Elevated levels of organochlorine pesticides such as DDE have been associated with low reproduction of nesting bald eagles on remote islands in the seemingly pristine Aleutian Archipelago in Alaska, according to recent research published in the September issue of the journal Environmental Toxicology and Chemistry.
Organochlorines are chemical compounds invented to kill agricultural insect pests. These chlorinated hydrocarbons work mainly by blocking nerve impulses necessary for normal bodily functions. Unfortunately, they are long-lived, toxic to most animals and can be converted to even more deadly compounds as they degrade or when eaten and released into the environment as metabolites. DDE is an example of a metabolite of DDT.
The study adds to a growing body of research that indicates organochlorine pesticides can be transported long distances on air and sea currents and affect wildlife populations in remote and pristine areas, said Dr. Bob Anthony, lead author and a scientist at the USGS Oregon Cooperative Fish and Wildlife Research Unit in Corvallis, Ore. Anthony's coauthors are Dr. Keith Miles and Dr. Jim Estes of the USGS Western Ecological Research Center in Sacramento, Calif., and Frank Isaacs of the Department of Fisheries and Wildlife at Oregon State University.
"The fact that elevated levels of pesticides such as DDT and DDE are more widely distributed than previously known raises concerns for the health of the Aleutian marine ecosystems where bald eagles forage," said Anthony.
Estes added, "The top predators of these Alaskan ecosystems -- sea
lions, seals and sea otters -- have declined substantially in the
North Pacific Ocean over the last several decades. While overfishing
and temperature regime shifts have been blamed, the rol
Contact: Gloria Maender
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United States Geological Survey