MPR: Frog Deformities Still Puzzle Scientists

Frog Deformities Still Puzzle Scientists
By Mary Losure
August 4, 1997

For the third summer in a row, researchers in Minnesota are finding frogs with serious deformities. As reports of abnormal frogs continue to come in here and from other states, scientists are widening their investigation to find both the cause and the geographical extent of the deformities.

Audio: Crickets fade up

By the side of a gravel road, Minnesota Pollution Control research scientist Judy Helgen and other field workers have set up a makeshift lab in the rolling farm country of Northwest Minnesota. Just down the hill is a small pond where they've netted 100 frogs, which are now frantically climbing over each other in a plastic bucket. They grab each wiggling animal, weigh and measure it, and check it for deformities.

Field Worker: Number five! (Laughs) Number five is lively! Is normal!

The pond is one of 15 sites across Minnesota where researchers are surveying frog populations, and testing the water and sediments of the ponds where the frogs live. They're searching for any possible connection between the frogs' environment and their abnormal development. That same day, she speaks to the local press - television and newspaper reporters who have driven out from Fargo and Grand Forks.

Helgen: We want to see if there's any tie between when the abnormalities appear in the tadpole, and all the different things we're measuring. We want to ask the question, 'When is this happening to the animals?'
TV Reporter: What type of deformities are you seeing and does that have any implications? Does that really mean it could jump species and occur in other animals?

Helgen explains that field workers are seeing the same kinds of deformities they've seen other years - missing eyes, missing limbs, extra limbs - and they've already found them in six species of frogs and toads this summer. But after two years of study, she still can't give the reporters the answers they are looking for: what the cause is, and whether it represents a threat to humans. Nobody knows that yet.

Helgen: No one expects to solve this within a summer of a year or two. We're hearing from scientists in federal agencies that it may take 3-5 years to solve this thing. Some feel it is one thing, etc., parasites, immune system.

The geographic range of the problem is another unknown. Scientists can't say whether high rates of frog deformities reported in Minnesota, Wisconsin, Vermont, and Quebec are indications of isolated hot spots, or the first signs of a much more widespread problem. This summer, they're calling on the public to help find the answer.

In July, the federal government set up an 800 number and Web page where citizens can file reports of deformed frogs. In the past, information from the public has helped scientists solve other biological mysteries; for example, the widespread decline of birds of prey in the 60s, later traced to the insecticide DDT. Doug Johnson, who directs the reporting project, says citizens can play a similar role now.

Johnson: There are only a handful of scientists looking at any particular issue at a given time, and they're scattered around the world. There are about 250,000,000 Americans, and they're all over the place doing things. They're in a much better position to detect these phenomena as they occur.

The federally-sponsored center opened in July and has already received more than 150 reports from 36 states and provinces. Johnson says he's now working on finding biologists and amateur herpetologists to check out the citizens' reports.

Johnson: By itself, a single malformed animal doesn't tell us much. If you go to a site and find one frog that has an extra leg, but there are 150 frogs that are normal, that might just be a standard rate at which those deformities occur. Whereas if you go to a site and there are 150 animals, and 30 or 40 of them have problems, then it's a very different situation.

The center has already received new confirmed reports of high rates of deformities. In Oregon, a researcher examined 185 Pacific tree frogs and found more than one third with missing or split hind legs. At a site in Delaware, nearly 80% of 115 bullfrogs surveyed were abnormal.

If scientists can get a picture of where the deformities are occurring, and at what rates, it may help them find the cause of the deformities. In the same way epidemiologists might find the cause of a rare cancer by tracing it to a cluster in a certain geographical area or occupation. But Sam Droege, of the federal government's Biological Resources Division, says gathering the statistically valid information scientists would need for that approach would take a series of well-designed - and expensive - surveys much like the US census. So far, those studies have not been designed or funded, and he says whether they are will depend largely on how much the public cares about the problem.

Droege: If it looks like it's a big issue, if it's carried a lot in the media, a lot of public concern, they write in to their Congressmen. If they write into different agencies, agency personnel decide that it's important, [and] it happens. Even though that's not the way things should work on a very cool and even-keeled scientific way, a lot of what happens has to come from the will of the public.

In the meantime, more limited studies are beginning. The New England region of the EPA is adding surveys of deformed frogs to its studies this summer. Fish and Wildlife service workers have been asked to check for deformed frogs at the country's nearly 600 National Wildlife refuges.

Audio: Swishing through the grass

At the Rydell National Wildlife refuge in Northwest Minnesota, workers with long-handled nets wade through the tall grass by the side of small pond, swooping up frogs. They collect 77 - three of them abnormal. A worker holds one of them, a young leopard frog, stretched out on its back as Judy Helgen of the Minnesota Pollution Control agency takes pictures.

Helgen: Can we get one of him stretched there on your hand?
Audio: Camera shutter clicks

The frog has green spotted skin and golden eyes. Extending from its pale underbelly there's an extra limb - a spindly, pinkish translucent arm - useless and pathetic.

Helgen's entire professional life is consumed with finding the reason behind such deformities. Like many other scientists, she is worried that whatever is deforming the frogs may also pose a threat to humans, but she says even if there is no health risk for humans, there is something profoundly wrong.

Helgen: It's not normal to have deformed frogs, we don't want people ever to get to the point of thinking that its just a normal thing to have this amount of abnormal animals in our background. I mean that's one thing that scares me is that we might just sort of get used to it.

Recent research has shown that frogs with missing limbs also have intestinal and reproductive abnormalities. Because they have permeable skin and live much of their lives in water, frogs are sensitive indicators of environmental problems. Finding the cause of the deformities is a puzzle scientists are putting together piece-by-piece, looking for clues not just about frogs, but about the world where we all live.

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