Causes of imposex in the dogwhelk Nucella lapillus (L.) and its use as a biological indicator of tributyltin contamination

Exposure to the oestrogen-mimic nonylphenol under laboratory conditions can cause imposes in dogwhelks Nucella lapillus. There were also elevated levels of imposex in N. lapillus collected from a shore adjacent to a gull roost, and from shores beneath cliffs which supported breeding colonies of seabirds. Gulls carry trematode parasites Par orchis acanthus which infect N. lapillus as intermediate hosts but, although parasites can affect the development of the genital system in gastropods, there was no relationship between levels of infestation and the severity of imposes. It is possible that, in these cases, compounds in the birds' excreta had caused imposes. These data have implications on the use of imposes as an indicator of environmental levels of TBT. (C) 2000 Elsevier Science Ltd. All rights reserved.