Community And Trophic Organization Of Nekton Utilizing Shallow Marsh Habitats, York River, Virginia

Abstract

Nekton were collected by trawl and Wegener ring at each of two stations within tidal creeks and at adjacent shoal stations in the polyhaline and oligomesohaline zones ofthe York River estuary, Virginia. Species richness was significantly higher (P 98% of the total number of individuals collected indicated that all wereessentially trophic opportunists feeding on a wide variety offood items. Ontogenetic shifts in diet were also observed for the five most abundant species. Lack of dietary specialization and the consequently large degree of diet overlap in all species may reflect the nonlimit· ing nature offood abundance in the primary nurseries, however a seasonal change in relative fullness values may indicate periodic food scarcity. The structural and functional role of shallow es­ tuarine habitats has received increasing attention in the past few years. Although widely recognized as primary nurseries, two of these habitats, marshes and seagrass meadows, have only re­ cently come under scrutiny in the lower Chesa­ peake Bay. Much of the impetus for these efforts was derived from priorities established by the Chesapeake Bay Program (Environmental Pro­ tection Agency 1979). As a result, areas covered with submerged aquatic vegetation (SAV) were