Tributyltin Concentrations and Pacific Oyster Deformations in Coos Bay, Oregon

The Oregon Department of Environmental Quality (DEQ) initiated a preliminary tributyltin (TBT) sampling program near South Slough Estuarine Sanctuary in Coos Bay, Oregon, when thickened, ball-shaped Pacific oysters (Crassostrea gigas) were discovered in commercial oyster growing areas. Since the oysters were cultivated near boatyards and marinas where TBT paints were used, and their shells exhibited deformities similar to those found in the United Kingdom, DEQ suspected that TBT may be the pollutant of concern. Water quality and oyster tissue samples were collected in several locations in Coos Bay, including the Estuarine Sanctuary, and analyzed for TBT. Oyster shells were sectioned to determine the degree of chambering. The data show that TBT was present in both the water and tissue samples. All but one of the oyster shells collected displayed a high degree of chambering, with the most significant effects found in oysters collected near the boat painting facilities. As a result, a cooperative interagency TBT management program is being developed to identify sources of TBT in other estuaries and to implement control strategies to eventually eliminate TBT from state waters.