THE EFFECT OF CADMIUM EXPOSURE ON DIGESTIVE ENZYMES IN THE EASTERN OYSTER CRASSOSTREA VIRGINICA

The Eastern oyster Crassostrea virginica is a marine bivalve that has been used extensively in metal bioaccumulation studies. We exposed C. virginica to 0 mg/L cadmium, 0.1 mg/L cadmium, or 0.5 mg/L cadmium in seawater for 96 h and then measure the activity of enzymes (amylase, laminarinase, and protease) in the digestive gland. The levels of cadmium in the gills and digestive glands of the animals were also determined. Exposure of the animals to 0.5 mg/L cadmium resulted in a significant decrease in the activities of amylase, laminarinase, and protease enzymes compared with oysters exposed to either 0 mg/L cadmium or 0.1 mg/L cadmium. This decrease corresponds to significantly higher cadmium levels in the gills and digestive glands of oysters exposed to 0.5 mg/L cadmium. The results of this study suggest that exposure to cadmium affects the ability of the animals to process ingested food.