When biologists and oceanographers first turned their attention to the Canadian Arctic in the 1960s, they went in search of pristine waters and ecosystems, so-called baseline data to compare with the industrialized southern oceans. Instead, they found evidence of human intrusion almost everywhere. More than three decades later, researchers continue to be surprised by the waters off Canada's third, largely unindustrialized coastline and by the animals that call it home.
Industrial chemicals known as organochlorines -- PCBs, toxaphene and the banned DDT -- as well as heavy metals, are present at every stage of the Arctic food chain. The pollution levels, says Ron Macdonald, a chemical oceanographer for the Department of Fisheries and Oceans, "do give us cause for concern. They are higher than we like them to be."
The concentrations of contaminants in the sea itself, and in algae, tiny crustaceans and other creatures that occupy the bottom levels of the marine food web, are still not considered threatening. But at the top of the web, says Macdonald, the contaminants have built up to troubling levels. They are found in the fat of polar bears, seals, and whales, and even in the breast milk of Inuit women, who have been advised to cut back on the amount of marine mammal fat they eat while pregnant or nursing. But so far, they evidence suggests that for most northerners, the traditional diet is still better than processed food imported from the South, according to the Northwest Territories' chief medical officer, Dr. André Corriveau.
Posing an even larger threat, however, is the global climate change that may be reducing ice cover and reshaping the North in ways that scientists are only now beginning to understand. In Tuktoyaktuk, on the Beaufort coast, the shoreline has receded by 100 metres in the past few decades. Studies point to increased storm surges and wave action that are the result of longer ice-free periods in recent summers. With computer models predicting even more ice-free days, oil companies are speculating about a year-round navigable Northwest Passage in the late 21st century. That could be a boon for the Arctic economy, but a disaster for wildlife that have evolved to live above, below and on the ice.
Again, polar bears are proving one of the best indicators of just how bad things might get. Canadian Wildlife Service biologist Ian Stirling has tentatively linked weight loss and a decline in birth rates with longer ice-free summers, during which the bears have trouble finding their main source of food, seals. More evidence, says Macdonald, that "the Arctic is a sentinel" for both climate change and industrial contamination.