Evidence of Endocrine Disruption in the Imposex-Affected Gastropod Bolinus brandaris

Testosterone/estradiol tissue levels and cytochrome P450-dependent aromatase activity have been evaluated in the gastropod Bolinus brandaris. Samples were collected from two locations on the Mediterranean coast (St. Carles and Barcelona) according to their different degrees of imposex development and organotin residues. St. Carles was chosen as a relatively clean site, as only 37% of the females were imposex affected compared to 100% of the females from Barcelona. A strong reduction of estradiol levels was seen in both males and females from the organotin-polluted site in comparison to those of the reference site, whereas weaker differences between the sites in testosterone levels were revealed. Despite the observed alterations in sex hormone levels, no changes in aromatase activity were recorded. These results suggest that mechanisms other than inhibition of aromatase activity might be involved in the development of imposex in B. brandaris.