Someone stop her before she kills again. Scientists have just named Mother Nature the chief suspect in a series of vicious attacks that left countless frogs in this country dead or missing and made others candidates for protection under the Frogs with Disabilities Act. The original suspect in the case - man -is free to go for the time being, but scientific authorities have not ruled the possibility of trying him as an accomplice in the slayings. Stay tuned.
Scientists have been concerned for some 15 years about accounts of deformed frogs and of declining frog populations. But it wasn't until a group of Minnesota school children reported finding dozens of misshapen leopard frogs in a farm wetland in 1995 that the public, politicians and the press got interested. When researchers reported that embryos of an African frog developed abnormally in a pond that served a source of drinking water from some Minnesota families, the state began handing out bottled water to them.
Since then, reports of deformed frogs have come in from another 41 states. U.S. Interior Secretary Bruce Babbitt panicked after getting the word. What scientists told him, he said, "hit like a flash of light in the night. They illuminated a landscape of potential extinction that extends all the way around the world." Authorities promptly rounded up the usual suspects in cases like this: global warming, pesticides, ozone depletion, the Reagan tax cuts. Said Mr. Babbitt's science adviser, William Brown, just last month, "I don't think anyone can attribute it to natural fluctuation," Brown said. "We need to get to the bottom of this."
Last week Science magazine began getting to the bottom of it by publishing two papers which concluded that nature, not man, was primarily responsible for the frog's problems. In one paper, biologist Stanley Sessions and two colleagues studied five species of frogs in 12 locations in California, Oregon, Arizona and New York and found they were suffering from deformities uncharacteristic of chemicals suspected of causing them. Instead they were the problems one would expect to result from parasite infections.
At the same time, another group of researchers led by Pieter Johnson exposed tadpoles to the parasites in carefully controlled conditions and discovered that the tadpoles grew into frogs suffering the same kind of deformities as those found in the wild. A group of tadpoles that the scientists did not expose to the parasites developed without deformity.
Both researchers Sessions and Johnson cited natural causes for the parasites, known as trematodes. They hatch in pond water, infect aquatic snails, often killing them in the process. In the water, trematode larvae attack tadpoles, burrowing into their hind-leg regions, causing the grown frogs to suffer from missing or abnormal limbs. Aquatic birds then prey on the deformed frogs (more so than on normal frogs). The trematodes return to the water through the birds' feces, and the process starts all over again.
Watching nature pick its own apart is not an attractive sight; nature can be that way. But no one is going to prosecute natural processes for this kind of crime either. It's man or his technology that is the target. There's "good evidence," a researcher told the Los Angeles Times, that chemicals have contributed to frog deformities. "That's what everyone worries about," he said. "I don't think anyone is losing sleep over trematode parasites." The "evidence" published in Science suggests otherwise.
The problem in this case and in cases like this one is that mere suspicion - stoked by the likes of Mr. Babbitt - got out ahead of the research. (Mr. Sessions told Science in 1997 that he had never seen a scientific or biological phenomenon grow so fast with so few publications.) Ensuing press coverage of the controversy alarmed Americans - unnecessarily it now appears - diverted scarce tax dollars from more pressing problems to handing out bottled water and aggravated an anti-technology bias in some quarters of this country that ignores its past benefits as well as those yet to come. That's unfortunate. Mother Nature causes problems enough without making up more.
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