HARTMAN, M.J.*; STANCYK, S.E.: Distribution of an Invasive Anomuran Decapod,Petrolisthes armatus,in the North Inlet-Winyah Bay National Estuarine Research Reserve on the South Carolina Coast

Petrolisthes armatus is a filter-feeding crab which appears to be extending its range northward along the southeast coast of the United States. P. armatus is native to Brazil and has been reported from Florida, Mississippi, Georgia and Charleston, South Carolina. Recently, P. armatus was found in the North Inlet-Winyah Bay National Estuarine Research Reserve (NERR) 60 miles north of Charleston, but it has not been detected in Murrells Inlet, 20 miles further north. This is a preliminary and ongoing project to study the distribution and biology of P. armatus in the North Inlet-Winyah Bay NERR and to monitor its northward movement. Sampling of P. armatus is conducted by randomly selecting sites on oyster bars in subtidal and lower intertidal zones and placing five 0.135 m² trays filled with oyster rubble at each zone. Trays are collected after one month and all P. armatus individuals are counted, sexed and measured for carapace width. Samples from July 2000 at three sites in North Inlet yielded an average of 34.8 individuals/m² in the subtidal zone (range: 0-103/m²)and 70.4 individuals/m² in the intertidal(range: 0-370/m²). Sex ratios were male-biased in both tidal zones: 1.5:1 subtidal and 1.7:1 intertidal. Future studies in the laboratory and field will examine substrate preference, movement of P. armatus over tidal cycles and behavioral interactions between xanthid crabs and P. armatus.