High levels of mercury in bald eagles in Catskills
Tue, Mar 24, 2009 at 02:26 PM
By The Nature Conservancy
Mercury concentrations in adult and juvenile bald eagles are elevated within New York’s Catskill Region and Catskill Park according to a report prepared by the BioDiversity Research Institute (BRI) of Gorham, ME, and the New York State Department of Environmental Conservation (NYSDEC) with support from The Nature Conservancy.
One-in-four bald eagle chicks in the Catskill Region had accumulated mercury from their recent diet (fish), and one-in-three adults had accumulated mercury over their lifetimes, to levels that are known to have negative effects in other birds such as common loons.
Mercury becomes an air pollutant largely through releases from coal-fired power plants, solid waste incinerators, and various smokestack industries. Airborne mercury eventually returns to earth in rain, snow, and fog droplets as well as in dry form. Under the right conditions, mercury is then transformed into methyl-mercury, which becomes magnified toward the top of the food web. Its toxic effects can include both neurological and reproductive harm to wildlife, and to people who consume contaminated wildlife.
“The average mercury level for eagle chicks in the Catskill Region – and especially those near the boundary of the Catskill Park – was comparable to levels found in regions associated with significant mercury pollution histories,” reports Chris DeSorbo, lead investigator of the study and Director of BRI’s Raptor Program.
These findings are consistent with previous research revealing that the Catskill Region in southern New York receives some of the highest rates of atmospheric deposition of mercury in the U.S. Fish and wildlife in this region are regularly exposed to mercury through their diet at levels that are of concern to scientists. The recent study, initiated by a grant from the Conservancy and executed by NYSDEC and BRI, is the first to comprehensively examine mercury exposure in New York’s bald eagles in general and in the Catskill Region in particular.
Dr. David Braun, director of conservation science for the Nature Conservancy’s Eastern New York Chapter, explains, “Research over the past few years has documented a tendency for mercury from air pollution to accumulate to harmful levels in wildlife in ‘hotspots,’ where environmental factors combine to move mercury more readily into forest and aquatic food webs. The Catskills appear to be one such hotspot.”
By the early 1970s, breeding bald eagles had nearly vanished from New York State and surrounding regions due to the combined impacts of DDT, habitat loss, and direct killing. Legal protections for eagles, their habitats, and the 1972 ban on DDT eventually led to widespread population recoveries throughout much of the continental U.S. Bald eagle populations have made a strong comeback in New York following intensive restoration efforts led by Peter Nye, leader of the (NYSDEC) Endangered Species Unit.
Initiated by a grant from the Conservancy, BRI and NYSDEC researchers teamed up to determine whether biologists should be concerned about mercury levels in bald eagles from the Catskill Region or elsewhere in New York State. Biologists collected 102 samples from bald eagle chicks and/or adults at 41 nests throughout the state and analyzed them for mercury.
A report released earlier this year by The Nature Conservancy and the Cary Institute of Ecosystem Studies, Threats From Above: Air Pollution Impacts on Ecosystems and Biological Diversity in the Eastern United States, found that no ecosystem in the eastern United States is free of the effects of air pollution. To view the full report, visit http://www.ecostudies.org/Threats_from_Above.pdf.
MNN is working with The Nature Conservancy to bring you state-by-state environmental information.
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