Abstract
In order to investigate a cause of the differences in the susceptibility of fish in toxicity tests, we determined the bioconcentration factors (BCFs) by examining the bioaccumulation of four chemicals, bis(tributyltin) oxide, triphenyltin chloride, cadmium and naphthalene in two species of marien fish: mummichog (Fundulus heteroclitus) and red sea bream (Pagrus major). We measured body concentrations of these chemicals in dead fish used in the acute toxicity tests, and compared the concentrations with critical body residues (CBRs) calculated by using the BCF and acute toxicity values. In the bioconcentration tests, it took about six weeks for the body concentrations of bis(tributyltin) oxide, triphenyltin chloride and cadmium to reach their respective equilibria. It took about one week for the body concentrations of naphthalene to reach its equilibrium, and naphthalene was quickly eliminated. The BCF values of the four chemicals tested in this study showed similar values for mummichog and red sea bream. We found that the concentrations of the test chemicals in dead mummichog were higher than those in dead red sea bream for all chemicals. We found that the concentrations in dead fish were lower than CBRs, except for naphthalene. These results revealed that susceptibility to the test chemicals was closely correlated with dead fish body residue than CBRs. Susceptibility was higher for the fish species in which lower body accumulation reached lethal, and lower for the fish species in which higher body accumulation reached lethal.
