Organotins in zebra mussels (Dreissena polymorpha) and sediments of the Quebec City Harbour area of the St. Lawrence River

Toxic antifouling agents such as tributyltin (TBT) and triphenyltin (TPT) h ave been released in aquatic ecosystems through the use of antifouling pain t applied to ship hulls. pleasure crafts and fish nets and these compounds can bioaccumulate in aquatic organisms. The purpose of this study was 1) to assess the extent of the distribution of organotins From a contaminated ma rina to the St. Lawrence River system by measuring organotin concentrations in zebra mussels (Dreissena polymorpha) and in sediments collected from 9 sites along the St. Lawrence River near Quebec City in July 1998, and 2) to examine the histopathological condition of zebra mussel tissues from these sites. TBT concentrations in zebra mussels were between 37 and 1078 ng Sn g(-1) wet weight, with the highest value found in the Bassin Louise marina. Elevated concentrations were also found in two other marinas. The concentr ations decreased sharply to background levels just outside the marinas. All butyltins were detected in all sediments analysed, with highest values fou nd in the Bassin Louise marina. Phenyltins were detected in three of the ni ne sites in low concentrations (< 55 ng Sn g(-1))in zebra mussels. There wa s a significant correlation between TBT in sediments and mussels. Gonadal d evelopment of zebra mussels varied largely between sites, and was negativel y associated to TBT levels in mussel tissue. This study shows that TBT cont amination remains a problem in localised freshwater sectors of the St. Lawr ence River. (C) 2001 Elsevier Science B.V. All rights reserved.