"Whatever happened to the ‘deformed frogs’ problem?"
This is a question that we get all the time.
I have tried to answer it for Ask NRRI:
The ‘deformed frogs’ problem has not disappeared, even though it no longer makes the nightly news. Although the widespread occurrence of amphibian skeletal malformations has been considered an important environmental issue and researched extensively around the world, causes of these deformities in wild populations have been difficult to pinpoint.
One thing that scientists agree on is that deformities can result from multiple causes and that these causes vary from region to region. Scientists also believe that many of the causes are primarily due to, or exacerbated by, human activities. The major causes of malformations identified so far are chemical contaminants, parasites, and injuries from predators. At any given location, one or more of these factors could cause amphibian skeletal malformations as well as amphibian population declines. Additionally, the causes of malformations at one site may differ from those at another site.
Deformed frogs continue to be found across Minnesota and around the world, although rarely in huge outbreaks like that discovered in 1995 at Ney Pond in Le Sueur County, and other locations around Minnesota. Research continues to resolve uncertainties in the amphibian malformation phenomena.
|Malformed metamorphic Northern leopard frog with extra digits (© NRRI/UMD)|
|Malformed metamorphic Northern leopard frog with missing foot (© NRRI/UMD)|
There is also a new book out by Judy Helgen (Peril in the Ponds: Deformed frogs, politics, and a biologist's quest) which documents how the research on amphibian malformations got started and her efforts to solve this 'mystery'.
Minnesota Public Radio covered this story this morning on Morning Edition (Deformed Minnesota frogs still largely a mystery 17 years later) and will be covering it again on All Things Considered (sometime between 3 and 6:30 pm). Here's a preview from the Bob Collins News Cut today (7/17/12):
"Minnesota made headlines around the world in 1995 when school children discovered dozens of grossly deformed frogs in a pond in south central Minnesota. Soon there were more reports of deformed frogs from around Minnesota and other states -- gruesome pictures of frogs with extra legs, or missing legs, or eyes in the wrong place. Everyone wondered if the frogs were a sign that something was wrong in the environment that could also spell trouble for humans. Seventeen years later scientists still have not completely solved the mystery of what caused frogs to develop those deformities. But we do know more about how the investigation unfolded and how the case of the deformed frogs spawned a fight within the Minnesota Pollution Control Agency about whether the agency should even look into the matter. MPR's Stephanie Hemphill will have the story."There is also an article on frog malformations in the local section of the Duluth News Tribune (printed MPR story).