A hormone-mimicking chemical often found in rivers can affect the mating choices of fish, leading to changes in their appearance and behavior and to more interspecies breeding, a new study led by a University of Minnesota scientist has found.
The study, published in Evolutionary Applications, reveals the threat to biodiversity when boundaries between species are blurred, according to Jessica Ward, an adjunct assistant professor in the Department of Fisheries, Wildlife and Conservation Biology.
While at Tulane University two years ago, Ward and her team examined the impact of Bisphenol A on two species of fish, blacktail shiner and red shiner.
BPA is an endocrine-disrupting compound used to harden plastics that, like other manmade chemicals and pharmaceuticals, has often found its way into the nation's rivers. Three years ago, Minnesota became the first of 11 states to ban its use in baby bottles and children's cups.
Ward's team collected fish from two streams in Georgia and separated them for two weeks in tanks, some of which contained BPA, which disrupts endocrine systems that control the release of hormones. That affects behavior and appearance, which can lead to mistaking a newly introduced species as a potential mate.
On the 15th day, the team began introducing fish from different tanks to each other.
"Our research shows how the presence of these manmade chemicals leads to a greater likelihood of hybridization between species," Ward said.
Earlier studies focused on the impacts of such chemicals on individual fish. This one, she said, "is one of the first studies to take a multiple-species approach" and examine how those fish interact with each other.
As invasive species move into new areas, Ward said, BPA and other hormone-mimicking chemicals can escalate the loss of native biodiversity by breaking down species barriers and promoting the invader.
"This can have severe ecological and evolutionary consequences," she said, "including the potential for the decline of our native species."
Dennis Lien can be reached at 651-228-5588. Follow him at twitter.com/DennisLienPP.