Meeting Abstract
Salt marshes provide many natural services that directly or indirectly affect our everyday lives. Understanding their complex systems is essential in sustaining those services and maintaining our livelihood. The mussel, Geukensia demissa, and fiddler crab, Uca pugnax, are facilitator species that increase the organic content of salt marsh sediments. In a local salt marsh at Tybee Island, Georgia, mussels are primarily found on raised portions of the substrate referred to as mounds and rarely on mudflats. Mounds tend to be common between the lower high marsh and the low marsh. They attract a variety of species including mud crabs, small box crabs, and juvenile and adult fiddler crabs. This study investigated whether higher organic content of the sediment on mounds lead to greater abundance and higher protein content of juveniles compared to off-mound sites. Four mound and 4 off-mound sites were flagged and the number of juvenile burrows, adult burrows and tunnels counted, and the heights of 10 Spartina stems recorded in the Summer of 2016 and Spring 2017. Sediment cores for organic content analysis and 10 juvenile fiddler crabs for protein determination were collected from each site. It was found that juvenile fiddler crabs are much more abundant on mounds than off, and that mounds have more silt-clay sediments than off mound sites. Protein content of juveniles was significantly higher in September than in October 2016 but did not differ on and off mounds. Variation in sediment nutrient content on and off mounds over time might contribute to differences in juvenile fiddler crab abundance and overall fitness.
