Antarctic whales, seals and penguins could be threatened by food shortages in the Southern Ocean. Numbers of Antarctic krill (Euphausia superba), a shrimp-like crustacean at the heart of the food chain, are declining. The most likely explanation is a dramatic decline in sea-ice. The results are published this week in the journal Nature.
Sea-ice is a vital feeding ground for the huge number of krill in the Southern Ocean. The new research shows that krill numbers have dropped by about 80% since the 1970's. Less sea-ice during the winter is likely to be the cause and may explain declines seen in several species of penguins.
Lead author Dr Angus Atkinson from British Antarctic Survey, says: "This is the first time that we have understood the full scale of this decline. Krill feed on the algae found under the surface of the sea-ice, which acts as a kind of 'nursery'. The Antarctic Peninsula, a key breeding ground for the krill, has warmed by 2.5°C in the last 50 years, with a striking decrease in sea-ice. We don't fully understand how the loss of sea-ice here is connected to the warming, but we believe that it could be behind the decline in krill."
The implications are commercial as well as scientific, as the Southern Ocean is a valuable resource for fisheries. Thousands of tourists are also attracted to Antarctica to enjoy the spectacular wildlife, most of which feed on krill. By knowing how the environment affects this unique food web, we can predict how it will respond to future change.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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