A study by University of Florida scientists has blamed agricultural chemicals as the cause of reproductive system abnormalities in amphibians.
Photo: Cane toad (Bufo Marinus). Credit froggydarb
In fact the researchers found that the nearer toads lived to farms,the more likely they were to suffer from sexual abnormalities including having both testes and ovaries.
“As you increase agriculture,” said Lou Guillette, a distinguished UF professor of zoology, “you have an increasing number of abnormalities.” Guillette is one of several UF authors of a paper on the research appearing in the online version of the journal Environmental Health Perspectives.
The study gives more impetus to the prevailing belief that the use of agricultural chemicals, along with climate change, pathogenic infections and habitat loss, is responsible for the alarming drop in amphibian numbers worldwide. However the study goes one step further, being the first peer-reviewed research to examine the comparative sexual health of wild amphibians from heavily farmed areas and those existing in suburban areas.
“Our study is the first to explicitly ask, of these two areas of human disturbance, do we see a greater proportion of abnormal animals in one versus another?” Guillette said.
“Because we know what chemicals are used at these agricultural sites, we can begin to pin down the chemical cause of these abnormalities by conducting controlled experiments with each chemical alone and in combination,” said Krista McCoy, lead author of the study who did the work as part of her UF School of Natural Resources and the Environment dissertation.
Examination of the amphibians revealed a disturbing pattern. The closer they were to heavy agriculture, the more sexual abnormalities the toads had. Referred to as "intersex" toads, the toads had "...both female and male internal reproductive organs, not a normal condition for this and most species of amphibians," said a UF statement.
The affected toads were also found to have less testosterone, suggesting a reduction in sexual capacity.
The research suggests serious implications for other animals including human, said McCoy. “What we are finding in Bufo marinus might also occur in other animals, including other amphibian species and humans,” she said. “In fact, reproductive abnormalities are increasing in humans and these increases could partially be due to exposure to pesticides.”
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