Organotins in Zebra Mussels ( Dreissena polymorpha) from the Saint Lawrence River

Abstract

Toxic antifouling compounds such as organotins have been released in the aquatic ecosystems throughout the world and can be bioaccumulating in biota. The purpose of this study was to assess the use of zebra mussels ( Dreissena polymorpha) as a biomonitor for investigating the geographical variations of organotin bioavailability along the St. Lawrence River. The presence of organotins (tributyltins (TBT) and triphenyltins (TPT)) and their degradation products were measured in the soft tissues of zebra mussels collected from 11 sites along the St. Lawrence River (between Cornwall and Ile d’Orleans) in June 1996. TBT and TPT were generally low (< 0.001 to 0.030 μg/g wet weight) and were similar to those reported in Kingston Harbour, Ontario in Canada and Nieuwkoop and Brielse meer in the Netherlands. The highest concentration of TBT (1.44 μg/g wet weight) was found in mussels from Bassin Louise, a marina in Quebec City. This suggests that zebra mussels are effive biomonitors of organotin compounds and that residual levels in the sediment, or illegal use of antifouling paints still remain problematic in localized sectors of the river. A more detailed study on the availability of TBT in marinas and harbors along the freshwater part of the St. Lawrence River is recommended.