Arctic bird poop loaded with environmental poisons
Sea birds foul their nests with mercury, cadmium
High Arctic seabirds carry a “cocktail” of contaminants, confirms new research, which analyzed the excrement of Arctic terns and eiders nesting on a small island north of Resolute Bay.
The seabirds’ cocktail is not a particularly healthy mix for the birds or the land they nest on, a team of biologists from the Canadian Wildlife Service and Queen’s University determined.
That’s because, in addition to pesticides, the seabirds are loaded with heavy metals like cadmium and lead, which they pick up from the foods they eat.
“The birds are like a funnel and they’re concentrating these contaminants,” says John Smol, a biologist from Queen’s University and one of the co-authors of a study on sea birds published in the May 24 edition of the journal of the Proceedings of the National Academy of Science.
The seabirds then excrete contaminants from their diet of fish and shellfish around their nesting sites, creating what Smol calls a “boomerang effect,” where contaminants found in the ocean return to the land.
To study terns and eiders, biologists visited Tern Island, a small island 130 kilometres northwest of Cornwallis Island.
There, they found two ponds — one used by terns, the other by eiders.
To see what these birds were eating, they took sediments from each of the lake bottoms and then analyzed them.
While nearing “Tern Pond,” researchers had to be extra careful and watch their heads, because the terns attacked as soon as they approached the nesting area.
Around the terns’ nesting area, they found the birds’ excrement contained high concentrations of cadmium and mercury.
Fish-eating Arctic terns have the longest yearly migration of any bird species, with some covering about 80,000 kilometres annually, all the way down to Antarctica and back.
Sampling at “Eider Pond” showed the excrement of eiders, who feed mainly on mussels, clams and starfish, contains high levels of lead, manganese and aluminum, which they absorb near Greenland where they winter over.
In the past, Mark Mallory of the Canadian Wildlife Service in Iqaluit, also involved the Tern Island study, has looked at a colony of 20,000 fulmars at Cape Vera on Devon Island.
Cape Vera is another isolated place, considered to be far from pollution by industrial and agricultural contaminants such as mercury, PCBs and DDT.
But Mallory found this bird colony sits in the middle of another High Arctic hot spot of contamination.
There, fulmars nest on cliffs, which are ringed by freshwater ponds at the bottom, and their excrement flows down into these ponds below-along with the contaminants.
Contaminant levels in sediments from 11 ponds from Cape Vera are up to 60 times higher than those found at nearby sites where there are no seabird populations.
Now biologists want to know more about how these contaminants travel through food chain, what the impact is, for example, when foxes eat the seabirds.
The good news is that the levels of metals don’t present any danger to Nunavummiut who eat tern eggs, eiders or eider eggs.
But there is some concern that contaminants could affect the overall health and numbers of terns, eiders and other seabirds in the Arctic.
The research findings also underline the need for more environmentally-sound practices to cut down on contaminants in fish and shellfish that have ended up in the oceans.
“At the end of the day, it’s a sad tale, that the oceans are polluted no matter where you are — that’s the bottom line,” Mallory says.