Laboratory study of the accumulation and distribution of cadmium in the Sydney Rock oyster Saccostrea commercialis (I & R)

Abstract

The Sydney rock oyster (S. commercialis) was exposed to a control and four concentrations of cadmium (nominally 0, 10,25,50 and 150µg I^-1) in a flowing seawater system in the laboratory. Oysters from the 10 and 50 µg 1^-1 groups were briefly exposed to ¹⁰⁹Cd, then frozen in liquid CO₂ and sectioned. The thin sections of whole oyster were apposed to X-ray film. The resulting images showed that ¹⁰⁹Cd accumulated mainly in the gut, kidney and gill, with little in the gonad and glycogen storage areas of the visceral mass. Oysters from all water concentrations of cadmium were removed after 1,4,8 and 16 weeks of treatment with cadmium. The visceral mass, gill, mantle, muscle and heart-kidney were analysed for total cadmium. All groups of oysters rapidly accumulated cadmium. The heart-kidney attained the highest concentration and the muscle invariably displayed the lowest concentration. The visceral mass contained the greatest amount of cadmium in all oysters. The gill changed its position in the ranking of the organ concentrations of cadmium, increasing with increasing water concentrations of cadmium. The results suggest that the gill may be the critical organ during a challenge with cadmium-at both lethal and sublethal concentrations. The long-term nature of this experiment reveals that the accumulation of cadmium in S. commercialis is non-linear at some water concentrations of cadmium.