THE ECOLOGICAL ROLE OF THE EASTERN OYSTER, CRASSOSTREA-VIRGINICA, WITH REMARKS ON DISEASE

Historical writings and the presence of pre-Colonial shell middens pro vide evidence that individual eastern oysters Crassostrea virginica (G melin, 1791) grew larger and formed more extensive reefs than they do under present-day conditions of harvesting, habitat destruction, and d isease. Their diminished abundance has reduced their roles in providin g hard substrate, in filtering the estuarine water column, and in affe cting energy flow and nutrient flux. The poorly understood interaction s among the abundant inhabitants of oyster assemblages have undoubtedl y also been affected, although it is not clear how or by how much. The one important difference between the results of mortality from harves ting compared with mortality from disease may be that the shells of di sease-stricken oysters remain on the oyster bar to continue to serve a s substrate. There may be a connection between stress imposed by overf ishing or habitat alteration and susceptibility of eastern oysters to disease.