Density Of Atlantic Marsh Fiddler Crabs Urca Pugnax In Relation To Saltmarsh Cordgrass Spartina Alterniflora F9orm And Density
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Density Of Atlantic Marsh Fiddler Crabs Urca Pugnax In Relation To Saltmarsh Cordgrass Spartina Alterniflora F9orm And Density
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Author : Yael B. Weiss
language : en
Publisher:
Release Date : 2016
Density Of Atlantic Marsh Fiddler Crabs Urca Pugnax In Relation To Saltmarsh Cordgrass Spartina Alterniflora F9orm And Density written by Yael B. Weiss and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Fiddler crabs categories.
Atlantic Marsh Fiddler
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Author :
language : en
Publisher:
Release Date : 1989
Atlantic Marsh Fiddler written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with Coastal ecology categories.
A Comparison Of Invasive And Non Invasive Techniques For Measuring Fiddler Crab Density In A Salt Marsh
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Author : Charles Robert Hubbard
language : en
Publisher:
Release Date : 2008
A Comparison Of Invasive And Non Invasive Techniques For Measuring Fiddler Crab Density In A Salt Marsh written by Charles Robert Hubbard and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Electronic dissertations categories.
Author's abstract: Quantifying the density of burrowing crabs is challenging, and several techniques have been developed to accomplish it, including burrow counting, visual surveys of surface-active crabs, and substrate excavation. These techniques have been compared in mangrove forests but not in a salt marsh, nor has anyone attempted to excavate traps repeatedly for multiple days. Previous comparisons have not examined these techniques over the course of several months, nor considered the cost and precision associated with each technique. Therefore, from May of 2007 to April 2008, I conducted burrow, visual, single excavation, and repeated excavation surveys to estimate Uca pugnax density in a salt marsh on Tybee Island, Georgia and estimated the cost and precision associated with each technique. Only single and repeated excavation accurately measured juvenile density, but these methods were more costly and caused temporary habitat damage. Burrow surveys yielded reliable adult density but visual surveys underestimated adult and juvenile density, likely due to the difficulty of spotting small crabs in thick vegetation. This information may be useful to management officials monitoring fiddler crab populations and their predators in salt marsh ecosystems.
Habitat Preferences Of Gulf Coast Fiddler Crabs And Responses Of Plant And Soil Characteristics To Their Burrowing
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Author : Gwendolyn A. Murphy
language : en
Publisher:
Release Date : 2020
Habitat Preferences Of Gulf Coast Fiddler Crabs And Responses Of Plant And Soil Characteristics To Their Burrowing written by Gwendolyn A. Murphy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Animal burrowing categories.
Positive rather than negative species interactions dominate in stressful environments like tidal marshes. Fiddler crabs have been shown to ameliorate environmental stress and increase primary productivity through their burrowing behavior. Most notably, bioturbation may facilitate growth of tidal marsh plants by altering soil oxygen concentration, decomposition rates, and soil drainage. In turn, plants provide protection from the elements, refuge from predators and roots provide structural support for burrows in soft substrate. However, dense vegetation may limit the fiddler crab's ability to maneuver on the surface and burrow. Similarly, there may be a threshold where fiddler crab activity becomes destructive to plant growth instead of facilitative. Relatively few fiddler crab and plant interaction studies have been conducted on the Gulf Coast compared to Atlantic Coast. Gulf Coast tidal marshes have distinct climate, dominant vegetation zones and dominant fiddler crab species, and consequently it is likely that community dynamics will differ from Atlantic Coast tidal marshes. To explore interactions between Gulf Coast fiddler crabs and tidal marsh plants, I conducted a seasonal fiddler crab habitat survey and a fiddler crab enclosure study. Both studies were conducted at Grand Bay National Estuarine Research Reserve in Mississippi, across four dominant tidal marsh vegetation zones (salt marsh, brackish marsh, fresh marsh and salt panne). Fiddler crab burrows and associated vegetation were randomly surveyed across the vegetation zones to determine fiddler crab burrow density and habitat preferences. Fiddler crab enclosures were established across the four vegetation zones. Enclosures provided a method to test impacts of fiddler crab burrowing on soil and plant parameters as well as to survey fiddler crab populations. Results of the habitat survey indicated that fiddler crabs utilized all four vegetation zones, but burrow density was statistically higher in the fresh marsh during winter compared to other zones. These results suggest that the fresh marsh may be important habitat for overwintering Gulf Coast fiddler crabs. Additionally, the fresh marsh was found to host higher fiddler crab species diversity and a more balanced sex ratio compared to other zones. The enclosure study established that fiddler crab activity had negligible impacts on plant growth in the salt and fresh marsh yet influenced plant growth in the brackish marsh (positively) and salt panne (negatively). The brackish marsh and salt panne are habitats of intermediate environmental stress for plants and fiddler crabs. Brackish marsh is more frequently inundated than the salt panne and hence bioturbation is likely to be more beneficial in the brackish marsh. Furthermore, brackish marsh below-ground structure is substantial and fiddler crab burrow density was low relative to the salt panne. My work indicates that vegetation abundance and fiddler crab burrow density may balance environmental stresses in tidal marshes and influence nature of fiddler crab and plant interactions.
Density Shell Use And Species Composition Of Juvenile Fiddler Crabs Uca Spp At Low And High Impact Salt Marshes On Georgia Barrier Islands
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Author : Michelle D. Carlson
language : en
Publisher:
Release Date : 2011
Density Shell Use And Species Composition Of Juvenile Fiddler Crabs Uca Spp At Low And High Impact Salt Marshes On Georgia Barrier Islands written by Michelle D. Carlson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Author's abstract: Purpose: Coastal wetlands offer refuge for juveniles of many species, with protection often coming in the form of dense vegetation. Human impacts have led to a 67% loss of coastal wetlands worldwide in the past 300 years, thus decreasing available refuges. There are no studies that show what affect this has on fiddler crabs (Uca spp.), a key species in salt marsh habitats. The present study looks at how human impacts are affecting juvenile fiddler crab densities, shell use, and species compositions. This study was conducted at 3 low and 3 high impact sites on Tybee and Skidaway Island, Georgia. Six collection trips were completed from June to August 2010 to each of the 6 sites. During each trip ten quadrats (1m 2) were placed at each site, and juvenile fiddler crab densities, Littoraria irrorata shell availability, and percent shell use were recorded. In the lab, juvenile fiddler crab carapace width and sex were determined and multiplex PCR was used to identify juvenile fiddler crab species. Juvenile fiddler crab densities were lower at high impact sites, while shell availability and shell use were similar at both low and high impact sites. Juvenile fiddler crab sizes and sex ratios did not differ between low and high impact sites on the substrate, nor did the sex ratios in shells. However low impact sites had significantly larger juvenile fiddler crabs found in shells as compared to high impact sites. Species compositions differed between low and high impact sites on the substrate and in shells, with an increase in Uca pugilator and U. minax at high impact sites. Impacts to salt marshes can cause a decrease in available refuge for juvenile fiddler crabs which could lead to higher mortality rates and an overall decrease in juvenile fiddler crab densities. Fiddler crabs are important in aerating the soil, soil drainage, and decomposition rates. A change in fiddler crab densities and behavior can have an adverse affect to the salt marsh and could lead to the loss of an important ecosystem.
Wave Fever
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Author : Kayla Martinez-Soto
language : en
Publisher:
Release Date : 2020
Wave Fever written by Kayla Martinez-Soto and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Climatic changes categories.
In 2014, scientists found that the Atlantic marsh fiddler crab had extended its northern limit by ~90 miles to New Hampshire, which is in the Gulf of Maine. Range expanding species can alter salt marsh characteristics such as biodiversity and food webs. In this lesson, students will combine sea surface temperature data from a federal database and fiddler burrow densities from field photos to determine the relationship between ocean warming and range expansions.
Effects Of Fiddler Crab Density Manipulation On Spartina Alterniflora In Natural And Restored Marshes In Southwest Louisiana
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Author : Rebecca L. Chiasson
language : en
Publisher:
Release Date : 2006
Effects Of Fiddler Crab Density Manipulation On Spartina Alterniflora In Natural And Restored Marshes In Southwest Louisiana written by Rebecca L. Chiasson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Marshes categories.
A Biogeographic Approach To Understanding Burrowing Crab Impacts On An Ecologically Important Salt Marsh Plant
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Author : Janet Burkert Walker
language : en
Publisher:
Release Date : 2020
A Biogeographic Approach To Understanding Burrowing Crab Impacts On An Ecologically Important Salt Marsh Plant written by Janet Burkert Walker and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Burrowing animals, such as earthworms, crabs, prairie dogs, ground squirrels, ghost shrimps, and rodents, are often considered ecosystem engineers because of their influence on plant communities. For example, in coastal salt marshes, burrowing crabs can influence plant communities by modifying plant zonation, plant production, plant colonization, nutrient cycling, and erosion. Their effects on vegetation can vary across spatial and temporal gradients. In particular, the direction of burrower impacts (positive or negative) can depend on variation in the surrounding animal and plant community, as well as external abiotic conditions. Given that global climate change can alter such environmental conditions, such as salinity and nutrient availability, there is a need to predict when, where, and how burrowers will influence vegetation. Unfortunately, this ability is impeded because few studies have used comparative-experimental approaches to examine animal impacts on plants across space and time. In this dissertation, I explore the effects of burrowing crabs on California salt marsh plant communities using field manipulations and laboratory feeding assays. In my first chapter, I conducted a multi-site, multi-year field manipulation to examine burrowing crab impacts on plant communities in southern California salt marshes. I focused on the effects of burrowing crabs (Pachygrapsus crassipes [lined shore crab] and Uca crenulata [fiddler crab]) on the abundance of the two dominant marsh plants (Spartina foliosa [cordgrass] and Sarcocornia pacifica [pickleweed]), and I explored mechanisms underlying these effects by monitoring plant characteristics and sediment biogeochemistry. Crab impacts on plant community structure differed between each of our three sites. In contrast to our predictions, 1) plant-grazing crabs (lined shore crabs) had positive effects on cordgrass cover at one site and no effect on cordgrass production at a nearby site in the same marsh (Kendall-Frost marsh), and 2) detritivorous crabs (fiddler crabs) did not stimulate cordgrass production at another marsh (San Dieguito Lagoon). In fact, burrowing crabs suppressed cordgrass abundance at San Dieguito Lagoon, the site with the greatest detritivorous crab density (~10x the density of all other sites). Because crabs affected assemblage characteristics of cordgrass in the direction consistent with changes in cordgrass cover, we propose that marsh-specific crab effects on community structure were largely mediated through changes in cordgrass, as opposed to pickleweed. Importantly, crabs facilitated cordgrass during marsh-wide cordgrass loss, suggesting that crabs may mitigate environmental stress for this ecologically important plant. Cordgrass abundance can be a critical measure of marsh functioning and is often a restoration target, and thus maintaining healthy salt marsh functions should require monitoring and management of crab and cordgrass populations. In my second chapter, I combined these results with a similar field manipulation (e.g. multi-site and multi-year) in northern California to create a framework that could more broadly predict burrowing crab effects. While many studies have addressed burrowing crab impacts, few have sought to observe and predict these effects across multiple sites, multiple years, or both. This is especially true for salt marshes along the Pacific coast, where burrowing crab effects on plants have gone untested. In conjunction with our field experiments, we estimated total consumption of marsh plants by the dominant, herbivorous burrowing crab (the lined shore crab) by conducting laboratory feeding assays. Then, we used statistical models to predict crab effects using factors related to the crab community and soil conditions. By combining field, laboratory, and statistical modeling, my comparative-experimental approach allowed me to examine crab impacts across all site-year combinations. Crab effects varied from strongly positive to strongly negative, and depended upon our estimate of the total consumption pressure exerted by crabs and environmental conditions (i.e. salinity and ammonium). Crabs facilitated cordgrass at low total consumption pressure, extreme salinities, and intermediate levels of ammonium. Additionally, my models provided estimates of the threshold values of these environmental factors where the magnitude and direction of crab effects changed. Moving forward, we must seek to mechanistically understand how these key factors (grazing, salinity, and ammonium) drive inter-site variation in crab effects on cordgrass- as such information may be critical to the restoration and management of Pacific coast salt marshes. In my third chapter, I focused on the trophic mechanism by which burrowing crabs influence plants. Herbivores can have important impacts on plant communities, and palatability is among the important factors influencing herbivore consumption and herbivore impacts on plant communities. Here, I assessed the relative palatability of dominant marsh plants among three northern California salt marsh sites- all within one degree of latitude of each other. Although biogeographic approaches reveal that plant palatability to herbivores can vary across broad geographic scales, less is known about how the relative palatability of multiple plant species can vary across small scales. Such variation could be common given the species-specific responses of plants and herbivores to environmental conditions. To address this gap, I conducted multi-choice feeding assays with the lined shore crab - a consumer that has access to the leaves and roots of both cordgrass and pickleweed plants. I assessed the influence of plant species and tissue-types (roots and leaves) on crab feeding preference and the mechanisms underlying them. Surprisingly, the relative palatability of cordgrass and pickleweed switched between marshes within the study region. This shift may have been related to an increase in the palatability of pickleweed leaves at one of our sites. Because cordgrass palatability did not differ among these sites, the change in relative palatability did not appear related to changes in cordgrass. These patterns may be related to nutrient availability at our sites because plants at sites with high pickleweed palatability had lower C:N ratios than the other sites. However, the shift in the palatability of these two dominant plants does not appear to drive shifts in crab impacts on northern salt marsh plant communities, suggesting that crab impacts on plant communities is multi-faceted. The impact of the burrowing activity by crabs on plants may outweigh the consumptive effects of crabs on plants. We encourage future studies examining plant palatability to consider within-region variability in order to understand how such small-scale differences in plant palatability can alter local community structure and ecosystem function. Salt marshes filter water, buffer coastlines, bury atmospheric carbon, protect critical fisheries, and provide habitat for endangered and endemic species. These salt marshes, and the services they provide, are being critically impacted by human development and face a myriad of additional threats due to anthropogenic climate change. However, it will be impossible to predict how these threats will impact marshes if we lack an understanding of the basic species interactions that control the abundance of the foundation species (e.g. cordgrass) within these critical ecosystems. My dissertation highlights that burrowing animals can strongly control plant community composition and the production of cordgrass, and that these plant-animal interactions are highly variable across space and time. By taking a comparative-experimental approach, I was able to delve into this variation to identify possible biotic and abiotic drivers (e.g. grazing rates and soil conditions) that may help predict the magnitude and direction of burrowing crab effects on cordgrass in California marshes. Additionally, recognizing how these drivers may change with environmental stress, especially the effects of severe climate events (e.g. drought, storms, and heat spells), may help develop adaptive management strategies to buffer salt marshes from climate change- preserving the critical ecosystems services which they provide.