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Burrowing and foraging activity of marsh crabs under different inundation regimes
Citation:
Szura, K., Rick Mckinney, C. Wigand, A. Oczkowski, Alana Hanson, J. Gurak, AND M. Garate. Burrowing and foraging activity of marsh crabs under different inundation regimes. JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY. Elsevier Science Ltd, New York, NY, 486:282-289, (2017).
Impact/Purpose:
New England salt marshes are susceptible to degradation and habitat loss arising from increased periods of inundation as sea levels rise. Further, increased inundation may exacerbate marsh degradation resulting from crab burrowing and foraging. Many recent studies have focused on how crab behavior affects the dominant low marsh plant species, Spartina alterniflora. This study sought to examined the relationship of the foraging and burrowing behavior of two dominant New England crab species, Sesarma reticulatum and Uca pugilator, and the combined effect of inundation, on the dominant high marsh plant species, Spartina patens. We found that Sesarma had a significant negative impact on both above and belowground biomass by physically clipping and uprooting the plants, whereas Uca had no significant impact. Overall, our results suggest the potential for Sesarma to negatively impact marsh stability, and that effects of crab burrowing and foraging may be heightened by increased inundation. Our results will help provide insight into potential changes in burrowing activity and foraging impacts on marsh plants with increasing inundation, information that could aid in understanding impacts to salt marshes from burrowing organisms as inundation increases under the current state of sea level rise. This will provide coastal managers with information to aid in the protection and restoration of salt marshes, and the ecosystem services they provide.
Description:
New England salt marshes are susceptible to degradation and habitat loss as a result of increased periods of inundation as sea levels rise. Increased inundation may exacerbate marsh degradation that can result from crab burrowing and foraging. Most studies to date have focused on how crab burrowing and foraging can impact the dominant low marsh plant species, Spartina alterniflora. Here we used a mesocosm experiment to examine the relationship of foraging and burrowing activity in two dominant New England crab species, Sesarma reticulatum and Uca pugilator, and the combined effect of inundation, on the dominant high marsh plant species Spartina patens using a 3 × 2 factorial design with three crab treatments (Sesarma, Uca, control) at two levels of inundation (low, high). Plants were labeled with a nitrogen (N) stable isotope tracer to estimate plant consumption by the two crab species. At both levels of inundation, we found that S. reticulatum had a significant negative impact on both above- and below-ground biomass by physically clipping and uprooting the plants, whereas U. pugilator had no significant impact. Low inundation treatments for both crab species had significantly greater aboveground biomass than high inundation. Stable N isotope tracer levels were roughly the same for both S. reticulatum and U. pugilator tissue, suggesting that the impact of S. reticulatum on S. patens was not through consumption of the plants. Overall, our results suggest the potential for S. reticulatum to negatively impact marsh stability, and that effects of crab foraging behavior may be heightened by increased inundation.
