ABSTRACT
Analysis of abundance data on mollusks from 65 stations in the Beaufort, North Carolina, area yielded evidence of level-bottom communities in transition. Three of these communities or associations occur within the estuary of the Newport River. From estuary mouth to head the communities are Tellina, Mulinia-Syndosmya, Retusa; Syndosmya-Aligena; and Macoma balthica. Only the last named community is sharply delineated. The association of the estuary mouth grades into the shallow open-ocean community of the area, the Tellina-Spisula community.
Several physical parameters, particularly salinity, water depth, sediment sorting, and grain size, are brought to bear on the distribution study. The results of this analysis are inconclusive. Salinity (and its correlative in this study, water depth) is more important than other factors studied.
One obstacle to studies of this type is lack of systematic and ecologic knowledge of species. Therefore, important species are illustrated, and known ranges and probable optimum conditions and trophic level are given for those species.
