Seabirds' diets cause metal contamination of Arctic ponds

Washington, May 26 (ANI): Potent metals like mercury and lead, which are ingested by Arctic seabirds feeding in the ocean, end up in the sediment of polar ponds, a collaborative research team led by Queen's University biologists found.

For the study, the team collected sediment cores from two ponds on a small island in the Canadian Arctic that is home to the nests of two kinds of seabirds-Arctic terns, which feed primarily on fish, and common eider ducks which feed mainly on mollusks.

The researchers analyzed the pond sediment for metals and other indicators of the birds' activity.

"Birds feeding on different diets will funnel different 'cocktails' of metal contaminants from the ocean back to terrestrial ecosystems, which can then affect other living organisms," said lead author Neal Michelutti.

They found significant differences between the samples that aligned with the birds' diets.

There were higher concentrations of metals such as mercury and cadmium in the sites inhabited by terns, while the nearby eider site recorded higher amounts of lead, manganese, and aluminum.

The patterns of metals in the sediment cores matched those recorded in the different bird species' tissues.

Queen's biology professor John Smol said that the findings could be applied to other locations.

"The High Arctic is an excellent 'natural laboratory' to undertake such studies, due to the lack of local industries. However, the presence of seabirds on every continent suggests similar processes are operating along coastlines worldwide," noted Smol.

"Our concern is that these areas of elevated metals and other contaminants occur exactly where biological activity is greatest," he added.

"The seabirds are obviously not directly to blame for the elevated metal concentrations in the ponds. They are simply carrying out their natural behaviours and lifecycles, but have become unwitting vectors of pollutants in an increasingly industrial age," said team member Jules Blais.

The study will be published in the Proceedings of the National Academy of Sciences USA. (ANI)