Macrobenthos-sediment relationships on the continental shelf off cape hatteras, North Carolina

Abstract

The complex current regime associated with Cape Hatteras, North Carolina results in an unusually broad range of sediment textures for open shelf areas of comparable spatial extent. The median grain size ranged from coarse to very fine sand, while the percentage of silt and clay ranged from 0 to 27%. Four assemblages of macrobenthic species were recognized, separable on the basis of sediment characteristics: (1) a muddy, very fine sand assemblage dominated by the polychaetous annelid Lumbrineris impatiens; (2) a fine to medium sand assemblage dominated by the archiannelid Polygordius sp.; (3) a well-sorted, fine sand assemblage dominated by the amphipod Protohaustorius cf. deichmannae; and (4) a medium to coarse sand assemblage characterized by the polychaetes Hemipodus roseus and Hesionura elongata. Multiple discriminant analysis and detrended correspondence analysis, a linear ordination technique, were used to identify which of eight sediment parameters were most useful in interpreting faunal patterns. Sediment sorting, as reflective of sediment mobility, was important in determining the dominance of fossorial species. The percentage of very fine sand and the combined percentage of silt and clay were found to be of greatest value in differentiating biotic assemblages. This conclusion is supported by similar results from previous estuarine studies, and is probably a result of surface area-related control of the type and quantity of food resources for deposit feeders. © 1988.