Climate change and weather
(Randy Boswell/Postmedia News, 8 September 2010) -- The ongoing disintegration of Arctic sea ice cover is posing a particular hazard for the narwhal — one of Canada's iconic polar species — according to a new U.S. study that details how the slow-moving whale with the spiralled tusk is increasingly threatened by the proliferation of giant ice floes and other changes to the Arctic seascape. The danger is being dramatically highlighted this year by a colossal, 70 kilometre-long "ice island" that broke away from a Greenland glacier and is now drifting toward Baffin Bay — the principal habitat for the world's estimated 80,000 narwhals. The study has calculated that narwhals must surface for air at least every 1.4 km, meaning that whole pods of whales could drown if they swim too far out beneath large ice floes like the 250-sq.-km Petermann Ice Island — the single biggest free-floating mass of ice in Arctic waters since the early 1960s. The U.S. study, published last week in the journal Marine Mammal Science, was co-authored by biologists Terrie Williams and Shawn Noren of the University of California and researcher Mike Glenn from Sea World of San Diego. "Rapid changes in sea ice cover associated with global warming are poised to have marked impacts on polar marine mammals," the U.S. researchers state. They note that several of the narwhal's physical traits — such as muscles built for long journeys rather than rapid swimming speeds — could place the air-breathing creatures at serious risk in their increasingly ice-choked Arctic habitats. "We found that extreme morphological and physiological adaptations enabling year-round Arctic residency by narwhals limit behavioural flexibility for responding to alternations in sea ice," the study states.
Posted 8 September 2010; 11:14:33 PM. Permalink