An assessment of tributyltin contamination in the North Atlantic using imposex in the dogwhelk Nucella lapillus (L.) as a biological indicator of TBTpollution

Surveys of imposer in the dogwhelk Nucella lapillus suggest that most parts of the north Atlantic are free of TBT contamination at biologically signif icant levels. Imposer was absent or poorly developed at the large majority of sites, including coasts adjacent to major shipping lanes passing through Pentland Firth, the Minches and North Channel. There were "hot-spots" of T BT pollution at ports and harbours along the northeast coast of England but , with the exception of the stretch of coast which includes the major ports of Hartlepool and Teesside, impacts were highly localised. The severity of imposer has declined dramatically during the past decade in those areas fo r which there are comparative data from earlier surveys. This can presumabl y be attributed to the success of regulations prohibiting the use of TBT-ba sed antifoulants on vessels <25 m in length.