Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Ehime 790-8566, Japan
Butyltin compounds (MBT, DBT, TBT) were determined in surface sediments, sediment cores, cultured fishes and pearl oysters collected from Uwa Sea, Japan. TBT concentrations in surface sediments ranged from 2.8 to 930ng/g dry wt, which were comparable to those in urban regions such as Tokyo Bay, Osaka Bay and Dokai Bay. ΣBTs (MBT+DBT+TBT) concentrations in surface sediments from fish culture areas were significantly higher than those from pearl oyster areas. In case of sediment cores, BTs concentration was the highest in the surface layer and decreased with core depth. ΣBTs concentrations in pearl oysters were lower than those in other species of bivalves from various coastal waters around the world, whereas ΣBTs concentrations in cultured fish from Uwa Sea were comparable to those reported in Osaka Bay. Higher proportions of TBT in ΣBTs residues were found in fish and pearl oysters than in sediments. Although TBT concentrations found in cultured fishes were less than the tolerable level estimated from ADI suggested by the Ministry of Health and Welfare, efforts to reduce the residue levels are needed for the conservation of ecosystems.