Antarctic krill are shrimp-like creatures that feed primarily on phytoplankton and live in large swarms in the Southern Ocean. Penguins, seals, seabirds and many whale species rely on the protein-rich, pinky-sized crustaceans as a source of food. Commercial fisheries are allowed to harvest up to 3 tons of the krill a year as food for farm-raised salmon and for oil, rich in omega-3 acids, which is used in human dietary supplements.
Around the Western Antarctic Peninsula, krill migrate in austral autumn from open ocean waters to phytoplankton-rich bays and fjords, where juveniles feed and the population overwinters under the protective cover of ice. There is a strong correlation between the amount of sea ice and the amount of krill that survive the long, harsh Antarctic winter.
"If there are more areas with large aggregations of krill hanging out in waters where sea ice has diminished, you could see a big decrease in the standing krill stock, especially if we have a few years of back-to-back bad ice and the krill can't replenish themselves," Friedlaender says.
Scientists already have documented drops in krill abundance over the last 50 years related to reduced sea ice cover. Further drops could have far-reaching consequences. Seals and penguins have a relatively small foraging range, and some can't eat any prey other than krill or hunt without the presence of sea ice. Whales can migrate longer distances and might be able to find food elsewhere, but may be affected in other ways, as evidenced by snippets of unexpected sounds being transmitted by 11 whales the Duke team tagged in the study.
|Contact: Tim Lucas|