HEMATOLOGIC AND SEROLOGIC VARIABILITY OF EASTERN OYSTERS FROM APALACHICOLA BAY, FLORIDA

Eastern oysters (Crassostrea virginica) were collected monthly from tw o sites approximately 15 km apart in Apalachicola Bay, FL, during a 1- y period. Hematologic and serologic measurements were made on hemolymp h withdrawn from the adductor muscle. The two sites experienced nearly identical temperature patterns during the study period, but salinity and other physical factors fluctuated. Significant differences attribu table to sampling date were found for circulating hemocyte density, ph agocytic activity, and superoxide anion (O-2(-))-producing ability and for serum protein, lysozyme, and agglutinating activity, with data fr om both sites combined. This variability was most likely related to te mperature or temperature-influenced reproductive cycling. Oyster hemoc yte locomotion did not vary significantly with time over the study per iod, nor were significant differences found between sites. Significant differences between site means (combined for all dates) were found fo r O-2(-) protein and lysozyme, and significant date site interaction s were found for phagocytosis, agglutination, and lysozyme, indicating that local conditions, such as salinity fluctuations, influenced thes e measurements. An accurate description of variability in oyster defen sive functions will require more frequent sampling and a better unders tanding of local environmental influences.