IMPACTS OF SESARMA CRABS IN A LOCALIZED SALT MARSH STUDY

Sesarma reticulatum are native, nocturnal crabs found in Eastern United States salt marshes. There is visual evidence of increased burrowing and foraging near creeks in the marshes. We hypothesized there is a direct correlation between these bare, burrow-ridden peat areas and expanded Sesarma abundance. A pitfall trapping experiment was conducted in the Little Bay salt marsh of Fairhaven, Massachusetts, comparing abundances along creek edges in bare “die-off” areas to vegetated "healthy" zones. Using 2 randomly placed quadrats we also counted the number of burrows (small and large), Spartina alterniflora stems, and the number of Sesarma-grazed stems in each healthy and die-off area. Our results suggest that in most cases there were more Sesarma in die-off areas than healthy areas. There were always more burrows found in the die-off areas as well as higher percentages of clipped stems. We can conclude that the Sesarma crabs are the current culprit of marsh grass loss in the die-off areas of our study. A possible removal effort may be introduced following more experimentation. This suggests more research is needed surrounding the reason behind Sesarma population booms and the possible ways to combat the degradation of coastal salt marsh vegetation.