Influence of temperature, salinity, and oxygen on the cadmium balance of mussels Mytilus edulis

Abstract

Juvenile mussels Mytilus edulis L. were culhvated in controlled flow-through aquana to investigate the influence of environmental temperature, salinity, and dissolved oxygen on cadmium balance. (1) Inverse relations between Cd concentration of soft tissues and physical condition of mussels were observed in response to temperature. The relation between Cd body burden and shell weight (Cd/shell-wt index) is independent of temperature between 7 and 25°C. (2) Reducing salinity (mg kg-'), while keeping dissolved Cd (pg I-') constant, increases the molar ratio of Cd and seawater salts. Accumulation of Cd in the soft tissues and of Ca in the shells of mussels is determined by Cd and Ca concentrations within the range of 15 to 30 960 salinity. Residues of Cd in mussels, therefore, are the Cd/shell-wt index is disproportionately higher, hlgher in samples from lower salinity. Below 15 %a corresponding to reduced shell growth In lower salimtles. Slightly lower index values were observed in 35 %. (3) Dissolved oxygen concentrahons between 2.5 and 6.5 m1 1-' have no influence on the Cd balance of mussels. (4) Experimental results were reproducible and corresponded to field observations. (5) Modifications of growth and performance were In accordance with the literature Lowest expen- mental temperature, salinity, and oxygen tested inhibited both growth of mussels and Cd uptake withn a small laboratory gradlent. Growth in the concerned environment is discussed as an essenhal aspect of research on metals and molluscs, and in relation to the mussel watch concept. found