patrickbdevaney/mia9 · Datasets at Hugging Face

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and Durako, 2019). The system was further perturbed when
Hurricane Irma passed over Florida Bay in 2017. In this paper,
we describe evidence based on remote sensing and field data
of how an expansion of a sediment plume in the western
region of Florida Bay resulted from these two disturbances.
Overall, we saw a 37% average increase in sediment plume area
as the plume expanded eastward post the 2015 die-off (time
series breakpoint is November 2016), with peak sediment values
reached post Hurricane Irma. The expansion of the plume into
individual basins was dependent on the scale and location of
the disturbance, expanding in Johnson soon after the die-off but
only expanding into Rankin after Hurricane Irma. Further, the
effect of the plume in Rankin was smaller and shorter lasting
than the more expansive and persistent effects in Johnson. We
also investigate the potential interaction of this sediment plume
expansion with seagrass, which we found to be basin specific.
The sediment plume was negatively related to seagrass cover
in the more and earlier impacted Johnson basin while had no
relationship in Rankin due to the recovery of seagrass before the
sediment plume reached Rankin.
How a system responds to a disturbance is spatially explicit,
dependent on the spatial scale (Norkko et al., 2006; Dumbrell
et al., 2008) and intensity of a disturbance event (Platt and
Connell, 2003; Miller et al., 2011). This is especially true in coastal
ecosystems, where different levels of exposure to a disturbance
result in a spatial gradient of effects on community composition
and function (Fonseca and Bell, 1998; Fonseca et al., 2008; Santos
and Lirman, 2012). For example, Stipek et al. (2020) found
that seagrass beds closer to pulses of freshwater experienced
Frontiers in Marine Science \| www.frontiersin.org 7 July 2021 \| Volume 8 \| Article 633240
Rodemann et al. Sediment Plume and Seagrass Resilience
TABLE 3 \| Breakpoint analysis used to determine significant changes in sediment plume size.
F p 1st breakpoint (95% CI) 2nd breakpoint (95% CI) BIC 1 break BIC 2 breaks BIC 3 breaks
(a) Sediment plume area 27.7 <0.001* 11/2016 (09/2015–02/2018) NA 60.2 63.2 65.5
(b) Proportion of Johnson covered 161.55 <0.001* 03/2015 (10/2014–09/2015) NA 28.9 33.4 38.2
(c) Proportion of Rankin covered 17.1 <0.001* 02/2017 (09/2015–11/2017) 02/2017 (09/2015–11/2017) 66.0 54.6 60.1
Three analyses were run: (a) the whole sediment plume area, (b) the proportion of Johnson Basin covered by the sediment plume, and (c) the proportion of Rankin Basin
covered by the sediment plume. Shown are the test statistic of the significance of the breakpoint (F), the approximate p-values for the null hypothesis that there is no
breakpoint (p), and the location of the breakpoint(s). Bayesian information criterion (BIC) was used to determine the number of significant breakpoints.
Significant values are denoted with *.
FIGURE 5 \| Temporal trend in the proportion of (A) Johnson, and (B) Rankin basins covered by the sediment plume. The blue lines represent the trend before the
breakpoint while the red lines represent the trend after the first breakpoint. Breakpoints are shown by vertical black lines with 95% confidence interval in gray shading.
higher fragmentation rates and higher mortality of small seagrass
patches. In our study, the expansion of the sediment plume in
response to the seagrass die-off and Hurricane Irma was also
spatially explicit due to the unique hydrological dynamics of
Florida Bay. Both disturbances contributed to the expansion of
the sediment plume, but at different spatial scales. We expected
high sediment mobilization after the seagrass die-off due to
the loss of the mechanisms that promote sediment stabilization
in densely covered SAV habitats (Fonseca and Fisher, 1986;
Nyström et al., 2012). Even though the sediment was more easily
mobilized after the seagrass die-off, the low water movement
within the system, due to restricted water exchange and high
residence time (Nuttle et al., 2000; Rudnick et al., 2005), may
explain why the plume did not expand immediately after the
die-off into certain areas of the Bay, such as in Rankin.
Hurricane Irma was a bay-scale disturbance that drastically
moved water throughout the estuary, and the combination of the
water movement and increased sediment mobility likely led to the
expansion of the sediment plume to its largest extent (Liu et al.,
2020). The different spatial extent and location at which the two
disturbances acted created a spatially explicit gradient in their
effects, as seen by the differences in the timing of breakpoints
between basins. Early during the study period, Johnson was on
the eastern border of the sediment plume (Figure 2). There was
a breakpoint in the proportion of Johnson covered with the
sediment plume that corresponded with the seagrass die-off. This
was not the case for Rankin, which is located east of Johnson,
where the sediment concentration before the disturbances was
zero. The sediment plume in Rankin was ephemeral, increasing
in size after Hurricane Irma in 2017 but exiting Rankin in 2019.
The timing of disturbances also plays a role in determining
effects on an ecosystem (Miller et al., 2011; Santillan et al.,
2019). In Florida Bay, Johnson Basin became turbid due to the
sediment plume right after the 2015 seagrass die-off while the
sediment plume did not migrate to Rankin Basin until 2017.
The difference in timing between when each basin experienced
the sediment plume may have affected seagrass recovery. Both
Johnson and Rankin lost most of their T. testudinum cover in
the drought-induced seagrass die-off in 2015 (Hall et al., 2016;
Hall and Durako, 2019). Since both systems were T. testudinumdominated before the die-off, the loss of this species resulted in
a severe reduction to the total seagrass cover as well. However,
recovery trajectories differ between the two basins (Hall and
Durako, 2019; McDonald et al., 2020). Total seagrass cover,
dominated by Halodule wrightii (a pioneer species), recovered
to near pre-die-off levels in Rankin within 2 years, whereas
Frontiers in Marine Science \| www.frontiersin.org 8 July 2021 \| Volume 8 \| Article 633240
Rodemann et al. Sediment Plume and Seagrass Resilience
FIGURE 6 \| Summary of ANOVA and correlation analyses. (A) Mean proportions (and 95% confidence intervals) of Johnson and Rankin Basins covered by the
sediment plume before and after the breakpoints. (B) Mean (and 95% confidence interval) Braun-Blanquet seagrass cover in Johnson and Rankin before and after
the breakpoints. (C) Relationship between the proportion of each basin covered by the sediment plume and the mean seagrass cover of each basin shown
separately by basin, showing the significant regression line for Johnson Basin. Linear regression model shown for Johnson Basin has an R
2
value of 0.55 following
the following equation: y = –1.4x + 3.7.
Johnson continues to lose T. testudinum and was not being
recolonized by H. wrightii until 2020 (McDonald et al., 2020).
This difference in seagrass recovery may be due to the high
proportion of the Johnson covered by the sediment plume that

and Durako, 2019). The system was further perturbed when

Hurricane Irma passed over Florida Bay in 2017. In this paper,

we describe evidence based on remote sensing and field data

of how an expansion of a sediment plume in the western

region of Florida Bay resulted from these two disturbances.

Overall, we saw a 37% average increase in sediment plume area

as the plume expanded eastward post the 2015 die-off (time

series breakpoint is November 2016), with peak sediment values

reached post Hurricane Irma. The expansion of the plume into

individual basins was dependent on the scale and location of

the disturbance, expanding in Johnson soon after the die-off but

only expanding into Rankin after Hurricane Irma. Further, the

effect of the plume in Rankin was smaller and shorter lasting

than the more expansive and persistent effects in Johnson. We

also investigate the potential interaction of this sediment plume

expansion with seagrass, which we found to be basin specific.

The sediment plume was negatively related to seagrass cover

in the more and earlier impacted Johnson basin while had no

relationship in Rankin due to the recovery of seagrass before the

sediment plume reached Rankin.

How a system responds to a disturbance is spatially explicit,

dependent on the spatial scale (Norkko et al., 2006; Dumbrell

et al., 2008) and intensity of a disturbance event (Platt and

Connell, 2003; Miller et al., 2011). This is especially true in coastal

ecosystems, where different levels of exposure to a disturbance

result in a spatial gradient of effects on community composition

and function (Fonseca and Bell, 1998; Fonseca et al., 2008; Santos

and Lirman, 2012). For example, Stipek et al. (2020) found

that seagrass beds closer to pulses of freshwater experienced

Frontiers in Marine Science | www.frontiersin.org 7 July 2021 | Volume 8 | Article 633240

Rodemann et al. Sediment Plume and Seagrass Resilience

TABLE 3 | Breakpoint analysis used to determine significant changes in sediment plume size.

F p 1st breakpoint (95% CI) 2nd breakpoint (95% CI) BIC 1 break BIC 2 breaks BIC 3 breaks

(a) Sediment plume area 27.7 <0.001* 11/2016 (09/2015–02/2018) NA 60.2 63.2 65.5

(b) Proportion of Johnson covered 161.55 <0.001* 03/2015 (10/2014–09/2015) NA 28.9 33.4 38.2

(c) Proportion of Rankin covered 17.1 <0.001* 02/2017 (09/2015–11/2017) 02/2017 (09/2015–11/2017) 66.0 54.6 60.1

Three analyses were run: (a) the whole sediment plume area, (b) the proportion of Johnson Basin covered by the sediment plume, and (c) the proportion of Rankin Basin

covered by the sediment plume. Shown are the test statistic of the significance of the breakpoint (F), the approximate p-values for the null hypothesis that there is no

breakpoint (p), and the location of the breakpoint(s). Bayesian information criterion (BIC) was used to determine the number of significant breakpoints.

Significant values are denoted with *.

FIGURE 5 | Temporal trend in the proportion of (A) Johnson, and (B) Rankin basins covered by the sediment plume. The blue lines represent the trend before the

breakpoint while the red lines represent the trend after the first breakpoint. Breakpoints are shown by vertical black lines with 95% confidence interval in gray shading.

higher fragmentation rates and higher mortality of small seagrass

patches. In our study, the expansion of the sediment plume in

response to the seagrass die-off and Hurricane Irma was also

spatially explicit due to the unique hydrological dynamics of

Florida Bay. Both disturbances contributed to the expansion of

the sediment plume, but at different spatial scales. We expected

high sediment mobilization after the seagrass die-off due to

the loss of the mechanisms that promote sediment stabilization

in densely covered SAV habitats (Fonseca and Fisher, 1986;

Nyström et al., 2012). Even though the sediment was more easily

mobilized after the seagrass die-off, the low water movement

within the system, due to restricted water exchange and high

residence time (Nuttle et al., 2000; Rudnick et al., 2005), may

explain why the plume did not expand immediately after the

die-off into certain areas of the Bay, such as in Rankin.

Hurricane Irma was a bay-scale disturbance that drastically

moved water throughout the estuary, and the combination of the

water movement and increased sediment mobility likely led to the

expansion of the sediment plume to its largest extent (Liu et al.,

2020). The different spatial extent and location at which the two

disturbances acted created a spatially explicit gradient in their

effects, as seen by the differences in the timing of breakpoints

between basins. Early during the study period, Johnson was on

the eastern border of the sediment plume (Figure 2). There was

a breakpoint in the proportion of Johnson covered with the

sediment plume that corresponded with the seagrass die-off. This

was not the case for Rankin, which is located east of Johnson,

where the sediment concentration before the disturbances was

zero. The sediment plume in Rankin was ephemeral, increasing

in size after Hurricane Irma in 2017 but exiting Rankin in 2019.

The timing of disturbances also plays a role in determining

effects on an ecosystem (Miller et al., 2011; Santillan et al.,

2019). In Florida Bay, Johnson Basin became turbid due to the

sediment plume right after the 2015 seagrass die-off while the

sediment plume did not migrate to Rankin Basin until 2017.

The difference in timing between when each basin experienced

the sediment plume may have affected seagrass recovery. Both

Johnson and Rankin lost most of their T. testudinum cover in

the drought-induced seagrass die-off in 2015 (Hall et al., 2016;

Hall and Durako, 2019). Since both systems were T. testudinumdominated before the die-off, the loss of this species resulted in

a severe reduction to the total seagrass cover as well. However,

recovery trajectories differ between the two basins (Hall and

Durako, 2019; McDonald et al., 2020). Total seagrass cover,

dominated by Halodule wrightii (a pioneer species), recovered

to near pre-die-off levels in Rankin within 2 years, whereas

Frontiers in Marine Science | www.frontiersin.org 8 July 2021 | Volume 8 | Article 633240

Rodemann et al. Sediment Plume and Seagrass Resilience

FIGURE 6 | Summary of ANOVA and correlation analyses. (A) Mean proportions (and 95% confidence intervals) of Johnson and Rankin Basins covered by the

sediment plume before and after the breakpoints. (B) Mean (and 95% confidence interval) Braun-Blanquet seagrass cover in Johnson and Rankin before and after

the breakpoints. (C) Relationship between the proportion of each basin covered by the sediment plume and the mean seagrass cover of each basin shown

separately by basin, showing the significant regression line for Johnson Basin. Linear regression model shown for Johnson Basin has an R

2

value of 0.55 following

the following equation: y = –1.4x + 3.7.

Johnson continues to lose T. testudinum and was not being

recolonized by H. wrightii until 2020 (McDonald et al., 2020).

This difference in seagrass recovery may be due to the high

proportion of the Johnson covered by the sediment plume that