Various forms of regression analysis are presented which show that there is a significant equilibrium relationship between total recoverable cadmium in seawater and its concentration in the mussel Mytilus edulis (P < 0.001).
The calculations show that the concentration of cadmium in seawater should not exceed 0.20/~g 1-1 if the mussel is not to reach a cadmium concentration of 2 mg kg -1 wet weight: a value frequently used as a food standard for human consumption. Further, when a cadmium value of 2 mg kg -1 wet weight is reached, the concentration factor by mussels for cadmium from seawater is 9 950.
Materials and methods
Selection of sample sites
A large number of sample sites in Port Phillip Bay and Western Port, Australia, were chosen so that a wide range of cadmium concentrations in seawater and in Mytilus edulis would be encountered. The selected sites in Port Phillip Bay (Fig. 1: Sites 1-16) are contaminated from Cdpolluted waters which circulate from Corio Bay (Talbot et al., 1976;Fabris, 1983). The sites in Westernport (Fig. 1: Sites 17-25) were chosen because no widespread contamination of mussels exists there except in localised areas (Harris et al., 1979).