Abstract
Imposex, i.e. penis and vas deferens development on females induced by tributyltin pollution from antifouling paint, was found in the dogwhelk Nucella lapillus (Linné, 1758) at 38 of 45 studied localities in southwestern, western and northwestern Iceland. Imposex was most frequent near Reykjavík and Hafnarfjörður in southwestern Iceland, but fairly widely distributed in the whole study area. Its absence from 16 % of the studied sites scattered in-between sites where imposex was present, is noteworthy, as imposex has elsewhere been found within this species on virtually all studied sites. The effects of the tributyltin were most often restricted to vicinity of the harbours < 18 km). The presence of imposex in Icelandic waters indicates that tributyltin pollution is widely distributed even in a fairly remote northern environment.