DENSITY OF UCA PUGNAX AND UCA MINAX (FIDDLER CRABS) AND THE USAGE OF VEGETATION IN PIERMONT MARSH, NEW YORK

Over the past two decades, Piermont Marsh, a brackish marsh located along the Hudson River, 40 kilometers north of Battery Park, has been colonized by Phragmites australis which is an invasive species of reed from Europe that was introduced in the late 1700s, early 1800s. Many studies have been conducted to establish the effect of P. australis upon native species (mostly flora) in Piermont Marsh; however, their effect upon the Atlantic marsh fiddler crab, Uca pugnax, had not been studied prior to this study conducted by student members of the Secondary School Field Research Program (SSFRP) program over the summer of 2016. This study examines where the fiddler crabs are making their burrows, and whether or not the species P. australis has any effect on the population density of U. pugnax. U.pugnax have only been sighted along the banks of the three creeks in Piermont Marsh: Sparkill, Tidal, and Crumkill, or near the intertidal zone. It was expected that no marsh fiddler crabs would be found in the interior of the marsh where the P. australis population is extremely dense. In this study, the density of fiddler crab burrows were determined, as well as the weight and carapace width of individual U. pugnax. Observations made in Piermont Marsh have led to the conclusion that the presence of P. australis does greatly limit - and in some cases prevent - the successful burrowing of the Atlantic marsh fiddler crab, U. pugnax. The population density of P. australis is highest in the marsh’s interior, where no live crabs were found. Atlantic marsh fiddler crabs were instead observed primarily along the banks of bodies of water within the marsh, with very few of them sighted further than five meters away from the banks.