Chemical confuses, threatens breeding fish

A chemical used in plastics is causing fish to court members of other species, resulting in interbreeding and loss of biodiversity, U.S. researchers say. Bisphenol A, or BPA, mimics the hormone estrogen and can affect the males of many species, sometimes "feminizing" them and impairing their ability to produce offspring, they said. But the effects can go much further than that, University of Minnesota researcher Jessica Ward said. Her experiments with two species of fish, blacktail shiners and red shiners, showed exposure to BPA affected courtship behavior, with fish exposed to BPA more likely to approach fish of the other species and court them. Red shiners are an invasive species and often interbreed with native species, with exposure to estrogen-mimicking chemicals like BPA making it even more likely they would do so. The resulting interbreeding is a threat to biodiversity, West said, although it has a lower profile than habitat loss and overhunting. "Hybridization is one of the most common and widespread causes of species loss, especially in fish," Ward said in a university release Thursday.