scholarly journals Top-down and bottom-up controls on southern New England salt marsh crab populations

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4876 ◽  
Author(s):  
Kenneth B. Raposa ◽  
Richard A. McKinney ◽  
Cathleen Wigand ◽  
Jeffrey W. Hollister ◽  
Cassie Lovall ◽  
...  
Keyword(s):  
Salt Marsh ◽  
New England ◽  
Sea Level Rise ◽  
Sea Level ◽  
Salt Marshes ◽  
Fiddler Crab ◽  
Water Levels ◽  
Southern New England ◽  
England Salt Marsh ◽  
Crab Abundance

Southern New England salt marsh vegetation and habitats are changing rapidly in response to sea-level rise. At the same time, fiddler crab (Uca spp.) distributions have expanded and purple marsh crab (Sesarma reticulatum) grazing on creekbank vegetation has increased. Sea-level rise and reduced predation pressure drive these changing crab populations but most studies focus on one species; there is a need for community-level assessments of impacts from multiple crab species. There is also a need to identify additional factors that can affect crab populations. We sampled crabs and environmental parameters in four Rhode Island salt marshes in 2014 and compiled existing data to quantify trends in crab abundance and multiple factors that potentially affect crabs. Crab communities were dominated by fiddler and green crabs (Carcinus maenas); S. reticulatum was much less abundant. Burrow sizes suggest that Uca is responsible for most burrows. On the marsh platform, burrows and Carcinus abundance were negatively correlated with elevation, soil moisture, and soil percent organic matter and positively correlated with soil bulk density. Uca abundance was negatively correlated with Spartina patens cover and height and positively correlated with Spartina alterniflora cover and soil shear strength. Creekbank burrow density increased dramatically between 1998 and 2016. During the same time, fishing effort and the abundance of birds that prey on crabs decreased, and water levels increased. Unlike in other southern New England marshes where recreational overfishing is hypothesized to drive increasing marsh crab abundance, we propose that changes in crab abundance were likely unrelated to recreational finfish over-harvest; instead, they better track sea-level rise and changing abundances of alternate predators, such as birds. We predict that marsh crab abundance will continue to expand with ongoing sea-level rise, at least until inundation thresholds for crab survival are exceeded.

Variability of vegetation in tidal marshes of Maine, U.S.A.

1989 ◽  
Vol 67 (1) ◽  
pp. 230-238 ◽  
Author(s):  
Heather A. Jacobson ◽  
George L. Jacobson Jr.
Keyword(s):  
Species Richness ◽  
Salt Marsh ◽  
Species Composition ◽  
New England ◽  
Salt Marshes ◽  
Tidal Marshes ◽  
Bay Of Fundy ◽  
Marsh Vegetation ◽  
Southern New England ◽  
England Salt Marsh

Systematic studies of vegetation on 18 salt marshes along the coast of Maine show that the vegetation is highly variable in species composition, species richness, and zonation pattern. Marshes with high species richness are found in relatively stable geologic settings, while unstable marshes at the base of erodible bluffs have low species richness. Species composition is influenced by freshwater input. Salt-marsh zonation varies greatly in both the number of zones present per marsh and the species assemblages within zones. With a few notable exceptions, the vegetation of salt marshes in southern Maine is similar to that of marshes in southern New England. Salt-marsh vegetation in northeastern Maine is more similar to that of marshes in the Bay of Fundy region. Key words: tidal marsh, salt marsh, Maine, vegetation, New England, Bay of Fundy.

scholarly journals Tidal frequencies and quasiperiodic subsurface water level variations dominate redox dynamics in a salt marsh system

2021 ◽  
Author(s):  
Emilio Grande ◽  
Bhavna Arora ◽  
Ate Visser ◽  
Maya Montalvo ◽  
Anna Braswell ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Sea Level Rise ◽  
Sea Level ◽  
Salt Marshes ◽  
Water Levels ◽  
Wavelet Coherence ◽  
Spatiotemporal Variability ◽  
Subsurface Water ◽  
Biogeochemical Processes ◽  
Water Level Variations

Salt marshes are hotspots of nutrient processing en route to sensitive coastal environments. While our understanding of these systems has improved over the years, we still have limited knowledge of the spatiotemporal variability of critical biogeochemical processes within salt marshes. Sea-level rise will continue to force change on salt marsh functioning, highlighting the urgency of filling this knowledge gap. Our study was conducted in a central California estuary experiencing extensive marsh drowning and relative sea-level rise, making it a model system for such an investigation. Here we instrumented three marsh positions with different degrees of inundation (6.7%, 8.9%, and 11.2% of the time for the upper, middle, and lower marsh positions, respectively), providing locations with varied geochemical characteristics and hydrological interaction at the site. We continuously monitored redox potential (Eh) at depths of 0.1, 0.3, and 0.5 m, subsurface water levels (WL), and temperature at each marsh position to understand how drivers of subsurface biogeochemical processes fluctuate across tidal cycles, using wavelet analyses to explain the interactions between Eh and WL. We found that tidal forcing significantly affects biogeochemical processes by imparting controls on Eh variability, likely driving subsurface hydro-biogeochemistry of the salt marsh. Wavelet coherence showed that the Eh-WL relationship is non-linear, and their lead-lag relationship is variable. We found that precipitation events perturb Eh at depth over timescales of hours, even though WL show relatively minimal change during events. This work highlights the importance of high-frequency measurements, such as Eh, to help explain factors that govern subsurface geochemistry and hydrological processes in salt marshes.

scholarly journals Tidal frequencies and quasiperiodic subsurface water level variations dominate redox dynamics in a salt marsh system

2021 ◽  
Author(s):  
Emilio Grande ◽  
Bhavna Arora ◽  
Ate Visser ◽  
Maya Montalvo ◽  
Anna Braswell ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Sea Level Rise ◽  
Sea Level ◽  
Salt Marshes ◽  
Water Levels ◽  
Wavelet Coherence ◽  
Spatiotemporal Variability ◽  
Subsurface Water ◽  
Biogeochemical Processes ◽  
Water Level Variations

Salt marshes are hotspots of nutrient processing en route to sensitive coastal environments. While our understanding of these systems has improved over the years, we still have limited knowledge of the spatiotemporal variability of critical biogeochemical processes within salt marshes. Sea-level rise will continue to force change on salt marsh functioning, highlighting the urgency of filling this knowledge gap. Our study was conducted in a central California estuary experiencing extensive marsh drowning and relative sea-level rise, making it a model system for such an investigation. Here we instrumented three marsh positions with different degrees of inundation (6.7%, 8.9%, and 11.2% of the time for the upper, middle, and lower marsh positions, respectively), providing locations with varied geochemical characteristics and hydrological interaction at the site. We continuously monitored redox potential (Eh) at depths of 0.1, 0.3, and 0.5 m, subsurface water levels (WL), and temperature at each marsh position to understand how drivers of subsurface biogeochemical processes fluctuate across tidal cycles, using wavelet analyses to explain the interactions between Eh and WL. We found that tidal forcing significantly affects biogeochemical processes by imparting controls on Eh variability, likely driving subsurface hydro-biogeochemistry of the salt marsh. Wavelet coherence showed that the Eh-WL relationship is non-linear, and their lead-lag relationship is variable. We found that precipitation events perturb Eh at depth over timescales of hours, even though WL show relatively minimal change during events. This work highlights the importance of high-frequency measurements, such as Eh, to help explain factors that govern subsurface geochemistry and hydrological processes in salt marshes.

A comparative assessment of salt marsh crabs (Decapoda: Brachyura) across the National Estuarine Research Reserves in New England, USA

2019 ◽  
Author(s):  
Kenneth B Raposa ◽  
Jason S Goldstein ◽  
Kristin Wilson Grimes ◽  
Jordan Mora ◽  
Paul E Stacey ◽  
...  
Keyword(s):  
Salt Marsh ◽  
New England ◽  
Multiple Stressors ◽  
Carcinus Maenas ◽  
The United States ◽  
Entire Region ◽  
National Assessment ◽  
Southern New England ◽  
Crab Abundance ◽  
National Estuarine Research Reserves

Abstract Salt marsh degradation and loss is accelerating in many regions of the United States as well as worldwide. Multiple stressors are often responsible, sometimes including crab burrowing and herbivory. A recent national assessment identified stark differences in crab indicators between northern and southern New England, with the latter exhibiting intense signs of impacts by crabs, but more details on crab patterns across the entire region are needed beyond this “broad-brush” assessment. Our study used green crab (Carcinus maenas (Linnaeus, 1758)) traps, intensive marsh platform burrow counts, and a new multi-metric index of relative crab abundance to examine patterns in marsh crabs across four National Estuarine Research Reserves in New England. Crab indicators from the multi-metric index and burrow counts were higher in southern New England marshes; patterns from trapping of green crabs were less clear. At the marshes examined, green crabs were very abundant in Maine, lower in New Hampshire, and intermediate in southern New England. Our study confirms that abundance and impacts by crabs vary dramatically between sites in northern and southern New England, and provides improved context for managers and researchers when considering impacts to marshes from multiple crab species across New England and elsewhere.

Macroinfauna of a Southern New England salt marsh: seasonal dynamics and production

1995 ◽  
Vol 121 (3) ◽  
pp. 431-445 ◽  
Author(s):  
R. Sard� ◽  
K. Foreman ◽  
I. Valiela
Keyword(s):  
Salt Marsh ◽  
New England ◽  
Seasonal Dynamics ◽  
Southern New England ◽  
England Salt Marsh
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