The effects of tributyltin (TBT) accumulation on adult dog-whelks, <i>Nucella lapillus</i>: long-term field and laboratory experiments

Populations of the gastropod, Nucella lapillus (L.), normally one of the commonest of rocky-shore macroinvertebrates, have recently suffered from declining numbers at many sites along the south coast of England. Bryan et al. (1986) showed that these declining populations exhibited a high degree of imposex (the induction of a penis and vas deferens in females) and that imposex was almost certainly caused by tributyltin (TBT) compounds leached from ships' antifouling paints. Evidence implicating TBT compounds in the development of imposex included: (1) a good relationship between the degree of imposex and the proximity of affected populations to harbours and marinas; (2) in Plymouth Sound, the degree of imposex increased dramatically between its discovery in 1969 (Blaber, 1970) and 1985, thus coinciding with the introduction and increasing usage of TBT-based paints; (3) tissue concentrations of tin as TBT increased consistently with the degree of imposex; (4) animals transplanted from a ‘clean’ area to a harbour site absorbed TBT and developed imposex; (5) preliminary experiments showed that imposex was induced by exposure to 20 ng/1 of tin as TBT leached from a TBT-based paint; (6) TBT is implicated in the induction of imposex in other stenoglossan gastropods including Nassarius obsoletus (Say) (Smith, 1981) and Ocenebra erinacea (L.) (Féral &amp; Gall, 1982).