Effect of environmental factors and parasitism on hemolymph lysozyme and protein of American oysters ( Crassostrea virginica)

The biological roles of lysozymes in bivalves are believed to be involved with the mechanisms of host defense and digestion. Experiments were carried out to examine hemolymph lysozyme activity and protein in oysters over a 1-year period to determine their relationship with seasonal environmental variables (temperature, salinity, and food availability) and whether they correlate with parasitism by Perkinsus marinus. Hemolymph lysozyme and protein exhibited seasonal fluctuations. Hemolymph lysozyme varied greatly between individual oysters, and it was higher in winter months than in summer months. No linkage was found between hemolymph lysozyme and protein concentration and infection of oysters by P. marinus. It is argued that the observed seasonal changes in hemolymph lysozyme and protein may relate to the oyster reproductive cycle.