ABSTRACT: Oysters Crassostrea virginica from Chesapeake Bay, Virginia, and Apalachicola Bay, Florida, USA, were collected in March and October 1992 to investigate possible differences in defense-related hemocyte activities between individuals from geographically separate populations. In March, hemolymph drawn from Chesapeake Bay oysters contained an average of 1.08 x 10⁶ hemocytes ml^-1 hemolymph, significantly lower than the average 1.63 x 10⁶ hemocytes ml^-1 hemolymph obtained from Apalachicola Bay oysters. Hemocyte number did not differ significantly in the October comparison. At both times of year, Chesapeake Bay oyster hemolymph samples contained significantly greater proportions of granular hemocytes compared to Apalachicola Bay hemolymph samples. Hemocyte samples from Chesapeake Bay oysters demonstrated a higher percentage of mobile hemocytes and greater particle binding ability than Apalachicola Bay oyster hemocytes when tested in March, but the reverse was found in the October experiments. Chesapeake Bay oyster hemocytes produced significantly more superoxide anion as measured by nitroblue tetrazolium reduction than did Apalachicola Bay oyster hemocytes in both March and October. Oyster hemolymph levels of the protozoan parasite Perkinsus marinus did not differ significantly between the 2 sites at either time of year. These results demonstrate the importance of background studies to characterize site-specific differences in oyster hemocyte defense-related functions.

KEY WORDS: Invertebrate immunology . Crassostrea virginica . Hemocytes . Phagocytosis

Published in DAO Vol. 22, No. 3 (1995) on July 13
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1995