Updated:
12:42 PM EDT
Increased Mercury Levels
Detected in Mammoth Cave
MAMMOTH CAVE, Ky. (Aug. 7) - 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 & 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.
08/07/05 12:26 EDT
