In 1995 at Ney Pond, Minnesota, local students found dozens of frogs and toads with extra limbs, missing limbs or even eyes in the wrong place. Shortly after, reports of other “hot spots” of malformed amphibians poured in from around the country.
"That was during probably the realization among many amphibian biologists that amphibians seemed to be declining in their study sites," said Karen Beard, Associate Professor of Ecology and Biology at Utah State University. "And so a lot of researchers were kind of wondering what was causing that, and there were a lot of hypothesis."
Frogs are considered the “canary in the coal mine” for environmental changes because they have permeable skin that can easily absorb chemicals, are susceptible to changes in climate, and have vulnerable eggs. People at the time wondered if the malformations and decline of frogs were indicators of something wrong with the environment.
The U.S. government commissioned the U.S. Fish and Wildlife Service to research the problem in 2000. After studying 68,000 specimens over 10 years, the findings were released this week. The research shows that less than two percent of frogs and toads sampled on 152 wildlife refuges had physical abnormalities involving the skeleton and eyes. Extra limbs were also extremely rare: just 0.025 percent of all frogs sampled.
Though the findings are promising, Beard said global analysis shows one-third of amphibian species are threatened with extinction.
"You know I think it’s great that it’s showing that at least within our refuges the populations don’t seem to be as impacted by pesticides and chemicals and other things that might be causing malformations," said Beard. "But I think, at a continental scale and at a global scale, that doesn’t mean that we are in the clear and that amphibian populations are doing well, because they’re not."
From this study, researchers have compiled one of the world’s largest databases on amphibian abnormalities.
For more information on the study, visit the website.