Listen to the podcast.

The Case of the Deformed Frogs

A decade after school children startled scientists with their discovery of deformed frogs in a Minnesota pond, researchers say there’s more than one answer as to why amphibians around the world have gone biologically haywire.

Pond water contaminated with agricultural chemicals appears to be one of the biggest culprits, but in a much more complicated way than was first believed. According to recent work by University of Wisconsin researcher Pieter Johnson, most of the deformities are caused by parasites that burrow in the joints of developing tadpoles.  The irritation causes their limbs to develop abnormally, sometimes even spawning two or more legs to grow where there should only have been one.  

But these parasites aren’t new.  So why has there been a recent rash of deformities?   It turns out that fertilizers that run off farmland into frog territory create fertile habitat for a type of snail that is part of the life cycle of the parasites.  More fertilizer means more snails, which in turn means more parasites.

But that isn’t the end of the story.  Other research shows that pesticides in the water decrease the tadpoles’ ability to resist the parasite. The bottom line is that agricultural chemicals are creating an environment that leads to waves of frog deformities.

Other studies have identified ultra violet rays at high altitudes as a culprit in frog deformities. Since the Minnesota pond discovery, deformed frogs have been found in 40 states and numerous countries around the world. Researchers continue to explore other possible explanations as well.

Scientists don’t believe the parasites cause a direct threat to human health, but researchers are concerned about the role of parasite-carrying frogs and other potential pathogens that can lead to infections in wildlife and humans. Excess nutrients in ponds and other bodies of water are problematic for other reasons as well. For example, they lower oxygen levels in the water and make it harder for aquatic life to survive.

For more information on research related to the deformed frogs, click here, read the article in Science Daily, or read the article in the Mankato Free Press.

To read more about this and other environmental health issues, go to: www.environmentalhealthnews.org, www.ourstolenfuture.org, or www.healthandenvironment.org