Understanding spatial and temporal dietary effects on cadmium exposure in B.C. oysters (Crassostrea gigas).

Although recent growth of oyster aquaculture in B.C. has been rapid their export to international markets has been hampered by high concentrations of cadmium. To date little is known about the effect of varying diets on oyster cadmium accumulation. An oyster growout experiment was conducted at ten sites between two regions over the course of two years. Stable isotope analysis of stomach contents and body tissue was coupled with trace metal analysis in an effort to determine the effect of diet on cadmium accumulation. Abiotic and biotic factors were also measured to assess their influence on cadmium accumulation. Oysters were found to accumulate higher levels of cadmium within Barkley Sound compared to Desolation Sound which coincided with significant differences in diets. Diets composed of isotopicaly lighter components were found to result in higher levels of cadmium. Important knowledge gaps however prevent making any specific recommendations to the shellfish industry.