Smokestacks may be the icon of pollution, but a new study shows that seabirds can spread industrial toxins more effectively than wind and ocean currents.
Fifteen years ago, scientists began to realize that the Arctic was not as pristine as some had believed. The Inuit, for example, had more toxins in breast milk than any other population in Canada. When researchers began to study broader patterns of pollution in the Arctic, they noticed a peculiar pattern. Wind and ocean currents tend to spread contaminants evenly over an area, but much of the pollution in the Artic seemed concentrated in specific ponds.
Environmental toxicologist Jules Blais of the University of Ottawa in Canada wondered whether animals were importing the pollutants. He and colleagues focused on Fulmarus glacialis, a migratory seagull-like bird that nests near Arctic ponds in the summer months. When the team tested 11 ponds in Cape Vera, Canada, for hexachlorobenzene, a toxic byproduct of plastic manufacturing, DDT, and mercury, they found that ponds inhabited by dense flocks of F. glacialis had higher concentrations of the pollutants. Ponds especially crowded with the birds had toxin levels up to 60-fold greater than ponds without the birds.
"The extent to which the concentrations increase next to colonies [of F. glacialis] was surprising," says Blais, whose team reports its work 15 July in Science. The birds pick up the toxins by feeding on contaminated fish, squid, and phytoplankton, then excrete them near the ponds where they nest. Blais believes the birds could be bringing the toxins from as far away as Greenland.
And it's not just the vector that's important, notes Don Mackay, director of the Canadian Environmental Modeling Center at Trent University in Peterborough, Canada. "There is a real need to focus more research on how these contaminants behave in cold climates because once they get there, they stay there."