites in 21 low- and middle-income countries in Asia, Africa, Latin America, and the Caribbean.They found that 13 per cent of the respondents reported some sort of injury while collecting water, and that women were twice as likely to be hurt as men.Dr Sera Young, from Northwestern University, said: "Thirteen percent is a big number, but it is probably an underestimate. It's highly likely that more people would have reported injuries if the survey had more detailed questions.Prof Paul Hunter, from UEA's Norwich Medical School, said: "This reinforces how the burden of water scarcity disproportionately falls on women, on rural populations, and on those who do not have water sources close to home."It highlights the importance of safe interventions that prioritise personal physical safety alongside traditional global indicators of water, sanitation, and hygiene."The researchers say that keeping track of such safety measures -- in addition to the usual measures of water quality and access -- could help better assess progress towards the United Nations' Sustainable Development Goal 6.1, which sets out "to achieve universal and equitable access to safe and affordable drinking water for all" by 2030.Dr Vidya Venkataramanan, also from Northwestern University, said: "It seems likely that water-fetching can contribute considerably to the global Water, Sanitation and Hygiene (WaSH) burden, but it usually goes unmeasured because we typically think about access and water quality. It is, therefore, a greatly underappreciated, nearly invisible public health challenge."It's really important that data on water-fetching injuries are systematically collected so that we can know the true burden of water insecurity. Currently, all of the broken bones, spinal injuries, lacerations and other physical injuries are not accounted for in calculations about the burden of water insecurity."
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Geography
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November 5, 2020
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https://www.sciencedaily.com/releases/2020/11/201105092911.htm
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Crown-of-thorns eat themselves out of house and home
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A world-first study on the Great Barrier Reef shows crown-of-thorns starfish have the ability to find their own way home -- a behaviour previously undocumented -- but only if their neighbourhood is stocked with their favourite food: corals.
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Australian researchers observed the starfish emerging from their shelters in the afternoons so they could feed on coral during the night before returning home at dawn."The crown-of-thorns starfish often partied all night, slept-in and only those with a well-stocked larder found their way home -- so it's very much a teenager model of behaviour," said lead author Dr Scott Ling from the Institute for Marine and Antarctic Studies at the University of Tasmania."Their preferred prey is Acropora corals," said co-author Professor Morgan Pratchett from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (CoralCoE at JCU). Acropora is an important coral species -- for the past two million years they have been the building blocks of reefs across the world."When populations of Acropora dropped, the starfish didn't return home," Prof Pratchett said. "Their behaviour is directly linked to the local abundance of Acropora."The results of the study show healthy reefs with a high cover of these corals may encourage crown-of-thorns aggregations and outbreaks. The outbreaks cause extensive, widespread and sustained coral loss throughout the Indo-Pacific region.Similar examples of predator infestations driving environmental devastation include sea urchins overgrazing on kelp forests and coral reef fishes munching through patches of seagrass.The researchers used in-situ time-lapse photography to track the movements of 58 starfish in the northern and southern Great Barrier Reef during an outbreak in 2015. In the absence of their preferred Acropora coral prey, starfish were typically homeless and instead roamed up to 20 metres per day."Unlike sea urchins that can switch diet once they overgraze kelp forests, results of the time-lapse monitoring indicate that the starfish will consume available Acropora and ultimately eat themselves out of house and home before dispersing in search of new feeding grounds," Dr Ling said.Previous outbreaks on the Great Barrier Reef were recorded in 1962, 1979, 1993 and 2009. Though mass-coral bleaching due to global warming is now the greatest threat to coral reefs worldwide, the combined impact of mass-bleaching and crown-of-thorns outbreaks is potentially catastrophic for coral reefs."By better understanding the behaviour of these starfish we can help prevent and control their outbreaks, which will help alleviate the pressures on coral reefs," Prof Pratchett said.
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Geography
| 2,020 |
November 4, 2020
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https://www.sciencedaily.com/releases/2020/11/201104102211.htm
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Magma 'conveyor belt' fuelled world's longest erupting supervolcanoes
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International research led by geologists from Curtin University has found that a volcanic province in the Indian Ocean was the world's most continuously active -- erupting for 30 million years -- fuelled by a constantly moving 'conveyor belt' of magma.
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It's believed this magma 'conveyor belt,' created by shifts in the seabed, continuously made space available for the molten rock to flow for millions of years, beginning around 120 million years ago.Research lead Qiang Jiang, a PhD candidate from Curtin's School of Earth and Planetary Sciences, said the studied volcanoes were in the Kerguelen Plateau, located in the Indian Ocean, about 3,000 kilometres south west of Fremantle, Western Australia."Extremely large accumulations of volcanic rocks -- known as large volcanic provinces -- are very interesting to scientists due to their links with mass extinctions, rapid climatic disturbances, and ore deposit formation," Mr Jiang said."The Kerguelen Plateau is gigantic, almost the size of Western Australia. Now imagine this area of land covered by lava, several kilometres thick, erupting at a rate of about 0.2 millimetres every year."0.2 millimetres of lava a year may not sound like much but, over an area the size of Western Australia, that's equivalent to filling up 184,000 Olympic-size swimming pools to the brim with lava every single year. Over the total eruptive duration, that's equivalent to 5.5 trillion lava-filled swimming pools!"This volume of activity continued for 30 million years, making the Kerguelen Plateau home to the longest continuously erupting supervolcanoes on Earth. The eruption rates then dropped drastically some 90 million years ago, for reasons that are not yet fully understood."From then on, there was a slow but steady outpouring of lava that continued right to this day, including the 2016 eruptions associated with the Big Ben volcano on Heard Island, Australia's only active volcano."Co-researcher Dr Hugo Olierook, also from Curtin's School of Earth and Planetary Sciences, explained such a long eruption duration requires very peculiar geological conditions."After the partial breakup of the supercontinent Gondwana, into the pieces now known as Australia, India and Antarctica, the Kerguelen Plateau began forming on top of a mushroom-shaped mantle upwelling, called a mantle plume, as well as along deep sea, mid-oceanic mantle ridges," Dr Olierook said."The volcanism lasted for so long because magmas caused by the mantle plume were continuously flowing out through the mid-oceanic ridges, which successively acted as a channel, or a 'magma conveyor belt' for more than 30 million years."Other volcanoes would stop erupting because, when temperatures cooled, the channels became clogged by 'frozen' magmas."For the Kerguelen Plateau, the mantle plume acts as a Bunsen burner that kept allowing the mantle to melt, resulting in an extraordinarily long period of eruption activity."Research co-author, Professor Fred Jourdan, Director of the Western Australia Argon Isotope Facility at Curtin University, said the team used an argon-argon dating technique to date the lava flows, by analysing a range of black basaltic rocks taken from the bottom of the sea floor."Finding this long, continuous eruption activity is important because it helps us to understand what factors can control the start and end of volcanic activity," Professor Jourdan said."This has implications for how we understand magmatism on Earth, and on other planets as well."The Curtin-led research was a collaboration with Uppsala University in Sweden and the University of Tasmania.
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Geography
| 2,020 |
November 3, 2020
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https://www.sciencedaily.com/releases/2020/11/201103191001.htm
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Gentoo penguins are four species, not one, say scientists
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Gentoo penguins should be reclassified as four separate species, say scientists at the Milner Centre for Evolution at the University of Bath, after analysing the genetic and physical differences between populations around the southern hemisphere.
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The researchers say that counting them as four separate species will aid in their conservation because it will make it easier to monitor any decline in numbers.Gentoo penguins, with the Latin name The researchers suggest these two sub species should be raised to species level and two new species created, which they have named P. poncetii after the Australian seabird conservationist Sally Poncet, and P. taeniata in recognition of a former proposal for this name dating to the 1920s.Their study, published in the journal They used genome data to create an evolutionary tree to understand the relationship between the different populations. When they combined these data with measurements of museum specimens from each of the populations, they found clear morphological (physical) and genetic differences between the four populations.Dr Jane Younger, Prize Fellow from the Milner Centre for Evolution at the University of Bath, led the study. She said: "For the first time, we've shown that these penguins are not only genetically distinct, but that they are also physically different too."Gentoos tend to stick close to their home colonies, and over hundreds of thousands of years have become geographically isolated from each other to the point where they don't interbreed with each other, even though they could easily swim the distance that separates them."The four species we propose live in quite different latitudes -- for example PhD student Josh Tyler said: "They look very similar to the untrained eye, but when we measured their skeletons we found statistical differences in the lengths of their bones and the sizes and shape of their beaks."It's a similar story to giraffes, which were revealed in 2016 to be four genetically distinct species."The scientists say that regarding the four populations as separate species, gives conservationists a better chance of protecting their diversity because if there's a decline in one of them it will change the threat status as defined by the IUCN Red List.Dr Younger said: "Currently gentoo penguins are fairly stable in numbers, however there is some evidence of the northern populations moving further south as the climate gets warmer, so we need to watch them closely."The proposed changes to the classification of gentoos will be reviewed by an international committee of scientists which will assess all the evidence in the scientific literature before the new taxonomy is accepted.The study was funded by the American Ornithological Society, Linnean Society, American Museum of Natural History and the Evolution Education Trust. The research team was a collaboration led by the University of Bath (UK) with scientists from Loyola University Chicago, Cornell University and the University of Minnesota (USA).
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Geography
| 2,020 |
November 3, 2020
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https://www.sciencedaily.com/releases/2020/11/201103104725.htm
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The craters on Earth
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Prof. Dr. Thomas Kenkmann, geologist from the University of Freiburg's Institute of Earth and Environmental Sciences, together with mineralogist Prof. Dr. Wolf Uwe Reimold from the University of Brasilia, Brazil, and Dr. Manfred Gottwald from the German Aerospace Center (DLR) published an atlas providing a comprehensive overview of all known impact craters on every continent. The authors present the more than 200 terrestrial impact sites in high-resolution topographic maps and satellite images, complete with detailed geological descriptions and photographs of the crater structures and their rocks. They also explain the essential details of each impact event.
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The formation of craters by asteroid and comet impact has always been a fundamental process in the solar system, explains Kenkmann. As the planets developed along with their moons, these impacts played an important part in accreting planetary mass, shaping the surfaces of planetary bodies, and later also influencing their development. And larger meteorite impacts eventually affected the development of life on Earth.Today, mapping of what can still be seen of the impact structures on the Earth's surface can be done by satellites in low Earth orbit. From 2010 to 2016, the DLR successfully measured the Earth's surface with the radar satellites of the TanDEM-X mission. The acquired data allowed, for the first time, to derive a worldwide terrain model with a height accuracy of up to one meter. From this global digital elevation model the authors have been able to produce this complete topographic atlas of 600 pages with information about all terrestrial impact craters known to date.
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Geography
| 2,020 |
November 2, 2020
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https://www.sciencedaily.com/releases/2020/11/201102173234.htm
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Two centuries of Monarch butterflies show evolution of wing length
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North America's beloved Monarch butterflies are known for their annual, multi-generation migrations in which individual insects can fly for thousands of miles. But Monarchs have also settled in some locations where their favorite food plants grow year round, so they no longer need to migrate.
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Micah Freedman, a graduate student at the Center for Population Biology at UC Davis, took a deep dive into museum collections to see how migration has shaped the species. Monarchs are native to North America, but have also established non-migrating populations in the Caribbean, Central and South America, and islands in the Pacific and Atlantic oceans. These island-hopping butterflies may have been blown by storms before being lucky enough to reach dry land.Monarchs that established new, non-migrating populations also had those larger wings. But over time, the wings of these colonists got smaller.The shift between longer and shorter wings shows two opposite selection forces at work, Freedman and colleagues wrote in a paper published this week in Alternatively, wing size could be influenced by other environmental factors depending on where butterflies are hatched and grow up. To test this, Freedman raised Monarch butterflies from non-migrating populations in Hawaii, Guam, Australia and Puerto Rico outdoors in Davis, California alongside native migrating Monarchs. The non-migrating butterflies retained their smaller wings, showing that the effect is due to genetics and not the rearing environment."Our findings provide a compelling example of how migration-associated traits may be favored during the early stages of range expansion, and also the rate of reductions in those same traits upon loss of migration," the authors wrote.
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Geography
| 2,020 |
November 2, 2020
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https://www.sciencedaily.com/releases/2020/11/201102110028.htm
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An underwater navigation system powered by sound
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GPS isn't waterproof. The navigation system depends on radio waves, which break down rapidly in liquids, including seawater. To track undersea objects like drones or whales, researchers rely on acoustic signaling. But devices that generate and send sound usually require batteries -- bulky, short-lived batteries that need regular changing. Could we do without them?
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MIT researchers think so. They've built a battery-free pinpointing system dubbed Underwater Backscatter Localization (UBL). Rather than emitting its own acoustic signals, UBL reflects modulated signals from its environment. That provides researchers with positioning information, at net-zero energy. Though the technology is still developing, UBL could someday become a key tool for marine conservationists, climate scientists, and the U.S. Navy.These advances are described in a paper being presented this week at the Association for Computing Machinery's Hot Topics in Networks workshop, by members of the Media Lab's Signal Kinetics group. Research Scientist Reza Ghaffarivardavagh led the paper, along with co-authors Sayed Saad Afzal, Osvy Rodriguez, and Fadel Adib, who leads the group and is the Doherty Chair of Ocean Utilization as well as an associate professor in the MIT Media Lab and the MIT Department of Electrical Engineering and Computer Science.It's nearly impossible to escape GPS' grasp on modern life. The technology, which relies on satellite-transmitted radio signals, is used in shipping, navigation, targeted advertising, and more. Since its introduction in the 1970s and '80s, GPS has changed the world. But it hasn't changed the ocean. If you had to hide from GPS, your best bet would be underwater.Because radio waves quickly deteriorate as they move through water, subsea communications often depend on acoustic signals instead. Sound waves travel faster and further underwater than through air, making them an efficient way to send data. But there's a drawback."Sound is power-hungry," says Adib. For tracking devices that produce acoustic signals, "their batteries can drain very quickly." That makes it hard to precisely track objects or animals for a long time-span -- changing a battery is no simple task when it's attached to a migrating whale. So, the team sought a battery-free way to use sound.Adib's group turned to a unique resource they'd previously used for low-power acoustic signaling: piezoelectric materials. These materials generate their own electric charge in response to mechanical stress, like getting pinged by vibrating soundwaves. Piezoelectric sensors can then use that charge to selectively reflect some soundwaves back into their environment. A receiver translates that sequence of reflections, called backscatter, into a pattern of 1s (for soundwaves reflected) and 0s (for soundwaves not reflected). The resulting binary code can carry information about ocean temperature or salinity.In principle, the same technology could provide location information. An observation unit could emit a soundwave, then clock how long it takes that soundwave to reflect off the piezoelectric sensor and return to the observation unit. The elapsed time could be used to calculate the distance between the observer and the piezoelectric sensor. But in practice, timing such backscatter is complicated, because the ocean can be an echo chamber.The sound waves don't just travel directly between the observation unit and sensor. They also careen between the surface and seabed, returning to the unit at different times. "You start running into all of these reflections," says Adib. "That makes it complicated to compute the location." Accounting for reflections is an even greater challenge in shallow water -- the short distance between seabed and surface means the confounding rebound signals are stronger.The researchers overcame the reflection issue with "frequency hopping." Rather than sending acoustic signals at a single frequency, the observation unit sends a sequence of signals across a range of frequencies. Each frequency has a different wavelength, so the reflected sound waves return to the observation unit at different phases. By combining information about timing and phase, the observer can pinpoint the distance to the tracking device. Frequency hopping was successful in the researchers' deep-water simulations, but they needed an additional safeguard to cut through the reverberating noise of shallow water.Where echoes run rampant between the surface and seabed, the researchers had to slow the flow of information. They reduced the bitrate, essentially waiting longer between each signal sent out by the observation unit. That allowed the echoes of each bit to die down before potentially interfering with the next bit. Whereas a bitrate of 2,000 bits/second sufficed in simulations of deep water, the researchers had to dial it down to 100 bits/second in shallow water to obtain a clear signal reflection from the tracker. But a slow bitrate didn't solve everything.To track moving objects, the researchers actually had to boost the bitrate. One thousand bits/second was too slow to pinpoint a simulated object moving through deep water at 30 centimeters/second. "By the time you get enough information to localize the object, it has already moved from its position," explains Afzal. At a speedy 10,000 bits/second, they were able to track the object through deep water.Adib's team is working to improve the UBL technology, in part by solving challenges like the conflict between low bitrate required in shallow water and the high bitrate needed to track movement. They're working out the kinks through tests in the Charles River. "We did most of the experiments last winter," says Rodriguez. That included some days with ice on the river. "It was not very pleasant."Conditions aside, the tests provided a proof-of-concept in a challenging shallow-water environment. UBL estimated the distance between a transmitter and backscatter node at various distances up to nearly half a meter. The team is working to increase UBL's range in the field, and they hope to test the system with their collaborators at the Wood Hole Oceanographic Institution on Cape Cod.They hope UBL can help fuel a boom in ocean exploration. Ghaffarivardavagh notes that scientists have better maps of the moon's surface than of the ocean floor. "Why can't we send out unmanned underwater vehicles on a mission to explore the ocean? The answer is: We will lose them," he says.UBL could one day help autonomous vehicles stay found underwater, without spending precious battery power. The technology could also help subsea robots work more precisely, and provide information about climate change impacts in the ocean. "There are so many applications," says Adib. "We're hoping to understand the ocean at scale. It's a long-term vision, but that's what we're working toward and what we're excited about."This work was supported, in part, by the Office of Naval Research.
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Geography
| 2,020 |
November 2, 2020
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https://www.sciencedaily.com/releases/2020/11/201102110022.htm
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Birdwatching from afar: Amazing new AI-enabled camera system to target specific behaviors
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A research team from Osaka University has developed an innovative new animal-borne data-collection system that, guided by artificial intelligence (AI), has led to the witnessing of previously unreported foraging behaviors in seabirds.
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Bio-logging is a technique involving the mounting of small lightweight video cameras and/or other data-gathering devices onto the bodies of wild animals. The systems then allow researchers to observe various aspects of that animal's life, such as its behaviors and social interactions, with minimal disturbance.However, the considerable battery life required for these high-cost bio-logging systems has proven limiting so far. "Since bio-loggers attached to small animals have to be small and lightweight, they have short runtimes and it was therefore difficult to record interesting infrequent behaviors," explains study corresponding author Takuya Maekawa."We have developed a new AI-equipped bio-logging device that allows us to automatically detect and record the specific target behaviors of interest based on data from low-cost sensors such as accelerometers and geographic positioning systems (GPS)." The low-cost sensors then limit the use of the high-cost sensors, such as video cameras, to just the periods of time when they are most likely to capture the specific target behavior.The use of these systems in combination with machine learning techniques can focus data collection with the expensive sensors directly onto interesting but infrequent behaviors, greatly increasing the likelihood that those behaviors will be detected.The new AI-assisted video camera system was tested on black-tailed gulls and streaked shearwaters in their natural environment on islands off the coast of Japan. "The new method improved the detection of foraging behaviors in the black-tailed gulls 15-fold compared with the random sampling method," says lead author Joseph Korpela. "In the streaked shearwaters, we applied a GPS-based AI-equipped system to detect specific local flight activities of these birds. The GPS-based system had a precision of 0.59 -- far higher than the 0.07 of a periodic sampling method involving switching the camera on every 30 minutes."There are many potential applications for the use of AI-equipped bio-loggers in the future, not least the further development of the systems themselves. "These systems have a huge range of possible applications including detection of poaching activity using anti-poaching tags," says Maekawa. "We also anticipate that this work will be used to reveal the interactions between human society and wild animals that transmit epidemics such as coronavirus."
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Geography
| 2,020 |
October 30, 2020
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https://www.sciencedaily.com/releases/2020/10/201030142118.htm
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China's most important trees are hiding in plain sight
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In ecosystems around the globe, the danger of being a common or widespread species is the tendency to be overlooked by conservation efforts that prioritize rarity.
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In forests, the most common species can be essential to ecosystem structure and function, which crumble with the decline of these pivotal trees, known collectively as foundation species.In an effort to identify forest foundation species and elevate their conservation status before they disappear, a unique research collaboration between Chinese and American scientists has synthesized long-term biodiversity data from 12 immense forest study plots spanning 1,500 miles, from China's far north to its southern tropics.Their results, published today in the journal The study comes on the heels of the latest "Red List" published by Botanic Gardens Conservation International, which showed that 36 out of the 158 maples species worldwide -- nearly a quarter of all maples -- are at high risk of extinction in the near future in the wild. Fourteen of those high-risk species exist only in China."Foundation species are the species upon which ecosystems are built and supported, just like the foundation of your house," explains Aaron Ellison, Senior Research Fellow at the Harvard Forest and a co-author of the study. "But they can be so common that they hide in plain sight, overlooked because they lack the cachet and appeal of rarities."The study was led by Xiujuan Qiao, an Associate Professor at the Wuhan Botanical Garden of the Chinese Academy of Sciences, who spent all of 2019 in residence at the Harvard Forest facilitating this global collaboration. She adds, "We should pay more attention to foundation species, identifying and protecting them before their inevitable decline."
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Geography
| 2,020 |
October 29, 2020
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https://www.sciencedaily.com/releases/2020/10/201028143124.htm
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Leaving more big fish in the sea reduces carbon dioxide emissions
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An international team of scientists has found leaving more big fish in the sea reduces the amount of carbon dioxide (CO
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When a fish dies in the ocean it sinks to the depths, sequestrating all the carbon it contains with it. This is a form of 'blue carbon' -- carbon captured and stored by the world's ocean and coastal ecosystems."But when a fish is caught, the carbon it contains is partly emitted into the atmosphere as COMr Mariani led a world-first study showing how ocean fisheries have released at least 730 million metric tons of COCo-author Professor David Mouillot from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (CoralCoE at JCU) and the University of Montpellier said the carbon footprint of fisheries is 25 percent higher than previous industry estimates."Fishing boats produce greenhouse gases by consuming fuel," Prof Mouillot said. "And now we know that extracting fish releases additional COLarge fish such as tuna, sharks, mackerel and swordfish are about 10 to 15 percent carbon."When these fish die, they sink rapidly," Prof Mouillot said. "As a result, most of the carbon they contain is sequestered at the bottom of the sea for thousands or even millions of years. They are therefore carbon sinks -- the size of which has never been estimated before."He says this natural phenomenon -- a blue carbon pump -- has been increasingly and greatly disrupted by industrial fishing.The authors also say the phenomenon has not only been overlooked until now, but it happens in areas where fishing is not economically profitable: in the Central Pacific, South Atlantic, and North Indian Oceans."Fishing boats sometimes go to very remote areas -- with enormous fuel consumption -- even though the fish caught in these areas are not profitable and fishing is only viable thanks to subsidies," Mr Mariani said.For the authors of the study, the new data strongly supports more reasoned fishing."The annihilation of the blue carbon pump represented by large fish suggests new protection and management measures must be put in place, so that more large fish can remain a carbon sink and no longer become an additional CO"We need to fish better," Prof Mouillot said.
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Geography
| 2,020 |
October 28, 2020
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https://www.sciencedaily.com/releases/2020/10/201028124539.htm
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how marine reserves can benefit fisheries across the globe
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Society will require more food in the coming years to feed a growing population, and seafood will likely make up a significant portion of it. At the same time, we need to conserve natural habitats to ensure the health of our oceans. It seems like a conflict is inevitable.
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"Marine protected areas are tools commonly used to conserve marine biodiversity by closing parts of the ocean to fishing," said Reniel Cabral, an assistant researcher at UC Santa Barbara's Environmental Market Solutions Lab. "This creates a potential dilemma when closures cause fishers to lose access to fishing grounds."A new study indicates that this need not be the case. The paper outlines where the benefits of fishing restrictions could enable a fishery to become more productive, even with the closures. The research, published in the The benefits of a well-considered marine protected area (MPA) can bolster the productivity of surrounding fisheries, especially when those fisheries are overexploited. The refuge enables populations to rebuild and then spill over into surrounding waters. Protecting an area from fishing also enables resident fish to grow older and larger, and scientists have found that these fish are proportionately more fertile than their smaller counterparts.What's more, fishing is not well regulated in many regions. The activity can be decentralized and target many different species using a variety of methods. Managing the industry can be nearly impossible, especially for agencies that are underfunded and underpowered. In this context, designating an MPA is relatively simple, especially compared to other management strategies."Past studies have shown that MPAs can improve catch when designed well and under the right fishery conditions," said Cabral, the study's lead author. "We asked how you could design a network of marine protected areas to improve fishery productivity, and what the results would be."Cabral and his colleagues at UC Santa Barbara, the Hawai?i Institute of Marine Biology, and the National Geographic Society began constructing a model of global fisheries that would account for both biologic and economic factors. They leveraged a database of 4,000 fishery stocks, their ecological characteristics, management status and global distributions in combination with a wealth of information on fisheries catch and fisher behavior in response to marine protected areas.The resulting bio-economic model forecasts how fish populations would respond to the creation of new MPAs based on a variety of factors such as the location and status of fisheries and species mobility and growth rates. This enabled the team to project harvest outcomes over a variety of different reserve designs. The researchers could then see where MPAs would be most beneficial."We found that there are a lot of places where you can get food benefits," said coauthor Steve Gaines, dean of UCSB's Bren School of Environmental Science & Management. "So, rather than having this traditional battle between fisheries and conservation, we can now identify the strategic places where we can potentially get both conservation and fishery benefits."Currently, only 2.5% of the ocean is covered by highly protected MPAs. The study found that strategically protecting an additional 5% of the ocean could increase future catch by 20%, or 9 to 12 million metric tons of fish.The most promising locations tended to cluster around the South Pacific, southeast Africa and the temperate coasts of North and South America. These are regions where well-placed MPAs have the greatest potential for increasing local catch, whether due to the ecology of the stocks, poor fishery regulation or a combination of the two.The results offer a rubric for determining what the best strategies will be and what regions will yield the best return. It's a gestalt look at the interplay between marine protected areas and fisheries that can be further developed in the future.The projections also come only from stocks that scientists have data on. There are plenty of species that don't have enough data for analysis, and they're likely to be in far worse shape than those we do have a tab on, Gaines explained. For these reasons, the team believes the benefits to fisheries would likely exceed the predictions in their paper.The model's strength lies in its ability to highlight areas where a marine reserve could have high potential benefits for fishing. "Our model can identify areas where MPAs would really improve fishery productivity," said Cabral, "but designing those at the local level will need to be site specific."In addition to being a relatively simple management tool, marine protected areas can provide a great starting point for getting communities involved in fishery management and encouraging ocean stewardship. "MPAs can encourage community participation, which increases the attention they pay to improving their management for fisheries that are not protected," Cabral said.Of course, to have this effect, governments need to actively include communities in the planning process. When done well, these stakeholders become active participants in shaping the future of their own resources.The Environmental Market Solutions Lab is currently applying this model at the country level as well. The results will establish a framework for individual nations to understand the potential benefits of their own marine protected areas.The team has also taken an active role in applying its research to real-world MPAs. "We are working with multiple countries around the world to support their efforts to place hundreds of thousands of square kilometers of ocean area under protection," said Darcy Bradley, one of the paper's coauthors and the co-director of the lab's Ocean and Fisheries Program.The group helps with spatial prioritization -- leveraging studies like this one -- as part of the planning process. They also collaborate with national agencies to design fishery monitoring programs and perform fishery assessments. "In each of these engagements, our goal is to take the best available MPA science and translate it into practical outputs to support thriving ocean ecosystems and economies," she said.
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Geography
| 2,020 |
October 28, 2020
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https://www.sciencedaily.com/releases/2020/10/201028124522.htm
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Sea turtle nesting season winding down in Florida, some numbers are up and it's unexpected
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Florida's sea turtle nesting surveying comes to a close on Halloween and like everything else in 2020, the season was a bit weird.
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The number of green sea turtle nests on central and southern Brevard County, Florida beaches monitored by University of Central biologists were way up during a year they should have been down based on nearly 40 years of historical data."Usually, green turtles alternate between high years and low years, but this year they defied expectations," says Chris Long, a doctoral candidate and research assistant with UCF's Marine Turtle Research Group. "Green turtles had the fifth highest year on the Archie Carr Refuge that we've recorded since 1982. There is no evidence pointing to high nesting as a result of fewer people on the beaches or anything pandemic-related like that. It's difficult to know why nesting differed from expectation."East-Central Florida's coastline (from Brevard to Indian River County) is among the most important nesting areas in the world for loggerhead sea turtles, and it also hosts about one-third of all green turtle nests in the state. The region is at the northern end of a "hotspot" for leatherbacks, which nest on the local beaches at a smaller scale as well. All sea turtles in the U.S. are protected under the Endangered Species Act.UCF has run a sea turtle monitoring and research program on the beaches of the Archie Carr National Wildlife Refuge (ACNWR) in southern Brevard County for more than 35 years. UCF findings about sea turtle abundance and behavior are among the reasons the refuge was created in 1991. The UCF Marine Turtle Research Group focuses on long-term nesting beach and coastal juvenile sea turtle research in Brevard and Indian River counties locally. The group also studies the oceanic "lost years" tracking turtles in the Gulf of Mexico, North and South Atlantic, and Indian Oceans.All sea turtles saw an increase in nests along the coastline this year compared to recent years. Here's a look at the numbers recorded by the UCF Marine Turtle Research Group's covering the 13 northernmost miles of the Archie Carr National Wildlife Refuge. Final counts won't be tallied until Oct. 31:Green turtle nests:Loggerhead nests:Leatherback nests:
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Geography
| 2,020 |
October 28, 2020
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https://www.sciencedaily.com/releases/2020/10/201028082942.htm
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Reforestation plans in Africa could go awry
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The state of mature ecosystems must be taken into account before launching massive reforestation plans in sub-Saharan Africa, according to geo-ecologist Julie Aleman, a visiting researcher in the geography department of Université de Montréal.
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"The biomes of the region we studied, which includes all the countries south of the Sahara, are divided into two fairly distinct types: savannah at about 70 per cent and tropical forest for the rest," said Aleman, co-author of a major new study on African biomes.Involving some 30 researchers, several from Africa itself, the study is published this week in the "When we analyze the assemblage of tree species in each biome, we find that each is extremely different," Aleman said. "Moreover, if we look closely at the history of these biomes, we realize that they have been fairly stable for 2,000 years. Reforestation with tropical forest species in areas that are more associated with savannahs would therefore be a mistake."Without wanting to point the finger at countries that might make this mistake, Aleman pointed out that reforestation plans include the planting of billions of trees. Even the intention is good, countries must try to avoid artificially creating tropical forests where savannahs have dominated for several millennia, she said.Moreover, the choice of species selected is decisive. Acacias are more associated with open environments, for example, whereas celtis trees are specific to forests. In some cases, eucalyptus plantations have proved to be "ecological disasters," according to Aleman.She does her work at UdeM's paleoecology laboratory, whose mission under director Olivier Barquez is to retrace the past of biomes. Aleman's main collaborator, Adeline Fayolle, a professor at the University of Liege, in Belgium, assembled the floristic data (lists of tree species) for the new study."To do this, we conducted a kind of old-fashioned data mining, in the sense that we analyzed a large amount of existing data, published and sometimes archived in forgotten documents, buried in dust, as well as data recently acquired in the field, to try to understand the history of the region," said Aleman.The study takes taken equal account floristic, environmental and paleoecological data to better understand the ecological functioning of forests and savannas, helped by analysing 753 sites in both environments. The environmental factors having the greatest impact on these environments are rainfall and its seasonality, as well as temperature, the researchers found.One of the most remarkable phenomena in the savannah is the frequency of disturbances that affect them. Brushwoods can flare up to three times a year in some places, for example. To protect public health, local governments sometimes want to limit these fires. These decisions are legitimate, but can have significant ecological consequences, the co-authors say.That's because, for the most part, large trees are unaffected by the flames, and the ashes regenerate the soil.The impact of human activity can be seen wherever the researchers carried out their research, but mainly in Tanzania, Congo and the Central African Republic. In some cases, some areas are almost devoid of wildlife.As early as 2017, when she published an article in the African edition of the online platform The Conversation, Aleman has been steadily trying to alert public opinion to the threats to African ecosystems. The Conversation.She believes that the situation is not desperate but that governments must be careful in how they intervene so as to not makes things worse. Aleman hopes that the new study will lead to a better understanding of the biological reality of the African continent."This is a rather theoretical contribution,: she said, "but I believe that we can use it to inform reforestation policies."
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Geography
| 2,020 |
October 27, 2020
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https://www.sciencedaily.com/releases/2020/10/201027161718.htm
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Australian scientists discover 500-meter-tall coral reef in the Great Barrier Reef
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Scientists have discovered a massive detached coral reef in the Great Barrier Reef -- the first to be discovered in over 120 years, Schmidt Ocean Institute announced. Measuring more than 500 meters high -- taller than the Empire State Building, the Sydney Tower and the Petronas Twin Towers -- the reef was discovered by Australian scientists aboard Schmidt Ocean Institute's research vessel Falkor, currently on a 12-month exploration of the ocean surrounding Australia.
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The reef was first found on Oct. 20, as a team of scientists led by Dr. Robin Beaman from James Cook University was conducting underwater mapping of the northern Great Barrier Reef seafloor. The team then conducted a dive on Oct. 25 using Schmidt Ocean Institute's underwater robot SuBastian to explore the new reef. The dive was live-streamed, with the high-resolution footage viewed for the first time and broadcast on Schmidt Ocean Institute's website and YouTube channel. [Editor's note: see link below.]The base of the blade-like reef is 1.5km-wide, then rises 500m to its shallowest depth of only 40m below the sea surface. This newly discovered detached reef adds to the seven other tall detached reefs in the area, mapped since the late 1800s, including the reef at Raine Island -- the world's most important green sea turtle nesting area."This unexpected discovery affirms that we continue to find unknown structures and new species in our Ocean," said Wendy Schmidt, co-founder of Schmidt Ocean Institute. "The state of our knowledge about what's in the Ocean has long been so limited. Thanks to new technologies that work as our eyes, ears and hands in the deep ocean, we have the capacity to explore like never before. New oceanscapes are opening to us, revealing the ecosystems and diverse life forms that share the planet with us.""We are surprised and elated by what we have found," said Dr. Beaman. "To not only 3D map the reef in detail, but also visually see this discovery with SuBastian is incredible. This has only been made possible by the commitment of Schmidt Ocean Institute to grant ship time to Australia's scientists."The discovery of this new coral reef adds to a year of underwater discoveries by Schmidt Ocean Institute. In April, scientists discovered the longest recorded sea creature -- a 45m siphonophore in Ningaloo Canyon, plus up to 30 new species. In August, scientists discovered five undescribed species of black coral and sponges and recorded Australia's first observation of rare scorpionfish in the Coral Sea and Great Barrier Reef Marine Parks. And the year started with the discovery in February of deep sea coral gardens and graveyards in Bremer Canyon Marine Park."To find a new half-a-kilometer tall reef in the offshore Cape York area of the well-recognized Great Barrier Reef shows how mysterious the world is just beyond our coastline," said Dr. Jyotika Virmani, executive director of Schmidt Ocean Institute. "This powerful combination of mapping data and underwater imagery will be used to understand this new reef and its role within the incredible Great Barrier Reef World Heritage Area."The Northern depths of the Great Barrier Reef voyage will continue until Nov. 17 as part of Schmidt Ocean Institute's broader year-long Australia campaign. The maps created will be available through AusSeabed, a national Australian seabed mapping program, and will also contribute to the Nippon Foundation GEBCO Seabed 2030 Project.
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Geography
| 2,020 |
October 27, 2020
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https://www.sciencedaily.com/releases/2020/10/201027161522.htm
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Post-wildfire hazards: Toward an understanding of when and how slope failure may occur
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Across the western U.S., severe wildfires fueled by tinder-dry vegetation have already burned more than 3.2 million hectares (8 million acres -- an area the size of Maryland -- as of th end of October, 2020, and nearly six times that area burned this year in Australia. And even though neither country's worst-ever fire year is not yet over, concerns are already mounting regarding the next hazard these regions will face: dangerous and destructive debris flows.
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Debris flows are fast-moving slurries of soil, rock, water, and vegetation that are especially perilous because they usually occur without any warning. Some debris flows are powerful enough to cart off everything in their paths, including trees, boulders , vehicles -- and even homes.Two years ago in Montecito, California, 23 people were killed and more than 400 homes damaged by a series of debris flows spawned by intense rain falling on hills scorched by what at the time had been the largest fire in California history.To better understand the origin of these hazards, researchers at the U.S. Geological Survey (USGS) studied slope failure at two sites in Southern California's San Gabriel Mountains. The first site burned in 2016 during the San Gabriel Complex fire, whereas a second, nearby site was charred during the 2014 Colby fire. The findings, presented Wednesday during the annual meeting of The Geological Society of America, indicate there were major differences in slope failure between the first and the third years following incineration. The results will help inform land managers and residents about when and where debris flows and other types of slope failure are more likely to occur."In the first year after each fire, we observed debris flows generated by rainfall runoff," says Francis Rengers, a USGS research geologist who led the study. "But as we continued monitoring, we were surprised to see that a storm with a higher rainfall intensity than the first year's storms, resulted in more than 280 shallow landslides, rather than debris flows, in the third year."In contrast to debris flows, which have fluid-like behavior, landslides glide as cohesive masses along a rupture plane. The researchers, including scientists from the University of Arizona, the Desert Research Institute, the USGS, and the German Research Centre (GFZ) believe this difference is due to changes in how much water can infiltrate into the ground during storms that follow wildfires. Because severe wildfires make soils more water-repellent, Rengers says, rainfall tends to run off burned ground. "If water is not soaking in," he explains, "it's flowing over the surface." By removing ground cover, wildfires also reduce a hillslope's roughness, which helps the slurry pick up speed. Incineration can also allow rainfall on bare soil to create what he calls a "surface seal" that further increases runoff.Because landslides have much shorter runouts than debris flows, they pose different hazards. "The landslides we observed would primarily impact local infrastructure in the forest, such as roads, transmission lines, and culverts," Rengers explains. By contrast, he says, debris flows move sediment much further downstream and therefore pose a hazard beyond the steep, mountainous hillslopes. "Runoff-generated debris flows threaten lives and property, including homes," he says.The results offer a ray of hope that the threat of slope failure has a limited duration: the researchers found that within five years, the density of landslides on burnt slopes in the San Gabriels was nearly equal to the density in unburned regions. This indicates the vegetation in this region recovers within half a decade.Based on these observations, the researchers have developed a new conceptual model of post-wildfire slope failure that has three distinct stages. During the 'no-recovery' phase, increased runoff makes debris flows more prevalent. Within a couple of years, increasing water percolation, combined with the decay of roots from vegetation destroyed in the fire, make the slopes more susceptible to landsliding during the 'initial recovery' stage. After about five years, new roots become established enough to stabilize the hillside in the final 'fully recovered' phase.In the future, the researchers plan to investigate whether this same model applies to other regions, such as the Rockies and the Pacific Northwest, which also experienced severe wildfires this year. For now, the results have immediate and practical applications for land managers who are dealing with the 2020 aftermath. "Our model suggests that debris flows will be the primary concern during the next one to two years, at least in the burn scars in Southern California, and after that the concern will shift toward shallow landslide hazards" says Rengers. "I hope our work offers land managers useful expectations regarding how these processes are likely to evolve and helps them prioritize post-wildfire mitigation and planning."
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Geography
| 2,020 |
October 27, 2020
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https://www.sciencedaily.com/releases/2020/10/201027105334.htm
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Large tides may have driven evolution of fish towards life on land
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Big tidal ranges some 400 million years ago may have initiated the evolution of bony fish and land vertebrates. This theory is now supported by researchers in the UK and at Uppsala University who, for the first time, have used established mathematical models to simulate tides on Earth during this period. The study has been published in
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"During long periods of the Earth's history, we've had small tidal ranges. But in the Late Silurian and Early Devonian, they seem to have been large in some parts of the world. These results appear highly robust, because even if we changed model variables such as ocean depth, we got the same patterns," says Per Ahlberg, professor of evolutionary organismal biology at Uppsala University.Between 420 and 380 million years ago (Ma) -- that is, during the end of one geological period, the Silurian, and beginning of the next, the Devonian -- Earth was a completely different world from now. Instead of today's well-known continents there were other land masses, clustered in the Southern Hemisphere. Stretching across the South Pole was the huge continent of Gondwana. North of it was another big one known as Laurussia, and squeezed between the two were a few small continents. Other salient differences compared with now were that Earth's day lasted only 21 hours, since our planet revolved faster on its own axis, and the Moon looked much larger because its orbit was closer to Earth.Life on land had gradually begun to get established. But the vertebrates, then consisting only of various kinds of fish, were still to be found only in the oceans. Then, during the Devonian, immense diversification of fish took place. One group to emerge was the bony fish, which make up more than 95 per cent of all fish today but were also the ancestors of terrestrial vertebrates. The earliest bony fish were the first animals to evolve lungs. What set off the evolution of bony fish, and how some of them started to adapt to a life on land, has not been clarified. One theory is that it happened in tidal environments where, in some periods, fish had been isolated in pools as a result of particularly large tides. This challenging habitat may have driven the evolution of lungs and, later on, the transformation of fins into front and hind legs.To test this tidal theory, researchers at Uppsala University, in collaboration with colleagues from the Universities of Oxford and (in Wales) Bangor, used an established mathematical model of the tidal system for the first time to simulate, in detail, the tides in the Late Silurian and Early Devonian. Data on the positions of the continents, the distance of the Moon, the duration of Earth's day, our planet's gravity and the physical properties of seawater were fed into the model. These simulations showed unequivocally that the period, just like that of the present day, was one when large tides occurred in some places. The small continent of South China on the Equator showed a difference of more than four metres in sea level between high and low tide. The existence of tides at the time has previously been verified through studies of geological strata, but determining the extent of the difference between low and high tide has not been feasible. To researchers this news has been interesting, since fossil finds indicate that it was specifically around South China that bony fish originated."Our results open the door to further and even more detailed tidal analyses of key episodes in Earth's past. The method can be used to explore the possible role of tides in other evolutionary processes of vertebrate development. And perhaps, conversely, whether tides, with their influence on ocean dynamics, played a part in the big marine extinctions that have taken place again and again in Earth's history," Ahlberg says.
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Geography
| 2,020 |
October 26, 2020
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https://www.sciencedaily.com/releases/2020/10/201026184007.htm
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Floating gardens: More than just a pretty place
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Floating gardens sound so idyllic. Now, a study proves that they are more than just a pretty place. The study, by researchers at Illinois State University, demonstrates that such constructed gardens can have a measurable, positive impact on water quality.
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Floating gardens are essentially rafts built on a frame of plastic caging, wrapped in coconut husks, and filled in with native plantings. As plants grow, they extend their roots into the water, growing hydroponically. On Chicago's North Branch of the Chicago River, non-profit Urban Rivers and partners are developing a mile-long, floating eco-park. Dubbed the Wild Mile, the re-development of this former industrial canal is Urban Rivers' flagship project. As part of the park, floating gardens, attached to shore, are being installed.The primary intent of the floating gardens is beautification. But the Illinois State team, from the University's Department of Geology, Geography, and the Environment, saw an ideal setup for a controlled experiment. "We got involved because it's the perfect opportunity to see if there's an impact on water quality," explains lead author Abigail Heath.Heath will present the results of the study in an online talk on Tuesday during the Geological Society of America's annual meeting.The study is novel: previous studies have explored floating gardens' impact on water quality over time, primarily in wastewater treatment ponds, but not over space, in moving water. The project also meshes well with Urban Rivers' broader goals. "The city is interested in water quality," says Phil Nicodemus, Urban Rivers Director of Research. "Happily, Illinois State got involved."Starting in spring 2018, Heath and co-authors have sampled water immediately upstream and downstream of a narrow 3 meter by 50 meter floating garden installed along the shoreline. Samples are collected weekly, at the surface and from 0.3 meters deep, the depth where roots reach from the garden's base into the water. Although the garden is set at the edge of Chicago's urban core, water quality is also impacted by upstream agriculture. Analyses are focused on nutrients including nitrate as nitrogen, chloride, sulfate, and phosphate.Could this small slice of human-made paradise improve water quality? An average of data collected over the course of the study show modest but definitive improvement. For example, nitrate as nitrogen dropped from 4.69 milligrams per liter in surface water just upstream of the garden to 4.43 milligrams per liter just downstream, a drop of about 1 percent. Phosphate was also lower downstream of the garden."Despite how small this garden was there was measurable improvement in water quality from upstream to downstream, especially for nitrates," notes Heath. She and colleagues see this as a scalable model for how larger floating gardens might help remediate water in similar settings. "Even this tiny garden makes a difference," she says.
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Geography
| 2,020 |
October 26, 2020
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https://www.sciencedaily.com/releases/2020/10/201026153939.htm
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Microplastics in groundwater (and our drinking water) present unknown risk
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Microplastics (plastics <5mm) and their negative health impacts have been studied in oceans, rivers, and even soils, and scientists are beginning to grapple with the myriad human health impacts their presence might have. One understudied, but critical, link in the cycle is groundwater, which is often a source of drinking water.
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While microplastics in groundwater likely affect human health, only a handful of studies have examined the abundance and movement of microplastics in groundwater. This gap means the potential for adverse health effects remains largely unknown.At the Geological Society of America's 2020 Annual Meeting today at 1:30, Teresa Baraza Piazuelo, a Ph.D. candidate at Saint Louis University, will help fill that knowledge gap by presenting new research on groundwater microplastics in a karst aquifer. "There hasn't been that much research looking at [micro]plastics and groundwater," Baraza says. "It's a very new topic. There's been a boom of research on microplastics in the ocean, even in soils... but to fully understand something, you have to explore it in all its aspects."Microplastics pose multiple physical and chemical risks to the ecosystems where they're present, and those risks are exacerbated by plastics' longevity in natural environments. "Since they're plastic, they're very durable," Baraza says, "which is why plastic is great. But it doesn't degrade easily." Microplastics' ability to linger in their environments for decades or longer likely has cumulative detrimental effects on both the organisms and quality of the ecosystem. Their chemical threat stems largely from their ability to transport harmful compounds on their surfaces; when organisms at the base of the food chain ingest microplastics, they ingest the toxins, too. As larger organisms consume the smaller ones, the toxins can build up (a process called bioaccumulation), eventually resulting in responses like organ dysfunction, genetic mutation, or death. "Cave ecosystems are known for being super fragile to begin with," she explains. "All the cave organisms -- salamanders, blind fish -- are sensitive, so any contaminants that are introduced could damage those ecosystems."Groundwater can stay in the same aquifer for tens to hundreds of years, or even longer. Combining that long residence time with plastics' resistance to degradation means that those chemical effects could effectively build up in the water and in any organisms within it, increasing the likelihood of toxic bioaccumulation. Together, these could result in long-term contamination of water sources with poorly-understood health effects and ecosystem damage.To understand where microplastics in groundwater come from and how they move through aquifers, Baraza and her Ph.D. advisor have been sampling groundwater from a Missouri cave weekly, all year long, and analyzing its chemistry and microplastics load. Because previous groundwater-microplastics studies have been limited to low-rainfall conditions, they're also studying how flooding events affect microplastics concentrations in groundwater.So far, they've found that while microplastics do increase in groundwater during a flood event, there's also a second peak in microplastics after the flooding has begun to wane. Their explanation is that there are two sources of microplastics for groundwater: those that are already in the subsurface, and those that are newly delivered from the surface. "Finding so much plastic later on in the flood, thinking that it could be coming from the surface... is important to understand the sourcing of microplastics in the groundwater," Baraza says. "Knowing where the plastic is coming from could help mitigate future contamination."Their current flood results are only based on one event, but Baraza will continue sampling through the rest of the year -- weather permitting. "Flood sampling is hard," she says, "especially in St. Louis, where the weather is so unpredictable. Sometimes we think it's going to rain and then it doesn't rain, and then sometimes it doesn't seem like it's going to rain, but it does... we caught a flood a week ago, and we are expecting to catch a couple more floods." The effort is worth it to determine if flooding events -- which are becoming more common under climate change -- are highly-effective deliverers of microplastics in groundwater reservoirs.
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Geography
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October 22, 2020
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https://www.sciencedaily.com/releases/2020/10/201022151741.htm
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Ancient Maya built sophisticated water filters
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Ancient Maya in the once-bustling city of Tikal built sophisticated water filters using natural materials they imported from miles away, according to the University of Cincinnati.
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UC researchers discovered evidence of a filter system at the Corriental reservoir, an important source of drinking water for the ancient Maya in what is now northern Guatemala.A multidisciplinary team of UC anthropologists, geographers and biologists identified crystalline quartz and zeolite imported miles from the city. The quartz found in the coarse sand along with zeolite, a crystalline compound consisting of silicon and aluminum, create a natural molecular sieve. Both minerals are used in modern water filtration.The filters would have removed harmful microbes, nitrogen-rich compounds, heavy metals such as mercury and other toxins from the water, said Kenneth Barnett Tankersley, associate professor of anthropology and lead author of the study."What's interesting is this system would still be effective today and the Maya discovered it more than 2,000 years ago," Tankersley said.UC's discovery was published in the journal The Maya created this water filtration system nearly 2,000 years before similar systems were used in Europe, making it one of the oldest water treatment systems of its kind in the world, Tankersley said.Researchers from UC's College of Arts and Sciences traced the zeolite and quartz to steep ridges around the Bajo de Azúcar about 18 miles northeast of Tikal. They used X-ray diffraction analysis to identify zeolite and crystalline quartz in the reservoir sediments.At Tikal, zeolite was found exclusively in the Corriental reservoir.For the ancient Maya, finding ways to collect and store clean water was of critical importance. Tikal and other Maya cities were built atop porous limestone that made ready access to drinking water difficult to obtain for much of the year during seasonal droughts.UC geography professor and co-author Nicholas Dunning, who has studied ancient civilizations most of his career, found a likely source of the quartz and zeolite about 10 years ago while conducting fieldwork in Guatemala."It was an exposed, weathered volcanic tuff of quartz grains and zeolite. It was bleeding water at a good rate," he said. "Workers refilled their water bottles with it. It was locally famous for how clean and sweet the water was."Dunning took samples of the material. UC researchers later determined the quartz and zeolite closely matched the minerals found at Tikal.UC assistant research professor Christopher Carr, an expert in geographic information system mapping, also conducted work on the UC projects at Bajo de Azúcar and Corriental."It was probably through very clever empirical observation that the ancient Maya saw this particular material was associated with clean water and made some effort to carry it back," Dunning said.UC anthropology professor emeritus Vernon Scarborough, another co-author, said most research on ancient water management has tried to explain how civilizations conserved, collected or diverted water."The quality of water put to potable ends has remained difficult to address," Scarborough said. "This study by our UC team has opened the research agenda by way of identifying the quality of a water source and how that might have been established and maintained."Of course, reconstructing the lives, habits and motivations of a civilization 1,000 years ago is tricky."We don't have absolute proof, but we have strong circumstantial evidence," Dunning said. "Our explanation makes logical sense.""This is what you have to do as an archaeologist," UC biologist and co-author David Lentz said. "You have to put together a puzzle with some of the pieces missing."Lentz said the filtration system would have protected the ancient Maya from harmful cyanobacteria and other toxins that might otherwise have made people who drank from the reservoir sick."The ancient Maya figured out that this material produced pools of clear water," he said.Complex water filtration systems have been observed in other ancient civilizations from Greece to Egypt to South Asia, but this is the first observed in the ancient New World, Tankersley said."The ancient Maya lived in a tropical environment and had to be innovators. This is a remarkable innovation," Tankersley said. "A lot of people look at Native Americans in the Western Hemisphere as not having the same engineering or technological muscle of places like Greece, Rome, India or China. But when it comes to water management, the Maya were millennia ahead."
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Geography
| 2,020 |
October 22, 2020
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https://www.sciencedaily.com/releases/2020/10/201022112604.htm
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Simple actions can help people survive landslides
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The March 2014 landslide in Oso, Washington, about 55 miles northeast of Seattle, became the deadliest landslide event in United States history. Forty-three people died and 49 homes and structures were destroyed.
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A University of Washington engineer who analyzed the event's aftermath began to investigate the circumstances that can make landslides so deadly. The resulting study shows that certain human actions increase the chance of surviving a devastating event, and suggests simple behavioral changes could save more lives than expensive engineering solutions.The open-access study, published in the October issue of "There are in fact some really simple, cost-effective measures that can be taken that can dramatically improve the likelihood that one will survive a landslide," said senior author Joseph Wartman, a UW professor of civil and environmental engineering.Worldwide, landslides cause on average more than 4,000 deaths a year recently, with about 25 to 50 of those deaths occurring each year in the U.S. These events may become more frequent as wildfires fueled by warmer temperatures can leave slopes bare and more vulnerable to slides.Wartman and a UW graduate student compiled and analyzed records of 38 landslides that affected occupied buildings. Most of the data came from the U.S., but it included landslides from around the world for which there were detailed records.The authors recorded the geologic details of each landslide, as well as the reports from survivors of the events. They used newspaper articles, scientific papers, medical examiner reports and other documents to produce a detailed catalog of fatalities caused by landslides hitting occupied buildings. The events, spanning from 1881 to 2019, included the Oso mudslide and the 2018 mudslide in Southern California, as well as events in Bangladesh, Philippines, China, Malaysia, Australia and New Zealand.Their analysis showed behavioral factors, such as a having an awareness of local landslide hazards and moving to a higher floor of a building during an event, had the strongest association with survival."Simply by being on an upper floor, an individual can increase their odds of survival by up to a factor of twelve. This is a powerful finding that we need to consider when we design the layout and vertical access routes in homes," said first author William Pollock, who did the work for his UW doctorate in civil and environmental engineering and is now a lecturer in the department.The analysis showed many things they predicted would be important, including the size or the intensity of landslide events, made little difference to the death toll for landslides below about 20 feet depth. Similarly, the distance between a building and the landslide slope, or an inhabitant's age and gender, didn't make a big difference to their survival.But the researchers found some behaviors, despite being performed by only a small number of people, often save lives. According to their results, those actions are:The results suggest practical ways to lower the number of lives lost to landslides in the United States, Wartman said. He hopes the information can be incorporated in education and community awareness programs."This is a message of hope," Wartman said. "What this work suggests is that a modest investment put toward social science, policy and education could have a very marked effect in protecting people from landslides."Residents who want to know if they are vulnerable to landslides can contact a local agency, such as the Washington State Department of Natural Resources, to learn more about local risks. Federal legislation is pending to make this information more easily accessible across the United States, Wartman said.The study was funded by the National Science Foundation.
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Geography
| 2,020 |
October 19, 2020
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https://www.sciencedaily.com/releases/2020/10/201019155759.htm
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Glimpse deep into Earth's crust finds heat source that may stabilize continents
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Rocks from the Rio Grande continental rift have provided a rare snapshot of active geology deep inside Earth's crust, revealing new evidence for how continents remain stable over billions of years, according to a team of scientists.
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"We tend to study rocks that are millions to billions of years old, but in this case we can show what's happening in the deep crust, nearly 19 miles below the surface of the Earth, in what geologically speaking is the modern day," said Jacob Cipar, a graduate student in geosciences at Penn State. "And we have linked what's preserved in these rocks with tectonic processes happening today that may represent an important step in the development of stable continents."The team, led by Penn State scientists, found evidence that heat from the mantle is melting the lower crust at the rift, where tectonic forces are pulling apart and thinning the lithosphere, or the crust and upper mantle that make up the rigid outer layer of Earth.Heating the continental crust is considered important to its development. But the process is often associated with crustal thickening, when continental plates collide and form mountains like the Himalayas, the scientists said."Our research suggests that these rocks that have been thought of as related to mountain building may have actually been cooked by a thinning lithosphere like what's happening in the modern-day Rio Grande rift," Cipar said. "And more broadly, thinning lithosphere may be more important than previously recognized for stabilizing continents and preventing them from sinking back into the mantle."The researchers recently reported their findings in the journal Earth's continents feature a unique silicon-rich, buoyant crust that allows land to rise above sea level and host terrestrial life, the scientists said. The crust also contains heat-producing elements like uranium that could destabilize it over geological time.Heating the crust creates molten rock that carries those elements toward the surface, resulting in a cooler and stronger lower crust that can protect continents from being absorbed into the mantle, the scientists said. But questions remain about the sources of that heat."We are suggesting that thinning of the lithosphere is really the removal of a barrier that keeps that heat away from the crust," said Andrew Smye, assistant professor of geosciences at Penn State and Cipar's adviser. "Removing or thinning that barrier at the Rio Grande rift appears to be what is generating the heat needed to initiate this process of stabilizing continental crust. And this has been overlooked in our understanding of how continents become so stable."The scientists tapped into rocks brought to the surface 20,000 years ago by volcanoes in New Mexico. The rocks are considered geologically young and are significant because they retain the context of the lower crust, the scientists said."In contrast, what we see in the rock record around the world is that oftentimes what it takes to get them up to the surface has disrupted their original relationship with the lower crust," said Joshua Garber, a postdoctoral researcher at Penn State. "This makes it really challenging to use older rocks to try to understand tectonics, and it makes the Rio Grande probably the best place to do this research."The scientists used analytical techniques to link the age of minerals in the rocks to the pressure and temperature they faced as they made their way through the crust.Similarities between the pressure and temperature path from the Rio Grande lower crust and rocks from other locations suggest that a thinning lithosphere is important for stabilizing Earth's continents, the scientists said."The snapshots of data we do have from other locations really nicely aligns with what we found in the Rio Grande rift," Garber said. "So that tells us this is not just happening now in the western United States. This shows the guts of continents have probably undergone this globally at least for the last billion years."
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Geography
| 2,020 |
October 19, 2020
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https://www.sciencedaily.com/releases/2020/10/201019125524.htm
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Oldest securely dated evidence for a river flowing through the Thar Desert, Western India
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Situated at the threshold of the South Asian monsoon, the Thar Desert is an important region for understanding how past environmental change impacted patterns of human migration and adaptation to new habitats. Recent research highlighting the role of the Thar Desert in human prehistory has indicated that humans spread eastwards into the region starting from 114 thousand years ago during a phase of enhanced monsoonal rainfall, when the desert was transformed into lush grasslands. However, more recent phases of sand dune activity have obscured these ancient landscapes inhabited by earlier human populations.
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In a new study published in Located at the threshold of monsoonal Asia, the Thar Desert marks the eastern extent of the desert belt that stretches westwards across Arabia and the Sahara. While this desert belt is typically thought of as inhospitable to early humans, it is becoming increasingly clear that during humid phases in the past human populations have prospered in these landscapes. This is perhaps best known in western South Asia from studying the Indus Civilisation (also known as the Harappan Civilisation) which flourished at the margins of the Thar Desert along the course of the now-seasonal Ghaggar-Hakra River between 3200-1500 BCE, and is thought to have inspired the mythological Saraswati River mentioned in the Rig Veda.Yet the potential importance of 'lost' rivers for earlier inhabitants of the Thar Desert have been overlooked. "The Thar Desert has a rich prehistory, and we've been uncovering a wide range of evidence showing how Stone Age populations not only survived but thrived in these semi-arid landscapes," says Jimbob Blinkhorn of MPISHH. "We know how important rivers can be to living in this region, but we have little detail on what river systems were like during key periods of prehistory."Studies of satellite imagery have shown a dense network of river channels crossing the Thar Desert. "These studies can indicate where rivers and streams have flown in the past, but they can't tell us when" explains Prof Hema Achyuthan of Anna University, Chennai. "To demonstrate how old such channels are, we had to find evidence on the ground for river activity in the middle of the desert."A deep deposit of river sands and gravels was studied by the team, which had been exposed by quarrying activity near the village of Nal, just outside of Bikaner. By studying the different deposits, the researchers were able to document different phases of river activity. "We immediately saw evidence for a substantial and very active river system from the bottom of the fluvial deposits, which gradually decreased in power through time" explained Achyuthan. "Standing in the middle of the desert, the question we had to answer was 'How old was this river?'."The researchers used a method called luminescence dating to understand when quartz grains in the river sands were buried. The results indicated that the strongest river activity at Nal occurred at approx. 172 and 140 thousand years ago, at a time when the monsoon was much weaker than today in the region. River activity continued at the site between 95 to 78 thousand years ago, after which only limited evidence for the presence of a river at the site, with evidence for a brief reactivation of the channel 26 thousand years ago.The age of this river flowing in the middle of the desert is of particular interest. The river was flowing at its strongest during a phase of weak monsoonal activity in the region, and may have been a life-line to human populations enabling them to inhabit the Thar Desert. The timeframe over which this river was active also overlaps with significant changes in human behaviour in the region, which have been linked with the earliest expansions of Homo sapiens from Africa into India. "This river flowed at a critical timeframe for understanding human evolution in the Thar Desert, across South Asia and beyond" says Blinkhorn, adding "This suggests landscape in which the earliest members of our own species, Homo sapiens, first encountered the monsoons and crossed the Thar Desert may have been very different to the landscape we can see today."The next phase of research is to demonstrate where the river flowed from. Studies of satellite images have suggested a potential connection with a Himalayan source, such as the Sutlej. "We can't demonstrate where the river flowed from at present" says Blinkhorn, adding "but the Indira Ghandi Canal, sourced from the Sutlej River, gives us some insight into what happens when a river flows through the centre of the Thar Desert -- plants and wildlife flourish, providing ideal conditions for early human populations."
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Geography
| 2,020 |
October 19, 2020
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https://www.sciencedaily.com/releases/2020/10/201019082834.htm
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Early-arriving endangered Chinook salmon take the brunt of sea lion predation
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The Columbia River is home to one of the West Coast's most important Chinook salmon runs. Through late spring and early summer, mature fish return from the sea and begin their arduous journey upriver to spawn. In recent years, these fish have faced an additional challenge: hungry California sea lions.
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A new University of Washington and NOAA Fisheries study found that sea lions have the largest negative effect on early-arriving endangered Chinook salmon in the lower Columbia River. The results of this study will publish Oct. 18 in the Opportunistic sea lions have learned that by swimming as far as 145 miles upriver, they can easily feast on migrating salmon, including those hindered by the Bonneville Dam."We investigated whether mortality rates varied depending on the specific threatened Chinook salmon population, determined by when they arrive in the river," said lead author Mark Sorel, a doctoral student at the UW School of Aquatic and Fishery Sciences. "We found that, based on their individual return timing and the abundance of sea lions in the river when they return, individual populations experience different levels of sea lion-associated mortality."Researchers learned that the earliest arriving populations of Chinook salmon experienced an additional 20% mortality over previous years, and the later arriving populations experienced an additional 10%. This increase in mortality was associated with increased sea lion abundance at those times of year in the period of 2013 to 2015 compared to the period of 2010 to 2012.The numbers of California sea lions are highest at the mouth of the Columbia in early spring, before they depart for their breeding grounds in southern California. The researchers also discovered that the earliest arriving salmon migrate through the lower Columbia River more slowly than those arriving later in the season, thereby increasing their exposure to predation."This information on how different populations are affected by sea-lion associated mortality is key because recovery of endangered Chinook salmon requires multiple of the individual populations to be healthy," said Sorel.California sea lions have seen their numbers rebound along much of the U.S. West Coast since the passage of the Marine Mammal Protection Act of 1972, which protects them from being killed, captured and harassed. The increased presence of sea lions is now at odds with the endangered salmon populations on which they feed, putting managers in a difficult position.Researchers are concerned that something must be done quickly as these hunting behaviors are learned, and the problem could continue to grow exponentially. In August, the National Marine Fisheries Service granted approval for Washington, Idaho, Oregon and several Pacific Northwest tribes to capture and euthanize both problematic California and Steller sea lions within a larger area of the lower Columbia and Willamette Rivers. Previously, only California sea lions could be killed in these rivers if managers deemed them a threat to salmon.This complicated decision was enacted after non-lethal methods, such relocation and hazing, to limit the impact sea lions have on salmon -- plus some targeted lethal removal -- were met with limited success."This is often a challenging management problem as both sea lions and salmon are of strong interest to the public, and both are protected under federal statutes," said Sorel. "Management must consider multiple social values and operate within existing legal frameworks."Continued monitoring will help to reduce the remaining uncertainty about the effects of sea lions on salmon and the expected outcomes of alternative management actions.
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Geography
| 2,020 |
October 16, 2020
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https://www.sciencedaily.com/releases/2020/10/201016100916.htm
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Protecting ecologically important krill in the Southern Ocean from overfishing
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Krill is rapidly gaining popularity. The small shrimp-like organism from the Antarctic is used as fish food in aquaculture and increasingly in dietary supplements and healing ointments. Although the krill catch is regulated, caution is required to avoid endangering the population itself and the species that depend on it, warns a group of krill experts headed by Prof. Dr. Bettina Meyer from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in the journal
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Antarctic Krill, Euphausia superba, is a five-centimetre-long, reddish, shrimp-like animal which at first glance, may not appear as an impressive inhabitant of the Southern Ocean. But krill make up for their small individual sizes with the sheer number of their entire population. There is an estimated 300-500 billion Mt of krill in the Southern Ocean comprised of some hundreds of trillions of individuals. This massive biomass makes krill a key component of the local ecosystem. It is the main food source for many predators from fish, penguins and seabirds to seals and whales.Humans have also developed an interest in krill over the past decades. Norway, along with Korea, China, Chile, the Ukraine and Japan trawl for krill in the Southern Ocean. But the fishing industry has become more efficient at catching krill using not only traditional fishing nets, but new continuous pumping systems. The demand for krill will likely increase, driven by at least two industries. First the increasing production of carnivorous fish through aquaculture, such as salmon, and the subsequent increase in demand for fish meals and marine byproducts. Second, the increasing demand for high value pharma- and nutraceutical products from krill oil and krill meals, such as wound ointment and krill oil capsules for human use and pet food.The krill fishery is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which was founded in 1982. This body uses surveys and model calculations to determine how much krill may be caught and where it may be caught. The Atlantic sector of the Southern Ocean has the highest concentration of both krill stocks and fishing fleets. This region alone has a maximum allowable catch of 620,000 tons per year distributed over different fishing areas.This is only a fraction of krill that are estimated to live in the ocean around Antarctica. CCAMLR had long assumed that the established catch limits would not cause serious damage, but krill experts like Bettina Meyer now see things differently. "The problem is that the catch regulations have, so far, been aimed primarily at protecting the krill eaters," explains the researcher. "Too little attention, has been paid to possible risks for the krill stocks themselves.This is due to the fact that relatively little is still known about some aspects of the biology of these small crustaceans." Financed by the Federal Ministry of Food and Agriculture (BMEL), Bettina Meyer, her colleague Dr. Ryan Driscoll and her research group are trying to shed more light on this issue. In a new publication, krill experts from around the globe summarize why there are several reasons to worry about the future of this key species.In brief, krill abundances in some regions fluctuate greatly from year to year. However, the causes of these fluctuations are not yet clear and the current management of krill does not adjust the catch accordingly. Furthermore, it is likely that only a small part of the population, limited to a relatively small area, provide the offspring for the entire Atlantic part of the Southern Ocean. Finally, little is known about where the new generation migrate to in their first year. This means that it is possible that the most important parts of the population, the future parents and their offspring, will be overfished.In 2019 CCAMLR decided to develop a new krill management system to address these issues. The committee is advised by the "Krill Action Group" under the umbrella of the Scientific Committee of Antarctic Research (SCAR), which was founded in 2018. It currently consists of 46 international members, half of which are established and half early career scientist. "Our goal is to provide CCAMLR with the latest knowledge on the size, distribution and dynamics of krill stocks." explains Bettina Meyer, who heads this expert group.The future of krill management will require answering lingering question in key areas of krill biology. For example, understanding how krill populations in different regions are connected and how adults and juveniles differ in their location and movement. Also unknown are the environmental conditions responsible for determining good or bad krill years. The Atlantic sector of the Southern Ocean is warming rapidly and so understanding how krill will adapt to climate change is crucial. As for the latter, "CCAMLR's previous models do not take this plasticity into account," explains Bettina Meyer, "But we need to know more about this if we are to be able to predict future changes in the ecosystem."Bettina Meyer and her colleagues have some concrete ideas about how the missing data can be collected. Since space and availability for scientific expeditions aboard research ships are limited, scientists could rely on the support of the fishing fleets. Together, these fishing vessels have the potential to collect a substantial amount of krill data which can help close critical knowledge gaps.In addition, new technology may help scientists advance their understanding of krill stocks and their distribution. For example, autonomous underwater gliders, which look like mini gliders with a wingspan of about 1.50 metres, can be equipped with cameras, sensors, and echosounders to search for krill. They can roam the ocean from the surface down to 1000 metres for several months, collecting data on the density and distribution of krill.Another promising technology are advanced moorings, equipped with arrays of sensors to measure water properties and krill density. These stationary devices can provide important information almost year-round in areas critical to the management of the krill fishery. Even krill predators, the whales, seals or penguins, can be recruited to help using attached camera systems and probes equipped with GPS."All of this can provide us with valuable new information for better krill management," says Bettina Meyer who is convinced by this approach. But in order to cover large areas of the Southern Ocean it is important to coordinate these research efforts internationally: "As a lone warrior, nobody can answer the complex questions of krill research."
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Geography
| 2,020 |
October 14, 2020
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https://www.sciencedaily.com/releases/2020/10/201014171332.htm
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Mapping out rest stops for migrating birds
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Each spring, billions of land birds -- thrushes, warblers, orioles, tanagers, and more -- migrate through the night, navigating the coast of the Gulf of Mexico. Even greater numbers migrate in the fall. During the day, these birds stop to rest, recover and refuel for the next leg of their journey. These two phases of migration -- passage (flight) and stopover (rest) -- are well understood in ornithology but had previously only been studied independently.
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Recently published research in the journal "The stopover-to-passage ratio is an indicator of the number of migrants that stop to rest during migration and those that continue heading north or south, depending on the season. The ratio varies from site to site," said co-author Kyle Horton, assistant professor at Colorado State University and an alumnus of UD's College of Agriculture and Natural Resources. "It's highly useful, from a conservation standpoint, to know if the majority of birds fly over a site or predominantly stop at a site to refuel or rest. The answer to this question can have important implications for what action is ultimately done on-the-ground to help migratory birds.""Characterization of stopover habitat use relative to passage represents a fundamental gap in our knowledge," said Emily Cohen, lead author and assistant professor at the University of Maryland Center for Environmental Science, Appalachian Laboratory. "This gap primarily exists because a methodology to collect broad-scale information about distributions of birds in terrestrial habitats during the day and in the airspace at night has only recently become possible with weather surveillance radar."Archived since the mid-1990s but only freely available since 2004, weather radar data collected by NOAA, the National Oceanic and Atmospheric Administration, now enables researchers to map the nocturnal habits of migratory bird populations. It is a herculean effort to process and synthesize these vast data sets; scientists must distinguish bird movement from precipitation data on the radar based on density, speed and knowledge of the natural history of bird behavior. Calculating both the traffic patterns of the birds in flight and their activity in stopover sites, the research team created migration maps and calculated the stopover-to-passage ratio along the entire U.S. Gulf Coast."Our findings were not what we expected," said Jeff Buler, University of Delaware associate professor of wildlife ecology and senior author on the paper. "We understand the phenology of migration quite well, so we know the absolute number of birds moving through an area at the peak of migration. The density of birds on the ground also peaks around the same time. When looking at stopover-to-passage ratio, we thought that we would see more birds stopping during the peak of migration but we actually found the opposite."Even though fewer birds migrate outside of the peak window, a larger percentage of that bird population stops at particular resting and foraging sites, indicating that those lands are of critical importance at that time."We saw a high stopover-to-passage ratio in the panhandle of Florida, which was unexpected because in the spring there aren't as many birds moving through that area," said Buler. "What that tells us is that the birds that are moving through that area need to stop, and it actually is indirect evidence that these are likely migrants that are coming from South America. They're flying over the Caribbean and the Atlantic Ocean, so they're making a farther journey than those that are just crossing the Gulf of Mexico. That first place to land in Florida is really important to them and most of them have to stop because they've run out of gas. From a conservation perspective, this really opens up a question of whether we need to rethink how we prioritize conserving stopover areas."Currently, breeding ground habitat receives far more conservation attention and protection than migratory stopover habitat. However, with migratory bird populations facing rapid declines due to many interacting factors including light pollution, climate change, and habitat loss and degradation, researchers hope that the stopover-to-passage ratio can offer additional insight and renewed interest in often overlooked stopover sites."These results show the critical importance of the habitats around the U.S. coast of the Gulf of Mexico and Florida for sustaining North America's migratory birds. We show for the first time that over half of the birds migrating through these coastlines stop there," said Cohen. "Further, disparities in disproportionate selection and absolute abundance at stopover sites revealed potential migratory bottlenecks where geography or restricted habitat may disproportionately concentrate birds along migration routes, highlighting that density of use alone is not a comprehensive measure of the conservation value of a stopover site for migrating birds, a topic that has not been addressed during migration. The areas where the stopover-to-passage ratio is high are potentially more important for migrating birds than was previously thought.""Linking aerial and terrestrial habitats with this new metric provides a unique opportunity to understand how migrating birds, in this case very large numbers of them, use a region where we know drastic and rapid changes are occurring," said co-author Andrew Farnsworth of the Cornell Lab of Ornithology. "Whether for prioritization of critical areas or for developing dynamic conservation planning, this kind of quantitative science is invaluable for supporting decision-making that can safeguard this incredible region and the spectacular movements of birds that occur here annually."
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Geography
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013150812.htm
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Mathematical tools predict if wave-energy devices stay afloat in the ocean
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Ocean waves represent an abundant source of renewable energy. But to best use this natural resource, wave-energy converters need to be capable of physically handling ocean waves of different strengths without capsizing.
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Texas A&M University researchers have developed analytical tools that can help characterize the movements of floating but anchored wave-energy devices. Unlike complicated simulations that are expensive and time-consuming, they said their technique is fast, yet accurate enough to estimate if wave-energy devices will turn over in an ever-changing ocean environment."Wave-energy converters need to take advantage of large wave motions to make electricity. But when a big storm comes, you don't want big wave, wind and current motions to destroy these devices," said Dr. Jeffrey Falzarano, professor in the Department of Ocean Engineering. "We have developed much simpler analytical tools to judge the performance of these devices in a dynamic ocean environment without necessitating massive amounts of simulations or physical model tests that take a lot of time to run and are cost-prohibitive."The mathematical tools are described online in the journal Wave-energy devices function in two modes. In "normal mode," they convert the energy from tidal waves into electricity. Thus, this mode largely determines whether the design of the wave-energy device is economically efficient. However, in "survival" mode, or when incident waves cause large motions in the wave-energy devices, the performance of the wave-energy devices is largely determined by a system of moorings that anchor the devices to a location at the bottom of the body of water.Moorings can be of several types, including wharfs and anchor buoys, and can be arranged in different configurations. In addition, there are considerable variations in the shape of wave-energy devices, making the prediction of whether the device will capsize nontrivial."Ships come in a variety of shapes and sizes; tankers, for example, are very different from fishing vessels or other military ships. These different geometries affect the ship's motion in the water," said Falzarano. "Similarly, the shape of wave-energy devices can be quite diverse."For the analysis, Hao Wang, Falzarano' s graduate student, used a cylindrical wave-energy device. This generic shape allowed the researchers to simplify the problem of prediction and extended their analysis to other wave-energy converters of similar shape. He also considered three mooring configurations.Hao used two analytical methods, the Markov and Melnikov approaches, to predict the risks of turning over under random excitation. More specifically, using information from the wave-energy device's geometry, the configuration of the mooring system and tidal wave properties, the methods yield a graph containing an envelope-like region. Intuitively, if the waves are really big, like during a storm, and the floating vessel escapes this envelope, it will likely turnover.The researchers noted that although the analytical models were completely different, they yielded almost the same results, validating their merit and accuracy. They also said that their mathematical approach can be applied to assess the performance of other floating devices, such as floating wind turbines."The platform for a floating wind turbine is the same as the one for wave-energy devices, and so floating turbines can also pitchpole or turnover if the waves are very high," said Falzarano. "My group has been leaders in developing methods for predicting ship stability. We're now looking at applying those approaches to renewable, floating energy devices."Video:
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Geography
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013105744.htm
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Study first to tally biomass from oceanic plastic debris using visualization method
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Trillions of plastic debris fragments are afloat at sea, creating the "perfect storm" for microbial colonization. Introduced more than 50 years ago, plastic substrates are a novel microbial habitat in the world's oceans. This "plastisphere" consists of a complex community comprised of bacterial, archaeal, and eukaryotic microorganisms and microscopic animals.
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These unnatural additions to sea surface waters and the large quantity of cells and biomass carried by plastic debris has the potential to impact biodiversity, ecological functions and biogeochemical cycles within the ocean. Biofilm formation in the marine environment -- a collective of one or more types of microorganisms that can grow on many different surfaces -- is a complex process, involving many variables.While several studies have surveyed microbial diversity and quantified specific members of these biofilm habitats, a new study is the first to holistically quantify total cell inventories under in situ conditions. This study is fundamentally different from others due to the relatively non-biased visualization methods used to arrive at a quantitative number for biomass, which is the first estimate of its kind.Researchers from Florida Atlantic University's Harbor Branch Oceanographic Institute and Harriet L. Wilkes Honors College, in collaboration with Utrecht University, Netherlands, the University of Amsterdam, and The Royal Netherlands Institute for Sea Research (NIOZ), examined cell abundances, size, cellular carbon mass, and how photosynthetic cells differ on polymeric and glass substrates over time. They investigated nanoparticle generation from plastic such as polystyrene, which is known to disintegrate into nanoparticles in sunlight and ultraviolet radiation, and how this might disrupt microalgae.Results of the study, published in the "In the open ocean, nutrients are limiting. Just like we need to put fertilizer on a garden, microorganisms in the ocean are limited by nitrogen, iron or phosphorus depending upon where they are -- except in the open ocean, there is typically no fertilizer, so something has to die for another organism to live," said Tracy Mincer, Ph.D., lead author and an assistant professor of biology/bio-geochemistry at FAU's Harbor Branch and Wilkes Honors College. "With the advantage of a surface, which concentrates nutrients, organisms colonizing plastics in the ocean are taking up those limiting nutrients that normally would have been consumed or out-competed by free-living microbes. So essentially, these microbes on plastics are taking habitat space away and represent the beginning of a regime shift for these habitats."Using confocal laser scanning microscopy with sophisticated imaging software, researchers directly obtained data ranging from cell counts, size and the characterization of microbial morphotypes to complete three-dimensional constructs. They tested a range of chemically distinct substrates that included polypropylene, polystyrene, polyethylene and glass. Polypropylene is used by the automotive industry, for consumer goods such as packaging, industrial applications and the furniture market; polystyrene is used to make clear products like food packing or laboratory equipment; and polyethylene is the most widely used plastic in the world ranging from products such as clear food wrap to shopping bags to detergent bottles.Data from the confocal laser scanning microscopy showed that early biofilms displayed a high proportion of diatoms (unicellular eukaryotic microalgae that have cell walls made of glass). These diatoms could play a key role in the sinking of plastic debris. Unexpectedly, plastic substrates appeared to reduce the growth of photosynthetic cells after eight weeks compared to glass."The quantification of cell numbers and microbial biomass on plastic marine debris is crucial for understanding the implications of plastic marine debris on oceanic ecosystems," said Shiye Zhao, Ph.D., first author and a post-doctoral fellow at FAU's Harbor Branch. "Future efforts should focus on how this biomass fluctuates with season and latitude and its potential to perturb the flux of nutrients in the upper layers of the ocean."
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Geography
| 2,020 |
October 13, 2020
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https://www.sciencedaily.com/releases/2020/10/201013191019.htm
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Sea star's ability to clone itself may empower this mystery globetrotter
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For decades, biologists have captured tiny sea star larvae in their nets that did not match the adults of any known species. A Smithsonian team recently discovered what these larvae grow up to be and how a special superpower may help them move around the world. Their results are published online in the
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"Thirty years ago, people noticed that these asteroid starfish larvae could clone themselves, and they wondered what the adult form was," said staff scientist Rachel Collin at the Smithsonian Tropical Research Institute (STRI). "They assumed that because the larvae were in the Caribbean the adults must also be from the Caribbean."Scientists monitor larvae because the larvae can be more sensitive to physical conditions than the adults and larval dispersal has a large influence on the distribution of adult fishes and invertebrates. Collin's team uses a technique called DNA barcoding to identify plankton. They determine the DNA sequence of an organism, then look for matches with a sequence from a known animal in a database."This mystery species was one of the most common in our samples from the Caribbean coast of Panama," Collin said. "We knew from people's studies that the DNA matched sequences from similar larvae across the Caribbean and it matched unidentified juvenile starfish caught in the Gulf of Mexico -- but no one had found a match to any known adult organism in the Caribbean. So we decided to see if the DNA matched anything in the global 'Barcode of Life' data base.""That's when we got a match with But why are the larvae common in the Caribbean if adult Valvaster starfish have never been found here? Are the adult starfish hidden inside Caribbean reefs, or are the larvae arriving from the other side of the world?"It's possible that the ability of the larvae to clone themselves is not just a clever way to stay forever young," Collin said. "There's a natural barrier that keeps organisms from the western Pacific and the Indian ocean from crossing the Atlantic to the Caribbean. After they make it around the tip of Africa, they are met by a cold current that presumably kills tropical species.""Just how cloning could help them get through the barrier is still not known, but it's intriguing that another sea star species from the Indo West Pacific that was collected for the first time in the Caribbean in the 1980s also has cloning larvae," Collin said.
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Geography
| 2,020 |
October 9, 2020
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https://www.sciencedaily.com/releases/2020/10/201009084934.htm
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Most nations failing to protect nature in COVID-19 pandemic recovery plans
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The COVID-19 pandemic provides an opportunity to reset the global economy and reverse decades of ecosystem and species losses, but most countries are failing to invest in nature-related economic reforms or investments, according to a Rutgers-led paper.
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Indeed, some countries, including the United States, Brazil and Australia, are back-tracking on existing laws and relaxing regulations and enforcement actions aimed at protecting nature, according to lead author Pamela McElwee, an associate professor in the Department of Human Ecology in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick."Just last week at the United Nations, more than 60 heads of state spoke at a virtual summit and pledged their support to tackle the biodiversity crisis. But when we look at what countries are doing, either in their prior budget and policies or especially in their post-COVID planning and recovery packages, very few governments are putting their money where their mouths are," McElwee said. "We still see huge amounts of financial support for harmful practices, such as subsidizing overfishing or fossil fuel production or building infrastructure that will harm ecological integrity. Only a small number of countries are addressing the biodiversity crisis in the serious manner it deserves."The paper, by economists, anthropologists and environmental scientists at many institutions on three continents, is published in the journal Unless action is taken, around 1 million species face extinction, many within decades, and the global rate of species extinction will accelerate, according to the 2019 Global Assessment Report on Biodiversity and Ecosystem Services from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). That report noted the extinction rate is "already at least tens to hundreds of times higher than it has averaged over the past 10 million years." The authors of this new paper were all contributors to the 2019 IPBES report.The new paper spells out the actions governments should be taking in their stimulus and recovery plans that would prioritize nature, provide immediate employment benefits and lead to longer-term transformations in the global economy. Examples include shifting from harmful fossil fuel subsidies to beneficial ones, including those that encourage environmentally friendly farming; carbon taxes that could support forest protection programs; and work programs that focus on ecological restoration and green infrastructure.While many scientists and politicians have promoted a COVID-19 recovery that is low carbon, how to include biodiversity and ecosystems in economic plans has received much less attention. Discussions of nature-related actions have largely focused on closing wildlife markets as a potential source of novel viruses, expanding protected natural areas or reducing tropical deforestation. While these can be important, they do not necessarily address the root causes of ecological disruptions, the authors say.A number of countries, including the United States and China, have allocated essentially zero stimulus funding to biodiversity or ecosystems. Only the European Union and member countries are making substantial financial investments in biodiversity for post-COVID planning. Other nations, including New Zealand, India and Pakistan, are proposing investments in nature-based jobs like ecological restoration, but at only modest levels."Governments are falling short of their stated promises and they need to do more -- immediately," McElwee said. "We will continue to monitor proposed recovery packages, stimulus measures and financial pledges for how they address the biodiversity crises going forward, particularly in light of the mega-summit on biodiversity to be held in China next May."
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Geography
| 2,020 |
October 8, 2020
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https://www.sciencedaily.com/releases/2020/10/201008142106.htm
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New species of aquatic mice discovered, cousins of one of the world's rarest mammals
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Ninety-three years ago, a scientist trapped a mouse in a stream in Ethiopia. Of all the mice, rats, and gerbils in Africa, it stood out as the one most adapted for living in water, with water-resistant fur and long, broad feet. That specimen, housed at Chicago's Field Museum, is the only one of its genus ever collected, and scientists think it may now be extinct. But in a new study in the
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"These two groups of mice have been confused with one another for a century," says Julian Kerbis Peterhans, one of the paper's authors and a researcher at the Field Museum who's studied these rodents for over 30 years. "They've been so elusive for so long, they're some of the rarest animals in the world, so it's exciting to finally figure out their family tree.""It's underappreciated how little is known about the biodiversity of small mammals, especially in tropical parts of the world. We're not discovering a whole lot of new lions, tigers, and bears, but there's an incredible potential for discovery of new species of small mammals because they're tough to find," says Tom Giarla, the paper's lead author and an assistant professor of biology at Siena College in New York. "And they're sort of underappreciated animals -- they're really cool when you start to learn about their ecology. These are semi-aquatic mice, so they're not just your average, everyday rodents."There are two main kinds of mice that the researchers focused on: But since they spend their time by water, they're hard to catch. They prefer shallow streams so that they can use their whiskers to help them hunt, but they've also been found in swampy areas and even rivers that are 3-4 feet deep in places (they hang out by the shallow edges). "To cross one of the rivers where I caught a For this study, the researchers conducted the first evaluation of Giarla was also able to extract DNA from a piece of dried tissue on the skull of the 93-year-old specimen of Learning about the different species of mice in streams halfway around the world has broad implications for conservation science. "The new species we named are part of a global effort to understand the biodiversity of African rainforests and highlight the critical areas to be preserved," says Demos. "There are vast areas of the Congo Basin that have barely been explored in the last seventy years, places that are hard to access due to political instability. We're not even completely sure how these animals are distributed, there are big gaps."The findings could even help inform public health efforts down the line. "COVID is a zoonotic disease, and biodiversity research is essential to understanding zoonotic disease," says Giarla. "We need to understand what species are present in natural areas, especially natural areas being changed by humans." (It's worth noting, the mice in this paper aren't known to carry diseases that affect humans -- studying them and other animals can help scientists get a better baseline of which species live where, and that can help pinpoint zoonotic diseases in the future.)The researchers also note that their research was made possible by a large international network of scientists. "If you look at the author list, but we have people from all over the world," says Giarla. "We have colleagues in Africa and Europe and the United States. Museums in the Czech Republic, Germany, the US, South Africa, Eswatini. We had people all over the world helping us with this effort: field workers, geneticists, morphologists. Science is a really global effort."
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Geography
| 2,020 |
October 6, 2020
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https://www.sciencedaily.com/releases/2020/10/201006165733.htm
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California's August Complex largest fire in state's history
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NOAA/NASA's Suomi NPP satellite captured another startling image of the August Complex of fires that has grown to over 1,000,000 acres burned (1,006,140 acres total) and because of that grim milestone the complex has been dubbed a "gigafire." The August Complex is only 58% contained. Inciweb reports that: "In the northeast zone, active behavior continues. Structures in Hidden Valley, Trinity Pines/Post Mountain, Wildwood and Platina are threatened by fire spread. Short range spotting and fire spread toward Hidden Valley has increased potential for impact to structures."
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Another view that can be captured by Suomi NPP satellite is a false-color image. The false-color image is collected by the VIIRS (Visible Infrared Imaging Radiometer Suite) instrument suite using corrected reflectance bands. Burned areas or fire-affected areas are characterized by deposits of charcoal and ash, removal of vegetation and/or the alteration of vegetation structure. When bare soil becomes exposed, the brightness in Band 1 may increase, but that may be offset by the presence of black carbon residue; the near infrared (Band 2) will become darker, and Band 7 becomes more reflective. When assigned to red/brown in the image, Band 7 will show burn scars as deep or bright reddish brown depending on the type of vegetation burned, the amount of residue, or the completeness of the burn. It is hard to see clearly due to the massive amounts of smoke covering the landscape.Inciweb reports the following weather concerns for this fires: "Hot and dry conditions persist. Smoke remains very thick in the lower valleys with visibility reduced under a mile. Temperatures will be 88-93 in the valleys and 75 to 80 in the higher elevations. The humidity will be 10-15% with 4-8 mph wind."NASA's satellite instruments are often the first to detect wildfires burning in remote regions, and the locations of new fires are sent directly to land managers worldwide within hours of the satellite overpass. Together, NASA instruments detect actively burning fires, track the transport of smoke from fires, provide information for fire management, and map the extent of changes to ecosystems, based on the extent and severity of burn scars. NASA has a fleet of Earth-observing instruments, many of which contribute to our understanding of fire in the Earth system. Satellites in orbit around the poles provide observations of the entire planet several times per day, whereas satellites in a geostationary orbit provide coarse-resolution imagery of fires, smoke and clouds every five to 15 minutes. For more information visit: NASA's Earth Observing System Data and Information System (EOSDIS) Worldview application provides the capability to interactively browse over 700 global, full-resolution satellite imagery layers and then download the underlying data. Many of the available imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks "right now." Actively burning fires, detected by thermal bands, are shown as red points. Image Courtesy: NASA Worldview, Earth Observing System Data and Information System (EOSDIS). Caption: Lynn Jenner with information from Inciweb.
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Geography
| 2,020 |
October 5, 2020
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https://www.sciencedaily.com/releases/2020/10/201005170834.htm
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Seeking ancient rainforests through modern mammal diets
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Closed-canopy rainforests are a vital part of the Earth's modern ecosystems, but tropical plants don't preserve well in the fossil record so it is difficult to tell how long these habitats have existed and where rainforests might have once grown. Instead, scientists look to the diets of extinct animals, which lock evidence of the vegetation they ate into their teeth. A new study led by scientists at the American Museum of Natural History finds that the paradigm used to identify closed-canopy rainforests through dietary signatures needs to be reassessed. The findings are published this week in the journal
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"The Amazon is the world's most diverse rainforest, home to one in 10 known species on Earth," said Julia Tejada-Lara, who led the study as a graduate student at the Museum and Columbia University. "Closed-canopy rainforests have been proposed to occur in this area since at least the Eocene, some 50 million years ago, but we know very little about their extent and evolution through time."To reconstruct ancient ecosystems, including rainforests, researchers often use stable carbon isotope (?13C) analyses on extinct and living herbivores. Stable carbon isotopes, which form in specific proportions inside plants, are preserved in the body tissues of the animals that eat those plants. Samples from the animal's bones, teeth, toenails, or other biological material can help scientists determine the kinds of plants that were consumed.In the new study, Tejada and her colleagues analyzed specimens from the American Museum of Natural History and the Museum of Natural History in Lima representing 45 modern herbivores and 12 species of "secondary consumers" (meat-, insect-, and fish-eaters) that live in western Amazonia. The authors then compared their results with a landmark analysis of modern mammals in equatorial Africa, a generally accepted proxy used to identify past closed-canopy rainforests on all continents. The researchers also determined nitrogen isotope values from 35 Amazonian mammal species, finding greater than expected complexity in how nitrogen from macromolecules (carbohydrates, proteins, and fats [lipids]) is incorporated into body tissues in animals from different levels of the food chain."Up to this point, there had only been one other broad isotopic sampling -- and inferences of food sources -- of a tropical closed-canopy rainforest mammal community, and that was in central Africa," said co-author John Flynn, Frick Curator of Fossil Mammals in the Museum's Division of Paleontology. "So we knew that if we wanted to learn more about both modern and ancient Amazon ecosystems, we had to test whether we should expect the tropical forest conditions to be roughly the same in these two continents that separated more than 90 million years ago and have a 1,600-mile-wide ocean between them today."The comparison reveals that Amazonian and African closed-canopy rainforests have a very similar mean dietary carbon isotopic value, and it may be representative of mammalian herbivores in any closed-canopy rainforest. Beyond this newly discovered way of recognizing ancient rainforests, Amazonian mammals in this study lacked highly negative dietary values found in a few of the African animals. These negative values are often used outright to infer closed-canopy rainforests in fossil records."We have found that these negative isotopic values can no longer be used as an indispensable indicator of a rainforest," Tejada said. "And further, that many of the longtime assumptions about ecological niches, feeding habits, and isotopic signatures characterizing tropical communities likely need to be reassessed."
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Geography
| 2,020 |
October 5, 2020
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https://www.sciencedaily.com/releases/2020/10/201005170826.htm
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Disproportionate extinction of South American mammals when Americas collided evident today
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When the Isthmus of Panama rose from the sea to connect North and South America millions of years ago, mammals could cross the bridge in both directions. But the result of this massive migration -- a large proportion of mammals with North American origins in South America, but not the other way around -- has long puzzled paleontologists. To explore the origins of this drastic asymmetry, researchers from the Smithsonian Tropical Research Institute (STRI), the Gothenburg Global Biodiversity Centre and collaborating institutions analyzed fossil data from the two continents.
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Their results, recently published in the journal "This faunal exchange can be seen as a natural experiment: two continents, each with its own kind of animals were connected by a narrow land bridge, allowing massive migrations in both directions," said Juan Carrillo, STRI fellow and lead author on the study at the National Museum of Natural History in Paris. "Our study shows how these migrations happened and that South American mammals had more extinctions. The effect of this exchange can be still seen today."Almost half of the living South American mammals today descend from North American immigrants. However, only 10% of the North American mammals are derived from South American ancestors, such as opossums, porcupines and armadillos. Some possible explanations for the increased extinctions of South American mammals during the interchange include habitat changes and increased predation and competition.The differences among predators on each continent could have played a role. South America had predators closely related to marsupials, a group that includes opossums, with large canines that resembled saber-toothed cats. When the North American predators or Carnivora, such as foxes, cats and bears, arrived with more specialized carnivorous teeth and larger brains, native South American mammals became more susceptible to predation. This could have contributed to higher extinction rates. By then, the South American predatory marsupials had also disappeared."We suspect that the emigration of so-called Carnivora to South America might have been one of the causes of the high extinction in South American mammals," said Søren Faurby, senior lecturer of Gothenburg University in Sweden and co-author of the study. "Carnivora appear to be more efficient predators than marsupials, potentially due to more specialized carnivorous teeth or larger brains, and many of the native South American mammals might not have been able to survive the invasion of more efficient predators."This new study is a clear reminder that when there are major disturbances in the biodiversity status quo there can be unexpected outcomes, visible both in the fossil record and in the distribution of species millions of years later. Ultimately, these findings could provide insights into the long-term consequences of the movement of species seen today.Video:
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Geography
| 2,020 |
September 28, 2020
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https://www.sciencedaily.com/releases/2020/09/200928152915.htm
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'Portfolio' of marine reserves enhances fish populations
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Scientists say a 'portfolio' of protected areas within marine parks such as the Great Barrier Reef can help secure sustainable fish populations.
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Dr Hugo Harrison from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE at JCU) led a study on the effects of marine reserves, or no-take zones, on fish populations."The Great Barrier Reef Marine Park has established networks of no-take zones," Dr Harrison said. "A 'portfolio' of these protected areas can help connect reefs and ultimately provide more reliable quantities of fish across an ecosystem."Dr Harrison says no-take zones -- areas closed to fishing -- on their own act as valuable sources of fish for neighbouring reefs. These areas support more fish, which then produce even greater numbers of baby fish. But, just how many babies survive and where they end up varies greatly from year to year. These fluctuations can be volatile and uncertain."Our findings are comparable to investing your resources wisely," said Professor Michael Bode, a co-author on the study from the Queensland University of Technology. "If you put all your money into one type of stock and then the value of that entire industry crashes, then all of your investment will crash too.""By investing in a variety of stocks you can buffer or dampen market volatility and still maintain a valuable portfolio. Our study proves that marine protected areas are like financial stocks: if you invest in multiple smaller reserves instead of putting all your effort into one large reserve, you ensure a stable supply of fish to both recreational and commercial fishers."The authors tracked more than 1,500 baby fish using DNA 'fingerprinting' techniques. The baby fish were traced back to their parents inside a network of four reserves.The researchers found that each reserve was an important but variable source of baby fish. However, together, the network of reserves generated a reliable source of offspring to replenish exploited fish stocks in surrounding reefs.The study coincides with two significant international reports illustrating the stark decline of the natural world: the Living Planet Report 2020 and the Global Biodiversity Outlook 5."Governments all around the world failed to meet any of the UN Sustainable Development Goals on Biodiversity Conservation," Dr Harrison said. "To stem the loss of natural habitats, they had committed in 2010 to expand the world's nature reserves across ten percent of coastal and marine areas by 2020.""Though protected ocean areas have tripled in these past ten years, the targets remain well below the recommendation of at least 30 percent protection recommended by the International Union for Conservation of Nature (IUCN)."The IUCN also recently released guidelines on protecting connectivity and 'corridors' within ecosystems, which are essential for healthy natural habitats -- for conservation and for climate change adaptation.Prof Bode says maintaining corridors between protected areas is easy to picture in a terrestrial realm -- for example, in a forest setting where animals can move freely between areas."But it's a lot harder in the marine realm, where connectivity pathways between habitats are difficult to predict," Prof Bode said. "We can't maintain 'corridors' in coral reef seascapes, so we need other mechanisms to ensure connectivity through these 'portfolios', as we do on the Great Barrier Reef."Dr Harrison said there is an urgent need for further discussions on the value of marine reserve networks -- both locally and internationally."Our research is a timely reminder of the value of marine networks in protecting not only biodiversity but industries including tourism and the millions of people globally whose livelihoods depend on healthy ecosystems."
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Geography
| 2,020 |
September 25, 2020
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https://www.sciencedaily.com/releases/2020/09/200925113346.htm
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Switching up: Marine bacteria shift between lifestyles to get the best resources
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To stay, or not to stay? When it comes to nutrient resource patches, researchers from Japan and Switzerland have discovered that marine bacteria have a knack for exploiting them efficiently, timing movements between patches to get the best resources.
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In a study published this month in Heterotrophic bacteria (i.e., those that cannot produce their own food, instead obtaining nutrition from other sources of organic carbon, such as plant or animal matter) are the main recyclers of dissolved organic matter (DOM) in the ocean. Hotspots of DOM that are made up of particles, such as marine snow, are important to the global carbon cycle."Some groups of heterotrophic bacteria take advantage of these hotspots," says one of the lead authors of the study Assistant Professor Yutaka Yawata. "We used bacteria from one of these groups to look at whether optimal foraging theory is applicable to microbes, because their influence on the global carbon cycle ultimately depends on bacteria's ability to find and obtain nutrients from particles. Borrowing from the field of behavioral ecology, we referred to this process as foraging."The researchers examined microbial foraging by studying the behavior of marine bacteria in seascapes of organic particles. They conducted experiments using single-cell tracking, where bacteria were video-recorded and the number of bacteria and the amount of time they spent on a surface was extracted and modelled."We found that foraging marine bacteria optimize nutrient uptake by rapidly switching between attached and planktonic lifestyles, and fine-tune the time spent on particles according to patch quality," explains Assistant Professor Yawata. "Bacteria stay longer on particles of higher quality, as predicted by patch use theory."Patch use theory, which is part of optimal foraging theory, predicts that organisms foraging in a mixed-resource environment balance the time spent on a patch that yields diminishing returns with the costs of leaving that patch to find a fresh one. Until this study, the applicability of optimal foraging theory to microorganisms has been largely unknown.Optimal foraging theory -- and specifically patch use theory -- provides a valuable framework for understanding microorganisms and their effects on ecosystems, such as quantifying and predicting the role of marine bacteria in the uptake and cycling of ocean nutrients.
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Geography
| 2,020 |
September 23, 2020
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https://www.sciencedaily.com/releases/2020/09/200923090431.htm
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Scientists predict potential spread, habitat of invasive Asian giant hornet
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Researchers at Washington State University have predicted how and where the Asian giant hornet, an invasive newcomer to the Pacific Northwest, popularly dubbed the "murder hornet," could spread and find ideal habitat, both in the United States and globally.
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Sharing their discoveries in a newly published article in the The Asian giant hornet could also find suitable habitat throughout the eastern seaboard and populous parts of Africa, Australia, Europe, and South America, if humans inadvertently transport it.The team's predictions underline the importance of Washington state's efforts to stop the large insects before they spread."We found many suitable climates in the U.S. and around the globe," said lead author Gengping Zhu, a postdoctoral scholar at WSU's Department of Entomology.Collaborating with Washington State Department of Agriculture scientist Chris Looney and WSU entomologists David Crowder and Javier Illan, Zhu examined more than 200 records from the hornet's native range in Japan, South Korea, and Taiwan, then used a set of ecological models incorporating climate data to predict likely global habitat across six continents."These predictions are scientific sleuthing," Illan said. "We're making an educated guess on how fast and far these insects can move, their rate of success in establishing a nest, and offering different scenarios, from least bad to worst. No one has done this before for this species."Native to forested parts of Asia, the Asian giant hornet, Vespa mandarinia, is a significant threat to Western honey bees, which have no natural defense. In late summer and fall, hornet colonies attack beehives, destroying entire bee colonies to feed their brood and produce new queens.Up to two inches long, the insect also deploys a potent sting, which is more dangerous than that of local bees and wasps.Asian giant hornets are most likely to thrive in places with warm summers, mild winters, and high rainfall. Extreme heat is lethal, so their most suitable habitats are in regions with a maximum temperature of 102 degrees Fahrenheit.Based on those factors, suitable habitat for the giant hornet exists along much of the U.S. west and east coasts, adjacent parts of Canada, much of Europe, northwestern and southeastern South America, central Africa, eastern Australia, and most parts of New Zealand.Much of the interior of the U.S. is inhospitable to the hornet due to extremes of heat, cold, and low rainfall. This includes the eastern parts of Washington state and British Columbia, as well as California's Central Valley, all of which have major fruit and nut crops that rely on honey bee pollination.Using data from a similar species, Vespa velutina, scientists predicted that without containment, Asian giant hornets could spread into southern Washington and Oregon, and north through British Columbia. Calculating that hornets could fly up to 68 miles per year, their worst-case scenario found that the insects could disperse throughout the western regions of Washington and Oregon in 20 years or less.However, scientists cautioned that these predictions are an educated guess."The information that we want -- how fast and far queens can fly, and when they fly -- is all unknown," Illan said. "A lot of basic biology is unknown. So, we're using a surrogate.""We know queens come out of their nest in the fall, mate, and fly -- somewhere," Looney said. But nobody knows how far they fly, or if they fly repeatedly. We don't know if they set up nests in the spring near where they hibernated, or if they start flying again. These are some of the things that make predicting natural dispersal a challenge."Nature alone cannot predict where the hornet may end up. Human activity plays a role in transporting invasive species around the globe. While colonies can only be started by mated queens, and a USDA analysis found that accidental transport by humans is unlikely, Looney said that human-assisted spread could be a concern."It's easy for some species to get moved accidentally from one side of the country to the other, even if there's a large swathe of unacceptable habitat in between," he said."Preventing the establishment and spread of Asian giant hornet in western North America is critical for protecting bees and beekeepers," Crowder said. "Our study can inform strategies to monitor and eradicate these invaders before they become established."
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Geography
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September 22, 2020
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https://www.sciencedaily.com/releases/2020/09/200922092154.htm
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Warming ocean, old-forest loss put a squeeze on an elusive seabird
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Squeezed by changing ocean conditions that limit their food options and the long-term loss of old forest needed for nesting, marbled murrelets would benefit most from conservation efforts that take both ocean and forest into account, new research by Oregon State University shows.
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Published in "It turns out that the same ocean conditions that influence salmon returns, including the forage fish murrelets need to successfully nest, had a huge influence on the likelihood that murrelets will come inland to breed," said lead author Matt Betts, a researcher in the Oregon State College of Forestry and the director of the OSU-based Forest Biodiversity Research Network. "Given that these prey items tend to be in lower abundance when ocean temperatures are high, changing climate conditions could reduce prey availability as well as the tendency for murrelets to nest in the future."Marbled murrelets are closely related to puffins and murres, but unlike those birds, murrelets raise their young as much as 60 miles inland in mature forests. Disturbance in either the ocean or forest environment has the potential to impact murrelet populations."There aren't many species like it," said study co-author and project director Jim Rivers, also a faculty member in the College of Forestry. "There's no other bird that feeds in the ocean and commutes such long distances inland to nest sites. That's really unusual."The dove-sized bird spends most of its time in coastal waters eating krill, other invertebrates and forage fish such as herring, anchovies, smelt and capelin. Murrelets can only produce one offspring per year, if the nest is successful, and their young require forage fish for proper growth and development.Murrelets generally nest in solitude, although multiple nests sometimes occur within a small area. They typically lay their single egg high in a tree on a horizontal limb at least 4 inches in diameter, with Steller's jays, crows and ravens the main predators of murrelet nests."The end goal for these birds is to be very secretive and quiet so predators don't find their nests and they can produce young,' said Rivers.Along the West Coast, marbled murrelets are found regularly from Santa Cruz, California, north to the Aleutian Islands. Their populations have been declining by about 4% a year in Washington, Oregon and California, and the species is listed as threatened under the U.S. Endangered Species Act in those states."Early on in our work, we noticed strong fluctuations in the numbers of marbled murrelets coming inland to nest, so this study was about trying to get to the bottom of those highs and lows," Betts said. "We found the first evidence that ocean conditions combined with old-forest nesting habitat influence the murrelets' long-term occupancy dynamics. In particular, we learned ocean conditions are a key driver of those dynamics."The finding has potential key implications for forest policy in Oregon, where any state-owned site that goes two consecutive years without murrelet detection is classified as unoccupied and thus available for timber harvest."Our data show that below-average ocean conditions might last for more than two successive years," Rivers said. "That means there could be a scenario where sites on state lands that are suitable for breeding go unused for more than two years which, under current guidelines, would let them be considered available for harvest. Thus, murrelets might be missing from inland sites not because the forest is unsuitable for nesting, but because they have inadequate forage fish during the summer breeding season. That means it is critical that we consider factors that influence both marine food resources and terrestrial nesting habitat when considering how to recover murrelet populations."Betts was part of a research collaboration that published a 2019 paper in the Proceedings of the National Academy of Sciences that showed that old forest is still declining across the Pacific Northwest 25 years into the Northwest Forest Plan, a 100-year federal road map to protect older forests."This is now less due to the saw and more due to fire," he said. "That means that even with strong land conservation measures, climate could not only result in warmer ocean conditions but also greater fire frequency and extent, and therefore more old forest loss."Other Oregon State researchers contributing to the study were Kim Nelson and Dan Roby of the College of Agricultural Sciences and Jennifer Fisher of the Cooperative Institute for Marine Resources Studies. Scientists from Trent University in Ontario, Canada, the University of Rhode Island and the U.S. Forest Service also took part.The OSU College of Forestry and the USDA National Institute of Food and Agriculture provided funding.
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Geography
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September 18, 2020
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https://www.sciencedaily.com/releases/2020/09/200918112140.htm
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Mapping the 1.6 billion people who live near forests
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Global maps of places where people and forests coexist show that an estimated 1.6 billion people live within 5 kilometers of a forest. The assessment, based on data from 2000 and 2012 and published September 18 in the journal
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"There were no data at all on how many people live in and around forests globally," says first author Peter Newton, an Assistant Professor in Environmental Studies at the University of Colorado Boulder. "The exercise was an initial step of trying to quantify the potential target population for projects that look at people's livelihoods in a forest environment."People who rely on forest resources for subsistence or income are commonly known as forest-dependent people. Although the number of forest-proximate people coincidently matches the 1.6 billion forest-dependent people from a widely cited estimation from the World Bank, living near the forest doesn't necessarily mean one relies on the forest for livelihood. Newton says that while "forest-dependent people" widely refers to people who derive some benefits from forests, the term "forest-proximate people" merely captures the spatial relationship between people and forests."Large numbers of people do live in and around forests, so that makes forests an important habitat and biome for thinking about sustainable development as well as about conservation," says Newton. "The programs, projects, and policies that affect forests also affect large numbers of people."To map out the spatial relationship between people and forests globally, Newton and his colleagues combined forest cover and human population density data for the year 2000 and 2012. They counted the number of people who lived within 5 km (3.1 miles) from the border of forests, which they defined as any area with more than 50 percent tree cover over 2 hectares (5 acres). But they excluded urban areas with a population above 1,500 people per square kilometer (0.4 square miles).The work provides a sketch to which other researchers and decision-makers could add on different layers of data, such as social, economic, or cultural details to paint a more complete picture. However, many of these datasets aren't available at a global level."What other researchers or we could do in the future is home in on a particular region where we did have data," says Newton. From local data, scientists could infer how many of those forest-proximate people were also forest dependent or living in poverty to help decision-makers implement spatial targeting and impact assessment.
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Geography
| 2,020 |
September 18, 2020
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https://www.sciencedaily.com/releases/2020/09/200918083715.htm
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Ancient human footprints in Saudi Arabia give glimpse of Arabian ecology 120000 years ago
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Situated between Africa and Eurasia, the Arabian Peninsula is an important yet understudied region for understanding human evolution across the continents. Recent research highlighting the role of the Arabian Peninsula in human prehistory shows that humans repeatedly dispersed into the peninsula's interior at times when its harsh deserts were transformed into lush grasslands. However, the nature and timing of these dispersals have remained elusive, due to a scarcity of datable material and poor-resolution paleoecological data associated with evidence for humans.
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In a new study published in Because the Arabian Peninsula is characterized by large, hyper-arid deserts inhospitable to early humans and the animals they relied on, Arabia has received considerably less attention than Africa or Eurasia, neighboring regions that are vital to understanding human prehistory. However, research over the last decade has shown that this was not always the case, and it is now well-understood that conditions in Arabia have fluctuated significantly over the past million years."At certain times in the past, the deserts that dominate the interior of the peninsula transformed into expansive grasslands with permanent freshwater lakes and rivers," explains Richard Clark-Wilson of Royal Holloway, one of the lead authors of the study. "It was during these periods of climatic upturn that human and animal populations dispersed into the interior, as shown by the archaeological and fossil record."The footprints described in the new study were discovered during a recent survey of the Nefud Desert in Saudi Arabia. At an ancient lake deposit dubbed 'Alathar' (meaning "the trace" in Arabic) by the team, hundreds of human and animal footprints were discovered embedded in the surface, having been exposed following the erosion of overlying sediments."We immediately realized the potential of these findings," says Mathew Stewart of MPI-CE, one of the study's lead authors. "Footprints are a unique form of fossil evidence in that they provide snapshots in time, typically representing a few hours or days, a resolution we tend not get from other records."Researchers were able to identify a number of animals from the footprints, including elephants, horses, and camels. The presence of elephants was particularly notable, as these large animals appear to have gone locally extinct in the Levant by around 400 thousand-years-ago."The presence of large animals such as elephants and hippos, together with open grasslands and large water resources, may have made northern Arabia a particularly attractive place to humans moving between Africa and Eurasia," says Michael Petraglia of MPI-SHH, who has been conducting research in the region for over a decade.The dense concentration of footprints and evidence from the lake sediments suggests that animals may have been congregating around the lake in response to dry conditions and diminishing water supplies. Humans, too, may have been utilizing the lake for water and the surrounding area for foraging."We know people visited the lake, but the lack of stone tools or evidence of the use of animal carcasses suggests that their visit to the lake was only brief," says Stewart. Human movements and landscape use patterns, therefore, may have been closely linked to the large animals they shared the area with.The age of the footprints is of particular interest. They date to a period known as the last interglacial, a time of relatively humid conditions across the region and an important moment in human prehistory. Environmental changes during the last interglacial would have allowed humans and animals to disperse across otherwise desert regions, which normally acted as major barriers to dispersal during the less humid periods. Fossil and archaeological records indicate that these conditions also facilitated human dispersal from Africa into the Levant."It is only after the last interglacial with the return of cooler conditions that we have definitive evidence for Neanderthals moving into the region," says Stewart. "The footprints, therefore, most likely represent humans, or Homo sapiens."These findings suggest that human movements beyond Africa during the last interglacial extended into northern Arabia, highlighting the importance of Arabia for the study of human prehistory.Researchers involved in this study work in close partnership with the Saudi Ministry of Culture. Additional partners include the Saudi Geological Survey, King Saud University, and other key institutions in the United Kingdom and Australia.
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Geography
| 2,020 |
September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917180405.htm
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Invasive shrimp-sucking parasite continues northward Pacific expansion
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Researchers have identified an invasive blood-sucking parasite on mud shrimp in the waters of British Columbia's Calvert Island. The discovery represents the northern-most record of the parasite on the West Coast and is likely an indication of its ability to spread without human transport.
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Orthione griffenis, a cough drop-sized crustacean native to Asia and Russia, has decimated mud shrimp populations in California and Washington over the past 30 years, causing the collapse of delicate mudflat ecosystems anchored by the shrimp. By the 2000s, it had reached as far as Vancouver Island. The discovery of O. griffenis at Calvert Island, described in a new study, represents a northward leap of more than 180 miles.Scientists found the parasite during a 2017 bioblitz, organized by the Hakai Institute and the Smithsonian Institution's Marine Global Earth Observatory, in which they intensely surveyed and documented marine life."I was on the lookout for things that seemed out of place," said study lead author Matt Whalen, a Hakai postdoctoral researcher at the University of British Columbia who studies coastal biodiversity. "But this particular parasite wasn't initially on my radar."Most scientists believed the parasites' expansion was exclusively mediated by human transport -- O. griffenisis thought to have first arrived in North America by traveling in ships' ballast water. Their appearance at Calvert Island, 150 miles from the nearest city of more than 5,000 people, shows "clearly, they can do it on their own," said study co-author Gustav Paulay, curator of invertebrate zoology at the Florida Museum of Natural History."This is such an astonishingly spectacular part of the planet," he said. "During the bioblitz, one of the things we talked about was that there were no invasive species at all. And then we found this thing."Whalen described the find as "a bit depressing.""We tended to associate this parasite with places that have a lot of marine traffic and aquaculture, like California and Oregon," he said in a statement. "Finding them on Calvert Island really suggests that there's very little preventing the spread because of the parasite's life cycle."The parasite is a bizarre crustacean called a bopyrid isopod. In the pre-adult part of its life, it hitches a ride on planktonic copepods -- an intermediate host that allows the isopods to travel to new and far-flung mudflats in search of shrimp blood. As adults, the parasites attach to the gills of another crustacean host, in this case a mud shrimp, Upogebia pugettensis, and proceed to sap the life from it. Infected mud shrimp are so hard done by that they lack the required energy to reproduce."They're essentially castrated," Paulay said.Mud shrimp may not be much to look at -- much like crayfish with stumpier claws -- but these homely crustaceans play an outsized role as environmental engineers in the mudflats of the Pacific Coast. They cycle nutrients when they filter food, pumping oxygenated water into an expansive network of tunnel dwellings, which provide housing for a suite of creatures, including gobies, worms, clams and other shrimp species. The shrimp's presence affects how the entire mudflat ecosystem functions -- or doesn't.When a parasite coevolves in the same place as its host, they often reach a sort of détente, Paulay said. After all, the parasite needs a host to survive, and killing it off at once would not make a great long-term strategy. But when a parasite is introduced from elsewhere, that armistice may never arrive."The infection rates on Calvert Island were higher than I would've anticipated," Whalen said. "About one in four hosts were parasitized. That's a pretty good chunk of the population."For now, scientists are tracking the northward spread of the parasite. The parasite's prevalence on Calvert Island shows that it may only be a matter of time before it reaches the North Coast of British Columbia and moves onward to Alaska, the upper edge of the mud shrimp's range.For Paulay, the discovery of O. griffenis also underscores how marine bioblitzes can function as early warning systems for invasions."Every bioblitz we do, we find invasive species," he said. "If you catch them early enough, you have a chance to do something about it."
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Geography
| 2,020 |
September 17, 2020
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https://www.sciencedaily.com/releases/2020/09/200917122832.htm
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Understanding the movement patterns of free-swimming marine snails
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A new study published in the journal
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Led by Ferhat Karakas, a graduate student in mechanical engineering at the University of South Florida (USF), the study was co-authored by Jordan Wingate, a National Science Foundation (NSF) Research Experiences for Undergraduates (REU) intern at the Bermuda Institute of Ocean Sciences (BIOS); Leocadio Blanco-Bercial and Amy Maas, both associate scientists at BIOS; and David Murphy an assistant professor at USF.The study looked at the movements, or swimming kinematics, of nine species of warm water pelagic snails found in the waters off Bermuda: seven thecosome pteropods (which may have coiled, elongated, or globular shells), one gymnosome pteropod (which loses its juvenile shell during development), and one heteropod (which has a spiral shell). Pteropods, perhaps the most well-known among the pelagic snails, are often referred to as "sea butterflies," as their snail foot has evolved into a pair of wing-like appendages that appear to "flap" as they move through the water.Historically, study of these delicate organisms has been difficult, as they cannot be grown and maintained in a laboratory environment. However, the proximity of BIOS to the open ocean allowed living organisms to be collected and transported back to shore in under than one hour.Data collection began immediately upon return and most experiments were completed within one day of collection.Using a low magnification, high speed 3-D photography system, the research team was able to study the swimming behaviors of the snails, developing detailed models showing their swimming paths (trajectories) through the water column, swimming speeds, "flapping" rates of their appendages, and even the speeds at which they sank and how their shells were oriented as they did so."While different large-scale swimming patterns were observed, all species exhibited small-scale sawtooth-shaped swimming trajectories caused by reciprocal appendage flapping," Blanco Bercial said.The researchers then analyzed zooplankton samples collected from the surface to 3000 feet (1000 meters) with a MOCNESS net system (an array of long, tapered nets and sensors towed behind a research vessel) to determine the abundance and distribution of these organisms off Bermuda. When combined with molecular data and imaging using ZooScan, a device used to make digital images of zooplankton, the team was also able to relate swimming behaviors to night time and day time vertical distributions. Larger species sank down and swam up much faster and could be active at much greater depths, whereas the slower and smaller species were limited to shallower depths. This indicates that size does play a role in the vertical structure of habitat, as well as in predator-prey interactions."This project combined the expertise of engineers, molecular biologists, and ecologists, as well as a variety of different technologies, to look at the movement, ecology, and distribution of this beautiful group of organisms," Maas said. "This type of transdisciplinary collaboration doesn't happen very often and it allowed us to learn about an aspect of ocean science that has previously been understudied."Adding to the uniqueness of this investigation is the role of the study's second author, Jordan Wingate, who was an NSF REU intern at BIOS in 2018 while attending Georgia Military College. During the course of her three-month internship, Wingate worked with Maas on a project that became the basis for this paper, eventually presenting the results of their research at the 2020 Ocean Sciences Meeting in San Diego, California."I feel so accomplished to be a published author in a peer-reviewed scientific journal as an undergraduate student," said Wingate, who will graduate from the University of West Florida in the fall of 2021 with a bachelor's degree in marine biology. "I was very fortunate to be able to see this project through from start to finish and I'm grateful to Amy for her mentorship and guidance as I worked through the challenges of learning about pteropods, new computer programming languages, and the data analysis skills required to get this study published."
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Geography
| 2,020 |
September 11, 2020
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https://www.sciencedaily.com/releases/2020/09/200911093014.htm
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Worldwide loss of phosphorus due to soil erosion quantified for the first time
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Phosphorus is essential for agriculture, yet this important plant nutrient is increasingly being lost from soils around the world. The primary cause is soil erosion, reports an international research team led by the University of Basel. The study in the journal
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The world's food production depends directly on phosphorus. However, this plant nutrient is not unlimited, but comes from finite geological reserves. How soon these reserves might be exhausted is the subject of scholarly debate. Just as controversial is the question which states own the remaining reserves and the political dependencies this creates.An international research team led by Professor Christine Alewell has investigated which continents and regions worldwide are suffering the greatest loss of phosphorus. The researchers combined high-resolution spatially discrete global data on the phosphorus content of soils with local erosion rates. Based on this, they calculated how much phosphorus is lost through erosion in different countries.An important conclusion of the study is that more than 50% of global phosphorus loss in agriculture is attributable to soil erosion. "That erosion plays a role was already known. The extent of that role has never before been quantified with this level of spatial resolution," Alewell explains. Previously, experts reported losses primarily due to lack of recycling, food and feed waste, and general mismanagement of phosphorus resources.Erosion flushes mineral bound phosphorus out of agricultural soils into wetlands and water bodies, where the excess of nutrients (called eutrophication) harms the aquatic plant and animal communities. The researchers were able to validate their calculations using globally published measurement data on phosphorus content in rivers: the elevated phosphorus content in waters mirrors the calculated loss of phosphorus in the soil in the respective region.Mineral fertilizers can replace the lost phosphorus in the fields, but not all countries are equally able to use them. Although countries such as Switzerland can develop solutions thanks to organic fertilizers and potentially relatively closed phosphorus cycles (see box) in agriculture, Africa, Eastern Europe and South America register the greatest phosphorus losses -- with limited options for solving the problem. "It's paradoxical, especially as Africa possesses the largest geological phosphorus deposits," says Alewell. "But the mined phosphorus is exported and costs many times more for most farmers in African countries than, for example, European farmers." In Eastern Europe economic constraints are also the most crucial factor of phosphorus deficiency.South America could potentially mitigate the problem with efficient use of organic fertilizer and/or better recycling of plant residues. On the other hand, farmers in Africa do not have this option: Africa has too little green fodder and too little animal husbandry to replace mineral fertilizers with manure and slurry, says Alewell.It is still unclear when exactly phosphorus for global agriculture will run out. New large deposits were discovered a few years ago in Western Sahara and Morocco, although how accessible they are is questionable. In addition, China, Russia, and the US are increasingly expanding their influence in these regions, which suggest that they might also control this important resource for global future food production. Europe has practically no phosphorus deposits of its own."95% of our food is directly or indirectly produced as a result of plants growing in the soil. The creeping loss of the plant nutrient phosphorus should be of concern to all people and societies," says Alewell. If countries want to secure their independence from those states that possess the remaining large deposits, they must seek to minimize phosphorus losses in soils.A drastic reduction in soil erosion is a major and important step in the right direction. Land managers can reduce erosion by ensuring ground cover for as long as possible; for example, through mulching, green manure and intercropping, and through topography-adapted cultivation -- tilling fields transversely to the slope or terracing.
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Geography
| 2,020 |
September 9, 2020
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https://www.sciencedaily.com/releases/2020/09/200909092824.htm
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New corals discovered in deep-sea study of Great Barrier Reef Marine Park
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For the first time, scientists have viewed the deepest regions of the Great Barrier Reef Marine Park, discovered five undescribed species consisting of black corals and sponges, and recorded Australia's first observation of an extremely rare fish. They also took critical habitat samples that will lead to a greater understanding of the spatial relationships between seabed features and the animals found in the Coral Sea.
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The complex and scientifically challenging research was completed aboard Schmidt Ocean Institute's research vessel Falkor, on its fourth expedition of the year, as part of the Institute's Australia campaign. Using a remotely operated underwater robot to view high-resolution video of the bottom of the ocean floor, some 1,820 meters deep, the science team examined deep sea bathymetry, wildlife, and ecosystems. The collaborative mission brought together scientists from Geoscience Australia, James Cook University, University of Sydney, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Queensland Museum Network, and Queensland University of Technology, to answer a range of questions about the geological evolution and biology of the deep sea canyons and reefs."This included the most comprehensive midwater robotic dive survey series to ever have been conducted in the South Pacific," said Dr. Brendan Brooke, the expedition's lead scientist from Geoscience Australia. "Research vessel Falkor has integrated a range of technologies that have allowed us to work across the full range of ocean depths in the Coral Sea and to provide data for multiple disciplines including geology, biology, and oceanography."During the expedition, researchers took the deepest samples ever collected of soft coral and scleractinian coral in the Coral Sea. They also collected the first sample of ancient bedrock beneath the Great Barrier Reef, estimated to be between 40 and 50 million years old. Scientists made the first recorded observation in Australia of the extremely rare fish Rhinopias agroliba , a colorful and well-camouflaged ambush predator in the scorpionfish family. The cruise also included the most comprehensive survey of midwater jellyfish in the South Pacific.In addition to the underwater dives, high-resolution mapping of the seafloor was conducted and covered 38,395 square kilometers, an area three times greater than Sydney. The maps include all the major coral atolls on the Queensland Plateau within the Coral Sea Marine Park and an 80-kilometer section of canyons off the northern Great Barrier Reef Marine Park."These maps, samples, and images are fascinating and provide a new understanding of the geological diversity and biological wealth of a region that is already world-renowned for its natural beauty," said Dr. Jyotika Virmani, executive director of Schmidt Ocean Institute. "The data will help marine park managers to protect these ecosystems that are so vital for our global biodiversity and human health. "Live streaming of the 18 underwater robotic dives via Schmidt Ocean's channel on YouTube and 112 hours of high definition underwater video during the month-long expedition, which ended August 30, allowed the science team to share their knowledge and excitement of the voyage's discoveries with the world. Through the livestreams, the scientists could interact directly with the public via chat and commentary."Schmidt Ocean Institute and the technology that it has brought to Australia is a huge enabler in better understanding our marine resources from a lens of diverse disciplines," said Dr. Scott Nichol, one of the lead expedition scientists from Geoscience Australia. "This work brings new understanding and will keep the scientists busy for years."
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Geography
| 2,020 |
September 9, 2020
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https://www.sciencedaily.com/releases/2020/09/200909085935.htm
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Virtual tourism could offer new opportunities for travel industry, travelers
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A new proposal for virtual travel, using advanced mathematical techniques and combining livestream video with existing photos and videos of travel hotspots, could help revitalize an industry that has been devastated by the coronavirus pandemic, according to researchers at the Medical College of Georgia at Augusta University.
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In a new proposal published in They call this proposed technology LAPO, or Live Streaming with Actual Proportionality of Objects. LAPO employs both information geometry -- the measures of an object's curvatures, angles and area -- and conformal mapping, which uses the measures of angles between the curves of an object and accounts for the distance between objects, to make images of people, places and things seem more real."This is about having a new kind of technology that uses advanced mathematical techniques to turn digitized data, captured live at a tourist site, into more realistic photos and videos with more of a feel for the location than you would get watching amovie or documentary," says corresponding author Rao. "When you go see the Statue of Liberty for instance, you stand on the bank of the Hudson River and look at it. When you watch a video of it, you can only see the object from one angle. When you measure and preserve multiple angles and digitize that in video form, you could visualize it from multiple angles. You would feel like you're there while you're sitting at home."Their proposed combination of techniques is novel, Rao says. "Information geometry has seen wide applications in physics and economics, but the angle preservation of the captured footage is never applied," he says.Rao and Krantz say the technology could help mediate some of the pandemic's impact on the tourism industry and offer other advantages.Those include its cost-effectiveness, because virtual tourism would be cheaper; health safety, because it can be done from the comfort of home; it saves time, eliminating travel times; it's accessibility -- tourism hotspots that are not routinely accessible to seniors or those with physical disabilities would be; it's safer and more secure, eliminating risks like becoming a victim of crime while traveling; and it requires no special equipment -- a standard home computer with a graphics card and internet access is all that's needed to enjoy a "virtual trip.""Virtual tourism (also) creates new employment opportunities for virtual tour guides, interpreters, drone pilots, videographers and photographers, as well as those building the new equipment for virtual tourism," the authors write."People would pay for these experiences like they pay airlines, hotels and tourist spots during regular travel," Rao says. "The payments could go to each individual involved in creating the experience or to a company that creates the entire trip, for example."Next steps include looking for investors and partners in the hospitality, tourism and technology industries, he says.If the pandemic continues for several more months, the World Travel and Tourism Council, the trade group representing major global travel companies, projects a global loss of 75 million jobs and $2.1 trillion in revenue.Rao is a professor of health economics and modeling in the MCG Department of Population Health Sciences.
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Geography
| 2,020 |
September 8, 2020
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https://www.sciencedaily.com/releases/2020/09/200908170537.htm
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California offshore winds show promise as power source
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As California aims to provide 60% of its energy from renewable sources by 2030 and 100% by 2045, a study from California Polytechnic State University provides some good news. Offshore winds along the Central Coast increase at the same time that people start using more energy -- in the evening.
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One of the challenges of moving toward fully renewable energy is matching production to demand. Though the state has high existing solar energy capacity and the potential for even more, the supply of solar power peaks in the middle of the day and ends when the sun goes down. Consumer demand, on the other hand, peaks in the evening when people return from work around or after sunset.Because storage of solar energy on a large scale is not yet practical, other renewable sources are needed to meet the Golden State's environmental milestone of going fully renewable.The Cal Poly research team found that offshore winds are strongest when demand is greatest, making it an ideal candidate to fill the gap left by solar and on-shore wind energy production. The team was led by research scientist Yi-Hui Wang and included biology professors Ben Ruttenberg and Crow White and physics Professor Ryan Walter."The alignment between potential offshore wind power production and demand highlights the important role that offshore wind energy could play in meeting California's ambitious renewable energy goals," Wang said.Even more promising, offshore winds reach their peak during the hot summer months when state energy use is highest due to the use of air conditioning. Offshore wind energy offers several other advantages over land-based wind and solar energy, including stronger and more consistent winds and less impact on other land uses.The greatest wind speeds, which would produce the most energy, are found farther from the coast. Most existing offshore wind farms are installed close to shore in shallow water less than 160 feet deep. However, several floating wind farms in deeper water farther from shore are now in operation in Europe, with more in the planning stages."Floating offshore wind farms are now a proven technology and game-changer in many respects," Walter said. "These floating platforms make offshore wind farms a new reality in many locations, with a single turbine having the potential to power more than 10,000 homes."The Bureau of Ocean Energy Management, which funded the study, is considering the Central Coast as a location for California's first offshore wind farm and has proposed priority areas for leasing by energy companies. The Cal Poly study provides crucial information that, along with other studies on economic, cultural and environmental factors, will help guide the evaluation and planning of offshore wind energy."Looking at this wind data in relation to maps of fisheries, whale and seabird activity will help identify locations where offshore wind farms could add the most value and yet have the least impact on local economies and marine wildlife," White said.The Cal Poly team is working on the next steps, which include estimating the total amount of electricity wind farms in the area could produce and how these wind farms might affect the broader economy of San Luis Obispo County."Ultimately, we hope this information and our ongoing work will inform the conversation, helping the policymakers and citizens of California decide if, how and where to prioritize renewable offshore wind energy," Ruttenberg said.
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Geography
| 2,020 |
September 7, 2020
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https://www.sciencedaily.com/releases/2020/09/200904100549.htm
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Japan's geologic history in question after discovery of metamorphic rock microdiamonds
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A collaboration of researchers based in Kumamoto University, Japan have discovered microdiamonds in the Nishisonogi metamorphic rock formation in Nagasaki Prefecture, Japan. Microdiamonds in metamorphic rocks are important minerals because they form in continental collision zones and show that the crust has penetrated deeper than 120 km below the surface. This is the second area in the world, after the Italian Alps, that shows microdiamonds can form in metamorphic rock through subduction of oceanic plates.
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In recent years, microdiamonds have received a great deal of attention because they have been discovered in metamorphic rocks around the world and it has become clear that they are formed in collisions between continents. It was thought that Japan would not produce such microdiamonds because it is not a continental collision zone, but an oceanic plate subduction zone. However, the first microdiamonds from metamorphic rocks in Japan were found in the Nishisonogi metamorphic rock formation in the west coast of Nagasaki Prefecture.The area where the microdiamonds were discovered is an approximately 100-million-year-old Cretaceous metamorphic rock formation. On the west coast of Saikai City in Nagasaki Prefecture, blocks of pelitic and basic schist are scattered amongst serpentinite that was created from mantle material. Such rocks are called a serpentinite mélange and indicate that they have risen from deep in the subduction zone. Researchers found microdiamonds here, in the serpentinite mélange. Their formation conditions have been estimated to be a temperature of about 450 °C and a pressure of about 2.8 GPa, which makes them the coldest diamonds ever formed. It has been thought that the Nishisonogi metamorphic rock was formed under a pressure of about 1 GPa, but it is now clear that they were ultrahigh-pressure metamorphic rocks that rose after subducting to 120 km -- a very unexpected discovery."The discovery of microdiamonds from Japan's first metamorphic rocks will rewrite Japan's geological history," said Professor Tadao Nishiyama, the leader of this study. "Until now, the Nagasaki metamorphic rocks were said to belong to a low-temperature, high-pressure-type metamorphic rock belt, the "Sanbagawa Belt," which crosses the Japanese mainland. It has become clear, however, that they are independently-formed ultrahigh-pressure metamorphic rocks. I expect that there will be many discussions about what kind of plate movement created this formation."
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Geography
| 2,020 |
September 5, 2020
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https://www.sciencedaily.com/releases/2020/09/200905121912.htm
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Researchers track nutrient transport in the Gulf of Mexico
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Researchers from Florida State University are shedding light on nutrient levels in the Gulf of Mexico with new findings published this month in the
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The Gulf of Mexico receives considerable levels of nutrients from the rivers that empty into it, especially the Mississippi River, which causes the Gulf's northern shelf waters to become overly enriched and more susceptible to algae growth. But scientists have remained unsure whether a significant portion of those nutrients ever leave the Gulf to potentially impact the chemistry of the North Atlantic Ocean."The Gulf of Mexico is an economically important body of water, as the surrounding areas rely on it for tourism, fisheries and oil production, and it also has significant ecological diversity," said Samantha Howe, a graduate student in the College of Arts and Sciences' Department of Earth, Ocean and Atmospheric Science, who led the research. "It is important to track the nutrient input from the Mississippi and Atchafalaya River System to the Gulf as those nutrients contribute to harmful algal blooms on the Northern Gulf Shelf."Researchers found no evidence that nitrate from the Mississippi-Atchafalaya River System is mixing across the Northern Gulf shelf into the open waters of the Gulf of Mexico. The findings are consistent with recent modeling work by fellow scientists that indicates 90 percent of Mississippi River nutrients are retained in the near-shore ecosystem, which implies that nutrients from the Mississippi River do not leave the Gulf."In order to assess and manage ecological challenges in the Gulf, it is critical to understand whether the nutrients are processed and retained nearshore or whether they are transported to the North Atlantic," Howe said. "This finding is valuable to know, as these ecosystems must harbor the nutrient burden."To conduct the study, the team collected and analyzed water samples taken during four different research cruises to the Gulf and the Florida Straits from 2011 to 2018.The research is the first ever to provide isotopic composition measurements of nitrate in the Gulf of Mexico, as well as a new isotopic profile from the Florida Straits. These new water column profiles were then compared with prior measurements from the North and South Atlantic and with the magnitude of nitrogen inputs to the Gulf.Howe, who earned her bachelor's degree in environmental science from FSU in Spring 2019, is now pursuing her master's in aquatic environmental science. She began the nutrient research as part of her honors undergraduate thesis while working in the research lab of study co-author, Associate Professor of Oceanography Angela Knapp."Samantha's thesis looked for distinct geochemical signatures of nitrate from the Mississippi River and whether this nitrate made it off the Northern Gulf of Mexico shelf into the deep waters of the Gulf that mix with the Loop Current and leave via the Florida Straits to enter the North Atlantic," Knapp said.Howe's collaborators on the study include co-authors Knapp and Carlos Miranda, a 2017 graduate of the FSU Department of Chemistry and Biochemistry and the FSU Department of Biological Science, and colleagues from the University of Southern Mississippi and the University of New Hampshire."This work has important implications for understanding the fate of nutrients from the Mississippi Atchafalaya River System and how to manage human inputs to coastal ecosystems," Knapp said.The research was funded by the National Science Foundation's Division of Ocean Sciences .
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Geography
| 2,020 |
September 4, 2020
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https://www.sciencedaily.com/releases/2020/09/200903195934.htm
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Indigenous knowledge still undervalued
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New research has found that Indigenous knowledge is regularly underutilised and misunderstood when making important environmental decisions.
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Published in a special edition of the journal The research, led by Dr Helen Wheeler of Anglia Ruskin University (ARU), involved participants from the Arctic regions of Norway, Sweden, Greenland, Russia, Canada, and the United States.Indigenous peoples inhabit 25% of the land surface and have strong links to their environment, meaning they can provide unique insights into natural systems. However, the greater resources available to scientists often creates a power imbalance when environmental decisions are made.The study's Indigenous participants identified numerous problems, including that Indigenous knowledge is often perceived as less valuable than scientific knowledge and added as anecdotes to scientific studies.They also felt that Indigenous knowledge was being forced into frameworks that did not match Indigenous people's understanding of the world and is often misinterpreted through scientific validation. One participant expressed the importance of Indigenous knowledge being reviewed by Indigenous knowledge holders, rather than by scientists.Another concern was that while funding for Arctic science was increasing, the same was not happening for research rooted in Indigenous knowledge or conducted by Indigenous peoples.Gunn-Britt Retter, Head of the Arctic and Environmental Unit of the Saami Council, said: "Although funding for Arctic science is increasing, we are not experiencing this same trend for Indigenous knowledge research."Sometimes Indigenous organisations feel pressured to agree to requests for collaboration with scientists so that we can have some influence in decision-making, even when these collaborations feel tokenistic and do not meet the needs of our communities. This is because there is a lack of funding for Indigenous-led research."Victoria Buschman, Inupiaq Inuit wildlife and conservation biologist at the University of Washington, said: "Much of the research community has not made adequate space for Indigenous knowledge and continues to undermine its potential for information decision-making. We must let go of the narrative that working with Indigenous knowledge is too challenging."The study concludes that values, laws, institutions, funding and mechanisms of support that create equitable power-relations between collaborators are necessary for successful relationships between scientists and Indigenous groups.Lead author Dr Helen Wheeler, Lecturer in Zoology at Anglia Ruskin University (ARU), said: "The aim of this study was to understand how to work better with Indigenous knowledge. For those who do research on Indigenous people's land, such as myself, I think this is an important question to ask."Our study suggests there are still misconceptions about Indigenous knowledge, particularly around the idea that it is limited in scope or needs verifying by science to be useful. Building capacity for research within Indigenous institutions is also a high priority, which will ensure Indigenous groups have greater power when it comes to informed decision-making."Indigenous knowledge is increasingly used in decision-making at many levels from developing international policy on biodiversity to local decisions about how to manage wildlife. However, as scientists and decision-makers use knowledge, they must do so in a way that reflects the needs of Indigenous knowledge holders. This should lead to better decisions and more equitable and productive partnerships."
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Geography
| 2,020 |
September 3, 2020
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https://www.sciencedaily.com/releases/2020/09/200903095607.htm
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Natural pest control saving billions
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Biological control of insect pests -- where 'natural enemies' keep pests at bay -- is saving farmers in Asia and the Pacific billions of dollars, according to University of Queensland-led research.
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Dr Kris Wyckhuys from UQ's School of Biological Sciences said biological control involved the careful release of an exotic natural enemy from a pest's native habitat."Scientists meticulously choose co-evolved beneficial insects that are the most effective and least likely to pose ecological upsets," Dr Wyckhuys said."We've reviewed how biological control introductions have effectively managed 43 insect pests in food, feed and fibre crops in the Asia-Pacific region over a century."The team found that biological control has helped regulate invasive pest threats in multiple key food crops such as banana, breadfruit and coconut."Our work shows these techniques are saving farmers in Asia around $20.1 billion to $26.8 billion (US$14.6-19.5 billion) per year," Dr Wyckhuys said."That's a phenomenal amount of money and benefit, particularly when compared to other innovations in the agricultural sector."A good point of comparison is the Green Revolution in Asia during the late 1960s, which tripled the output of local rice production but also saw a rise of chemical fertilisers, agrochemicals and newer methods of cultivation."A large part of the Green Revolution impacts can be ascribed to double-yielding rice varieties, which generated $4.8 billion (US$4.3 billion) per year in Asia."UQ's Associate Professor Michael Furlong said recognition of the success of biological control might lead to greater uptake and more resilient, prosperous farming globally."Biological control offers great opportunities for some of the world's poorest farmers," Dr Furlong said."It's promoted rural growth and prosperity even in marginal, poorly endowed, non-rice environments."A great example is the coconut scale (Aspidiotus destructor), which jeopardised the economic prosperity and food security of entire nations."This coconut scale posed a serious problem to crops like coconut, bananas and copra industries in Fiji at the start of the Twentieth Century."In 1928, lady beetles from Trinidad and millimetre-long parasitic wasps were introduced, and the results were almost immediate."Coconut scale ceased to be an economic issue on all of the main Fijian islands within nine months, and after 18 months, the scale was so rare it was difficult to find."These innovative approaches, with increasingly better science, are helping feed the world, safeguard on-farm biodiversity and increase farmers' quality of life."We're hoping this research provides lessons for future efforts to mitigate invasive species, restore ecological resilience, and sustainably increase the output of our global food system."
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Geography
| 2,020 |
September 1, 2020
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https://www.sciencedaily.com/releases/2020/09/200901164503.htm
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Fish invasions follow Panama and Suez canal expansions
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World maritime trade grows each year, aided by canal waterways that connect oceans and reduce shipping time, energy consumption and carbon emissions. Following recent expansions of the Panama and Suez canals, non-native fish species are invading new habitats according to a new report in
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"We're seeing a shift from predominantly freshwater fishes to marine fishes in the Panama Canal (Lake Gatun) in a short period of time," said Mark Torchin, STRI marine ecologist. "The concern is that if fish invasions continue there is a good chance of some of those fishes moving into the other ocean, with unknown environmental consequences."Larger locks to allow transit of NeoPanamax vessels (NeoPanamax refers to ships too big to pass through the original 1914 locks) through the Panama Canal were finished in 2016. Expansion of the Suez Canal to include a new, 35-kilometer channel concluded in 2015."During the planning phases of both projects, researchers warned about the risks of expanding these two canals," said Gustavo Castellanos-Galindo, postdoctoral fellow at STRI and guest scientist at ZMT. "This report documents those changes in real time."Only four years after the Panama Canal expansion, long-term monitoring recorded the presence of 11 new marine fish species in Lake Gatun, which has served as a freshwater barrier to movement of marine fauna between Pacific and Atlantic Oceans since the canal opened in 1914. This takes the total number of marine fish species known from in the lake from 18 to 29. Marine fishes such as jacks, snooks, mojarras and ladyfish have entirely replaced freshwater fishes in some parts of the lake.Salinity in the lake increased, although the cause has not yet been determined. Possibilities include increased ship traffic and lock usage and the new locks' design, which incorporates recirculation of some lockage water."These marine fish invasions are an early warning sign of what could happen if no corrective measures are taken," Castellanos-Galindo said. "Along both coasts of Panama there are hundreds of fish species that could tolerate the conditions of an even slightly brackish canal. We don't know what the ecological and socioeconomic consequences of these fishes crossing the canal to either the Pacific or the Atlantic would be.""We can document the Panama Canal invasions because we have good, standardized and quantitative pre-expansion data," said D. Ross Robertson, STRI ichthyologist. "We need to get back out there to collect more data to find out exactly what is going on and to provide the science that will help policy makers mitigate the potential impact. This is a really good example of how the pandemic has interrupted field work with important implications for environmental decision making."Whereas the barrier to fish crossing from ocean to ocean in Panama is a freshwater lake, in the Suez waterway, the Bitter Lakes were originally saltier than the Mediterranean and Red Sea, which also limited species movement. Nonetheless, throughout the history of the Suez Canal, more than 400 non-native animal species, including more than 100 species of marine fishes from the Red Sea, have entered the Mediterranean. With canal expansion, increased water flow diluted the lakes and eight new fish species entered the Mediterranean during the past five years.Because fees for shipping through the canals account for roughly 10% of the gross domestic product in Panama and in Egypt, there is an economic incentive to continue to increase shipping traffic through the canals. The authors suggest creative, science-based solutions to limit environmental and socioeconomic damage. They propose that the UN Decade of Ocean Science for Sustainable Development (2021-2030) may provide the ideal opportunity for ensuring that the canals are included in international maritime policy to limit the environmental and economic impacts of invasive species. In addition, because policy changes can take a long time to implement, they also suggest that the shipping industry could proactively address this issue.The UN agency responsible for sustainable shipping, the International Maritime Organization, has implemented guidelines and obligations to reduce the spread of non-native species through ballast water -- but they do not apply specifically to the canals.In the case of the Suez Canal, it may be possible to use the hypersaline effluent from desalinization plants to make the Bitter Lakes saltier again, with the caveat that this alternative should be studied carefully before implementing. In both cases, sophisticated monitoring tools -- using DNA in water samples to generate lists of the species detected and using sound to detect invaders, may help to catch invaders early before they establish large populations. Technology may also be put to work to directly address invasion by means of acoustic and/or electric barriers to deter invaders.The authors hope that all of the stakeholders will recognize the importance of having the best scientific data in hand as they design new policy and mitigation measures.
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Geography
| 2,020 |
September 1, 2020
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https://www.sciencedaily.com/releases/2020/09/200901120734.htm
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A multinational study overturns a 130-year old assumption about seawater chemistry
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There's more to seawater than salt. Ocean chemistry is a complex mixture of particles, ions and nutrients. And for over a century, scientists believed that certain ion ratios held relatively constant over space and time.
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But now, following a decade of research, a multinational study has refuted this assumption. Debora Iglesias-Rodriguez, professor and vice chair of UC Santa Barbara's Department of Ecology, Evolution, and Marine Biology, and her colleagues discovered that the seawater ratios of three key elements vary across the ocean, which means scientists will have to re-examine many of their hypotheses and models. The results appear in the Proceedings of the National Academy of Sciences.Calcium, magnesium and strontium (Ca, Mg and Sr) are important elements in ocean chemistry, involved in a number of biologic and geologic processes. For instance, a host of different animals and microbes use calcium to build their skeletons and shells. These elements enter the ocean via rivers and tectonic features, such as hydrothermal vents. They're taken up by organisms like coral and plankton, as well as by ocean sediment.The first approximation of modern seawater composition took place over 130 years ago. The scientists who conducted the study concluded that, despite minor variations from place to place, the ratios between the major ions in the waters of the open ocean are nearly constant.Researchers have generally accepted this idea from then on, and it made a lot of sense. Based on the slow turnover of these elements in the ocean -- on the order of millions of years -- scientists long thought the ratios of these ions would remain relatively stable over extended periods of time."The main message of this paper is that we have to revisit these ratios," said Iglesias-Rodriguez. "We cannot just continue to make the assumptions we have made in the past essentially based on the residency time of these elements."Back in 2010, Iglesias-Rodriguez was participating in a research expedition over the Porcupine Abyssal Plain, a region of North Atlantic seafloor west of Europe. She had invited a former student of hers, this paper's lead author Mario Lebrato, who was pursuing his doctorate at the time.Their study analyzed the chemical composition of water at various depths. Lebrato found that the Ca, Mg and Sr ratios from their samples deviated significantly from what they had expected. The finding was intriguing, but the data was from only one location.Over the next nine years, Lebrato put together a global survey of these element ratios. Scientists including Iglesias-Rodriguez collected over 1,100 water samples on 79 cruises ranging from the ocean's surface to 6,000 meters down. The data came from 14 ecosystems across 10 countries. And to maintain consistency, all the samples were processed by a single person in one lab.The project's results overturned the field's 130-year old assumption about seawater chemistry, revealing that the ratio of these ions varies considerably across the ocean.Scientists have long used these ratios to reconstruct past ocean conditions, like temperature. "The main implication is that the paleo-reconstructions we have been conducting have to be revisited," Iglesias-Rodriguez explained, "because environmental conditions have a substantial impact on these ratios, which have been overlooked."Oceanographers can no longer assume that data they have on past ocean chemistry represent the whole ocean. It has become clear they can extrapolate only regional conditions from this information.This revelation also has implications for modern marine science. Seawater ratios of Mg to Ca affect the composition of animal shells. For example, a higher magnesium content tends to make shells more vulnerable to dissolution, which is an ongoing issue as increasing carbon dioxide levels gradually make the ocean more acidic. "Biologically speaking, it is important to figure out these ratios with some degree of certainty," said Iglesias-Rodriguez.Iglesias-Rodriguez's latest project focuses on the application of rock dissolution as a method to fight ocean acidification. She's looking at lowering the acidity of seawater using pulverized stones like olivine and carbonate rock. This intervention will likely change the balance of ions in the water, which is something worth considering. As climate change continues unabated, this intervention could help keep acidity in check in small areas, like coral reefs.
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Geography
| 2,020 |
August 31, 2020
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https://www.sciencedaily.com/releases/2020/08/200831154405.htm
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Secret weapon to stop invasive honeysuckle: Satellites
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One common invasive species is so widespread that you can see it from space.
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The University of Cincinnati found that satellite imagery can identify nonnative and invasive Amur honeysuckle, an ornamental shrub introduced from Asia that has spread in forests across much of the United States.UC graduate Bridget Taylor, UC biology professor Denis Conover and UC geography professor Richard Beck used satellite imagery to find nonnative invasive Amur honeysuckle in several urban parks and cemeteries from space.Using one of the satellites in a series of Earth-observing missions jointly managed by NASA and the U.S. Geological Survey, the Landsat-8 satellite can measure the reflection of wavelength energy in the red and near-infrared bands. The ratio of the two wavelengths helps scientists identify foliage of different plants from orbit.UC found that the method was effective in detecting Amur honeysuckle, according to a study published in the journal Amur honeysuckle bushes grow in thick patches, often crowding out and outcompeting other plants in a forest's understory. It has an extended growing season, leafing out earlier and staying green far later in the year than many native trees and shrubs.UC used Landsat-8 images to examine five urban forests in Greater Cincinnati. The goal: to develop an inexpensive and efficient remote mapping approach for ecological restoration in urban forests. They used global-positioning satellites to corroborate their mapping observations on the ground. They found that their maps were 82% accurate."The fact that it was possible to use the satellite imagery in an urban setting was pretty unique," said Taylor, the study's lead author."Urban areas have a lot of noise in satellite imagery. So it's harder to identify specific details," she said.Taylor has participated in efforts to eradicate the nonnative Amur honeysuckle in places like Burnet Woods, the park adjacent to UC's Uptown campus."It's very bushy. Birds like to eat the berries and spread the seeds," she said. "It has a chance to green up and leaf out sooner than native plants, so native wildflowers often get killed off when they're growing under honeysuckle."The study shows that satellite images can provide an effective, inexpensive alternative to using drones or ground surveys to identify larger patches of the invasive bushes for ecological restoration, Taylor said.
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Geography
| 2,020 |
August 27, 2020
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https://www.sciencedaily.com/releases/2020/08/200827133549.htm
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Land use change leads to increased flooding in Indonesia
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While high greenhouse gas emissions and biodiversity loss are often associated with rapid land-use change in Indonesia, impacts on local water cycles have been largely overlooked. Researchers from the University of Göttingen, IPB University in Bogor and BMKG in Jakarta have now published a new study on this issue. They show that the expansion of monocultures, such as oil palm and rubber plantations, leads to more frequent and more severe flooding. The multidisciplinary team explains this increase in flooding with a complex interplay of ecohydrological and social processes, including soil degradation in monocultures, the expansion of oil palm plantations into wetlands, and the construction of flood protection dams. The results have been published in the journal
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For the study, the authors conducted almost 100 interviews with Indonesian smallholders, people from the village and decision-makers in the Jambi province of Sumatra. They then compared and supplemented their analyses of these results with scientific measurements of precipitation, river and groundwater levels, soil properties as well as land use mapping from the region. "Many studies on the relationship between land use changes and flooding are only based on analyses by individual disciplines and thus provide only fragmentary insights into the underlying processes," says lead author Jennifer Merten, Department of Human Geography at the University of Göttingen. "It was therefore important for us to use the widest possible range of data from different disciplines and also to include observations from the local population."In their study, the scientists of the German-Indonesian Collaborative Research Centre EFForTS (Ecological and Socio-Economic Functions of Tropical Lowland Rainforest Transformation Systems) show that the current expansion of oil palm and rubber plantations has a significant impact on local water cycles. "The large-scale land-use change leads to a compaction of the soil, so that less rain is absorbed by the soil and the water quickly runs off at the surface," explains co-author Christian Stiegler, Bioclimatology Group at the University of Göttingen. "In particular, the advancing destruction of floodplains plays an important role in this process." From the perspective of the village population, the construction of flood dams and drainage channels also contributes to a change in local patterns of flooding. As oil palm plantations in particular are increasingly cultivated in wetlands such as river floodplains or peatlands, larger plantation owners are trying to control flooding on their land by means of such constructions. "However, such dams often lead to increased flooding on neighbouring smallholder plantations," Merten reports following her experiences from the area. This means that the observed increase in flooding also leads to new social tensions and conflicts.In order to reduce the impact of land use change on the water cycle, soil protection and improved land use planning, especially in floodplains and wetlands, can play an important role. "Yet, it is just as important to regulate and control landscape interventions for flood protection and drainage more closely," says Merten. "Otherwise it might happen that the effects of increasing flooding will affect above all the poorest in society, because larger companies simply pass on the water."
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Geography
| 2,020 |
August 27, 2020
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https://www.sciencedaily.com/releases/2020/08/200827102111.htm
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Fossil evidence of 'hibernation-like' state in 250-million-year-old Antarctic animal
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Hibernation is a familiar feature on Earth today. Many animals -- especially those that live close to or within polar regions -- hibernate to get through the tough winter months when food is scarce, temperatures drop and days are dark.
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According to new research, this type of adaptation has a long history. In a paper published Aug. 27 in the journal The creature, a member of the genus Lystrosaurus, was a distant relative of mammals. Antarctica during Lystrosaurus' time lay largely within the Antarctic Circle, like today, and experienced extended periods without sunlight each winter.The fossils are the oldest evidence of a hibernation-like state in a vertebrate animal, and indicates that torpor -- a general term for hibernation and similar states in which animals temporarily lower their metabolic rate to get through a tough season -- arose in vertebrates even before mammals and dinosaurs evolved."Animals that live at or near the poles have always had to cope with the more extreme environments present there," said lead author Megan Whitney, a postdoctoral researcher at Harvard University who conducted this study as a UW doctoral student in biology. "These preliminary findings indicate that entering into a hibernation-like state is not a relatively new type of adaptation. It is an ancient one."Lystrosaurus lived during a dynamic period of our planet's history, arising just before Earth's largest mass extinction at the end of the Permian Period -- which wiped out about 70% of vertebrate species on land -- and somehow surviving it. The stout, four-legged foragers lived another 5 million years into the subsequent Triassic Period and spread across swathes of Earth's then-single continent, Pangea, which included what is now Antarctica."The fact that Lystrosaurus survived the end-Permian mass extinction and had such a wide range in the early Triassic has made them a very well-studied group of animals for understanding survival and adaptation," said co-author Christian Sidor, a UW professor of biology and curator of vertebrate paleontology at the Burke Museum.Paleontologists today find Lystrosaurus fossils in India, China, Russia, parts of Africa and Antarctica. These squat, stubby, creatures -- most were roughly pig-sized, but some grew 6 to 8 feet long -- had no teeth but bore a pair of tusks in the upper jaw, which they likely employed to forage among ground vegetation and dig for roots and tubers, according to Whitney.Those tusks made Whitney and Sidor's study possible. Like elephants, Lystrosaurus tusks grew continuously throughout their lives. The cross-sections of fossilized tusks can harbor life-history information about metabolism, growth and stress or strain. Whitney and Sidor compared cross-sections of tusks from six Antarctic Lystrosaurus to cross-sections of four Lystrosaurus from South Africa.Back in the Triassic, the collection sites in Antarctica were at about 72 degrees south latitude -- well within the Antarctic Circle, at 66.3 degrees south. The collection sites in South Africa were more than 550 miles north during the Triassic at 58-61 degrees south latitude, far outside the Antarctic Circle.The tusks from the two regions showed similar growth patterns, with layers of dentine deposited in concentric circles like tree rings. But the Antarctic fossils harbored an additional feature that was rare or absent in tusks farther north: closely-spaced, thick rings, which likely indicate periods of less deposition due to prolonged stress, according to the researchers."The closest analog we can find to the 'stress marks' that we observed in Antarctic Lystrosaurus tusks are stress marks in teeth associated with hibernation in certain modern animals," said Whitney.The researchers cannot definitively conclude that Lystrosaurus underwent true hibernation -- which is a specific, weeks-long reduction in metabolism, body temperature and activity. The stress could have been caused by another hibernation-like form of torpor, such as a more short-term reduction in metabolism, according to Sidor.Lystrosaurus in Antarctica likely needed some form of hibernation-like adaptation to cope with life near the South Pole, said Whitney. Though Earth was much warmer during the Triassic than today -- and parts of Antarctica may have been forested -- plants and animals below the Antarctic Circle would still experience extreme annual variations in the amount of daylight, with the sun absent for long periods in winter.Many other ancient vertebrates at high latitudes may also have used torpor, including hibernation, to cope with the strains of winter, Whitney said. But many famous extinct animals, including the dinosaurs that evolved and spread after Lystrosaurus died out, don't have teeth that grow continuously."To see the specific signs of stress and strain brought on by hibernation, you need to look at something that can fossilize and was growing continuously during the animal's life," said Sidor. "Many animals don't have that, but luckily Lystrosaurus did."If analysis of additional Antarctic and South African Lystrosaurus fossils confirms this discovery, it may also settle another debate about these ancient, hearty animals."Cold-blooded animals often shut down their metabolism entirely during a tough season, but many endothermic or 'warm-blooded' animals that hibernate frequently reactivate their metabolism during the hibernation period," said Whitney. "What we observed in the Antarctic Lystrosaurus tusks fits a pattern of small metabolic 'reactivation events' during a period of stress, which is most similar to what we see in warm-blooded hibernators today."If so, this distant cousin of mammals isn't just an example of a hearty creature. It is also a reminder that many features of life today may have been around for hundreds of millions of years before humans evolved to observe them.The research was funded by the National Science Foundation.
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Geography
| 2,020 |
August 25, 2020
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https://www.sciencedaily.com/releases/2020/08/200825113607.htm
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Computer modeling used to predict reef health
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A UBC Okanagan researcher has developed a way to predict the future health of the planet's coral reefs.
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Working with scientists from Australia's Flinders' University and privately-owned research firm Nova Blue Environment, biology doctoral student Bruno Carturan has been studying the ecosystems of the world's endangered reefs."Coral reefs are among the most diverse ecosystems on Earth and they support the livelihoods of more than 500 million people," says Carturan. "But coral reefs are also in peril. About 75 per cent of the world's coral reefs are threatened by habitat loss, climate change and other human-caused disturbances."Carturan, who studies resilience, biodiversity and complex systems under UBCO Professors Lael Parrott and Jason Pither, says nearly all the world's reefs will be dangerously affected by 2050 if no effective measures are taken.There is hope, however, as he has determined a way to examine the reefs and explore why some reef ecosystems appear to be more resilient than others. Uncovering why, he says, could help stem the losses."In other ecosystems, including forests and wetlands, experiments have shown that diversity is key to resilience," says Carturan. "With more species, comes a greater variety of form and function -- what ecologists call traits. And with this, there is a greater likelihood that some particular traits, or combination of traits, help the ecosystem better withstand and bounce back from disturbances."The importance of diversity for the health and stability of ecosystems has been extensively investigated by ecologists, he explains. While the consensus is that ecosystems with more diversity are more resilient and function better, the hypothesis has rarely been tested experimentally with corals.Using an experiment to recreate the conditions found in real coral reefs is challenging for several reasons -- one being that the required size, timeframe and number of different samples and replicates are just unmanageable.That's where computer simulation modelling comes in."Technically called an 'agent-based model', it can be thought of as a virtual experimental arena that enables us to manipulate species and different types of disturbances, and then examine their different influences on resilience in ways that are just not feasible in real reefs," explains Carturan.In his simulation arena, individual coral colonies and algae grow, compete with one another, reproduce and die. And they do all this in realistic ways. By using agent-based models -- with data collected by many researchers over decades -- scientists can manipulate the initial diversity of corals, including their number and identity, and see how the virtual reef communities respond to threats."This is crucial because these traits are the building blocks that give rise to ecosystem structure and function. For instance, corals come in a variety of forms -- from simple spheres to complex branching -- and this influences the variety of fish species these reefs host, and their susceptibility to disturbances such as cyclones and coral bleaching."By running simulations over and over again, the model can identify combinations that can provide the greatest resilience. This will help ecologists design reef management and restoration strategies using predictions from the model, says collaborating Flinders researcher Professor Corey Bradshaw."Sophisticated models like ours will be useful for coral-reef management around the world," Bradshaw adds. "For example, Australia's iconic Great Barrier Reef is in deep trouble from invasive species, climate change-driven mass bleaching and overfishing.""This high-resolution coral 'video game' allows us to peek into the future to make the best possible decisions and avoid catastrophes."The research, supported by grants from the Natural Sciences and Engineering Research Council of Canada and the Canada Foundation for Innovation, was published recently in
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Geography
| 2,020 |
August 25, 2020
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https://www.sciencedaily.com/releases/2020/08/200825110626.htm
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Two major microbial groups living deep underground can't breathe
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A new scientific study has revealed unique life strategies of two major groups of microbes that live below Earth's surface. A publication in
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"These microbes, which belong to the groups Patescibacteria and DPANN, are really special, really exciting examples of the early evolution of life," said Ramunas Stepanauskas, a senior research scientist at Bigelow Laboratory for Ocean Sciences and an author of the paper. "They may be remnants of ancient forms of life that had been hiding and thriving in the Earth's subsurface for billions of years."Stepanauskas led a research team that used advanced molecular techniques and bioinformatics to analyze thousands of microbial genomes and learn about their evolutionary history. Reading their genetic code revealed that these two groups of abundant microbes lack the capability to breathe in order to synthesize ATP, the common energy currency of life.The team found that these microbes, which live in a variety of environments in Earth's interior, appear to gain energy only through the process of fermentation. Many organisms are capable of fermentation, including humans when their muscles run out of oxygen during intense exercise -- but they use it only as a supplementary source of energy."Our findings indicate that Patescibacteria and DPANN are ancient forms of life that may have never learned how to breathe," Stepanauskas said. "These two major branches of the evolutionary tree of life constitute a large portion of the total microbial diversity on the planet -- and yet they lack some capabilities that are typically expected in every form of life."The researchers found that the most recent common ancestors of these two lineages lacked the ability to breathe, just as their modern descendants do. For the first two billion years of Earth's existence, there was no oxygen in the atmosphere. Today, oxygen is a key component of Earth's atmosphere and essential to the life it can support -- but just a few hundred feet underground, conditions have not changed, and this recent discovery suggests that some subsurface life hasn't, either.Scientists had previously speculated that because Patescibacteria and DPANN have very simple genetic features and metabolism, they must live symbiotically and depend upon host organisms to survive. In the new study, the research team found no evidence that Patescibacteria and DPANN are dominated by symbionts -- most of them seem to live as free cells and rely on the primitive pathway of fermentation to supply themselves with energy."Dependence on other organisms is a feature of life," said Jacob Beam, a former postdoctoral researcher at Bigelow Laboratory and the lead author of this study. "There are no absolutes in biology, and our research shows that microbes can vary along the spectrum of interdependencies."Scientists analyzed microbes from diverse environments around the globe, including a mud volcano at the bottom of the Mediterranean Sea, hydrothermal vents in the Pacific, and the world's deepest gold mines in South Africa. Bigelow Laboratory Bioinformatics Scientist Julie Brown, Research Scientist Nicole Poulton, former Postdoctoral Research Scientists Eric Becraft and Oliver Bezuidt, and Research Experience for Undergraduates intern Kayla Clark worked on this project, alongside with an international team of scientists who contributed to fieldwork, laboratory, and computational analyses.In addition to revealing the inner workings of Earth's subsurface and the evolution of life, these findings can provide a model system of what life on other planets may look like. Environments on Mars and other bodies in the solar system likely resemble Earth's subsurface, and Patescibacteria and DPANN represent examples of life that appear to require very little energy to survive, which scientists expect would be a requirement for life on other planets."This project would not have been possible without the collaboration of this diverse group of scientists collecting samples around the world and uniting their expertise," Beam said. "Through the collaboration of a global group of scientists working together, we know more about the inner workings of these microbes that form a major fraction of the total biodiversity on our planet."This work was funded by the National Science Foundation, the United States Department of Energy, the Simons Foundation, the Russian Science Foundation, and the National Aeronautics and Space Administration.
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Geography
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August 24, 2020
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https://www.sciencedaily.com/releases/2020/08/200824120038.htm
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Living at higher altitudes associated with higher levels of child stunting
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Residing at higher altitude is associated with greater rates of stunting, even for children living in "ideal-home environments" according to a new study from researchers at the International Food Policy Research Institute (IFPRI) and Addis Ababa University. The study provides new insight in the relationship between altitude and undernutrition and the additional efforts needed to ensure policy interventions are appropriately tailored to high altitude contexts.
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"More than 800 million people live at 1,500 meters above sea level or higher, with two-thirds of them in Sub-Saharan Africa, and Asia. These two regions host most of the world's stunted children so it is important to understand the role that altitude plays in growth" said IFPRI Senior Research Fellow and co-author of the study, Kalle Hirvonen."If children living at altitude are, on average, more stunted than their peers at sea level, then a more significant effort to address high altitude stunting is needed."The study, "Evaluation of Linear Growth at Higher Altitudes," co-authored by Hirvonen and Addis Ababa University Associate Professor Kaleab Baye, was published in the Children were classified as having lived in an ideal-home environment if they were born to highly educated mothers, had good health-service coverage and high living conditions. Global tracking of growth rates relies on the assumption that children living in such environments have the same growth potential, irrespective of genetic makeup or geographic location."The data clearly indicated that those residing in ideal-home environments grew at the same rate as the median child in the growth standard developed by the World Health Organization (WHO), but only until about 500 meters above sea level (masl). After 500 masl, average child height-for-age significantly deviated from the growth curve of the median child in the reference population," said Hirvonen. The research further shows that these estimated growth deficits are unlikely to be due to common risk factors such as poor diet and disease.The study suggests that the effects of altitude were most pronounced during the perinatal period i.e., the time leading up to, and immediately after, the birth. "Pregnancies at high-altitudes are characterized by chronic hypoxia, or an inadequate supply of oxygen, which is consistently associated with a higher risk of fetal growth restriction. Restricted growth in the womb is in turn a leading risk factor for linear growth faltering" said Hirvonen.There is some evidence to suggest that residing at high altitude over multiple generations may lead to some genetic adaption, but these findings did not hold for women with only a few generations of high-altitude ancestry. "Women of high-altitude ancestry were able to partially cope with the hypoxic conditions through increased uterine artery blood flow during pregnancy, but it may take more than a century before such adaptions are developed," said Baye.Hirvonen and Baye conclude that the WHO growth standards for children should not be adjusted because growth faltering at high altitudes is unlikely to be the result of physiological adaptations. Instead, they call for greater attention and health-care guidance for managing pregnancies in high-altitude settings."A first step is to unravel the complex relationship linking altitude, hypoxia and fetal growth to identify effective interventions. Failing to address altitude-mediated growth deficits urgently can fail a significant proportion of the world population from meeting the Sustainable Development Goals and World Health Assembly nutrition targets" said Baye.
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Geography
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August 24, 2020
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https://www.sciencedaily.com/releases/2020/08/200824110114.htm
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Global forest restoration and the importance of empowering local communities
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Forest restoration is a crucial element in strategies to mitigate climate change and conserve global biodiversity in the coming decades, and much of the focus is on formerly tree-covered lands in the tropics.
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But recent forest restoration research rarely acknowledges the social dimensions or environmental justice implications of such projects. A new study finds that nearly 300 million people in the tropics live on lands suitable for forest restoration, and about a billion people live within 5 miles of such lands. Many of these people live in poverty.Just and equitable implementation of restoration projects will require that communities be empowered to manage and use local forests, according to the authors of the study published in the journal "We argue that the success of global forest restoration critically depends on prioritizing local communities," said study lead author James Erbaugh of Dartmouth College, who earned a doctorate from the University of Michigan School for Environment and Sustainability."Empowering local communities to restore forests can provide human well-being benefits to millions of the most deprived and marginalized people, as well as environmental benefits for all."Study co-authors include SEAS professor Arun Agrawal, as well as other current and former graduate students and postdoctoral researchers at the U-M school.Their analysis examines the overlap between opportunities for tropical forest restoration, human populations, development and national policies for community forest ownership. The researchers focused on the opportunities in tropical countries because of the potential there for removing atmospheric carbon, promoting biodiversity conservation and contributing to the well-being of local residents.For the study, the researchers combined two datasets: one that classifies forest restoration opportunities using demographic, geographic and land-cover data, and another that uses estimates from a land-change model to predict carbon removal from forest restoration.They found that 294.5 million people live in recently tree-covered areas in the tropics that hold promise for forest restoration -- places the researchers call forest restoration opportunity areas. About 1 billion people live within 5 miles of land predicted to be suitable for forest restoration over the next 30 years if a moderate carbon-tax incentive of around $20 per ton of carbon dioxide is implemented.Brazil, the Democratic Republic of the Congo, India and Indonesia have the greatest number of people living in or near forest restoration opportunity areas with the greatest potential to remove heat-trapping carbon dioxide from the atmosphere and sequester it in forests, according to the study.Within low-income countries in the tropics, 12% of the population lives in forest restoration opportunity areas, a finding that highlights the potential for improving the livelihood and well-being of millions of people who are often underserved by standard investments in infrastructure and development, according to the authors.Nighttime satellite images showing the brightness and extent of artificial lighting on the Earth's surface can be used as a proxy for multiple development indicators. In the current study, areas in low-income nations with the least nighttime light radiance and the greatest carbon-removal potential indicated the places where forest restoration projects might best complement sustainable development agendas."There are many opportunities in central, eastern and southern Africa to restore forests and provide socioeconomic and infrastructure benefits to local people facing many multidimensional deprivations," said U-M's Agrawal, who is also editor-in-chief of the journal World Development."Forest landscape restoration that prioritizes local communities by affording them rights to manage and restore forests provides a promising option to align global agendas for climate mitigation, conservation, environmental justice and sustainable development."On the other hand, denying decision-making powers to affected locals could pose serious ethical problems, especially if some of those individuals are displaced by forest-restoration projects designed to help mitigate human-caused climate change and preserve biodiversity.Such exclusion would force some of the most multidimensionally poor people -- those who live in rural areas within low-income countries -- to move or give up their current livelihood for a global carbon and biodiversity debt to which they contributed little, according to the researchers.And while local communities should be empowered to manage forests for restoration, opportunities to expand community forest ownership must also be explored, they say..Most of the forest restoration opportunity areas analyzed in the study are in countries with preexisting legal frameworks for community forest ownership, which represents a stronger set of resource rights than community forest management.Continued efforts to expand community forest ownership are especially important in countries with a substantial proportion of people living in forest restoration opportunity areas, such as the Central African Republic, the Democratic Republic of the Congo, Thailand and the Lao People's Democratic Republic.Forest restoration projects in the tropics involve planting trees on land previously cleared for agriculture, timber harvesting or other purposes. Increasing support for such efforts is becoming available from both government agencies and nongovernmental organizations, Agrawal says.The authors of the Proponents of FLR say it contributes to human well-being through the use and sale of forest products, that it promotes increases in local food and water security, and that it respects diverse cultural values that local peoples hold for trees and forests."Our study highlights the critical need for close ties between researchers, decision makers and local communities to secure greater wellbeing for people and ecosystems," Agrawal said. "Those working on forests -- whether government agencies or researchers -- forget far too often the necessity of working with people, not against them."
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Geography
| 2,020 |
August 24, 2020
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https://www.sciencedaily.com/releases/2020/08/200824105611.htm
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Big mammals at higher risk of extinction in world's poorest countries
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Big mammals such as elephants, rhinos and primates are at highest risk of extinction in the national parks and nature reserves of the world's poorest countries, a new global review has found.
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The review, which looked at 81 studies carried out between 1980 and 2020, found that illegal hunting was causing worrying declines in the big mammal populations of protected areas across the globe, and particularly in poorer countries.In the four continents included in the study, 294 different mammal species were discovered to have been illegally hunted in the national parks created to protect them.The threat species face in poorer countries may be down to a boom in bushmeat trade and a lack of resources for conservation.In order to protect species, governments and policy makers need to focus on tackling human poverty, the researchers urge.Lead author of the study, Dr Alfan Rija, of Tanzania's Sokoine University of Agriculture who conducted the review while a PhD student at the University of York, said: "We have known for several years that illegal hunting reduces mammal populations, but our review reveals that this is happening even inside protected areas and particularly affects larger mammals (those with a body mass of over 100kg) in the poorest countries. In poorer countries such as my home of Tanzania, bushmeat is a valuable source of income and protein in some areas and there is also less resources available to invest in the security and policing of national parks."The threat from illegal hunting is particularly dangerous to large mammals because they have slow growth rates and so over-hunting is likely to cause population decline."Aside from concerns about the future of many of these species being in peril, the loss of mammals due to illegal hunting pressure has been related to substantial loss of important functional characteristics in an ecosystem. They support many ecological interactions -- such as seed dispersal and regeneration -- and their decline threatens wider biodiversity."The study found that in general across the globe, stricter protected areas showed lower rates of large mammal population decline. However, this was not the case in Asia, where stricter national parks had higher rates of illegal hunting and species decline.Senior author of the study, Dr Colin Beale from the Department of Biology at the University of York, said: "Our research adds to a growing number of studies that suggest Asia is currently a particular focus for the illegal trade of wildlife body parts. Despite strict laws, illegal hunters may be forced to enter protected areas where most sought-after species such as snow leopard, tiger, pangolin, orangutans and sun bears still remain."Improving the effectiveness of Asian protected areas will be important to strengthen biodiversity conservation across continental Asia, and is likely to need a range of measures including ensuing effective law enforcement as well as work with communities in and around valuable wildlife areas."The study was carried out in collaboration with the Department of Wildlife Management, Sokoine University of Agriculture, in Tanzania.
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Geography
| 2,020 |
August 24, 2020
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https://www.sciencedaily.com/releases/2020/08/200824092000.htm
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East Antarctic melting hotspot identified
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Ice is melting at a surprisingly fast rate underneath Shirase Glacier Tongue in East Antarctica due to the continuing influx of warm seawater into the Lützow-Holm Bay.
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Hokkaido University scientists have identified an atypical hotspot of sub-glacier melting in East Antarctica. Their findings, published in the journal The 58th Japanese Antarctic Research Expedition had a very rare opportunity to conduct ship-based observations near the tip of East Antarctic Shirase Glacier when large areas of heavy sea ice broke up, giving them access to the frozen Lützow-Holm Bay into which the glacier protrudes."Our data suggests that the ice directly beneath the Shirase Glacier Tongue is melting at a rate of 7-16 meters per year," says Assistant Professor Daisuke Hirano of Hokkaido University's Institute of Low Temperature Science. "This is equal to or perhaps even surpasses the melting rate underneath the Totten Ice Shelf, which was thought to be experiencing the highest melting rate in East Antarctica, at a rate of 10-11 meters per year."The Antarctic ice sheet, most of which is in East Antarctica, is Earth's largest freshwater reservoir. If it all melts, it could lead to a 60-meter rise in global sea levels. Current predictions estimate global sea levels will rise one meter by 2100 and more than 15 meters by 2500. Thus, it is very important for scientists to have a clear understanding of how Antarctic continental ice is melting, and to more accurately predict sea level fluctuations.Most studies of ocean-ice interaction have been conducted on the ice shelves in West Antarctica. Ice shelves in East Antarctica have received much less attention, because it has been thought that the water cavities underneath most of them are cold, protecting them from melting.During the research expedition, Daisuke Hirano and collaborators collected data on water temperature, salinity and oxygen levels from 31 points in the area between January and February 2017. They combined this information with data on the area's currents and wind, ice radar measurements, and computer modelling to understand ocean circulation underneath the Shirase Glacier Tongue at the glacier's inland base.The scientists' data suggests the melting is occurring as a result of deep, warm water flowing inwards towards the base of the Shirase Glacier Tongue. The warm water moves along a deep underwater ocean trough and then flows upwards along the tongue's base, warming and melting the ice. The warm waters carrying the melted ice then flow outwards, mixing with the glacial meltwater.The team found this melting occurs year-round, but is affected by easterly, alongshore winds that vary seasonally. When the winds diminish in the summer, the influx of the deep warm water increases, speeding up the melting rate."We plan to incorporate this and future data into our computer models, which will help us develop more accurate predictions of sea level fluctuations and climate change," says Daisuke Hirano.
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Geography
| 2,020 |
August 24, 2020
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https://www.sciencedaily.com/releases/2020/08/200824092026.htm
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Fossil pollen record suggests vulnerability to mass extinction ahead
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Reduced resilience of plant biomes in North America could be setting the stage for the kind of mass extinctions not seen since the retreat of glaciers and arrival of humans about 13,000 years ago, cautions a new study published August 20 in the journal
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The warning comes from a study of 14,189 fossil pollen samples taken from 358 locations across the continent. Researchers at the Georgia Institute of Technology used data from the samples to determine landscape resilience, including how long specific landscapes such as forests and grasslands existed -- a factor known as residence time -- and how well they rebounded following perturbations such as forest fires -- a factor termed recovery."Our work indicates that landscapes today are once again exhibiting low resilience, foreboding potential extinctions to come," wrote authors Yue Wang, Benjamin Shipley, Daniel Lauer, Roseann Pineau and Jenny McGuire. "Conservation strategies focused on improving both landscape and ecosystem resilience by increasing local connectivity and targeting regions with high richness and diverse landforms can mitigate these extinction risks."The research, supported by the National Science Foundation, is believed to be the first to quantify biome residence and recovery time over an extended period of time. The researchers studied 12 major plant biomes in North America over the past 20,000 years using pollen data from the Neotoma Paleoecology Database."We find that the retreat of North American glaciers destabilized ecosystems, causing large herbivores -- including mammoths, horses and camels -- to struggle for food supplies," said McGuire, an assistant professor in Georgia Tech's School of Biological Sciences and School of Earth and Atmospheric Sciences. "That destabilization combined with the arrival of humans in North America to land a one-two punch that resulted in the extinction of large terrestrial mammals on the continent."The researchers found that landscapes today are experiencing resilience lower than any seen since the end of the Pleistocene megafauna extinctions."Today, we see a similarly low landscape resilience, and we see a similar one-two punch: humans are expanding our footprint and climates are changing rapidly," said Wang, a postdoctoral researcher who led the study. "Though we know that strategies exist to mitigate some of these effects, our findings serve as a dire warning about the vulnerability of natural systems to extinction."By studying the mix of plants represented by pollen samples, the researchers found that over the past 20,000 years, forests persisted for longer than grassland habitats -- averaging 700 years versus about 360 years, though they also took much longer to re-establish after being perturbed -- averaging 360 years versus 260 years. "These findings were somewhat surprising," said McGuire. "We had expected biomes to persist much longer, perhaps for thousands of years rather than hundreds."The research also found that forests and grasslands transition quickly when temperatures are changing fast, and that they recover most rapidly if the ecosystem contains high plant biodiversity. Yet not all biomes recover; the study found that only 64% regain their original biome type through a process that can take up to three centuries. Arctic systems were least likely to recover, the study found.Landscape resilience, the ability of habitats to persist or quickly rebound in response to disturbances, have helped maintain terrestrial biodiversity during periods of climactic and environmental changes, the researchers noted."Identifying the tempo and mode of landscape transitions and the drivers of landscape resilience is critical to maintaining natural systems and preserving biodiversity given today's rapid climate and land use changes," the authors wrote. "However, resilient landscapes are difficult to recognize on short time scales, as perturbations are challenging to quantify and ecosystem transitions are rare."Contrary to prevailing ecological theory, the researchers found that pollen richness -- indicating diversity of species -- did not necessarily correlate with residence time. Ecological theory suggests that biodiversity increases ecosystem resilience by improving "functional redundancy," allowing a system to maintain stability even if a single or several species are lost. "But species richness does not necessarily reflect functional redundancy, and as a result may not be correlated with ecosystem stability," the researchers wrote.The study used pollen data from five forest types -- forest/tundra, conifer/hardwood, boreal forest, deciduous forest, and coastal forest, five shrub/herb biome types -- Arctic vegetation, desert, mountain vegetation, prairies, and Mediterranean vegetation, and two no?analog biome types -- spruce parkland and mixed parkland.The Neotoma Paleoecology Database contains fossil pollen and spores that are ubiquitous in lake and mire sediments. Collected through core sampling, the samples represent a wide diversity of plant taxa and cover an extended period of time.Though the effects of climate change and human environmental impacts don't bode well for the future of North American plant biomes, there are ways to address it, Wang said. "We know that strategies exist to mitigate some of these effects, such as prioritizing biodiverse regions that can rebound quickly and increasing the connectivity between natural habitats so that species can move in response to warming."
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Geography
| 2,020 |
August 21, 2020
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https://www.sciencedaily.com/releases/2020/08/200821155749.htm
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Nutrients make coral bleaching worse
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A new study shows nutrients can aggravate the already negative effects of climate change on corals to trigger mass coral bleaching.
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Coral reef environments are typically low in naturally occurring nutrients such as nitrogen and phosphorus compounds. But ocean currents passing by can bring in a concentration of nutrients from elsewhere. Similarly, nutrients from human-made fertilisers and stormwater runoff enter reefs from adjacent coastlines.Lead author Dr Thomas DeCarlo from the King Abdullah University of Science and Technology (KAUST) says corals are sensitive to high levels of nutrients."As the climate warms, mass coral bleaching could occur as often as annually within this century," Dr DeCarlo said. "In our study, we found that already heat-stressed corals exposed to excess nutrient levels were even more susceptible to bleaching."The study suggests ecosystem managers can reduce the impacts of coral bleaching by implementing strategies to reduce nutrient stress in areas subject to thermal stress.Co-author Professor John Pandolfi from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at The University of Queensland says this and previous studies, including on the Great Barrier Reef, related coral bleaching to combinations of heat and nutrient stresses."Our results provide a roadmap for coral reef conservation efforts to be at their most effective," Prof Pandolfi said. "We suggest oceanographic processes should be included when deciding when and where to allocate resources or protection."Using the skeletal cores of long-living corals, the authors studied the past few decades worth of bleaching events in the Red Sea. They found the reefs historically suffered severe bleaching only when high sea surface temperatures were coupled with high nutrient levels.The Red Sea was chosen as a study site as it is one of the only marine environments where the effects of summertime nutrients and heat stress are independent of each other: only one area has a single major source of nutrients in the summer, when a water mass brings nutrients to the surface through a process called upwelling.Previous field tests on the role of nutrients in coral bleaching were otherwise difficult: nutrients and temperature often co-vary in the ocean, making it difficult to disentangle their effects. Nutrient loads are also difficult to measure in the same way sea surface temperatures are, via satellite."The fact that nutrients are more difficult to measure than temperature may be restricting our recognition of their importance," Dr DeCarlo said. "And we need greater longer-term monitoring efforts of nutrient levels on coral reefs.""Incorporating nutrient-supplying ocean currents into coral bleaching forecasts will enhance those predictions that are based on temperatures alone," Prof Pandolfi said."Our research suggests that projections of coral reef futures should move beyond solely temperature-based stress to incorporate the influence of ocean current systems on coral reef nutrient enrichment, and thus susceptibility to bleaching," Dr DeCarlo said.
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Geography
| 2,020 |
August 21, 2020
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https://www.sciencedaily.com/releases/2020/08/200821155746.htm
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Arctic ocean moorings shed light on winter sea ice loss
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The eastern Arctic Ocean's winter ice grew less than half as much as normal during the past decade, due to the growing influence of heat from the ocean's interior, researchers have found.
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The finding came from an international study led by the University of Alaska Fairbanks and Finnish Meteorological Institute. The study, published in the The moorings measured the heat released from the ocean interior to the upper ocean and sea ice during winter. In 2016-2018, the estimated heat flux was about 10 watts per square meter, which is enough to prevent 80-90 centimeters (almost 3 feet) of sea ice from forming each year. Previous heat flux measurements were about half of that much."In the past, when weighing the contribution of atmosphere and ocean to melting sea ice in the Eurasian Basin, the atmosphere led," said Igor Polyakov, an oceanographer at UAF's International Arctic Research Center and FMI. "Now for the first time, ocean leads. That's a big change."Typically, across much of the Arctic a thick layer of cold fresher water, known as a halocline, isolates the heat associated with the intruding Atlantic water from the sea surface and from sea ice.This new study shows that an abnormal influx of salty warm water from the Atlantic Ocean is weakening and thinning the halocline, allowing more mixing. According to the new study, warm water of Atlantic origin is now moving much closer to the surface."The normal position of the upper boundary of this water in this region was about 150 meters. Now this water is at 80 meters," explained Polyakov.A natural winter process increases this mixing. As sea water freezes, the salt is expelled from ice into the water. This brine-enriched water is heavier and sinks. In the absence of a strong halocline, the cold salty water mixes much more efficiently with the shallower, warm Atlantic water. This heat is then transferred upward to the bottom of sea ice, limiting the amount of ice that can form during winter."These new results show the growing and spreading influence of heat associated with Atlantic water entering the Arctic Ocean," added Tom Rippeth, a collaborator from Bangor University. "They also suggest a new feedback mechanism is contributing to accelerating sea ice loss."Polyakov and his team hypothesize that the ocean's ability to control winter ice growth creates feedback that speeds overall sea ice loss in the Arctic. In this feedback, both declining sea ice and the weakening halocline barrier cause the ocean's interior to release heat to the surface, resulting in further sea ice loss. The mechanism augments the well-known ice-albedo feedback -- which occurs when the atmosphere melts sea ice, causing open water, which in turn absorbs more heat, melting more sea ice.When these two feedback mechanisms combine, they accelerate sea ice decline. The ocean heat feedback limits sea ice growth in winter, while the ice-albedo feedback more easily melts the thinner ice in summer."As they start working together, the coupling between the atmosphere, ice and ocean becomes very strong, much stronger than it was before," said Polyakov. "Together they can maintain a very fast rate of ice melt in the Arctic."Polyakov and Rippeth collaborated on a second, associated study showing how this new coupling between the ocean, ice and atmosphere is responsible for stronger currents in the eastern Arctic Ocean.According to that research, between 2004-2018 the currents in the upper 164 feet of the ocean doubled in strength. Loss of sea ice, making surface waters more susceptible to the effects of wind, appears to be one of the factors contributing to the increase.The stronger currents create more turbulence, which increases the amount of mixing, known as shear, that occurs between surface waters and the deeper ocean. As described earlier, ocean mixing contributes to a feedback mechanism that further accelerates sea ice decline.Accelerated currents have practical implications in the Arctic. Ship captains need accurate maps of currents for navigation. Since currents move sea ice, oil and gas extraction activities also need information about currents.
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Geography
| 2,020 |
August 21, 2020
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https://www.sciencedaily.com/releases/2020/08/200821120043.htm
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Understanding how birds respond to extreme weather can inform conservation efforts
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When it comes to climate change, University of Wisconsin-Madison forest and wildlife ecology Professor Ben Zuckerberg says birds are the proverbial canary in the coal mine. They are both responsive and sensitive to changes in the environment, including the extreme weather events associated with a warming planet.
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However, not all birds are the same, and not all weather events have the same impact. How do different bird species respond to extreme weather events that occur for different amounts of time, ranging from weekly events like heat waves to seasonal events like drought? And how do traits unique to different species -- for example, how far they migrate or how commonly they occur -- predict their vulnerability to extreme weather?To answer these questions, ecologists would traditionally observe a small number of bird species at a few sites over a few years, and then draw general conclusions. However, Zuckerberg and UW-Madison postdoctoral researcher Jeremy Cohen, along with Daniel Fink of the Cornell Lab of Ornithology, had more ambitious goals: they looked at 109 species across eastern North America over a 15-year period, and integrated this information with fine-scale satellite temperature and precipitation data.In a study recently published in the journal The researchers used data from eBird, a global citizen-science initiative where bird enthusiasts submit checklists of bird sightings online. These checklists include which species were seen, how many, the location and time, and other observations.The researchers compiled more than 830,000 of these checklists and integrated each one with weather data summarized over the week, month and three months before the observation was recorded. They relied on advanced computing to manage this large amount of information."The study we did would not have been remotely possible without data science," says Cohen. The emerging field of data science involves the study, development or application of methods that reveal new insights from data.Zuckerberg points out that the combination of citizen science and data science makes research possible at a scale that was previously unimaginable for ecologists. However, citizen science has its limitations. Researchers have less control over the scientific process, and data quality can vary."Someone can go out for five minutes or two hours and submit eBird data. They can submit a checklist for 10 species or 40 species," says Zuckerberg. "We've adopted data science methods for working with large, unstructured data sets."After controlling for this noisy data, the researchers observed that some species are less sensitive to extreme weather, and populations are not equally exposed to its effects because some geographic areas are warming faster than others.When it comes to heat waves, Cohen notes, "long-distance migrants were not super affected by really hot periods. They winter in tropical environments and should be tolerant of heat."However, resident birds and short-distance migrants such as robins and red-winged blackbirds responded negatively to heat waves, with their numbers sometimes declining 10% to 30% over several weeks.As for drought, commonly occurring species like crows were more resilient than rare birds, particularly if the drought was severe and long-lasting."Rarer species have more specialized habitat and food requirements -- this is a general rule in ecology," says Cohen. "More common species usually have more options. If habitat quality declines due to drought, a generalist can go somewhere else."Cohen says this is the first large-scale study, spanning half a continent, to look at how birds respond immediately after weather events. Because of the scope of the project, conservationists can better understand how many different bird species are likely to be affected by climate change, and mitigate some of the negative effects."If birds are truly winged sentinels of climate change, the greater likelihood of drought, flooding and extreme temperature conditions like heat waves will have significant consequences," says Zuckerberg. "We need to think about how we help species adapt to climate extremes."The study was funded in part by the National Science Foundation (grants CCF-1522054, CNS-1059284 and DBI-1356308) and the UW-Madison Data Science Initiative.
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Geography
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August 21, 2020
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https://www.sciencedaily.com/releases/2020/08/200821103907.htm
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Sea-level rise linked to higher water tables along California coast
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In the first comprehensive study of the link between rising sea levels and inland water tables along the California coast, researchers found an increased threat to populated areas already at risk from rising water tables, and the possibility of flooding in unexpected inland areas.
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In the new study, researchers modeled the effects of rising sea level along the entire California coastline. While results varied with local topography, the study indicates rising sea levels could push inland water tables higher, resulting in damage to infrastructure and increased severity of flooding."Increased roadway fatigue, reduced sewer and septic drainage, and the potential for mobilizing contaminants in soils currently above the water table will eventually be triggered farther inland as the water table rises with higher sea levels," researchers concluded.Kevin Befus, assistant professor of geosciences at the University of Arkansas, is the first author of the study, published in the journal Nature Climate Change.While many coastal areas are focused on overland flooding as a result of sea level rise, the threat of rising groundwater tables, known as "shoaling," is not as well known or understood. Shoaling occurs when rising seawater pushes inland. The denser marine water underlies shallow freshwater aquifers, pushing them upward. In some low-lying areas, shoaling could force groundwater water to the surface, increasing the likelihood of flood damage.Researchers identified key infrastructure at risk from shoaling, including the Port of Los Angeles and airports in Santa Barbara and San Francisco.But groundwater does not need to emerge to cause problems, the authors noted. Rising water tables, for instance from 6 feet below ground to 3 feet, could impact buried infrastructure such as wastewater pipes, electrical conduits and building foundations. Places like Miami and Hawaii have long grappled with this immediate connection between the ocean and their groundwater. But for most coastal communities in California, the connection is more subtle and has not yet become a part of their climate planning.
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Geography
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August 21, 2020
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https://www.sciencedaily.com/releases/2020/08/200821094830.htm
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End of Green Sahara linked to SE Asia megadrought
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Physical evidence found in caves in Laos helps tell a story about a connection between the end of the Green Sahara -- when once heavily vegetated Northern Africa became a hyper-arid landscape -- and a previously unknown megadrought that crippled Southeast Asia 4,000 to 5,000 years ago.
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In a paper published today in Nature Communications, scientists at the University of California, Irvine, the University of Pennsylvania, William Paterson University of New Jersey and other international institutions explain how this major climate transformation led to a shift in human settlement patterns in Southeast Asia, which is now inhabited by more than 600 million people."In this study, we provide the first proof for a strong link between the end of the Green Sahara and Southeast Asian monsoon failure during the mid- to late Holocene period," said co-author Kathleen Johnson, UCI associate professor of Earth system science. "Our high-resolution and well-dated record suggests a strong connection between Northern Africa and mainland Southeast Asia during this time."To create a paleoclimate record for the study, Johnson and other researchers gathered stalagmite samples from caves in Northern Laos. In her UCI laboratory, they measured the geochemical properties of the oxygen and carbon isotopes, carbon-14, and trace metals found in the specimens. This helped them verify the occurrence of the drought and extrapolate its impacts on the region.Johnson said they combined data from the analysis of these stalagmite-derived proxies with a series of idealized climate model simulations -- conducted by co-author Francesco Pausata of the University of Quebec in Montreal -- in which Saharan vegetation and dust concentrations were altered in a way that permitted them to investigate the ocean-atmosphere feedbacks and teleconnections associated with such an abrupt shift in precipitation.The modeling experiments suggested that reduced plant growth in the Sahara led to increased airborne dust that acted to cool the Indian Ocean and shift the Walker circulation pattern eastward, causing it to behave in ways similar to modern-day El Niño events. This, ultimately, led to a large reduction in monsoon moisture across Southeast Asia that lasted more than 1,000 years, according to Johnson.Anthropologists and archaeologists have previously studied the effects of the demise of the Green Sahara, also known as the African humid period, on population centers closer to Western Asia and North Africa, noting the collapse of the Akkadian Empire of Mesopotamia, the de-urbanization of the Indus Civilization (near present-day Pakistan and India) and the spread of pastoralism along the Nile River.But the link to the origin of the Southeast Asia megadrought and lifestyle pattern shifts in the region had not been previously investigated, according to lead author Michael Griffiths, professor of environmental science at William Paterson University of New Jersey."Archaeologists and anthropologists have been studying this event for decades now, in terms of societal adaptations and upheavals, but its exact cause has eluded the scientific community," said Griffiths, who was a National Oceanic and Atmospheric Administration-supported postdoctoral scholar in Johnson's lab and has collaborated with her on this research topic for more than 10 years."Results from this work provide a novel and convincing explanation for the origin of the Southeast Asia megadrought and could help us better understand, to varying degrees, the observed societal shifts across many parts of the tropics and extra-tropics," he said.The researchers suggest that the centuries-long megadrought corresponds to the "missing millennia" in Southeast Asia between 4,000 and 6,000 years ago, a time characterized by a noticeable lack of archaeological evidence in interior Southeast Asia compared to earlier and later portions of the Holocene.They propose that the mid-Holocene megadrought may have been an impetus for mass population movements and the adoption of new, more resilient subsistence strategies -- and that it should now be considered as a possible driver for the inception of Neolithic farming in mainland Southeast Asia."This is outstanding evidence for the type of climate change that must have affected society, what plants were available, what animals were available," said co-author Joyce White, adjunct professor of anthropology at the University of Pennsylvania. "All of life had to adjust to this very different climate. From an archaeological point of view, this really is a game changer in how we try to understand or reconstruct the middle Holocene period."
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August 20, 2020
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https://www.sciencedaily.com/releases/2020/08/200820151335.htm
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Anthropogenic CO2 increase is unprecedented
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A new measurement technology developed at the University of Bern provides unique insights into the climate of the past. Previous CO
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In 2008, the Bern ice core specialists were able to show that the COThe fact that rapid COThe researchers compared the CO
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Geography
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August 20, 2020
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https://www.sciencedaily.com/releases/2020/08/200820143830.htm
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Past rapid warming levels in the Arctic associated with widespread climate changes
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Abrupt climate changes during the Last Glacial Period, some 115,000 to 11,700 years ago, happened at the same time across a region extending from the Arctic to the Southern Hemisphere subtropics, new research has revealed.
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The study, led by University of Melbourne PhD student Ellen Corrick and published today in the journal, "Some of the largest and most abrupt climate changes in Earth's geological recent past occurred during the Last Glacial Period, a cold interval that extended between 115,000 and 11,700 years ago," Ms Corrick said.Greenland ice cores recorded more than 25 abrupt warming episodes during this period. These so called 'Dansgaard-Oeschger events' were associated with increases in air temperature over Greenland of up to 16°Celsius, sometimes in a matter of a few decades.Researchers say the findings provide important information for testing numerical models used to predict future climate changes and demonstrate that profound climate changes can occur simultaneously, highlighting the unstable nature of the climate system.Co-author, University of Melbourne Associate Professor Russell Drysdale, said: "Demonstrating synchrony in the climate response across such a broad region marks a major advance in the study of Dansgaard-Oeschger events. It allows scientists to improve understanding of how the events are propagated globally via the ocean and atmosphere system."The research team, which involved scientists from Denmark, the UK, Germany, China, France and Switzerland, collated 63 individual climate records derived from stalagmites collected from caves across Europe, Asia and South America. The records represent over 20 years' worth of published research from scientific teams around the world.Stalagmites -- a type of cave mineral formation -- preserve information on regional temperature and rainfall as they grow. Crucially, they can be dated very precisely, allowing the timing of climate events to be compared between records from different regions.University of Melbourne Geochronologist Dr John Hellstrom, said that resolving the issue of timing has proved difficult because precisely dated records of past climate are required to determine exactly when the events took place."Such records are relatively rare, and it is only now that we have enough high-quality records to actually answer the question of synchrony," Dr Hellstrom said.According to co-author Professor Eric Wolff from the University of Cambridge, the findings resolve a long-standing dilemma within the paleoclimate community, who study ancient climates."They provide confirmation of a persistent but, until now, unsubstantiated assumption that climate changes between the tropics and the Arctic were synchronous."
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Geography
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August 20, 2020
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https://www.sciencedaily.com/releases/2020/08/200820143827.htm
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Greenland ice sheet shows losses in 2019
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The Greenland Ice Sheet recorded a new record loss of mass in 2019. This was the finding of a team of international researchers after evaluating data from satellite observations and modelling data. The total loss amounted to 532 billion metric tons, more than in the previous record year 2012 (464 billion metric tons), which equates to an average global sea-level rise of 1.5 mm. After two years characterised by low loss of mass in 2017 and 2018, the ice sheet is now heading toward increasing mass losses. The five years with the greatest losses all occurred in the last decade. The ice loss in 2019 exceeded the increase due to snowfall by over 80%. The study was published today in the journal
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In order to determine the ice loss, researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), the German Research Centre for Geosciences GFZ and international partners evaluated satellite data from the GRACE mission, and its successor mission, GRACE Follow-On (GRACE-FO). The satellites provided highly accurate measurements, which were used to create monthly maps of Earth's gravity. The redistribution of the masses, e.g. ice losses in the oceans, leads to temporal and spatial changes in Earth's gravitational forces. The researchers compared the satellite data with regional climate models that are specially designed to calculate the snowfall and the melting of the ice sheet."After a two-year 'breather', in 2019 the mass loss increased steeply and exceeded all annual losses since 1948, and probably for more than 100 years," says Ingo Sasgen, a glaciologist at the AWI in Bremerhaven and first author of the study. "There are increasingly frequent, stable high-pressure areas over the ice sheet, which promote the influx of warm air from the middle latitudes. We saw a similar pattern in the previous record year 2012."The mass balance for a given a year is calculated using the difference between the ice increase due to snowfall and ice loss due to melting and ice discharge at the edge of the ice sheet. "The snowfall in 2019 was below the long-term average, and that also contributed to the record figure," explains Marco Tedesco, a professor at Columbia University and co-author of the study. "By comparing satellite data with regional climate models, we were able to see precisely which processes were involved and to what extent, and which general weather conditions were dominant," he adds.The two satellite missions GRACE and GRACE-FO, which monitor the Earth's gravitational field, play a vital role in the continuous observations of the Greenland Ice Sheet. The measurements allow the mass changes in the ice sheet to be quantified. "The GRACE satellite mission, which ended in summer 2017, provided us with essential data on ice loss in the polar regions over a period of 15 years," explains Christoph Dahle from the GFZ, who is responsible for calculating the gravitational fields from the mission's raw data. "After a gap of about a year, in summer 2018 we were able to resume monitoring with the follow-on mission, GRACE-FO."In summer, the Arctic warms roughly one and a half times as quickly as the global average. Added to this are the various feedback effects that increase the ice loss. "2017 and 2018 were very cold years in Greenland, with high snowfall," says Sasgen. The GRACE/GRACE-FO data shows, however, that in these years the mass balance was negative due to the high discharge from the glacier into the ocean. "We see substantial variations from year to year. But the five years with the highest losses since 1948 were all in the last decade," reports Sasgen.
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Geography
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August 20, 2020
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https://www.sciencedaily.com/releases/2020/08/200820112850.htm
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Larger variability in sea level expected as Earth warms
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A team of researchers from the University of Hawai'i (UH) at M?noa School of Ocean and Earth Science and Technology (SOEST) identified a global tendency for future sea levels to become more variable as oceans warm this century due to increasing greenhouse gas emissions. Sea level variability alters tidal cycles and enhances the risks of coastal flooding and erosion beyond changes associated with sea level rise.
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Sea level rise is occurring as Earth warms due to two main factors: melting of land-based ice such as glaciers and ice sheets, and the expansion of seawater as it warms -- termed thermal expansion. Previously unknown was whether the rate of thermal expansion, which accelerates with warming, will also affect the variability of sea level.In a study published this week in "Whereas it is well understood that the rate of global mean sea level rise will accelerate with future warming, in part due to the oceans expanding faster at higher temperatures, it was previously unexplored how this nonlinear thermal expansion property of seawater will affect future sea level variability," said Widlansky."Following thermodynamic laws, sea level variability increases in a warmer climate because the same temperature variations, for example related to the seasonal cycle, cause larger buoyancy and sea level fluctuations," added Fabian Schloesser, a researcher at the UH Sea Level Center who collaborated on the study.In places where changes due to ocean thermodynamics and other climate variability processes align, the team found the largest increases in future sea level variability.Coastal flooding occurs increasingly often due to a combination of slowly rising sea levels and ocean variability. The new findings therefore further emphasize the importance of sea level monitoring and forecasting."Forecasting can potentially provide alerts months in advance if sea levels are likely to cause tides to be more extreme than otherwise expected," said Widlansky.While the science team explores how to develop better forecast outlooks, the UH Sea Level Center is actively monitoring extremes through a global network of tide gauge observations, including in Honolulu, Hawai'i.
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Geography
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August 19, 2020
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https://www.sciencedaily.com/releases/2020/08/200819170229.htm
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A how-to guide for teaching GIS courses online with hardware or software in the cloud
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In a new paper this week, geographer Forrest Bowlick at the University of Massachusetts Amherst and colleagues at Texas A&M offer first-hand accounts of what is required for GIS instructors and IT administrators to set up virtual computing specifically for providing state-of-the-art geographic information systems (GIS) instruction.
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Bowlick says, "Our research is very applicable in the current remote learning era that we're working through, because it provides expertly driven insight into how to set up a virtual computing environment in different modes: with hardware and with software in the cloud. While tailored to those needing GIS support, it is also very applicable for other high-performance software needs.""By capturing the experiences of both setting up the system and of students using the system, we provide an important resource for others needing to make this investment of time, equipment and energy," he adds. Such technical practice is becoming required for GIS and other instruction, he points out.Writing in the He says, "UMass is just one of several programs nationally, but regionally it's very attractive, especially at the graduate level, because there are not that many in New England. Ours certainly started at the right time, too. With the turn toward using more computational skills and GIS practices, how to use different computer constructs and programming language are become more fundamental needs in education."Bowlick has directed a one-year M.S. geography degree program with an emphasis in GIS at UMass Amherst since 2017. He says there may be 10 or 15 students from every college on campus with different majors in the introductory course in a given semester. They need to gain fundamentals of spatial thinking, operating software and problem solving applicable to the diverse interests that students bring to the course.Generally, these applications involve how to think through spatial problems on such topics as political geography, for example, which might ask who is voting and where, or on gerrymandering and how to discover it. Others are creating COVID-19 virus maps and spatial data to show its prevalence for spatial epidemiology and health geography, while others are modeling ecosystems for fish and wildlife.Bowlick explains that geographic information science is "a bridging science" -- a suite of technologies, a way of thinking and a way to store spatial data including satellite systems for navigation. GIS handles imagery, computer mapping, spatial planning, modeling land cover over time, even helping businesses decide where to open their next location.GIS was first developed in the late 60s when the Canada Land Inventory needed ways to store, manage and analyze land resource maps over huge areas using new computer technology, Bowlick says. His two co-authors at Texas A&M, both experienced GIS instructors, are Dan Goldberg, an associate professor in geography, and Paul Stine, an IT system administrator for geography.The authors describe the setup, organization and execution of teaching an introductory WebGIS course while considering student experiences in such a course.The paper also defines an operational set of resource metrics needed to support the computing needs of students using virtual machines for server-based CyberGIS classes, as well as comparing costs and components needed to build and support an on-premise private cloud teaching environment for a WebGIS course in an on-premise private cloud teaching environment vs. a comparable cloud-based service provider.
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Geography
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August 19, 2020
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https://www.sciencedaily.com/releases/2020/08/200819120704.htm
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If sustainably managed, wild fisheries and mariculture could help meet rising demand for food
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Demand for food is set to rise substantially in the coming decades, which raises a question: How well can the ocean fill the gap between current supply and future need?
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To find an answer, the High Level Panel for a Sustainable Ocean Economy -- 14 world leaders working to facilitate a more resilient future for people and planet -- turned to an international consortium of experts whose breadth of knowledge encompasses economics, biology, ecology, nutrition, fisheries and mariculture."Basically the question we were trying to answer was: Does sustainably managing the ocean over the next 30 years mean we will produce more food, or less?" said Christopher Costello, a professor of environmental and resource economics at UC Santa Barbara's Bren School of Environmental Science & Management. Costello is the lead author of an Ocean Panel paper as well that is also new research published in the journal Given the growing demand for food and the constraints of expanding land-based food production, ocean-based foods -- nutrient-rich and a good source of protein -- are poised to be the next great stand against food insecurity for the estimated 9.8 billion people on the planet by 2050. But can we produce more from the ocean without collapsing its ecosystems?"I think many of us went into this thinking that to manage the ocean sustainably, we would have to extract less, which would mean less food from the sea," Costello said. What the researchers found, however, was the opposite."If done sustainably, you could actually increase food from the sea, and by an outsize proportion relative to expansion of land-based food," said Costello. "And it could be done in a way that's much more environmentally friendly for the climate, biodiversity and other ecosystem services than food production on land."In fact, sustainability is key to the successful increase in food production from the ocean. "By improving sustainability and equity through a range of actionable policy and business commitments, food from the sea has the potential to expand in the future, nourishing the growing human population," said Stefan Gelcich, an associate professor at the Pontificia Universidad Católica de Chile and a co-author on the study."We've had a history of overexploiting many fisheries, but we're seeing governments starting to implement better fisheries management policies," Costello said. "And when you rebuild fisheries, you restore the health of the ocean and that allows you to have more food." The researchers estimate a roughly 16% increase in wild-caught seafood by 2050 if fisheries are sustainably managed. Conversely, failure to improve management could lead to significant reductions in seafood production from wild fisheries.Farmed seafood stands to see an even greater increase in food production if done in balance with nature; some places with unsustainable mariculture would have to be scaled back, possibly rehabilitated, and other areas encouraged to develop sustainable seafood farms. With innovations that reduce mariculture's dependency on fish-based feed and effective policies that can lower the barriers to initiating environmentally friendly mariculture operations, farmed fish and shellfish production can increase dramatically."More rapid alternative feed adoption and efficiency improvements in aquaculture will be key for scaling sustainable marine production," said Halley Froehlich, an assistant professor in UC Santa Barbara's Department of Ecology, Evolution, & Marine Biology and Environmental Studies and also a co-author on the study. While sustainable supply could increase by more than six-fold, when both supply and demand are considered, she added, the likely increase in mariculture is between 2 to 4 times, depending on future demand.There's no better time than the present to start sustainably planning and growing the system that could be feeding us in a generation, according to Costello, who pointed out that increases in population and wealth, along with the awareness that seafood is particularly nutritious, will drive future demand."Demand for meat tends to increase with wealth," said Costello, adding that the group also looked at the potential demand for seafood -- a rare and sometimes overlooked assessment -- and found that potential growth in supply could more than meet projected demand.Projections of population and income by 2050 suggest a future need for more than 500 million metric tons of edible meat per year for human consumption, a 38% increase from today's production. Supplying that demand with land-based meat production would be difficult due to less available space and environmental impacts; shifting to ocean production could ease that pressure while supplying meat that is sustainably sourced and overall healthier for people."As people's diets shift, as they get wealthier, as the population grows, as they start to realize that fish are more nutritious and healthier than land-based sources of meat, the demand grows," said Costello. "That raises prices and creates an economic incentive to generate food from the sea."
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Geography
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August 19, 2020
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https://www.sciencedaily.com/releases/2020/08/200819102815.htm
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Heating our climate damages our economies: Study reveals greater costs than expected
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Rising temperatures due to our greenhouse gas emissions can cause greater damages to our economies than previous research suggested, a new study shows. Scientists from the Potsdam Institute for Climate Impact Research (PIK) and the Mercator Research Institute for Global Commons and Climate Change (MCC) took a closer look at what climate change does to regions at the sub-national level, such as US states, Chinese provinces or French départments, based on a first-of-its-kind dataset by MCC. If CO
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"Climate damages hit our businesses and jobs, not just polar bears and coral reefs," says Leonie Wenz from PIK, one of the two authors of the study. "Rising temperatures make us less productive which is relevant in particular for outdoor work in the construction industry or agriculture. They affect our harvests and they mean extra stress and thus costs for our infrastructure as for instance computer centres need to be cooled. By statistically evaluating climate and economic data from the past decades, we found that the aggregated economic damages from rising temperatures are even greater than previously estimated because we looked at the sub-national effects which provide a more comprehensive picture than national averages."Previous research suggested that a 1°C hotter year reduces economic output by about 1%, whereas the new analysis points to output losses of up to three times that much in warm regions. Using these numbers as a benchmark for computing future damages of further greenhouse gas emissions, the researchers find significant economic losses: 10% on a global average and more than 20% in the tropics by 2100. This is still a conservative assessment since the study did not take into account damages from, for example, extreme weather events and sea-level rise, which will also be substantial but are hard to pin down for single regions.The new insight was made possible by building a novel MCC-dataset of climate and economy for 1500 regions in 77 states around the world that, for some regions, dates back to the 1900s. Data coverage is best for industrialized countries, however, with economic information lacking in particular for large parts of Africa. While the calculations show a substantial impact on economic production, they do less so for permanent economic growth reductions, which might be a reason for hope once emissions are reduced. Importantly, the damages are distributed very unevenly across the world with tropical and already poor regions suffering most from continued warming whereas a few countries in the North might even profit.The findings have important implications for climate policy, and namely COBy way of comparison: the carbon price in European emissions trading currently fluctuates between 20 and 30 euros per tonne; the national carbon price in Germany rises from 25 euros next year to 55 euros in 2025. These current carbon prices thus reflect only a small part of the actual climate damage. According to the polluter-pays principle, they would need to be adjusted upwards significantly.
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Geography
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August 19, 2020
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https://www.sciencedaily.com/releases/2020/08/200819085003.htm
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Alaska's salmon are getting smaller, affecting people and ecosystems
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The size of salmon returning to rivers in Alaska has declined dramatically over the past 60 years because they are spending fewer years at sea, according to a new study led by researchers at the University of California, Santa Cruz, and the University of Alaska Fairbanks.
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Salmon are critically important to both people and ecosystems in Alaska, supporting commercial and subsistence fisheries and transporting nutrients from the ocean to inland areas, fertilizing the ecosystems in and around the rivers where they spawn. Smaller salmon provide less food for people who depend on them, less value for commercial fishers, and less fertilizer for terrestrial ecosystems.For years, people in Alaska have been noticing that wild salmon were getting smaller, but the reasons have been unclear. In the new study, published August 19 in The results showed that the decreases in body size are primarily due to salmon returning to their spawning grounds at younger ages than they have in the past. Alaskan salmon can spend up to seven years at sea, although this varies by species. During this time they feed and grow to maturity, migrating great distances in the North Pacific Ocean before returning to fresh water to spawn."There are two ways they could be getting smaller -- they could be growing less and be the same age but smaller, or they could be younger -- and we saw a strong and consistent pattern that the salmon are returning to the rivers younger than they did historically," said corresponding author Eric Palkovacs, professor of ecology and evolutionary biology and associate director of the Fisheries Collaborative Program in the Institute of Marine Sciences at UC Santa Cruz.The researchers identified a range of factors that appear to be driving this shift, some acting across all regions and others affecting only certain species or populations."There's not a single smoking gun," said first author Krista Oke, a postdoctoral scientist initially at UC Santa Cruz and now at University of Alaska Fairbanks. "Small contributions from a lot of factors are adding up to drive these changes."Two factors -- climate change and competition with growing numbers of wild and hatchery salmon in the ocean -- have clearly contributed to size declines across all species and regions, Palkovacs said. In contrast, the effect of commercial fishing appears to be important only for some salmon populations. Similarly, the results were mixed for another proposed driver of size declines, the recovering populations of marine mammals that prey on salmon."We know that climate drives changes in ocean productivity, and we see a consistent signal of climate factors associated with decreasing salmon size," Palkovacs said. "Another consistent association is with the abundance of salmon in the ocean, especially pink salmon. Their abundance in the North Pacific is at historic highs due in part to hatchery production in Alaska and Asia, and they compete with other salmon for food."The observation that salmon are returning to freshwater streams at younger ages implies that the ocean is becoming a riskier place for them to be, he said. By staying in the ocean longer and growing larger, salmon can have greater success in spawning and lay more eggs, but each additional year increases the risk of not returning to reproduce at all."Natural selection has always pushed in both directions, but the balance between the two is changing, pushing harder against the older, larger salmon," Palkovacs said. "It seems that the ocean is becoming a riskier place to be."According to Oke, understanding exactly what is going on in the ocean to drive this shift is a difficult challenge that will require further study. "That's the next hard step I hope we can get to soon," she said. "It could be that they're having to spend more time feeding, which is putting them in risky places. Lots of things could be happening to increase the overall risk of mortality in the ocean, but we weren't able to pin that down."The consequences for people and ecosystems, however, are more clear. Smaller salmon means fewer meals per fish for subsistence fishers, lower profits for commercial fishers, fewer eggs laid to sustain salmon populations, and fewer nutrients to support the productivity and biodiversity of freshwater and riparian ecosystems."Smaller fish is a real problem for people who depend on salmon for their food and well being," Oke said. "For commercial fishers, smaller fish tend to fetch lower prices, and below a certain size they can't be made into high-value products and might have to be canned."On the ecosystem side, the nutrients delivered by salmon runs provide critical support for bears, insects, birds, trees, and juvenile salmon themselves. Palkovacs noted that an extensive body of research has tracked the movement of marine nitrogen from salmon into the terrestrial ecosystems around the streams where they spawn."Salmon go up into these small streams, and whether they are caught by predators or die after spawning, their nutrients are transferred into the forests and freshwater ecosystems," he said. "It's a classic salmon ecosystem service, and the amount of nutrients they deliver depends on their body size."The study had its origins in a working group organized by the National Center for Ecological Analysis and Synthesis (NCEAS) at UC Santa Barbara through its State of Alaska's Salmon and People project. With funding from the Gordon & Betty Moore Foundation, the researchers were able to work with the Alaska Department of Fish and Game to compile data the agency had been collecting for decades, but which was dispersed among different field offices in various smaller databases."At NCEAS, we had two data scientists who compiled all the data into one massive database on Alaskan salmon that is now publicly available," Palkovacs said. "It took a lot of time and energy, but that's what enabled us to do this comprehensive analysis."Oke added that getting the data in the first place was no small task either. "When you think about the fact that we used data from 12.5 million salmon, that's how many times someone from ADF&G measured a salmon. It's an exceptional amount of work to make a dataset like this possible," she said.In addition to Oke and Palkovacs, the coauthors of the paper include corresponding author Peter Westley at University of Alaska Fairbanks, as well as researchers at Alaska Pacific University in Anchorage, UC Davis, UC Berkeley, NCEAS, McGill University in Montreal, Washington Department of Fish and Wildlife, Virginia Polytechnic Institute, Alaska Department of Fish and Game, Simon Fraser University, and Tanana Chiefs Conference, Fairbanks.
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Geography
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August 19, 2020
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https://www.sciencedaily.com/releases/2020/08/200819094756.htm
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Microbes living on air a global phenomenon
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In their first follow-up to a high-profile 2017 study which showed microbes in Antarctica have a unique ability to essentially live on air, researchers from UNSW Sydney have now discovered this process occurs in soils across the world's three poles.
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Specifically, researchers found the target genes responsible for the atmospheric chemosynthesis phenomenon they discovered are abundant and widely distributed in the polar soils of the Antarctic, Arctic and Tibetan Plateau in the Hindu Kush-Himalayas.The new research was published in the journal The study's senior author Associate Professor Belinda Ferrari, of UNSW Science, said living on air was such a minimalistic way to survive that their findings lent further potential for microbial life to exist on other planets."This is what NASA's Mars 2020 Perseverance Rover is aiming to do -- to search for signs of ancient microbial life in core samples of Martian rock and soil," A/Prof Ferrari said."A future mission will take the samples back to Earth and NASA scientists will analyse the soil in a similar way we do, to try and see whether there are any indicators of life."A/Prof Ferrari said the researchers' findings meant that microbes which use trace gases as their energy and carbon source to grow -- unlike photosynthesis which uses light -- was not a process isolated to Antarctica."There are whole ecosystems probably relying on this novel microbial carbon fixation process where microbes use the energy obtained from breathing in atmospheric hydrogen gas to turn carbon dioxide from the atmosphere into carbon -- in order to grow," she said."We think this process occurs simultaneously alongside photosynthesis when conditions change, such as during the polar winter when there is no light, but we aim to confirm this hypothesis in the next stage of our research."So, while more work is needed to confirm this activity occurs globally, the fact that we detected the target genes in the soils of the three poles means this novel process likely occurs in cold deserts around the world, but has simply been overlooked until now."Researchers analysed 122 soil samples from 14 terrestrial cold desert sites across Antarctica (Windmill Islands and Vestfold Hills), the high Arctic and Tibetan Plateau, which they collected between 2005 and 2019.The study's lead author, UNSW PhD candidate Angelique Ray, said one of the big questions the team had when they finished their previous study was whether this new process of atmospheric chemosynthesis -- also known as carbon fixation or carbon sink -- was similarly occurring in other places around the world."So, this time we did a global study. We collected the top 10-centimetre layer of soil from various sites at the three poles, which is the depth where most of the organisms we study are found," she said."The ground at those locations is completely frozen for most of the year -- and there's not a lot of soil because it's mostly rock."The researchers extracted DNA from the soil samples and then sequenced the DNA to detect the target genes responsible for the process of carbon fixation.Ms Ray said the scientists also conducted environmental analyses of each location to gauge the conditions under which the microbes lived."By looking at the environmental parameters in the soil, that's how we knew there was low carbon, low moisture and other factors at play," she said."So, we correlated the target genes for the carbon fixation process against the different sites and found the locations which are drier and lower in nutrients -- carbon and nitrogen -- had a greater potential to support this process, which made sense."A/Prof Ferrari said the researchers' findings would change the way scientists thought about the limitations required for life to exist, as well as how microbiology was taught."By investigating places outside Antarctica, we can determine how significant the contribution of this new form of chemotrophy is to the global carbon budget," she said."Before we discovered this new carbon sink process, the two main known chemotrophic forms were photosynthesis and geothermal chemotrophy -- the latter is where bacteria harness inorganic compounds like hydrogen sulfide to fix carbon."But now we have found the genes involved in this process are abundant in cold deserts, although we are yet to study hot deserts, our finding probably indicates atmospheric chemosynthesis is contributing to the global carbon budget."A/Prof Ferrari said it was likely the bacteria which survived on nothing but air had become key players in the environments in which they lived."A lot of these ecosystems are quite dry and nutrient poor -- so, these locations are mostly dominated by bacteria," she said."Particularly at the original east Antarctic sites we studied, there is not much else there apart from some mosses and lichens (fungus)."Because these bacteria have adapted to survive and have the ability to use trace gases to live, their environment has selected them to become significant contributors to their ecosystems."A/Prof Ferrari said the researchers looked forward to making new discoveries in carbon fixation."As part of the next phase, we aim to isolate one of these novel bacteria in the laboratory -- to obtain a pure culture," she said."This is difficult because the bacteria are used to growing on very little and an agar plate is different to their natural environment."Hopefully then, we can fully understand the conditions these bacteria need to carry out this unique process of living on air."
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Geography
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August 18, 2020
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https://www.sciencedaily.com/releases/2020/08/200818142145.htm
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Surprising coral spawning features revealed
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When stony corals have their renowned mass spawning events, in sync with the moon's cycle, colonies simultaneously release an underwater "cloud" of sperm and eggs for fertilization. But how do the sperm and eggs survive several hours as plankton, given threats from predators, microbes and stresses such as warming waters?
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A Rutgers-led team has discovered some surprising features in coral sperm and eggs (collectively called gametes), according to a study in the journal While coral eggs are large and sperm cells are tiny and far more numerous, the scientists showed for the first time that eggs and sperm appear to be surprisingly similar when it comes to the gene functions they express during the planktonic stage. Proteins encoded by genes, in a process called gene expression, play many critical roles and perform most of the work in cells.The scientists also identified two genes that may be involved in how coral sperm and eggs recognize each other in dynamic ocean waters, allowing fertilization."Much more attention needs to be paid to coral gametes because both egg and sperm are vulnerable to climate change and other insults," said senior author Debashish Bhattacharya, a distinguished professor in the Department of Biochemistry and Microbiology in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. "It goes without saying that without robust sperm and egg, the coral reproductive cycle will be significantly weakened. Therefore, we need to understand in more detail how natural selection has acted on coral gametes to ensure their survival, leading to successful fertilization."Coral reefs protect coastlines from erosion and storms; serve as habitat, nursery and spawning grounds for fish; and provide food for about 500 million people as well as their livelihoods, according to the National Oceanic and Atmospheric Administration. But corals are threatened by global climate change that warms the ocean and leads to coral bleaching, disease, sea-level rise and ocean acidification. Other threats include unsustainable fishing, land-based pollution, tropical storms, damage from vessels, marine debris and invasive species.By analyzing the genes of the Hawaiian stony coral "Our results pave the way for future genetic investigations, particularly in the context of climate change influences on the marine environment," Bhattacharya said.
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Geography
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August 18, 2020
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https://www.sciencedaily.com/releases/2020/08/200818142120.htm
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Study maps the roots of global mangrove loss
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Using high-resolution data from the joint NASA-U.S. Geological Survey Landsat program, researchers have created the first map of the causes of change in global mangrove habitats between 2000 and 2016 -- a valuable tool to aid conservation efforts for these vital coastline defenders.
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Mangroves are hardy trees and shrubs that grow in the salty, wet, muddy soils of Earth's tropical and subtropical coastlines. They protect the coastlines from erosion and storm damage; store carbon within their roots, trunks, and in the soil; and provide habitats for commercially important marine species. The study showed that overall, mangrove habitat loss declined during the period. However, losses from natural causes like erosion and extreme weather declined more slowly than human causes such as farming and aquaculture. For conservation and resource managers trying to prevent loss or re-establish new habitats, this finding highlights the need for strategies that account for natural causes of loss.The global map will benefit researchers investigating the carbon cycle impacts of mangrove gain and loss, as well as help conservation organizations identify where to protect or restore these vital coastal habitats.In 2010, mangroves covered about 53,000 square miles of Earth's coastlines, straddling the line between salt water and muddy soil with their long, stilt-like root systems. The majority of these ecosystems are found in Southeast Asia, but they exist throughout the tropical and subtropical latitudes over the globe.These hardy trees and shrubs provide a "triple whammy" of environmental benefits, said Lola Fatoyinbo Agueh, an environmental scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Mangroves are uniquely efficient carbon sinks: locations where carbon is stored out of the atmosphere. They make up only 3 percent of Earth's forest cover, but if they were all cut down, they could contribute up to 10 percent of global carbon emissions. Adapted to withstand salty water, strong tides, low-oxygen soils and warm tropical temperatures, mangroves protect the coastlines from erosion and storm surges and provide a "nursery" for marine creatures."Mangroves provide shoreline protection from extreme storms and tidal waves," said Fatoyinbo. "Because they are amphibious trees, their root structure protects the inland areas from the coast, and they also protect the coast from the inland areas, because they're able to accumulate a lot of the soil that comes in from upstream or from the coast. They hold that sediment in their roots and essentially grow new land. If you have areas where you have increased erosion due to sea level rise, mangroves might counter that."Mangroves have been threatened by deforestation for decades, as agriculture and aquaculture, urban development and harvesting have caused the loss of more than a quarter of mangrove forests in the past 50 years. Forests in Southeast Asia have been especially hard-hit, as countries like Indonesia clear mangroves to make room for shrimp and rice farming.When planning conservation or restoration efforts for these crucial forests, experts need to know what the primary human and natural threats are for their area. Using high-resolution imagery from Landsat 5, 7 and 8, Fatoyinbo and her colleagues used machine learning algorithms to create a high-resolution map of mangrove losses between 2000 and 2016, with an important addition: They showed what drove those losses.The team found that nearly 1300 square miles of mangrove forests were lost during the study period, or about 2 percent of global mangrove area. Sixty-two percent of the lost area was due to human causes, mainly farming and aquaculture. The rest was due to natural causes, including erosion and extreme weather events.Over the period, both human and natural drivers of loss declined, the team said. But human impact declined more quickly."On the one hand, it's great," said lead author Liza Goldberg, a NASA Goddard intern and rising freshman at Stanford University. "It shows that conservation efforts are increasing in effectiveness on a local scale, and there's an increase in awareness of the importance of mangroves, economic damage from storms, and loss of life. But on the flip side, the decline in losses, especially in Southeast Asia, means that in many areas, there are simply no more mangroves to lose."While natural drivers of loss also decreased, they did so more slowly, the team said. This shift in the proportion of loss drivers poses challenges for conservation and resource managers."The main takeaway is that conservation and restoration efforts should continue to increase their focus on evaluating and mitigating natural threats," Goldberg said.Besides their role in stabilizing coastal ecosystems, mangroves are vital to Earth's carbon cycle -- the exchange of carbon between the land, ocean, atmosphere and living things. Their leaves fall to the soil and decompose very slowly, creating carbon-rich peat instead of releasing it back into the atmosphere. When these trees and shrubs are cut down or destroyed by storms or floods, that carbon instead escapes into the atmosphere, where it contributes to climate change as a greenhouse gas."The type of carbon emissions you'll see from mangroves depend on what type of conversion is happening," said Fatoyinbo. "If you're doing clear-cutting and digging up the soil where most of the carbon is stored to put in a shrimp pond, that will have a very different rate of emission from, let's say, a tropical storm that comes in and damages standing trees, but where you might have regrowth happening afterwards."The team is collaborating with nonprofit and other organizations to put their data to work, helping with carbon emissions estimation, conservation planning and other initiatives to protect these ecosystems for future generations.Goldberg began working with Fatoyinbo and David Lagomasino when she was just 14, starting with basic lab tasks and advancing quickly to writing her own analysis codes for mangrove data. She recently completed her senior year of high school at Atholton High School in Maryland and will begin undergraduate studies at Stanford University this fall."Working with Liza has been really amazing. She's very inspiring," said Fatoyinbo. "We had a lot of discussion with her and large international organizations that are interested in mangroves, and when we asked what would help them better implement their policies and procedures, we kept hearing about needing better change maps and better understanding what the drivers of change are. Liza took that and ran with it."Goldberg plans to continue partnering with Fatoyinbo's team during her undergraduate studies."It's been an honor to work with Lola and her team for the last couple of years," Goldberg said. "It's rare to find an environment where people are so supportive regardless of your age and level of expertise, and it's been invaluable for my own research as I go into college. This environment is unique to NASA and to Goddard."
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Geography
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August 18, 2020
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https://www.sciencedaily.com/releases/2020/08/200818142111.htm
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Primate habitat endangered by climate change mapped around the globe
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Stewart began looking at the effects of climate change on primate habitats with spatial data from the Coupled Model Intercomparison Project Phase 5, which estimates regional and seasonal temperature change per unit of CO
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Specifically, she looked at annual average temperatures to see if they would exceed the pre-industrial seasonal maximum temperature (PSMT), or if they already had. In other words, she wanted to see how much hotter future To do this, she created individual range maps for each of the 426 species and subspecies of primates. She then estimated temperature increases as a direct result of the amount of COAccording to her calculations, a 2 degree Celsius increase in global average temperatures above pre-industrial levels -- the ceiling affirmed by the Paris Agreement -- would lead to more than a quarter of all species ranges' experiencing temperatures higher than those of pre-industrial times. For eight per cent of species, their entire current range would be significantly hotter than in the pre-industrial past."That's where my assumption really gets its power," she explains. "The maximum pre-industrial temperature under which these primates could function could have been a very brief period of time, for instance, the hottest week of the summer. But with this model, it becomes the average annual temperature."While two-thirds of primates still live in habitats with average temperatures below their PSMT, one-third are living in ranges that have experienced higher temperatures. That can spell serious trouble, especially if their ranges are particularly small."When it gets really hot, the primates need to rest in shade more. That means they can't forage for food or socialize and play as much as they should," she says. "Their food supply could also be at risk, and seasonal changes in temperature can even affect their reproductive cycles."She notes that nine species, several of them endangered and two critically so, are currently living in habitats that are entirely above their threshold temperature.Her work has clearly impressed her supervisors. Turner says she is "a superb young researcher exploring scientific questions in animal behaviour while making her research relevant to conservation and sustainability. This study models potential climate change impacts on our closest animal relatives, and Brogan is continuing to bring together primates and sustainability issues in her current PhD research."Stewart is well aware that the struggle to mitigate the effects of climate change is not the work of a single individual, but rather a collaborative effort that requires sharing knowledge among researchers. She hopes the 426 maps she created for this paper will be of use to future colleagues."If someone is looking for specific data, I could send them my maps where I isolate different species in different areas," she says. "It would be ideal if this research actually contributed to conservation efforts."
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Geography
| 2,020 |
August 18, 2020
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https://www.sciencedaily.com/releases/2020/08/200818114940.htm
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There is at least 10 times more plastic in the Atlantic than previously thought
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The mass of 'invisible' microplastics found in the upper waters of the Atlantic Ocean is approximately 12- 21 million tonnes, according to research published in the journal
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Significantly, this figure is only for three of the most common types of plastic litter in a limited size range. Yet, it is comparable in magnitude to estimates of all plastic waste that has entered the Atlantic Ocean over the past 65 years: 17 million tonnes. This suggests that the supply of plastic to the ocean have been substantially underestimated.The lead author of the paper, Dr Katsiaryna Pabortsava from the National Oceanography Centre (NOC), said "Previously, we couldn't balance the mass of floating plastic we observed with the mass we thought had entered the ocean since 1950. This is because earlier studies hadn't been measuring the concentrations of 'invisible' microplastic particles beneath the ocean surface. Our research is the first to have done this across the entire Atlantic, from the UK to the Falklands."Co-author, Professor Richard Lampitt, also from the NOC, added "if we assume that the concentration of microplastics we measured at around 200 metres deep is representative of that in the water mass to the seafloor below with an average depth of about 3000 metres, then the Atlantic Ocean might hold about 200 million tonnes of plastic litter in this limited polymer type and size category. This is much more than is thought to have been supplied. ""In order to determine the dangers of plastic contamination to the environment and to humans we need good estimates of the amount and characteristics of this material, how it enters the ocean, how it degrades and then how toxic it is at these concentrations. This paper demonstrates that scientists have had a totally inadequate understanding of even the simplest of these factors, how much is there, and it would seem our estimates of how much is dumped into the ocean has been massively underestimated."Pabortsava and Lampitt collected their seawater samples during the 26th Atlantic Meridional Transect expedition in September to November 2016. They filtered large volumes of seawater at three selected depths in the top 200 metres and detected and identified plastic contaminants using state-of-the-art spectroscopic imaging technique. Their study focussed on polyethylene, polypropylene and polystyrene, which are commercially most prominent and also most littered plastic types.This study builds on the NOC's cutting-edge research into marine plastic contamination, which aims to better understand the magnitude and persistence of exposure to plastics and the potential harms it can cause. This work was supported by the EU H2020 AtlantOS programme and the NOC. The AMT programme was supported by the UK Natural Environment Research Council's National Capability, Climate Linked Atlantic Sector Science (CLASS) programme.
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Geography
| 2,020 |
August 18, 2020
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https://www.sciencedaily.com/releases/2020/08/200818094013.htm
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The tropics are expanding, and climate change is the primary culprit
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Earth's tropics are expanding poleward and that expansion is driven by human-caused changes to the ocean, according to new research.
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The tropics wrap around Earth's middle like a warm, wet belt. This part of the globe gets the most direct sunlight throughout the year and is characterized by high average temperatures and heavy rainfall. In contrast to the tropics' lush interior, however, this region's edges are hot and parched.Scientists have noticed for the past 15 years that these arid bands are expanding toward the poles into regions like the Mediterranean, southern Australia and southern California. Interestingly, these dry areas have expanded more in the Southern Hemisphere than the Northern Hemisphere and researchers have struggled to pinpoint exactly what is driving the trend.A new study in AGU's ,Tropical expansion could have profound economic and social implications: the process could shift storm paths and cause more severe wildfires and droughts in places like California and Australia that are already water-stressed.The new findings provide the clearest evidence yet that tropical expansion is in fact primarily driven by climate change, according to the study authors. While natural long-term climate fluctuations contribute to the observed trends, these variations alone cannot explain the extent to which expansion has already occurred.This means, the authors argue, that climate change might have already significantly contributed to tropical expansion, especially in the ocean-dominated Southern Hemisphere."We demonstrate that the enhanced subtropical ocean warming is independent from the natural climate oscillations," said Hu Yang, a climate scientist at the Alfred Wegner Institute in Bremerhaven, Germany and lead author of the new study. "This is a result of global warming."A 2006 paper published in the journal Science announced a troubling finding: in some parts of the world, the tropics were expanding. Researchers have attempted to figure out the culprit ever since that paper was published. Scientists estimate from satellite observations that this widening is happening at a rate of 0.25 to 0.5 degrees latitude per decade. But without pinpointing a root cause, they cannot accurately model how quickly the expansion will occur in the future or what regions it will impact.Some researchers have suggested greenhouse gas emissions, ozone depletion and aerosols in the atmosphere are driving the expansion. But climate models using these variables to explain the expansion consistently underestimate the speed of the shift and do not account for why expansion is happening in some regions but not others. This has led some researchers to theorize that tropical expansion can simply be explained by natural oscillations in Earth's climate. But natural variation does not quite fit the patterns scientists have already observed.Yang and colleagues began to take notice of tropical expansion in 2015, when analyzing ocean currents that carry warm water toward the poles. This got them thinking: what if tropical expansion was driven not by changes in the atmosphere, but changes in the ocean?Because the ocean and atmosphere are highly connected systems, it is often difficult to tell which is driving the other, Yang said. In the new study, Yang and his colleagues analyzed water temperatures in the major ocean gyres, large circular ocean currents that carry warm water toward the poles and cold water toward the equator. They used satellite observations of sea surface temperature between 1982, the year observations began, and 2018, and compared these observations to data on the expanding tropics that stretches back to 1979.They found excess heat building up in the subtropical oceans since global warming began in the mid-1800s has driven tropical edges and ocean gyres toward the poles. When the researchers compared movement of the ocean gyres to tropical expansion, they found the two phenomena matched: tropical expansion was happening in places where the ocean gyres were moving poleward."I actually am really impressed with this paper," said Kristopher Karnauskas, associate professor in the Department of Atmospheric and Oceanic Sciences at the University of Colorado Boulder who was not connected to the new study. "There really aren't a lot of papers out there that really investigate the role of the ocean in the tropical expansion problem."
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Geography
| 2,020 |
August 17, 2020
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https://www.sciencedaily.com/releases/2020/08/200817191756.htm
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North American cold-climate forests are already absorbing less carbon, study shows
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Trees are one of humans' biggest allies in the fight against climate change, soaking up around 30% of the carbon we pump into the atmosphere by burning fossil fuel.
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And over the past several decades, it has appeared that cold-climate forests at high latitudes have become even more effective carbon sinks as rising temperatures and higher COBut a new study led by University of Michigan researchers gives a clearer picture of what's happening in different regions, and it has cast additional uncertainty on whether those ecosystems will continue to absorb carbon as they become hotter and drier in the decades ahead.Published in The study is the first to quantify how carbon emitted from specific surface regions during the annual carbon flux affects the seasonal cycle of COKnowing this seasonal flux gives researchers a picture of how productive different forest regions are and how much carbon they remove from the atmosphere.The varied carbon flux across different forests of similar latitudes suggests that, while some forests, like those in Siberia, are continuing to increase their carbon uptake, others, like those in North America, may not. They may even absorb less as the climate changes."This research shows that we need to be thinking differently about how we understand the carbon cycle," said study co-author Gretchen Keppel-Aleks, U-M assistant professor of climate and space sciences and engineering. "We can't just lump ecosystems together by their latitude. We need to be thinking about individual species and specific seasonal cycles of temperature and precipitation."Researchers know that the swings in annual seasonal carbon flux have increased substantially in the past several decades. In the Northern Hemisphere, the intensity of the flux has gone up 30-50% since the 1960s, suggesting widespread ecological change. But because previous studies have focused on planetwide or hemisphere average fluxes, it has been unclear exactly what's driving the increase.There's been a simple narrative that warmer temperatures have been universally fueling plant photosynthesis across the high latitudes, said Brendan Rogers of Woodwell Climate Research Center (formerly Woods Hole Research Center)."While that's true on the whole, we found starkly divergent responses across regions," Rogers said. "Siberia has been greening, strengthening its carbon sink and driving increases in seasonal CO"Going forward, we need to make sure our carbon budgets and models are fully incorporating what's happening in Alaska and Canada, as these patterns are largely not captured in models and the region may soon transition from a carbon sink to a source."To produce their findings, the team began with actual measurements of atmospheric COThey then worked backwards, using a computer model to calculate the regional surface emissions that would result in atmospheric carbon levels that matched the actual observations."We used these realistic surface fluxes and released them to the atmosphere in our model, and what's unique is that we tagged individual regions differently," Keppel-Aleks said. "We could watch red CONOAA doesn't measure fluxes but instead measures carbon dioxide in the atmosphere and has been tracking the increase in the seasonal cycle since 1976 at sites like the Barrow Observatory in Alaska."These observations and the magnitude of the change we have measured are unparalleled compared with the many other sites across the globe where we track COThe research also corroborates earlier data that shows significant greening in Siberian forests alongside much less greening at similar latitudes in North America."It's really significant that, using completely independent atmospheric data, we're corroborating the browning and greening trends in the remote sensing data and showing that Siberian ecosystems do in fact seem to be growing more productive in the summer," Keppel-Aleks said."It's another unambiguous sign that humans are causing changes in the Earth's ecosystems, and it shows that we need to develop a better understanding of those ecosystems if we want to predict what's in store for the planet."
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Geography
| 2,020 |
August 17, 2020
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https://www.sciencedaily.com/releases/2020/08/200817191754.htm
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New research will improve early warning of devastating megastorms
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Ground-breaking scientific research will make it easier to predict the path of some of the world's most powerful storms, enabling communities to better protect themselves from severe flooding.
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Mesoscale convective systems (MCSs) are 'megastorms' that affect large parts of the world, including Africa, Australia, Asia and the Americas, causing human and livestock deaths plus major damage to infrastructure. They can potentially:In Sahelian Africa, these extreme storms have tripled in frequency since the 1980s due to global warming.Until now, it was thought that the path of these complex weather systems was largely unpredictable.However, a new study by the UK Centre for Ecology & Hydrology (UKCEH) has found that land surface conditions frequently affect the direction and intensity of megastorms after they have formed.The research is now helping scientists to develop online tools to better forecast the path and strength of an approaching storm, which will inform alert systems for communities across Africa, providing them with up to six hours' warning. This includes Senegal, where UKCEH is working with the national meteorological service, ANACIM, to see how useful very short-term forecasts are for local emergency responses.The new study, published in the journal The researchers looked at satellite data on the activity of thousands of storms, plus land temperatures, in the Sahel for the period 2006 to 2010.Lead author Dr Cornelia Klein of UKCEH explains: "It is well known that heat provides thunderstorms with great energy, but it was commonly thought that once they are moving, they were not affected by the state of the ground over which they travelled."However, we found that drier soils increased the intensity of an MCS mid-storm, affecting the amount of rainfall they release and also where they travel. Conversely, we found storms were often weakened over moister soils.""Our finding means that, for the first time, we can predict, from satellite-observed surface conditions, how these extremely large West African storms may behave when, for example, they approach a city. A more effective alert system will enable local people to take action to protect themselves as well as their homes, livestock and possessions, plus plan emergency responses."Flash flooding frequently occurs during the storm season in the Sahel, peaking between June and September, and can have a serious impact, with water entering homes and people losing property and a safe, dry space to live. Flooding can also cause sewage overflow from inadequate drainage systems, posing a health risk to humans and animals.The study's authors say the results have important implications for 'nowcasting' (forecasting for several hours ahead) of severe weather not just in the Sahel, but potentially other MCS hotspot regions of the world.Professor Chris Taylor of UKCEH, co-author of the new paper, adds: "The pattern of these megastorms is supposed to be difficult to forecast but we found a surprising level of predictability. Very dry soils influenced around half of storms in late afternoon or early evening, when they are at their peak."Further research and advances in satellite technology will increase our certainties about their movement. In decades to come, scientists will look back at this latest study as a gamechanger in the reliable forecasting of these devastating storms."The research is part of the UKCEH-led AMMA-2050 project, which is carrying out multidisciplinary climate research to support improved forecasting, in order to enable better decision making by town planners, farmers and communities. Comprising partners from Europe and West Africa, it is funded by DFID and NERC.A DFID spokesperson said:"Highly destructive megastorms are becoming much more common because of climate change. They can devastate entire communities and it is the world's poorest people who are most at risk."UK aid is supporting ground-breaking research, led by British experts, to better anticipate storms so vulnerable African communities can better prepare for their impact, protecting themselves and their families, and making their economies more resilient to climate shocks."Thousands of people were displaced in northern Burkina Faso in mid-June 2020 after shelters were damaged there. Ouagadougou, the country's capital, has been regularly hit by flash flooding in recent years. In 2009, a downpour of 263mm over several hours forced 150,000 residents to leave their homes and eight people were killed. Within a few weeks in mid-2016, heavy rain and strong winds caused flash floods, leaving 15 dead and severely affecting healthcare facilities.
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Geography
| 2,020 |
August 17, 2020
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https://www.sciencedaily.com/releases/2020/08/200817144121.htm
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Researchers track slowly splitting 'dent' in Earth's magnetic field
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A small but evolving dent in Earth's magnetic field can cause big headaches for satellites.
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Earth's magnetic field acts like a protective shield around the planet, repelling and trapping charged particles from the Sun. But over South America and the southern Atlantic Ocean, an unusually weak spot in the field -- called the South Atlantic Anomaly, or SAA -- allows these particles to dip closer to the surface than normal. Particle radiation in this region can knock out onboard computers and interfere with the data collection of satellites that pass through it -- a key reason why NASA scientists want to track and study the anomaly.The South Atlantic Anomaly is also of interest to NASA's Earth scientists who monitor the changes in magnetic field strength there, both for how such changes affect Earth's atmosphere and as an indicator of what's happening to Earth's magnetic fields, deep inside the globe.Currently, the SAA creates no visible impacts on daily life on the surface. However, recent observations and forecasts show that the region is expanding westward and continuing to weaken in intensity. It is also splitting -- recent data shows the anomaly's valley, or region of minimum field strength, has split into two lobes, creating additional challenges for satellite missions.A host of NASA scientists in geomagnetic, geophysics, and heliophysics research groups observe and model the SAA, to monitor and predict future changes -- and help prepare for future challenges to satellites and humans in space.The South Atlantic Anomaly arises from two features of Earth's core: The tilt of its magnetic axis, and the flow of molten metals within its outer core.Earth is a bit like a bar magnet, with north and south poles that represent opposing magnetic polarities and invisible magnetic field lines encircling the planet between them. But unlike a bar magnet, the core magnetic field is not perfectly aligned through the globe, nor is it perfectly stable. That's because the field originates from Earth's outer core: molten, iron-rich and in vigorous motion 1800 miles below the surface. These churning metals act like a massive generator, called the geodynamo, creating electric currents that produce the magnetic field.As the core motion changes over time, due to complex geodynamic conditions within the core and at the boundary with the solid mantle up above, the magnetic field fluctuates in space and time too. These dynamical processes in the core ripple outward to the magnetic field surrounding the planet, generating the SAA and other features in the near-Earth environment -- including the tilt and drift of the magnetic poles, which are moving over time. These evolutions in the field, which happen on a similar time scale to the convection of metals in the outer core, provide scientists with new clues to help them unravel the core dynamics that drive the geodynamo."The magnetic field is actually a superposition of fields from many current sources," said Terry Sabaka, a geophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Regions outside of the solid Earth also contribute to the observed magnetic field. However, he said, the bulk of the field comes from the core.The forces in the core and the tilt of the magnetic axis together produce the anomaly, the area of weaker magnetism -- allowing charged particles trapped in Earth's magnetic field to dip closer to the surface.The Sun expels a constant outflow of particles and magnetic fields known as the solar wind and vast clouds of hot plasma and radiation called coronal mass ejections. When this solar material streams across space and strikes Earth's magnetosphere, the space occupied by Earth's magnetic field, it can become trapped and held in two donut-shaped belts around the planet called the Van Allen Belts. The belts restrain the particles to travel along Earth's magnetic field lines, continually bouncing back and forth from pole to pole. The innermost belt begins about 400 miles from the surface of Earth, which keeps its particle radiation a healthy distance from Earth and its orbiting satellites.However, when a particularly strong storm of particles from the Sun reaches Earth, the Van Allen belts can become highly energized and the magnetic field can be deformed, allowing the charged particles to penetrate the atmosphere."The observed SAA can be also interpreted as a consequence of weakening dominance of the dipole field in the region," said Weijia Kuang, a geophysicist and mathematician in Goddard's Geodesy and Geophysics Laboratory. "More specifically, a localized field with reversed polarity grows strongly in the SAA region, thus making the field intensity very weak, weaker than that of the surrounding regions."Although the South Atlantic Anomaly arises from processes inside Earth, it has effects that reach far beyond Earth's surface. The region can be hazardous for low-Earth orbit satellites that travel through it. If a satellite is hit by a high-energy proton, it can short-circuit and cause an event called single event upset or SEU. This can cause the satellite's function to glitch temporarily or can cause permanent damage if a key component is hit. In order to avoid losing instruments or an entire satellite, operators commonly shut down non-essential components as they pass through the SAA. Indeed, NASA's Ionospheric Connection Explorer regularly travels through the region and so the mission keeps constant tabs on the SAA's position.The International Space Station, which is in low-Earth orbit, also passes through the SAA. It is well protected, and astronauts are safe from harm while inside. However, the ISS has other passengers affected by the higher radiation levels: Instruments like the Global Ecosystem Dynamics Investigation mission, or GEDI, collect data from various positions on the outside of the ISS. The SAA causes "blips" on GEDI's detectors and resets the instrument's power boards about once a month, said Bryan Blair, the mission's deputy principal investigator and instrument scientist, and a lidar instrument scientist at Goddard."These events cause no harm to GEDI," Blair said. "The detector blips are rare compared to the number of laser shots -- about one blip in a million shots -- and the reset line event causes a couple of hours of lost data, but it only happens every month or so."In addition to measuring the SAA's magnetic field strength, NASA scientists have also studied the particle radiation in the region with the Solar, Anomalous, and Magnetospheric Particle Explorer, or SAMPEX -- the first of NASA's Small Explorer missions, launched in 1992 and providing observations until 2012. One study, led by NASA heliophysicist Ashley Greeley as part of her doctoral thesis, used two decades of data from SAMPEX to show that the SAA is slowly but steadily drifting in a northwesterly direction. The results helped confirm models created from geomagnetic measurements and showed how the SAA's location changes as the geomagnetic field evolves."These particles are intimately associated with the magnetic field, which guides their motions," said Shri Kanekal, a researcher in the Heliospheric Physics Laboratory at NASA Goddard. "Therefore, any knowledge of particles gives you information on the geomagnetic field as well."Greeley's results, published in the journal Space Weather, were also able to provide a clear picture of the type and amount of particle radiation satellites receive when passing through the SAA, which emphasized the need for continuing monitoring in the region.The information Greeley and her collaborators garnered from SAMPEX's in-situ measurements has also been useful for satellite design. Engineers for the Low-Earth Orbit, or LEO, satellite used the results to design systems that would prevent a latch-up event from causing failure or loss of the spacecraft.In order to understand how the SAA is changing and to prepare for future threats to satellites and instruments, Sabaka, Kuang and their colleagues use observations and physics to contribute to global models of Earth's magnetic field.The team assesses the current state of the magnetic field using data from the European Space Agency's Swarm constellation, previous missions from agencies around the world, and ground measurements. Sabaka's team teases apart the observational data to separate out its source before passing it on to Kuang's team. They combine the sorted data from Sabaka's team with their core dynamics model to forecast geomagnetic secular variation (rapid changes in the magnetic field) into the future.The geodynamo models are unique in their ability to use core physics to create near-future forecasts, said Andrew Tangborn, a mathematician in Goddard's Planetary Geodynamics Laboratory."This is similar to how weather forecasts are produced, but we are working with much longer time scales," he said. "This is the fundamental difference between what we do at Goddard and most other research groups modeling changes in Earth's magnetic field."One such application that Sabaka and Kuang have contributed to is the International Geomagnetic Reference Field, or IGRF. Used for a variety of research from the core to the boundaries of the atmosphere, the IGRF is a collection of candidate models made by worldwide research teams that describe Earth's magnetic field and track how it changes in time."Even though the SAA is slow-moving, it is going through some change in morphology, so it's also important that we keep observing it by having continued missions," Sabaka said. "Because that's what helps us make models and predictions."The changing SAA provides researchers new opportunities to understand Earth's core, and how its dynamics influence other aspects of the Earth system, said Kuang. By tracking this slowly evolving "dent" in the magnetic field, researchers can better understand the way our planet is changing and help prepare for a safer future for satellites.
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August 17, 2020
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https://www.sciencedaily.com/releases/2020/08/200817132333.htm
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Rotating microscope could provide a new window into secrets of microscopic life
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Like spirits passing between worlds, billions of invisible beings rise to meet the starlight, then descend into darkness at sunrise. Microscopic plankton's daily journey between the ocean's depths and surface holds the key to understanding crucial planetary processes, but has remained largely a mystery until now. A new Stanford-developed rotating microscope, outlined in a study published Aug. 17 in
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"This is a completely new way of studying life in the ocean," said study first author Deepak Krishnamurthy, a mechanical engineering PhD student at Stanford.The innovation could provide a new window into the secret life of ocean organisms and ecosystems, said study senior author Manu Prakash, associate professor of bioengineering at Stanford. "It opens scientific possibilities we had only dreamed of until now."On Earth, half of all the conversion of carbon to organic compounds occurs in the ocean, with plankton doing most of that work. The tiny creatures' outsized role in this process, known as carbon fixation, and other important planetary cycles has been hard to study in the ocean's vertically stratified landscape which involves vast depth and time scales.Conventional approaches to sampling plankton are focused on large populations of the microorganisms and have typically lacked the resolution to measure behaviors and processes of individual plankton over ecological scales. As a result, we know very little about microscale biological and molecular processes in the ocean, such as how plankton sense and regulate their depth or even how they can remain suspended in the water column despite having no appendages that aid in mobility."I could attach a tag to a whale and see where it goes, but as things get smaller and smaller it becomes extremely difficult to know and understand their native behavior," Prakash said. "How do we get closer to the native behavior of a microscopic object, and give it the freedom that it deserves because the ocean is so large a space and extremely vertically oriented?"To bridge the gap, Prakash and researchers in his lab developed a vertical tracking microscope based on what they call a "hydrodynamic treadmill." The idea involves a simple yet elegant insight: a circular geometry provides an infinite water column ring that can be used to simulate ocean depths. Organisms injected into this fluid-filled circular chamber move about freely as the device tracks them and rotates to accommodate their motion. A camera feeds full-resolution color images of the plankton and other microscopic marine critters into a computer for closed-loop feedback control. The device can also recreate depth characteristics in the ocean, such as light intensity, creating what the researchers call a "virtual reality environment" for single cells.The team has deployed the instrument for field testing at Stanford's Hopkins Marine Station in Monterey, in Puerto Rico and also on a research vessel off the coast of Hawaii. The innovative microscope has already revealed various microorganisms' behaviors previously unknown to science. For example, it exposed in minute detail how larvae of marine creatures from the Californian coast, such as the bat star, sea cucumber and Pacific sand dollar employ various methods to move through the sea, ranging from a steady hover to frequent changes in ciliary beat and swimming motion or blinks. This could allow scientists to better understand dispersal properties of these unique organisms in the open ocean. The device has also revealed the vertical swimming behaviors of single-celled organisms such as marine dinoflagellates, which could allow scientists to link these behaviors to ecological phenomena such as algal blooms.In Puerto Rico, Krishnamurthy and Prakash were shocked to observe a diatom, a microorganism with no swimming appendages, repeatedly change its own density to drop and rise in the water -- a puzzling behavior that still remains a mystery."It's as if someone told you a stone could float and then sink and then float again," Krishnamurthy said.Prakash credit the device's success to the interdisciplinary nature of his lab's team, which includes electrical, mechanical and optical engineers, as well as computer scientists, physicists, cell biologists, ecologists and biochemists. The team is working to extend the microscope's capabilities further by virtually mapping all aspects of the physical parameters that an organism experiences as it dives into depths of the ocean, including environmental and chemical cues and hydrostatic pressure."To truly understand biological processes at play in the ocean at smallest length scales, we are excited to both bring a piece of the ocean to the lab, and simultaneously bring a little piece of the lab to the ocean," said Prakash.Prakash is also a senior fellow at the Stanford Woods Institute for the Environment; a member of Bio-X, the Maternal & Child Health Research Institute and the Wu Tsai Neurosciences Institute; a faculty fellow at the Howard Hughes Medical Institute; and an investigator at the Chan Zuckerberg Biohub.Study co-authors include Hongquan Li, a graduate student in electrical engineering; François Benoit du Rey, and Pierre Cambournac, former summer interns in the Prakash lab from École Polytechnique; Ethan Li, a graduate student in bioengineering and Adam Larson, a postdoctoral research fellow in bioengineering.Portions of the technology described here are part of a pending U.S patent.Funding provided by a Bio-X Bowes and SIGF fellowships, the National Science Foundation, the Gordon and Betty Moore Foundation, the HHMI Faculty Fellows Program.
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August 17, 2020
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https://www.sciencedaily.com/releases/2020/08/200817123045.htm
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New research reveals effect of global warming on Greenland ice melt
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New analysis of almost 30 years' worth of scientific data on the melting of the Greenland Ice Sheet predicts global sea level rise of at least 10 centimetres by the end of the 21st Century if global warming trends continue.
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The estimates, which scientists warn are "conservative" given the powerful effects of changes in weather systems and possible ways of accelerating ice loss, are broadly consistent with recent predictions reported by the Intergovernmental Panel on Climate Change.Professor Edward Hanna of the University of Lincoln, UK, led an international team involving Belgian, Danish, Swiss and American glaciologists and climatologists in the new study that quantifies the response of the Greenland Ice Sheet to climate change. Their findings are published in the The Greenland Ice Sheet is a giant reservoir of ice that contains enough water to ultimately raise global sea-level by seven metres.The researchers provide an updated analysis of Greenland surface air temperature data for the last three decades through to 2019, focusing mainly on coastal weather stations but also analysing records from relatively long-running sites on the interior plateau of the ice sheet. They found that Greenland coastal regions warmed significantly by about 4.4 degrees Celsius (degC) in winter and 1.7 degC in summer from 1991 to 2019. Their work, combining Greenland temperature data with computer model output of ice-sheet mass balance for 1972 to 2018, shows that each 1degC of summer warming corresponds to some 91 billion tonnes per year of surface mass loss and 116 billion tonnes per year of total mass loss from the ice sheet.The research team then used some of the latest available global and regional climate modelling tools to estimate that, under sustained strong global warming (a "business as usual" scenario), Greenland is likely to warm 4.0 to 6.6 degC by the year 2100. These recent and projected future Greenland warmings are considerably greater than global temperature changes for equivalent time periods, reflecting a high sensitivity of the polar regions to climate change.The scientists then used the relation they derived between recent changes in Greenland summer temperature and surface mass balance to calculate a 10 to 12.5 centimetres increase in global sea-level rise by 2100 arising from increased Greenland ice melt and surface mass loss.Prof. Hanna's team also explored the relation between Greenland air temperature changes and a phenomenon called atmospheric high pressure blocking which involves a greater than normal mass of air sometimes positioned over Greenland. This relation is generally present but has strengthened in spring and summer in recent decades. The authors show Greenland blocking played a crucial role in the near-record Greenland melt in the summer of 2019 (narrowly surpassed by the all-time record in 2012), and point out that possible future changes in blocking need to be better considered in computer-model projections of climate change.Prof. Hanna, Professor of Climate Science and Meteorology in Lincoln's School of Geography and Lincoln Centre for Water and Planetary Health, said "The Greenland Ice Sheet is one of the most sensitive and reliable measures of global climate change. Here we have used relatively simple statistical analysis of data and model output from the last 30 years as a sense-check on prediction of future ice-sheet surface mass change. Our work, which represents in part a major updated analysis of Greenland climate records, is highly interdisciplinary since it cross-cuts between climate science and glaciology, and so will help improve interpretation of recent ice-sheet changes."
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Geography
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August 14, 2020
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https://www.sciencedaily.com/releases/2020/08/200814142952.htm
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Traces of ancient life tell story of early diversity in marine ecosystems
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If you could dive down to the ocean floor nearly 540 million years ago just past the point where waves begin to break, you would find an explosion of life -- scores of worm-like animals and other sea creatures tunneling complex holes and structures in the mud and sand -- where before the environment had been mostly barren.
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Thanks to research published today in "We can see from the trace fossils -- tracks, trails, borings, and burrows animals left behind -- that this particular environment of the ocean floor, the offshore, served as a 'crucible' for life," said USask paleobiologist Luis Buatois, lead author of the article. "Over the next millions of years, life expanded from this area outwards into deeper waters and inwards into shallower waters."The research is the culmination of over 20 years of work from Buatois and the team which examined hundreds of rock formations in locations across every continent."Until now, these two events -- the Cambrian Explosion and the Great Ordovician Biodiversification Event -- have been understood mostly through the study of body fossils -- the shells, carapaces and the bones of ancient sea creatures," said Buatois. "Now we can confidently say that these events are also reflected in the trace fossil record which reveals the work of those soft-bodied creatures whose fleshy tissues rot very quickly and so are only very rarely preserved."For the first time, the team has shown evidence of animals actively "engineering" their ecosystem -- through the construction of abundant and diverse burrows on the sea floor of the world's oceans in this ancient time."Never underestimate what animals are capable of doing," said USask paleobiologist Gabriela Mángano, co-author of the paper. "They can modify their physical and chemical environment, excluding other animals or allowing them to flourish by creating new resources. And they were definitely doing all these things in these ancient seas."The trace fossil-producing animals' engineering efforts may have laid the foundation for greater diversity in marine life. The researchers identified a 20-million-year time lag during the Cambrian Explosion (the time when most of the major groups of animals first appear in the fossil record) between diversification in trace fossils and in animal body fossils, suggesting the later animals exploited changes which enabled them to diversify even more.The research also helps resolve a big question from the geochemical record, which indicated much of the ancient ocean was depleted of oxygen and unsuitable for life. Like oceans today, the Cambrian ocean had certain areas that were full of life, while others lacked the necessary conditions to support it."The fact that trace fossil distribution shows that there were spots where life flourished adjacent to others devoid of animal activity all through the early Cambrian period is a strong argument in favor of the idea that zones with enough oxygen to sustain a diversity of animals co-existed with oxygen-depleted waters in deeper areas," said Mángano. "It's a situation similar to what happens in modern oceans with oxygen minimum zones in the outer part of the continental shelf and the upper part of the continental slope, but oxygenated ones in shallower water."The research could provide new insights from an evolutionary perspective into the importance of extensive rock formations of a similar vintage found in Canada and elsewhere, and help society to prepare for coming challenges."Understanding changes that took place early in the history of our planet may help us to face present challenges in modern oceans, particularly with respect to oxygen changes," said Buatois.Other members of the team are: USask PhD student Kai Zhou, University of Portsmouth researcher Nic Minter, Senckenberg am Meer institute (Hamburg) researcher Max Wisshak, College of Wooster (Ohio) paleontologist Mark Wilson, and statistician Ricardo Olea of the United States Geological Survey.The research was funded by grants from Canada's Natural Sciences and Engineering Research Council awarded to Buatois and Mángano.
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August 13, 2020
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https://www.sciencedaily.com/releases/2020/08/200813152244.htm
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Reconstructing global climate through Earth's history
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A key component when forecasting what the Earth's climate might look like in the future is the ability to draw on accurate temperature records of the past. By reconstructing past latitudinal temperature gradients (the difference in average temperature between the equator and the poles) researchers can predict where, for example, the jet stream, which controls storms and temperatures in the mid-latitudes (temperate zones between the tropics and the polar circles), will be positioned. The trouble is, many of the existing data are biased toward particular regions or types of environments, not painting a full picture of Earth's ancient temperatures.
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Researchers from the Department of Earth and Environmental Sciences, including Emily Judd '20 Ph.D., Thonis Family Assistant Professor Tripti Bhattacharya and Professor Linda Ivany, have published a study titled, "A dynamical framework for interpreting ancient sea surface temperatures," in the journal "Geophysical Research Letters," to help account for the offset between location-biased paleoclimate data and the 'true' average temperature at a given latitude through Earth's history. Their work was funded by the National Science Foundation.According to Judd, accurate temperature estimates of ancient oceans are vital because they are the best tool for reconstructing global climate conditions in the past, including metrics like mean global temperature and the latitudinal temperature gradient. While climate models provide scenarios of what the world could look like in the future, paleoclimate studies (study of past climates) provide insight into what the world did look like in the past. Seeing how well the models we use to predict the future can simulate the past tells us how confident we can be in their results. It is therefore of utmost importance to have thorough, well-sampled data from the ancient past."By understanding how latitudinal temperature gradients have changed over the course of Earth's history and under a variety of different climate regimes, we can start to better anticipate what will happen in the future," says Judd.To determine ancient temperatures, geologists study proxies, which are chemical or biological traces that record temperatures from sedimentary deposits preserved on the sea floor or continents. Due to the recycling of ancient seafloor into the Earth's mantle, there is an 'expiration date' on the availability of seafloor data. Most ancient temperature proxies therefore come from sediments that accumulated on continental margins or in shallow inland seas where records can persist for much longer.Judd, Bhattacharya and Ivany use temperature data from modern oceans to reveal consistent, predictable patterns where the ocean surface is warmer or cooler, or more or less seasonal, than otherwise expected at that latitude."The biggest offsets happen to be in the two settings that are most represented in the geologic past," says Ivany. "Knowing how those regions are biased in comparison to the global mean allows researchers to better interpret the proxy data coming from the ancient Earth."Data from shallow, semi-restricted seas (e.g., the Mediterranean and Baltic Seas) show that sea surface temperatures are warmer than in the open ocean. As a result, a key finding of their paper theorizes that estimates of global mean temperature from the Paleozoic Era (~540-250 million years ago), a time when the majority of data come from shallow seas, are unrealistically hot.Even in the more recent geologic past, the overwhelming majority of sea surface temperature estimates come from coastal settings, which they demonstrate are also systematically biased in comparison to open ocean temperatures.In order to have a more accurate record of average ocean temperature at a given latitude, Bhattacharya says researchers must account for the incomplete nature of paleotemperature data. "Our work highlights the need for the scientific community to focus sampling efforts on under-sampled environments," says Bhattacharya. "New sampling efforts are essential to make sure we are equally sampling unique environmental settings for different intervals of Earth's history."According to Judd, the paleoclimate community has made major advances toward understanding ancient climates in the past few decades. New, faster, and cheaper analytical techniques, as well as a surge in expeditions that recover ocean sediment cores, have led to massive compilations of ancient sea surface temperature estimates. Despite these advancements, there are still significant disagreements between temperature estimates from different locations within the same time interval and/or between temperature estimates and climate model results."Our study provides a framework within which to reconcile these discrepancies," says Judd. "We highlight where, when and why temperature estimates from the same latitudes may differ from one another and compare different climate models' abilities to reconstruct these patterns. Our work therefore lays the groundwork to more holistically and robustly reconstruct global climate through Earth's history."
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Geography
| 2,020 |
August 13, 2020
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https://www.sciencedaily.com/releases/2020/08/200813123550.htm
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Warming Greenland ice sheet passes point of no return
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Nearly 40 years of satellite data from Greenland shows that glaciers on the island have shrunk so much that even if global warming were to stop today, the ice sheet would continue shrinking.
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The finding, published today, Aug. 13, in the journal "We've been looking at these remote sensing observations to study how ice discharge and accumulation have varied," said Michalea King, lead author of the study and a researcher at The Ohio State University's Byrd Polar and Climate Research Center. "And what we've found is that the ice that's discharging into the ocean is far surpassing the snow that's accumulating on the surface of the ice sheet."King and other researchers analyzed monthly satellite data from more than 200 large glaciers draining into the ocean around Greenland. Their observations show how much ice breaks off into icebergs or melts from the glaciers into the ocean. They also show the amount of snowfall each year -- the way these glaciers get replenished.The researchers found that, throughout the 1980s and 90s, snow gained through accumulation and ice melted or calved from glaciers were mostly in balance, keeping the ice sheet intact. Through those decades, the researchers found, the ice sheets generally lost about 450 gigatons (about 450 billion tons) of ice each year from flowing outlet glaciers, which was replaced with snowfall."We are measuring the pulse of the ice sheet -- how much ice glaciers drain at the edges of the ice sheet -- which increases in the summer. And what we see is that it was relatively steady until a big increase in ice discharging to the ocean during a short five- to six-year period," King said.The researchers' analysis found that the baseline of that pulse -- the amount of ice being lost each year -- started increasing steadily around 2000, so that the glaciers were losing about 500 gigatons each year. Snowfall did not increase at the same time, and over the last decade, the rate of ice loss from glaciers has stayed about the same -- meaning the ice sheet has been losing ice more rapidly than it's being replenished."Glaciers have been sensitive to seasonal melt for as long as we've been able to observe it, with spikes in ice discharge in the summer," she said. "But starting in 2000, you start superimposing that seasonal melt on a higher baseline -- so you're going to get even more losses."Before 2000, the ice sheet would have about the same chance to gain or lose mass each year. In the current climate, the ice sheet will gain mass in only one out of every 100 years.King said that large glaciers across Greenland have retreated about 3 kilometers on average since 1985 -- "that's a lot of distance," she said. The glaciers have shrunk back enough that many of them are sitting in deeper water, meaning more ice is in contact with water. Warm ocean water melts glacier ice, and also makes it difficult for the glaciers to grow back to their previous positions.That means that even if humans were somehow miraculously able to stop climate change in its tracks, ice lost from glaciers draining ice to the ocean would likely still exceed ice gained from snow accumulation, and the ice sheet would continue to shrink for some time."Glacier retreat has knocked the dynamics of the whole ice sheet into a constant state of loss," said Ian Howat, a co-author on the paper, professor of earth sciences and distinguished university scholar at Ohio State. "Even if the climate were to stay the same or even get a little colder, the ice sheet would still be losing mass."Shrinking glaciers in Greenland are a problem for the entire planet. The ice that melts or breaks off from Greenland's ice sheets ends up in the Atlantic Ocean -- and, eventually, all of the world's oceans. Ice from Greenland is a leading contributor to sea level rise -- last year, enough ice melted or broke off from the Greenland ice sheet to cause the oceans to rise by 2.2 millimeters in just two months.The new findings are bleak, but King said there are silver linings."It's always a positive thing to learn more about glacier environments, because we can only improve our predictions for how rapidly things will change in the future," she said. "And that can only help us with adaptation and mitigation strategies. The more we know, the better we can prepare."This work was supported by grants from NASA. Other Ohio State researchers who worked on this study are Salvatore Candela, Myoung Noh and Adelaide Negrete.
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Geography
| 2,020 |
August 13, 2020
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https://www.sciencedaily.com/releases/2020/08/200813103121.htm
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Cancer mapping may solve puzzle of regional disease links
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QUT researchers have used nationwide cancer mapping statistics to develop a new mathematical model so health professionals can further question patterns relating to the disease.
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Epidemiologists use disease atlases to identify disease prevalence and mortality rates and QUT researchers say data could be expanded by including factors such as remoteness to investigate health inequalities.QUT PhD student Farzana Jahan is the lead author of a study, published in the The study, which drew upon the Australian Cancer Atlas, considered cancers from geographical regions including major cities, inner regional, outer regional and remote areas.Cancers having higher incidence in remote areas were head and neck, liver, lung, esophageal for males and females and cervical and uterine cancers for females.While in major cities, cancers more likely to have greater incidence include brain, myeloma, non-Hodgkin lymphoma, pancreatic, stomach, thyroid cancer for both sexes, kidney cancer for males, leukemia, and ovarian cancer for females.Some cancers more likely to occur in regional areas included bowel, melanoma for both males and females, kidney cancer for females, leukemia, and prostate cancer for males.Ms Jahan said the research was an attempt to create a method by which any available disease maps or summary disease measures can be further modelled to "unmask new insights about health and medical issues" without having to go back to the individual health records."Our research provides a method for further analysing information that goes beyond the scope of disease summaries," Ms Jahan said.Dr Susanna Cramb, a biostatistician and epidemiologist based at QUT's Faculty of Health and who co-authored the study, said disease atlases are helpful for showing patterns but rarely adjusted for anything beyond age and population size."People might be interested in considering whether for instance the distance to the nearest radiotherapy facility affects survival, or the proportion of workers with high sun exposure is associated with melanoma incidence," Dr Cramb said."Comparing socioeconomic associations with certain cancer types and with other countries worldwide is another potential area to investigate."This study unlocks data from sources like the Cancer Atlas to explore and refine research hypotheses."
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Geography
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August 13, 2020
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https://www.sciencedaily.com/releases/2020/08/200813103120.htm
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Sea-level rise could make rivers more likely to jump course
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Sea-level rise due to climate change is poised to shift the way that rivers naturally chart their path to the shoreline. The nature of that change will depend on both the rate of sea-level rise and the sediment load carried by the river, according to new models by Caltech researchers and their colleagues.
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Periodically, a river will change its course to the sea, forming a new path through a process called river avulsion. River avulsions are a natural part of a river's life and are responsible for building new land and nourishing wetland ecosystems with water, nutrients, and sediment. However, river avulsions are also catastrophic natural hazards. They were responsible for some of the deadliest floods in human history, including the 1887 Yellow River floods and the 1931 China floods, which together claimed an estimated six million lives. On some rivers, like the Mississippi, engineers have built bypass channels and levees to counter the dangers of river avulsion."A river avulsion is a catastrophic flood that is also crucial for sustaining coastal land," says Austin Chadwick, lead author of a paper about the new model that was published by Sea level has been rising overall since the start of the 20th century, and at an accelerating pace. In 2014, the Intergovernmental Panel on Climate Change (IPCC) projected that sea level could creep up as much as three feet by the end of this century. Earth scientists have had an ongoing debate about how this could affect river avulsions on deltas, the fertile landscapes created where a river meets an ocean or lake -- a critical question, given that deltaic landscapes host roughly 10 percent of the human population."Avulsions are the earthquakes of rivers," Lamb says. "They are sudden and sometimes catastrophic natural events that occur with statistical regularity, shifting the direction of major rivers. We are trying to understand where and when the next avulsions will occur." Lamb, Chadwick, and Ganti combined theory, numerical modeling, and field observations to explain how often river avulsions will occur, and how their frequency would respond to a changing climate.They found that the occurrence of future avulsions depends mainly on two factors: the rate of sea-level rise, and the amount of silt and sand carried by a river.On most deltas, including the Mississippi River delta, sea-level rise is expected to cause more frequent catastrophic river avulsions. This is because, as sea level rises, rivers respond by depositing more of their sediment into the channel, which raises the riverbed relative to the neighboring land, making the river unstable. Eventually, a levee breach will force the river to find a shorter and steeper path to the sea. More frequent avulsions could flood coastal communities like New Orleans, Louisiana, that are already vulnerable to inundation by sea-level rise.Sea-level rise could affect not only when, but also where, future river avulsions occur. "If sea level rises faster than rivers can deposit sediment, then the zone of deposition and avulsion will shift upstream, introducing new avulsion hazards to upstream communities," Chadwick says. In such a scenario, existing river-management infrastructure (dams and levees) could be rendered obsolete, and costly avulsion-mitigation efforts would need to shift upstream.Chadwick, Lamb, and Ganti hope that this work could help guide river management on densely populated deltas, offering them a framework for calculating what to expect over the coming decades.
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Geography
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August 12, 2020
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https://www.sciencedaily.com/releases/2020/08/200812115308.htm
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Researchers identify human influence as key agent of ocean warming patterns in the future
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The oceans play an important role in regulating our climate and its change by absorbing heat and carbon.
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The implications of their results, published today in The results imply widespread ocean warming and sea level rise, compared to the past, including increased warming near the Eastern edges of ocean basins leading to more sea level rise along the Western coastlines of continents in the North Atlantic and Pacific Oceans.Co-author, Laure Zanna, Visiting Professor in Climate Physics at Oxford University and Professor in the Center of Atmosphere Ocean Science at NYU Courant, said: 'In the future, the imprint of rising atmospheric temperatures on ocean warming will likely dominate that of changes in ocean circulation. Initially, we might think that as the climate warms more, changes in ocean currents and their impact on ocean warming patterns will become larger. However, we show that that this is not the case in several regions of the ocean.'A new method, developed by scientists at Oxford University, uses climate models to suggest that ocean warming patterns will increasingly be influenced by simple uptake of atmospheric warming -- making them easier to predict. This is in contrast to now and the past when circulation changes were key factors in shaping ocean warming patterns.Changes in ocean warming due to the simple uptake of atmospheric warming are easier to model and so the scientists hope that where previous models have struggled, they might become more accurate for future projections.Lead author, Dr Ben Bronselaer, who began conducting this research while a PhD student at Oxford University, said: 'I think it is an encouraging possibility that climate models, which struggle to simulate past ocean warming, might be better at predicting future warming patterns. Better prediction of warming patterns implies better prediction of regional sea level rise, which will help to mitigate climate impacts such as flooding on individual communities. Of course, we do need to understand predictions of ocean circulation better to solidify this result.'During our research, we found a surprising relationship between ocean heat and carbon storage which appears to be unique. While there is a connection between these two quantities that is not yet fully understood, we think we have made significant progress towards uncovering it.'The These results highlight a deep and fundamental connection between ocean and carbon uptake, which has implications for atmospheric heat and carbon. While ocean carbon and heat are separate systems, this study shows that they are deeply interconnected, via the capacity of the ocean to absorb these quantities. These results help explain why atmospheric warming depends linearly on cumulative carbon emissions.Prof Laure Zanna said: 'We find that the ocean's capacity to absorb heat and carbon are coupled, and constrained by the ocean state. This implies that the present ocean state will regulate surface warming whether CO2 emissions continue to rise or decline.'The rates of ocean warming over the past 60 years have been significantly altered by changes in ocean circulation, particularly in the North Atlantic and parts of the Pacific Ocean, where we can identify cooling over some decades. However, in the future changes in ocean currents appear to play a smaller role on patterns of ocean warming, and the oceans will transport the excess anthropogenic heat in the ocean in a rather passive manner in these regions.'The modelling in this study relied on a set of creative simulations done by colleagues at The Geophysical Fluid Dynamics Laboratory (GFDL), and other published work. Using these simulations, the scientists were able to draw hypotheses on how the patterns of heat and carbon are related and how they differ.Building on this research, the scientists will now attempt to understand how the storage of heat and carbon in the ocean will affect the decline of atmospheric temperature and CO2 levels if carbon emissions start going down.They will also use the component of ocean warming that is driven by circulation changes to better understand ocean circulation changes, which are difficult to measure directly, and their impact on regional sea level in the Tropics.
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Geography
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August 12, 2020
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https://www.sciencedaily.com/releases/2020/08/200812115321.htm
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Collaboration is key to rebuilding coral reefs
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The most successful and cost-effective ways to restore coral reefs have been identified by an international group of scientists, after analysing restoration projects in Latin America.
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The University of Queensland's Dr Elisa Bayraktarov led the team that investigated 12 coral reef restoration case studies in five countries."Coral reefs worldwide are degrading due to climate change, overfishing, pollution, coastal development, coral bleaching and diseases," Dr Bayraktarov said."Coral reef restoration -- or rebuilding what we have lost -- may become critical, especially for coral species that are threatened with extinction."Much of this work is led by environmental non-Government organisations (ENGOs), tourism operators, community groups, national resource management groups and governments who rarely publish their great depth of knowledge."So we decided to bridge the gap between academia, ENGOs and other groups that restore coral reefs."The researchers analysed the motivations and techniques used for each project, providing estimates on total annual project cost per unit area of reef restored, project duration and the spatial extent of interventions.The team found the most successful projects had high coral survival rates or an increase in coral cover, but that they also offered socioeconomic benefits for their surrounding communities."Projects that train local fishermen or recreational divers to participate in restoration, or engage with dive operators or hotels to support the maintenance of the coral nurseries, were much more effective and long-lived," Dr Bayraktarov said."We also found that coral reef restoration efforts in Latin American countries and territories were cheaper than previously thought -- with the median cost of a project around US$93,000 (~AUD$130,000) to restore one hectare of coral reef.A one-year-old coral"The projects also had run for much longer than assumed, with some active for up to 17 years."And best of all, an analysis of all the studied projects revealed a high likelihood of overall project success of 70 per cent."Co-author Dr Phanor Montoya-Maya, director and founder of the Colombian-based organisation Corales de Paz, said he was excited about the project's collaborative nature."Twenty-five Latin-American coral reef restoration scientists and practitioners from 17 institutions in five countries worked on this research," he said."We wanted to showcase the efforts of Spanish-speaking countries that depend on their local coral reefs to the global coral reef restoration community."And to share the diversity of objectives, techniques, tools used, and methods to measure success in Latin America to encourage others to carry out similar work."We're providing critical project information -- such as total annual project cost per unit area of reef restored, spatial extent of restored site and duration -- on how to best save our degraded reefs.
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Geography
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August 12, 2020
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https://www.sciencedaily.com/releases/2020/08/200812094846.htm
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Climate change projected to increase seasonal East African rainfall
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According to research led by The University of Texas at Austin, seasonal rainfall is expected to rise significantly in East Africa over the next few decades in response to increased greenhouse gases.
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The study, published in July in "There are two East African rainy seasons with different sensitivities to greenhouse gases," said Kerry Cook, a professor in the Jackson School of Geosciences' Department of Geological Sciences. "Our paper shows that the short rains will continue to increase -- in fact, flooding and locust infestations are already occurring -- and that there is no drying trend for the long rains."Both the transportation of water vapor by atmospheric circulation and the distribution of rain are sensitive to differences between ocean and land temperatures. These differences occur because oceans warm and cool more slowly than the land due to differences in heat capacity.When the short rains develop, typically with a peak in November, the southern hemisphere circulation is in a summer pattern, with high pressure over the ocean and low pressure over land in the subtropics, setting up a circulation pattern that funnels more moisture over East Africa. It is this rainy season that is more sensitive to greenhouse-gas induced climate change.The region's long rains, on the other hand, appear to be less sensitive to greenhouse gas forcing. This season occurs from March through May, peaking near the northern hemisphere's spring equinox, when continental low pressures are centered over the equator.The newly published simulations have a 30 kilometer resolution that resolves the complex East African topography, and more accurately represent currently observed rainfall amounts and seasonality than coarser resolution global models. Simulations of rainfall through 2050 are consistent with currently observed rainfall amounts and seasonality. These results show that the pattern of the long rains is not changing. But the short rains are increasing: rainfall in November over East Africa will increase by about one-third by 2050 and double by 2100."This research will allow people to plan ahead in East Africa," said Cook. "But future work will need to see how additional rainfall will be delivered because, if it is as intense as in the current observations and continues to impact agriculture, developing infrastructure will be important."
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Geography
| 2,020 |
August 11, 2020
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https://www.sciencedaily.com/releases/2020/08/200810160149.htm
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Discovery transforms understanding of hydrogen depletion at the seafloor
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The discovery of hydrothermal vents -- where volcanoes at the seafloor produce hot fluid exceeding 350 degrees Celsius, or 662 degrees Fahrenheit, fundamentally changed our understanding about Earth and life in the 1970s. Yet, life at and underneath the seafloor is still very much a mystery today.
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Gaining a better understanding of these volcanically active areas is important, as the chemistry at seafloor vents impacts ocean chemistry more generally. In addition, the seafloor's unique environment supports biological and non-biological processes that offer clues as to how life on Earth first began, how it is sustained over time?and the potential for life on other planetary bodies.According to geochemist Jill McDermott, a professor in the Department of Earth and Environmental Science at Lehigh University, past studies of the chemistry of hydrothermal vent fluids have revealed reductions in certain gas species, such as molecular hydrogen. These depletions were thought to be caused by microbiological communities living in the shallow seafloor, collectively called the subseafloor biosphere.However, results of a new study by McDermott and colleagues contradict that assumption. The researchers analyzed gas-tight hydrothermal fluid samples from the world's deepest known vent field, the Piccard hydrothermal field at the Mid-Cayman Rise, which is at a depth of 4970 meters, or about 16,000 feet below sea level. They observed chemical shifts in their samples, including a large loss of molecular hydrogen, that could only be the result of abiotic (non-biological) and thermogenic (thermal breakdown) processes, because the fluid temperatures were beyond the limits that support life?understood to be 122 degrees Celsius, or around 250 degrees Fahrenheit, or lower.The results were published online today in an article "Abiotic redox reactions in hydrothermal mixing zones: decreased energy availability for the subsurface biosphere" in the "Our study finds that these shifts in chemistry are driven by non-biological processes that remove energy before microbial communities gain access to it," says McDermott. "This could have critical implications for constraining the extent to which global geochemical cycles can sustain a deep biosphere, and for the global hydrogen budget."She adds "This also means the subsurface biosphere is likely receiving less energy than anyone had realized previously. The degree to which non-biological hydrogen consumption in the oceanic crust may reduce the impact of life inhabiting the seafloor is a great target for future studies."Using chemical analysis of dissolved gases, inorganic compounds, and organic compounds, the team found that the low-temperature fluid samples originated from mixing between seawater and the nearby Beebe Vents black smokers, so named because the fluid expelled from the vents resembles black smoke from a chimney. In these mixed fluid samples, many chemical species are either high or low in abundance, according to McDermott. The sample with the largest shifts in the amount of gas had a seafloor temperature of 149 degrees Celsius, or 300 degrees Fahrenheit, a temperature that is too hot to host life. Thus, they concluded, the process responsible for the geochemical changes could not directly involve life.The non-biological reactions they identified as responsible for these chemical shifts include sulfate reduction and the thermal degradation of biomass, and are supported by mass balance considerations, stable isotope measurements, and chemical energetics calculations.The samples were collected during two research expeditions using two remotely operated vehicles, Jason II and Nereus, both designed for deep-water exploration and to conduct a diverse range of scientific investigations in the world's oceans."This was a really exciting field program that provided a rare opportunity for us to explore the complex interplay between the chemistry of a natural environment and the life that it supports," said Seewald. "We are now in a much better position to estimate the amount of microbial life that may exist beneath the seafloor."Discovered in 2010, the Piccard Hydrothermal Field is located just south of Grand Cayman in the Caribbean. The fluid samples the researchers examined vented at 44 to 149 degrees Celsius (111 to 300 degrees Fahrenheit), providing a rare opportunity for the team to study the transition between life-supporting and non-life-supporting environments."The cool (hot) thing about this study is that we were able to find a set of vents that spanned from where it was too hot for life, to where it was just right," says German. "That particularly cute set of circumstances opened up the possibility to gain new insights into what life might (and might not) be able to do, down beneath the seafloor."Shifts in hydrothermal vent fluid temperature and chemical composition are known to serve as an important control on microbial community structure and function in the oceanic crust throughout the world's oceans."This relationship exists because hydrothermal fluids provide energy for specific microbial metabolic reactions," says McDermott. "However, the reverse question of whether vent fluid chemistry is modified by life itself, or instead by non-living processes, is an important one that is rarely addressed."The team's discovery may serve to open up a new path of exploration toward assessing whether non-biological processes serve as important controls on energy availability, in addition to microbial processes.
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Geography
| 2,020 |
August 10, 2020
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https://www.sciencedaily.com/releases/2020/08/200810160151.htm
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Indigenous property rights protect the Amazon rainforest
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One way to cut back on deforestation in the Amazon rainforest -- and help in the global fight against climate change -- is to grant more of Brazil's indigenous communities full property rights to tribal lands. This policy focus is suggested by a new University California of San Diego study published in the
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Led by UC San Diego political science researcher Kathryn Baragwanath, the study uses an innovative method to combine satellite data of vegetation coverage in the Amazon rainforest, between 1982 and 2016, with Brazilian government records of indigenous property rights. The study found significantly reduced deforestation rates in territories that are owned fully and collectively by local tribes -- when compared to territories that are owned only partially by the tribes or not at all. The average effect was a 66% reduction in deforestation.The Amazon accounts for half of the Earth's remaining tropical forest, is an important source of the biodiversity on our planet and plays a major role in climate and water cycles around the world. Yet the Amazon basin is losing trees at an alarming rate, with particularly high levels in recent years, due to a combination of massive forest fires and illegal activities.Who owns the Amazon, meanwhile, is hotly contested, with numerous actors vying for the privilege. Some private entities go ahead with illegal mining or logging, for example, to demonstrate "productive use of land" and thereby gain title to that land. At present, about 2 million hectares of indigenous land are still awaiting official designation as tribal territories.Also debated is whether collective property rights are effective in curbing deforestation. These rights are granted to indigenous peoples in Brazil through a complex and lengthy constitutional process, and are distinct from the private property rights most of us are more familiar with.UC San Diego's Baragwanath and co-author Ella Bayi, now at Columbia University, say "yes, collective property rights are effective" -- if you focus your analysis on the final stage of the titling process in Brazil (which can take up to 25 years to complete), or the point at which tribes gain full property rights.Full property rights give indigenous groups official territorial recognition, enabling them not only to demarcate their territories but also to access the support of monitoring and enforcement agencies, the researcher say."Our research shows that full property rights have significant implications for indigenous people's capacity to curb deforestation within their territories," said Baragwanath. "Not only do indigenous territories serve a human rights role, but they are a cost-effective way for governments to preserve their forested areas and attain climate goals. This is important since many indigenous territories have yet to receive their full property rights and it points to where policymakers and NGOs concerned about the situation in Brazil should now focus their efforts."
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Geography
| 2,020 |
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