Multiple stressors result in reduced reproductive effort by Thalassia testudinum in Florida Bay, USA

2020 ◽  
Vol 647 ◽  
pp. 65-78
Author(s):  
MM Peñalver ◽  
MJ Durako ◽  
BT Furman ◽  
MO Hall
Keyword(s):  
Sexual Reproduction ◽  
Large Scale ◽  
Reproductive Effort ◽  
Multiple Stressors ◽  
Florida Bay ◽  
Thalassia Testudinum ◽  
Spatiotemporal Variability ◽  
Heat Accumulation ◽  
Short Shoots ◽  
Hurricane Irma

Sexual reproduction remains an understudied aspect of seagrass ecology. We examined spatiotemporal variability in the percentage of short shoots with sexual reproductive structures and the proportion of sites that had flowered as an indicator of Thalassia testudinum sexual reproductive effort (RE) across Florida Bay, USA. Short shoots were collected annually during spring within 13 basins across the bay from 2006-2019. The sample period followed 2 very active hurricane seasons and included 2 subsequent major disturbance events, a large-scale die-off of seagrasses in 2015, and the passage of Hurricane Irma in 2017. On average, 4.7% of the collected short shoots had flowered between 2006 and 2019, ranging from 1.3-8.5% at the bay scale and 0-30% at the basin level. Regression analyses indicated that RE varied significantly among basins and years, with high multiyear variability in several basins. RE was negatively correlated with annual heat accumulation, and positively correlated with the number of days below 28°C. Annual heat accumulation rose steadily from 2006-2019; accordingly, bay-wide RE declined. RE was higher in western basins, which were the most affected by recent disturbance events, indicating a potentially important role for sexual reproduction in recovery from disturbance. However, significant reductions in RE following the 2015 die-off and Hurricane Irma show limits to the plasticity and resilience of T. testudinum, both in terms of reduced compensatory RE following successive disturbances and reductions in basal RE correlated with rising annual temperatures.

scholarly journals Impact of Extreme Disturbances on Suspended Sediment in Western Florida Bay: Implications for Seagrass Resilience

2021 ◽  
Vol 8 ◽  
Author(s):  
Jonathan R. Rodemann ◽  
W. Ryan James ◽  
Rolando O. Santos ◽  
Bradley T. Furman ◽  
Zachary W. Fratto ◽  
...  
Keyword(s):  
Satellite Imagery ◽  
Large Scale ◽  
Regime Shift ◽  
Florida Bay ◽  
Potential Interaction ◽  
Seagrass Cover ◽  
Seagrass Ecosystems ◽  
Average Size ◽  
Hurricane Irma

Seagrasses are threatened worldwide due to anthropogenic and natural disturbances disrupting the multiple feedbacks needed to maintain these ecosystems. If the disturbance is severe enough, seagrass systems may undergo a regime shift to a degraded system state that is resistant to recovery. In Florida Bay, Florida, United States, two recent, large-scale disturbances (a drought-induced seagrass die-off in 2015 and Hurricane Irma in 2017) have caused 8,777 ha of seagrass beds to degrade into a turbid, unvegetated state, causing a large sediment plume. Using satellite imagery digitization and long-term seagrass cover data, we investigate the expansion of this sediment plume between 2008 and 2020 and the potential interaction of this sediment plume with seagrass recovery in two focal basins in Florida Bay affected by the die-off, Johnson and Rankin. The average size of the sediment plume increased by 37% due to the die-off and Hurricane Irma, increasing from an average of 163.5 km2 before the disturbances to an average of 223.5 km2. The expansion of the plume was basin-specific, expanding into Johnson after the 2015 seagrass die-off with expansive and long-lasting effects, but only expanding into Rankin after Hurricane Irma with less severe and short-term effects. Furthermore, the sediment plume was negatively correlated with seagrass cover in Johnson, but held no relationship with seagrass cover in Rankin. Thus, different disturbances can act upon seagrass ecosystems at varying scales with varying consequences. This study illustrates the advantage of combining satellite imagery with field data to monitor disturbances as well as highlights the importance of investigating disturbances of seagrass ecosystems at various scales to comprehend seagrass resilience in the context of future extreme events.

scholarly journals Inconclusive evidence of sexual reproduction of invasive Halophila stipulacea: a new field guide to encourage investigation of flower and fruit production throughout its invasive range

2020 ◽  
Vol 63 (6) ◽  
pp. 537-540
Author(s):  
Fee O.H. Smulders ◽  
Kelcie L. Chiquillo ◽  
Demian A. Willette ◽  
Paul H. Barber ◽  
Marjolijn J.A. Christianen
Keyword(s):  
Sexual Reproduction ◽  
Clonal Growth ◽  
Large Scale ◽  
Fruit Production ◽  
Morphological Evidence ◽  
Invasive Range ◽  
Reproductive Structures ◽  
Halophila Stipulacea ◽  
The Caribbean ◽  
Low Rate

AbstractThe dioecious seagrass species Halophila stipulacea reproduces mainly through fast clonal growth, underlying its invasive behavior. Here, we provide morphological evidence to show that the first findings of fruits in the Caribbean were misidentified. Consequently, H. stipulacea reproduction is likely still only asexual in the Caribbean. Therefore, we introduce an identification key of H. stipulacea reproductive structures to encourage careful identification and quantification throughout its invasive range. Until large-scale seed production in invaded habitats is reported, the apparent low rate of sexual reproduction needs to be considered in current studies investigating the invasion capacity of this species.

scholarly journals Mechanism of large-scale flow reversals in turbulent thermal convection

2018 ◽  
Vol 4 (11) ◽  
pp. eaat7480 ◽  
Author(s):  
Yin Wang ◽  
Pik-Yin Lai ◽  
Hao Song ◽  
Penger Tong
Keyword(s):  
Thermal Convection ◽  
Large Scale ◽  
Careful Analysis ◽  
Extreme Value Statistics ◽  
Convection Cell ◽  
Heat Accumulation ◽  
Thermal Plumes ◽  
Minute Amount ◽  
Large Scale Flow ◽  
Experimental Findings

It is commonly believed that heat flux passing through a closed thermal convection system is balanced so that the convection system can remain at a steady state. Here, we report a new kind of convective instability for turbulent thermal convection, in which the convective flow stays over a long steady “quiet period” having a minute amount of heat accumulation in the convection cell, followed by a short and intermittent “active period” with a massive eruption of thermal plumes to release the accumulated heat. The rare massive eruption of thermal plumes disrupts the existing large-scale circulation across the cell and resets its rotational direction. A careful analysis reveals that the distribution of the plume eruption amplitude follows the generalized extreme value statistics with an upper bound, which changes with the fluid properties of the convecting medium. The experimental findings have important implications to many closed convection systems of geophysical scale, in which massive eruptions and sudden changes in large-scale flow pattern are often observed.

Changes in Yangtze Precipitation Extremes and the association with thermodynamic, dynamic, and local drivers  

2021 ◽  
Author(s):  
Xin Li
Keyword(s):  
Global Warming ◽  
Extreme Precipitation ◽  
Large Scale ◽  
Global Climate ◽  
Yangtze River Basin ◽  
Precipitation Extremes ◽  
Spatiotemporal Variability ◽  
Local Effects ◽  
Dynamic Factors ◽  
The Yangtze River Basin

<p>Spatioteporal variability of precipitation extremes is increasingly the focus of attention in both the climate and hydrology communites, especailly in the context of global climate change. Indicated by the Clausius-Clapeyron equation under the constant relative humudity assumption, it is expected, from the thermodynamic perspective, that extreme precipitation would increase as globe warms. However, when it comes to the regional response of precipitation to global warming, the resutls could be highly uncertain due to the influences of dynamic factors such as large-scale circlation patterns and local effects. Here, we investigate trends in a set of extreme precipitation indices (EPIs) over the Yangtze River Basin (YRB) during the period of 1960-2019. Also, we explore the possible associations between spatiotemporal variability of the EPIs and global warming, ENSO, and local effects. Our resutls show marked rising trends in frequency and intensity of Yangtze precipitation extremes. Global warming tends to enhance the frequency and intensity of preciptation extremes over the YRB. The La Niña phase of ENSO could lead to an increase of precipitation extremes in the current year, but a decrease of precipitation extremes in the coming year. Local warming mainly exerts a reducing effect on precipitation extremes, which is likely associated with the significant decrease of relative humidity in the YRB. Our findings highlight the need for a systematic approach to investigate changes in precipitation extremes over the YRB.</p>

scholarly journals Impacts of Hurricane Irma on the Circulation and Transport in Florida Bay and the Charlotte Harbor Estuary

2019 ◽  
Vol 43 (5) ◽  
pp. 1194-1216 ◽  
Author(s):  
Yonggang Liu ◽  
Robert H. Weisberg ◽  
Lianyuan Zheng
Keyword(s):  
Florida Bay ◽  
Charlotte Harbor ◽  
Hurricane Irma

scholarly journals Comparing atmospheric transport models for future regional inversions over Europe – Part 1: mapping the atmospheric CO<sub>2</sub> signals

2007 ◽  
Vol 7 (13) ◽  
pp. 3461-3479 ◽  
Author(s):  
C. Geels ◽  
M. Gloor ◽  
P. Ciais ◽  
P. Bousquet ◽  
P. Peylin ◽  
...  
Keyword(s):  
High Resolution ◽  
High Altitude ◽  
Large Scale ◽  
Fossil Fuel ◽  
Atmospheric Transport ◽  
Inverse Methods ◽  
Spatiotemporal Variability ◽  
Transport Models ◽  
Sources And Sinks ◽  
Low Altitude

Abstract. The CO2 source and sink distribution across Europe can be estimated in principle through inverse methods by combining CO2 observations and atmospheric transport models. Uncertainties of such estimates are mainly due to insufficient spatiotemporal coverage of CO2 observations and biases of the models. In order to assess the biases related to the use of different models the CO2 concentration field over Europe has been simulated with five different Eulerian atmospheric transport models as part of the EU-funded AEROCARB project, which has the main goal to estimate the carbon balance of Europe. In contrast to previous comparisons, here both global coarse-resolution and regional higher-resolution models are included. Continuous CO2 observations from continental, coastal and mountain sites as well as flasks sampled on aircrafts are used to evaluate the models' ability to capture the spatiotemporal variability and distribution of lower troposphere CO2 across Europe. 14CO2 is used in addition to evaluate separately fossil fuel signal predictions. The simulated concentrations show a large range of variation, with up to ~10 ppm higher surface concentrations over Western and Central Europe in the regional models with highest (mesoscale) spatial resolution. The simulation – data comparison reveals that generally high-resolution models are more successful than coarse models in capturing the amplitude and phasing of the observed short-term variability. At high-altitude stations the magnitude of the differences between observations and models and in between models is less pronounced, but the timing of the diurnal cycle is not well captured by the models. The data comparisons show also that the timing of the observed variability on hourly to daily time scales at low-altitude stations is generally well captured by all models. However, the amplitude of the variability tends to be underestimated. While daytime values are quite well predicted, nighttime values are generally underpredicted. This is a reflection of the different mixing regimes during day and night combined with different vertical resolution between models. In line with this finding, the agreement among models is increased when sampling in the afternoon hours only and when sampling the mixed portion of the PBL, which amounts to sampling at a few hundred meters above ground. The main recommendations resulting from the study for constraining land carbon sources and sinks using high-resolution concentration data and state-of-the art transport models through inverse methods are given in the following: 1) Low altitude stations are presently preferable in inverse studies. If high altitude stations are used then the model level that represents the specific sites should be applied, 2) at low altitude sites only the afternoon values of concentrations can be represented sufficiently well by current models and therefore afternoon values are more appropriate for constraining large-scale sources and sinks in combination with transport models, 3) even when using only afternoon values it is clear that data sampled several hundred meters above ground can be represented substantially more robustly in models than surface station records, which emphasize the use of tower data in inverse studies and finally 4) traditional large scale transport models seem not sufficient to resolve fine-scale features associated with fossil fuel emissions, as well as larger-scale features like the concentration distribution above the south-western Europe. It is therefore recommended to use higher resolution models for interpretation of continental data in future studies.

scholarly journals Impacts of Hurricane Irma on Florida Bay Islands, Everglades National Park, USA

2019 ◽  
Vol 43 (5) ◽  
pp. 1070-1089 ◽  
Author(s):  
G. Lynn Wingard ◽  
S. E. Bergstresser ◽  
B. L. Stackhouse ◽  
M. C. Jones ◽  
M. E. Marot ◽  
...  
Keyword(s):  
National Park ◽  
System Analysis ◽  
Florida Bay ◽  
South Florida ◽  
Everglades National Park ◽  
Elevation Changes ◽  
Geographic Information System Analysis ◽  
Bay Islands ◽  
Hurricane Irma

AbstractHurricane Irma made landfall in south Florida, USA, on September 10, 2017 as a category 4 storm. In January 2018, fieldwork was conducted on four previously (2014) sampled islands in Florida Bay, Everglades National Park to examine changes between 2014 and 2018. The objectives were to determine if the net impact of the storm was gain or loss of island landmass and/or elevation; observe and quantify impacts to mangroves; and identify distinctive sedimentary, biochemical, and/or geochemical signatures of the storm. Storm overwash deposits were measured in the field and, in general, interior island mudflats appeared to experience deposition ranging from ~ 0.5 to ~ 6.5 cm. Elevation changes were measured using real-time kinematic positioning and satellite receivers. Comparison of 2014 to 2018 elevation measurements indicates mangrove berms and transitional areas between mudflats and berms experienced erosion and loss of elevation, whereas interior mudflats gained elevation, possibly due to Hurricane Irma. Geographic information system analysis of pre- and post-storm satellite imagery indicates the western-most island, closest to the eye of the storm, lost 32 to 42% (~ 11 to 13 m) of the width of the eastern berm, and vegetated coverage was reduced 9.3% or ~ 9700 m2. Vegetated coverage on the eastern-most island was reduced by 1.9% or ~ 9200 m2. These results are compared to previous accounts of hurricane impacts and provide a baseline for examining long-term constructive and destructive aspects of hurricanes on the islands and the role of storms in resiliency of Florida Bay islands.

Forcings of mass-balance variability in Karakoram-Himalaya

2020 ◽  
Author(s):  
Pankaj Kumar ◽  
Vladimir A. Ryabchenko ◽  
Aaquib Javed ◽  
Dmitry V. Sein ◽  
Md. Farooq Azam
Keyword(s):  
Mass Balance ◽  
Large Scale ◽  
Climate Model ◽  
Model Simulation ◽  
Large Fraction ◽  
Water Security ◽  
Spatiotemporal Variability ◽  
Glacier Mass Balance ◽  
Russian Science ◽  
The Impact

&lt;p&gt;Glacier retreat is a key indicator of climate variability and change. Karakoram-Himalaya (KH) glaciers are the source of several perennial rivers protecting water security of a large fraction of the global population. The region is highly vulnerable to climate change impacts, hence the sensitivity of KH glaciers to regional microclimate, especially the impact of individual parameters forcing have been not quantified yet. The present study, using a coupled dynamical glacier-climate model simulation results, analyses the modelled interannual variability of mass-balance for the period 1989-2016. It is validated against available observations to quantify for the first time the sensitivity of the glaciers mass-balance to the individual forcing over KH. The snowfall variability emerges as the key factor, explaining ~60% of the variability of regional glacier mass balance. We provide insight into the recent divergent glacier response over the Karakoram Himalaya. The results underline the need for careful measurements and model representations of snowfall spatiotemporal variability, one of the HK's least-studied meteorological variables, to capture the large-scale, but region-specific, glacier changes at the third pole.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Acknowledgement:&lt;/p&gt;&lt;p&gt;The work was supported by Indian project no. DST/INT/RUS/RSF/P-33/G, and the Russian Science Foundation (Project 19-47-02015).&lt;/p&gt;

The cost of reproduction to the clonal herb Asarum canadense (wild ginger)

1995 ◽  
Vol 73 (10) ◽  
pp. 1683-1686 ◽  
Author(s):  
Angela M. Muir
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Energy Cost ◽  
Reproductive Effort ◽  
Cost Of Reproduction ◽  
Net Energy ◽  
Subsequent Growth ◽  
Subsequent Storage ◽  
The Cost ◽  
And Storage

The cost of reproduction to the clonal understorey herb Asarum canadense (wild ginger) was examined by measuring subsequent growth and storage. All connected vegetative rhizome was controlled and fully measured. Three important aspects of reproductive effort were addressed: (i) the effect of sexual reproduction on subsequent storage and growth of fragments, (ii) the effect of asexual reproduction on subsequent storage and growth of fragments, and (iii) a comparison to determine the least costly method of reproduction. It was found that sexual reproduction in wild ginger has an energy cost that diverts energy from storage and growth. Asexual reproduction represents neither a net energy cost nor gain to the fragment and is the least costly mode of reproduction to wild ginger. Key words: Asarum canadense, reproduction, rhizome, clonal.

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