Fewer Female Snail Penises

Researchers are now spotting fewer cases of imposex—in which female sea snails develop male sexual organs—as a result of a chemical ban instituted in 2008.

Tracy Vence
Jan 14, 2014

Nucella lapillus, one of the species affected by TBT.WIKIMEDIA, MARTIN TALBOTThe scientists who first discovered imposex more than two decades ago now report that the incidence of this devastating condition—in which female sea snails grow penises after coming into contact with a chemical used in the paint on ships—appears to be waning. While snail populations once suffered as a result of diminished female fertility (some were even completely wiped out), the incidence of the condition has decreased dramatically since 2008, when tributyltin (TBT), once a choice antifouling pesticide for marine paint, was banned.

“To a large extent we are seeing good recovery,” Peter Matthiessen, an aquatic ecotoxicologist and consultant with WCA Environment in the U.K., told the Australian Broadcasting Company (ABC). “In areas where the populations were wiped out we are now beginning to see slow recovery since the complete [TBT] ban kicked in.”

Scott Wilson, a marine biologist from Central Queensland University, told ABC that at some sites he recently sampled, he found no evidence of imposex at all. But snails and other sea life are still far from safe. While TBT has a half-life of only six days in seawater, it can persist in some marine sediments for years. According to ABC, Wilson “estimates that based on current rates of recovery, the most heavily impacted areas in Australia won’t be free of imposex until at least 2040.”