After a decade of national field research, scientists have found clusters of deformed frogs in three regions of the country, and Alaska is one of the hotspots.
Scientists consider frogs to be barometers for the health of wetlands because they absorb liquid and gas through their skin, so they literally breath their environment, said Mari Reeves, ecologist in the U.S. Fish and Wildlife Service's Anchorage office and lead author on the report.
The report is the largest national study of frog deformities ever conducted, she said.
Research shows that the two Alaska hotspots for abnormal frogs are in the Kenai National Wildlife Refuge and the Tetlin National Wildlife Refuge southeast of Tok, two of the five Alaska refuges included in the study, she said.
The study, published last month, also found hotspots in the Mississippi River Valley and California's Central Valley, where industrial-scale farms have been using agricultural chemicals for decades.
Reeves said the study found that 2 percent of all amphibians studied were abnormal, and one-third of every test had no frogs with deformities.
The study looked at 68,000 frogs from 152 wildlife refuges and found that 2 percent of frogs had skeleton or eye problems, she said.
In 2000, the U.S. Fish and Wildlife Service sought $500,000 a year to fund the 10-year project, said Gavin Shire, spokesman for the service.
He said Congress asked scientists to research frog health in 2000 after middle school students found deformed frogs at a Minnesota wetland in 1995.
The yearly money approved by Congress ranged between $440,000 and $500,000, which put the budget a bit below the requested $5 million, he said.
Shire said the large sample size and number of scientists on the project made it a challenge to ensure consistent testing around the nation.
He said adding Alaska's data was well worth the difficulty of traveling around the biggest state.
The location of frog habitat is the best indicator and predictor for deformities, Reeves said.
Researchers studied 9,000 frogs in five the 16 wildlife refuges in Alaska: Innoko, on the Yukon River east of Norton Sound; Arctic, above the Arctic Circle in northeast Alaska; Yukon Delta in western Alaska; Kenai and Tetlin.
Scientists found the most common deformity in the Alaska frogs to be missing or shrunken limbs, Reeves said.
The study wasn't designed to determine the cause of the deformities, but Alaska was the only state in the study where researchers were able to find why frogs were deformed, she said.
Reeves said those deformities are related to a combination of now-banned pesticides still in the atmosphere seeping into the frogs, along with metals in the water where frogs live. Predators were found to attack the limbs of frogs and tadpoles.
Researchers discovered banned insecticides and pesticides like lindane and aldrin in sediment, which they found to be associated with growth-stunted tadpoles, she said. Scientists don't know where the chemicals originally came from, she said.
The Environmental Protection Agency banned lindane as an insecticide in 2006 and aldrin, used against insects resistant to DDT, in 1987.
"We live in the freezer," she said. "Even the stuff that was banned a while ago sticks around."
The low levels of metals, specifically copper, slow frogs down and caused them to be on the surface of the water, which makes it easier for dragonfly larvae to see and catch them, she said.
"They act drunk," she said. "They're intoxicated by the copper."
When drivers use their brakes, copper dust flies off and ends up on the road. Runoff carries the material into wetlands, she said.
Reeves said one of the factors alone couldn't cause the damage throughout a wetland, but when pesticides and metals combine, frogs become easier prey for predators.
She said frog deformities shouldn't stop anyone from enjoying the wetlands.
"They're not that bad because they're not dead," she said.
Scientists see the frog deformities as beacons for wetlands that may need more research, she said.
Researchers are already working on a study that will determine how roadways affect wetlands and come up with recommendations for locating and designing roads to protect the health of frogs, she said.
"They can show us places where amphibians need a little help."