Deformed frogs such as this one have been found in wetlands in much of North America. Copyright Pieter Johnson
Eutrophication is caused by higher phosphorous and nitrogen that create a profound impact on the food web, threatening the frogs’ existence. Copyright Pieter Johnson
It’s like a scene out of a Stephen King novel, begun in the nineties and continued at a more rapid pace in the oughts: scores of deformed frogs flopping around as best they can, found often near cattle ponds and other wetlands throughout North America.
Researchers looked for chemical pollutants or hormonal changes in the frogs as culprits. But recent evidence linked the deformities - missing, extra, or deformed limbs - to the presence of Ribeiroia ondatrae, a frog parasite that has been noted in the scientific literature for a century and a half. But no one could explain why the incidence of deformities has increased to upwards of 20 to 30 percent of some frog populations in the 21st century compared with probably less than one percent historically.
Now a collaboration involving ecologists at Washington University in St. Louis and the University of Wisconsin strongly points to farming practices and development, two factors that create a condition called eutrophication in ponds and wetlands. Eutrophication is caused by higher phosphorus and nitrogen (prime components of agricultural fertilizer) levels in wet ecosystems. Higher levels of these nutrients cause a profound impact on the food web that imperils the frogs’ existence.
Tony Fitzpatrick | EurekAlert!
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