Seabirds Fly Pollutants to Arctic Coast, Study Says
for National Geographic News
|July 14, 2005|
With rising levels of toxins in the Arctic threatening wildlife and
humans alike, scientists are on the hunt for what's behind the pollution
boom. Wind currents carrying pollutants from industrialized countries
are known to be largely responsible for toxins in the Arctic seas. But
on the coasts birds are the key culprits, a new study says.
Researchers who studied a large seabird colony in the Canadian Arctic found that ponds below the birds' breeding cliffs are laced with persistent organic pollutants, or POPs.
The birds, it seems, are eating carrion, squid, and other marine animals from POP-contaminated seas. The flyers then return to their coastal home and deposit their contaminated preyin the form of excrementin local ponds, which see their POP levels skyrocket as a result.
Experts say the study adds to concerns over the impact of toxic substances on the health of the Arctic's wildlife and people.
"What's unique about this study is that it identifies a new method of bio-transmission that's potentially causing contamination to the local environment," said Russel Shearer. Shearer is the manager of the Canadian government's Northern Contaminants Program, based in Hull, Quebec. The program investigates the risks and impacts of chemical pollutants to remote communities in northern Canada.
"Such contamination should be taken more seriously," Shearer added.
The researchers' findings are based on observations of a colony of more than 20,000 northern fulmars at Cape Vera on Devon Island in the Canadian province of Nunavut. The study will be reported tomorrow in the journal Science.
"This mode of chemical movement can lead to surprisingly high levels of contaminants, because the contaminants are first accumulated in the food chain and then funneled into relatively small areas where the birds nest," said the study's lead author, Jules M. Blais. Blais is a biogeochemistry professor at the University of Ottawa, Ontario.
Northern fulmars are a keystone Arctic species, providing vital nutrients to an otherwise desolate landscape.
"We have a unique ecological situation, where birds that feed over the ocean are nourishing an entire ecosystem under their cliffs," Blais said. "If the seabird colony left, mosses, lichen, insects, and small birds like snow buntingsand even small carnivores like foxes and jaegers [a type of large bird]would probably be displaced or disappear altogether."
But the "biological pump" provided by seabirds is now also transporting industrially produced contaminants.
The team found high levels of contaminantsincluding DDT, HCB, PCBs, and mercuryin ponds beneath the seabird colony.
PCBs (polychlorinated biphenyls) are human-made chemicals used in electrical equipment and flame retardants. They're also created as by-products of paper bleaching in pulp mills.
DDT (dichlor diphenyl trichlor) and HCB (hexachlorobenzene) were used in pesticides. Burning of fossil fuels accelerates the rate at which mercury gets into the atmosphere.
Other studies have linked POPs to malformed reproductive organs, reduced fertility, and increased susceptibility to tumors and infections in top Arctic predators such as seals and polar bears.
Previously, wind currents were thought to be the main source of pollutants on Arctic coasts.
The study team says that POP levels are much higher in ponds just below the seabirds' cliffside colony than in other Cape Vera pondsHCB concentrations are ten times higher, Mercury levels are 25 times higher, and DDT levels 60 times higher.
Blais says these pollutants could be ingested by other animals which in turn could affect indigenous peoples who eat Arctic animals. (See "Toxins Accumulate in Arctic Peoples, Animals, Study Says.")
"The marine food chain is the main source of contaminant exposure in the human population, particularly indigenous peoples such as the Inuit," said Shearer, the Northern Contaminants Program manager. "Marine mammals which have high levels of contaminants stored in their fat, organs, and skin are heavily consumed by Inuits as part of their traditional diets."
These mammals include beluga whales, narwhals, and ring seals. Shearer says some Inuit communities have been found to have high concentrations of POPs in their bloodup to 20 times higher than World Health Organization guideline levels.
"In [some Inuit] breast milk, levels of POPs are among the highest found anywhere in the world," he added. "We're dealing with a serious public health issue for the Inuit population."
Preliminary studies by the Northern Contaminants Program suggest Inuit children are especially vulnerable to POPs.
Shearer says the pollutants are thought to affect neural development and the immune system. As a result, they may lead to IQ deficits and increased incidences of infections such as colds and earaches.
Shearer says alternative, POP-free food sources often aren't available to Inuit.
Many Inuit communities are remote and have limited access to food sources. "It's not just a case of saying, Stop eating marine-mammal tissue ," Shearer said.
Canadian health authorities have now advised Inuit women of childbearing age to reduce their consumption of marine mammals, substituting them with other meat, such as caribou, whenever possible.
"Research that's coming out of the Canadian north has been instrumental in pushing governments to wake up and take notice of the potential impact these pollutants may have," Shearer said.
Several legally binding agreements have now been established to address the issue, including the Stockholm Convention on Persistent Organic Pollutants, an international treaty overseen by the United Nations Environment Programme.
Jules Blais, the University of Ottawa professor, calls for even stronger international controls on the production and release of POPs into the atmosphereparticularly pollutants of the type found at Cape Vera, which accumulate in food chains.
Free E-Mail News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
|© 1996-2008 National Geographic Society. All rights reserved.|