LAUREL - The U.S. Fish and Wildlife Service is out to solve an international mystery. Call it the case of the malformed frogs.
For years, biologists throughout the world have been finding increasing numbers of frogs, toads and salamanders with oversized jaws, undersized, missing or extra limbs, or without eyes. Yesterday, the service launched a study of amphibians in 43 of its wildlife refuges in 31 states, including Alaska and Hawaii, in an effort to find out what's going on.
"Something really strange is happening to the frogs around here," said Jamie Rappaport Clark, director of the Fish and Wildlife Service, during a ceremony at the Patuxent Research Refuge. "We don't know what's causing it, but the most disturbing thing is the victims are frogs here. If frogs here, in a wildlife refuge, aren't safe, you can just imagine the scope of the problem."
Scientists suspect fertilizers and other pollutants washing off the land, a thinning ozone layer and ultraviolet radiation, or any combination of those might be to blame. Or it could be parasites or disease, fungal infections or habitat loss.
Frogs are like the canaries coal miners once used to warn them when the air in the shafts was bad. If canaries died, the miners knew they couldn't survive much longer.
Frogs and toads are highly sensitive to the environment because they breathe at least partly through their skins. If they are being born malformed and some species are disappearing, "it means something's out of balance here," said Clark. "Everything in nature is interconnected. So go frogs and toads, so go humans."
Scientists have been watching the decline of some species of amphibians for almost a decade. Fourteen species have disappeared from Australia in recent years, and another species in Costa Rica is thought to be extinct. Eighteen species of frogs, toads or salamanders in the United States and Puerto Rico are listed as threatened or endangered - five of those are in the Pacific Northwest.
Andrew Blaustein, a professor of zoology at Oregon State University in Corvallis, has linked a parasite, rising levels of ultraviolet radiation and nitrites in water supplies to a decline in amphibians there.
The issue came to national attention in 1995 when a group of Minnesota middle-school pupils on a nature trip discovered a large number of frogs with misshapen, extra or missing limbs. Since then, scientists and others have discovered an increasing number of frogs and toads with malformations.
Surveys conducted in 1997 at national wildlife refuges in the Midwest and Northeast - including Patuxent and Eastern Neck Wildlife Refuge at the mouth of the Chester River in Kent County - found malformation rates as high as 18 percent.
"If you have a rate of about 1 percent of the frogs with malformations, that's about normal," said Keisha Johnson, a fish and wildlife service biologist on the sur- vey. "If you get 4 percent or more, then you know something's going on, and you want to start by checking the water."
The rate at Patuxent was between 5 percent and 6 percent, said James Forester, a field crew leader for the survey.
Yesterday, the wildlife service turned to Washington-area Girl Scouts to start their survey in Mabbott Pond, one of 44 bodies of water that were built in the 1950s on the 1,300-acre refuge to protect the Patuxent from run-off from a nearby sand and gravel operation.
Armed with dip nets, the girls combed through the tall weeds on the edge of the pond, ready to leap at the first squiggly creature they saw. Suddenly, Alex Fries, a 13-year-old Scout from Fairfax County, Va., jammed her net into the water, twisting it as she lifted. Somewhere in the mass of muck she scooped up was a northern cricket frog.
Biologist Fred Pinkney carefully picked it out and plopped it into a plastic container with air holes for safekeeping. But when Alex got a good look at her frog, she was disappointed.
"He's not deformed," she cried.
The search went on for the cameras, eventually netting two more cricket frogs and three southern leopard frogs, none of them malformed. Fortunately, the staff had a Fowler's toad with a clubbed foot and a cricket frog with a missing leg for demonstration purposes.
Clark said scientists have found no links between nearby land uses, such as industrial plants, and frog malformations, so the service chose the survey sites to get a good cross section of different habitat and nearby land uses.
They chose Patuxent to start the study for its symbolic value. Scientists there were the first to link the pesticide DDT to reproductive problems with peregrine falcons and bald eagles in the 1960s, leadingto a DDT ban in 1972.