PARENT SESSION
PT2 - Endocrine Disruption
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P560) Imposex as an indicator of butyltin exposure in the veined rapa whelk, Rapana venosa.

Jestel, Ethan^*,1, Unger, Michael¹, ¹ Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA, USA

ABSTRACT- Tributyltin (TBT) is an organometallic contaminant that is toxic to many marine organisms and that induces imposex (the imposition of male sexual characteristics on females) in many gastropod species. The veined rapa whelk, Rapana venosa, is an invasive species in the Chesapeake Bay and may seriously impact the economically important clam population. Imposex has been observed in Rapana venosa. In order to investigate a causal link between imposex occurrence and butyltin exposure, the body burdens of butyltins in Rapana venosa were measured. Rapana venosa were collected from the lower James River and analyzed individually for TBT and a degradation product of TBT, Dibutyltin (DBT). Imposex females had TBT concentrations (dry weight) of 17±10 ng/g and DBT concentrations of 23±9 ng/g. A significant positive relationship was found between imposex expression and the concentration of DBT in the female whelks. Male whelks had TBT concentrations of 44±15 ng/g and DBT concentrations of 40±15 ng/g. There were significantly higher concentrations of TBT in male whelks than in imposex females. While TBT has been shown to be the predominant inducer of imposex in gastropods, DBT may be the best indicator of historic TBT exposure for this species. Maternal transfer to eggs may be a significant route for TBT elimination for female whelks.

Key words: tributyltin, imposex, rapana venosa, endocrine disruption