Pectoral Sandpiper. Photo: All Canada Photos/Alamy

Science

High Mercury Levels Pose Another Setback for Arctic Birds

Gone unchecked, the element can lead to sickness, sterility, or even death in breeding shorebirds.

Life in the Arctic has its challenges. The shorebirds that breed there each summer have to complete some of the longest migrations on record. Once they arrive, they're forced to deal with harsh living and foraging conditions—made worse by the ill effects of a changing climate.

Now scientists are adding another hardship to the list: mercury poisoning. A new study by researchers at McGill University and the U.S. Fish and Wildlife Service shows that Arctic shorebirds are exhibiting high levels of mercury, which could be dangerous for their population numbers. “The concentrations in some were much higher than we would have ever expected for small birds that are foraging on insects,” says Marie Perkins, a PhD candidate at McGill and lead author of the study.

These toxic levels are often seen in bigger animals that eat large prey items, given that mercury accumulates as it moves further up the food chain. But because the concentrations in the Arctic birds varied from species to species, the researchers think it could be related to the avians’ foraging habits. Those favoring wetland habitats might be exposed to more methylmercury—a deadly compound that’s created when inorganic mercury (a byproduct from coal plants and mining operations) settles onto microbe-rich areas. Insects are another source of the toxin, with larger, predatory species harboring higher concentrations than smaller ones. This in turn is reflected in shorebirds that feed in wetlands or on insects, such as Pectoral Sandpipers, Semipalmated Sandpipers, and Red Phalaropes.

But how is the pollution escaping so far north? The study point out that winds from circumpolar rivers and atmospheric circulation patterns can carry solid and gaseous mercury all over the world. Though far removed from power plants and gold mines, the Arctic has somehow become a giant mercurial trap; the region’s unique climatic and environmental conditions are causing major amounts of the element to be pulled into the icy ecosystem.

As a result, species that breed on the tundra are facing a whole host of problems: High concentrations of mercury can damage a bird’s reproductive success, weaken its immune system, change its songs and feather colors, and even cause its plumage to grow asymmetrically. Those effects aren’t unique to Arctic shorebirds, says Nils Warnock, executive director of Audubon Alaska, but the rapid pace at which the element is accumulating in the region is very concerning.

Climate change isn’t helping matters, either. Cracks in the Arctic sea ice can alter chemical processes in the environment and drive up mercury levels in the air. Meanwhile, melting permafrost unleashes stores of mercury compounds into the atmosphere.

The new findings do point to some clear solutions, however. Tighter restrictions on coal plants could help clamp down on toxic byproducts and carbon emissions that cause climate change, tackling two of the main drivers of the problem. Those stronger regulations are “a mandatory step,” Warnock says.

There has already been some movement on this front: Back in 2013, the World Bank announced that it would only fund overseas coal projects in countries with “no feasible alternatives.” Here in the United States, the Clean Power Plan, which is currently tied up in federal courts, could limit greenhouse gas emissions from power plants across the country.

Perkins, for one, is hopeful about the progress. Reining in mercury levels would be beneficial to both birds and humans, she says: in certain forms, the element is a known neurotoxin that can cause serious problems for developing babies. “One of the downsides of mercury is that it’s very persistent . . . it remains in the environment for a long, long time,” she adds. The clean-up process may be slow, and it may not come with instant results—but it’ll be worth it for the future of the Arctic and the planet.

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