The most common form of wildlife in the Arctic, seabirds are responsible for transporting most of the human-made contaminants to some coastal ecosystems, the researchers found. "The effect is to elevate concentrations of pollutants such as mercury and DDT to as much as 60 times that of areas not influenced by seabird populations," says team member John Smol, a biology professor at Queen's University and Canada Research Chair in Environmental Change.
The multidisciplinary study, led by Dr. Jules Blais, professor of environmental toxicology at the University of Ottawa, will be published July 15 in the journal Science.
Other team members are Marianne Douglas from the University of Toronto, D.McMahon and Linda Kimpe from the University of Ottawa, Bronwyn Keatley from Queen's University, and Mark Mallory from the Canadian Wildlife Service (Iqaluit).
Calling it a "boomerang" effect, Dr Blais says: "These contaminants had been washed into the ocean, where we generally assumed they were no longer affecting terrestrial ecosystems. Our study shows that sea birds, which feed in the ocean but then come back to land, are returning not only with food for their young but with contaminants as well. The contaminants accumulate in their bodies and are released on land."
The study took place at Cape Vera on northern Devon Island in the Canadian High Arctic, far from industrial and agricultural sources of pollutants. However, chemicals are emitted into the air and oceans from the populated parts of the globe, and are transported by air and ocean currents toward cold areas like the Arctic.
"Some chemicals will build up in the food webs that comprise northern traditional diets," says Ms Kimpe. "As a result, some of our northern Canadian populations are among the most mercury and PCB-expose d people on the globe."
Dr. Mallory has led a team of researchers studying the Cape Vera colony of about 10,000 breeding pairs of birds called northern fulmars. The fulmars nest on the high cliffs, which are ringed by a series of freshwater ponds at their base. Although environmental monitoring in High Arctic locations is often very difficult due to logistical difficulties, lake sediments archive important information on environmental changes.
"Lakes slowly accumulate sediments, and incorporated in these sediments is an archive of past environmental changes, much like pages in a book," says Dr. Douglas, the Canada Research Chair in Global Change. The team analyzed contaminants from the sediments of the shallow ponds that ringed the base of the cliffs, as monitors of past contaminant inputs.
Noting that Canada has the longest coastline in the world, and seabirds are typically the dominant wildlife found in these coastal ecosystems, Dr. Blais says: "Most of Canada's coastline is at our northern fringe, and northern aboriginal communities rely on these ecosystems as a source of nutrition, economic development, traditional customs, and culture.
"We now have evidence that seabirds can concentrate industrial contaminants in coastal areas to levels that can be affecting those ecosystems."