WAVE 3 TV Louisville, KY | Scientists Concerned About Mercury Levels In Mammoth Cave Bats

Scientists Concerned About Mercury Levels In Mammoth Cave Bats

(MAMMOTH CAVE, Ky.) -- Scientists have observed increased levels of mercury among bats in Mammoth Cave National Park, and they blame the rise in part on pollution from coal-fired power plants.

Western Kentucky University and park experts, who conducted the research aimed at measuring the amount of toxic metals in park wildlife, said the endangered Indiana bat is among those with excess mercury levels.

Mercury from power plants and other sources accumulates in microscopic plants, which are eaten by tiny animals, which are eaten by insects, which are consumed by bats. In each stage, the amount of mercury contained in the body grows.

Park officials said they believe mercury contamination largely comes from emissions from coal-fired power plants, which utility companies say they are reducing. The utilities pointed out that some mercury in the atmosphere comes from natural sources, such as volcanoes and forest fires.

Bob Carson, the park's air resource specialist, and others involved in the study said they have not determined whether the amount of mercury in the bats is large enough to cause any central nervous system damage or reduced reproduction.

That would require a better understanding among scientists of how much mercury bats can tolerate, officials said. But the researchers said they found mercury in bats' hair at nearly 10 parts per million, which is above the level beyond which detrimental effects have been detected in people and rodents.

"When I hear 10 parts per million, I would worry a bit," said David Evers, an expert on mercury and the environment who is the executive director of the Biodiversity Research Institute in Gorham, Maine, who is conducting bat studies in the Northeast that are similar to the work being done at Mammoth Cave National Park.

The study being done at the park involved teams using nets to capture hundreds of bats over two summers, said Steve Thomas, a park ecologist.

Thomas estimated that about 6,000 to 8,000 bats inhabit the park.

Like people, the amount of mercury in bats' hair has been shown to correlate with the amount of mercury in their bodies.

Bats are especially vulnerable to the accumulation of mercury "because their high metabolic rate requires they consume large amounts of insects," said Kurt Helf, a park service ecologist who worked on the bat study.

Mercury could seriously affect bats' reproduction, said Daniel Cristol, associate professor of biology at the College of William and Mary in Williamsburg, Va. Cristol is studying how mercury affects wildlife along the Shenandoah River.

Environmentalists call Kentucky a "hot spot" for mercury because of its many coal-fired power plants. And state officials have issued mercury warnings about eating fish from waters in all 120 counties.

Mercury pollution isn't the only thing worrying park officials. The bat study arose from concerns several years ago that proposed coal-fired power plants in the region could hurt the park's plants and animals, including rare or endangered mussels, cave shrimp and bats.

"We were wondering about the impact, but we had nothing to go on," Carson said.

(Copyright 2005 by The Associated Press. All rights reserved.)