Across Latitudes: Using Molluscs as Biomonitors to Assess Spatial and Temporal Distribution of Tributyltin (TBT) in Eastern Canada and the British Virgin Islands

摘要

Three species of molluscs (Nucella lapillus, Mytilus edulis and Strombus gigas) were used as biomonitors to evaluate tributyltin (TBT) pollution spatially and temporally in two Maritime Provinces in Atlantic Canada and the British Virgin Islands (BVI) during the summers of 2007 to 2009. In addition, a review of the literature on the effects of organotins on female gastropods from 1962 to 2009 was undertaken in an effort to summarize how the terminology, science and theories have evolved over the last 40 plus years.;In Canada, data confirm that TBT was bioavailable based on chemical analysis of samples collected at locations within harbour sites, and TBT levels were high enough to induce imposex, the superimposition of a penis and/or vas deferens, in N. lapillus at harbour sites where they were found. A comparison of the current study with previous surveys in the same geographic areas implies that the 1989 Canadian regulations on TBT have been effective in reducing TBT levels in sediment and imposex severity in N. lapillus in Saint John Harbour and Halifax Harbour. Conversely, during the same time period, TBT levels in sediment from Sydney Habour increased. Butyltins were also detected in sediment from reference sites where vessels < 25 m in length were docked at marinas and fishing harbours.;In the BVI, data from this study verify that TBT is bioavailable based on the incidence of imposex in female S. gigas collected from areas adjacent to boating activity e.g. shipyards, marinas and harbours, and the presence of TBT and its degradative product, dibutyltin (DBT), in S. gigas, turtle grass (Thalassia testidium) and marine algae from corresponding sites.;To date, female masculinisation (FM) of gastropods has been documented in > 260 species globally. Although most studies attribute FM in gastropods to TBT, there is evidence that "pseudo-imposex" occurred prior to TBT's use as a biocide in antifouling paint in the 1960s, "natural imposex" occurs, and there are other compounds besides TBT that can cause FM. Even after 40+ years of research, there is no consensus on how the actual mechanism of induction occurs, although five theories have been proposed.