HABITAT PARTITIONING BETWEEN THE XANTHID CRABS PANOPEUS-HERBSTII AND EURYPANOPEUS-DEPRESSUS ON INTERTIDAL OYSTER REEFS (CRASSOSTREA-VIRGINICA) IN SOUTHEASTERN NORTH-CAROLINA

The abundances of the xanthid crabs Panopeus herbstii and Eurypanopeus depressus were examined relative to surface oyster shell cover, surfa ce oyster cluster volume, subsurface shell content, substrate sand and silt composition, and oyster reef elevation. During August 1986 throu gh July 1987, xanthid crabs were collected monthly from twelve 0.25 m2 x 15 cm deep quadrats, during low tide, from intertidal oyster reefs in Mill Creek, Pender County, North Carolina, USA, with respective qua drat details recorded. The abundance of P. herbstii, and to a lesser d egree E. depressus, was positively correlated with surface shell cover . The abundance of E. depressus, and to a lesser degree P. herbstii, w as positively correlated with surface cluster volume. The majority of P. herbstii inhabited the subsurface stratum of the oyster reef, where as the majority of E. depressus inhabited the cluster stratum. Seasona lity (i.e., temperature) appeared to influence the strata habitation o f both species, with a higher incidence of cluster habitation during w armer months and a lower incidence during colder months. Crab abundanc e was not related to other factors examined, such as subsurface shell, substrate sand and silt composition, or elevation within the oyster r eef. The analyses show that P. herbstii and E. depressus have partitio ned the intertidal oyster reef habitat, with E. depressus exploiting s urface shell clusters and P. herbstii the subsurface stratum.