- LONDON (Reuters) - Global
warming and disappearing sea ice in the Southern Ocean are causing food
shortages that could threaten Antarctic whales, seals and penguins,
scientists
said Wednesday.
-
- The vanishing ice in the winter has resulted in an 80
percent drop in the number of Antarctic krill, a shrimp-like crustacean
that is a major source of food for animals in the region.
-
- "This is the first time that we have understood
the full scale of this decline," said Dr Angus Atkinson, a marine
biologist at the British Antarctic Survey (BAS).
-
- Krill feed on algae under the ice sheet in the ocean
but warmer temperatures over the last 50 years have meant there is less
ice and fewer krill.
-
- Air temperature at the Antarctic Peninsula, a key
breeding
ground for krill, has risen by over 2.5 degrees Centigrade in the last
half century.
-
- "The most important finding was that there was such
a direct link between sea ice duration and extent and krill
abundance,"
Atkinson said in an interview.
-
- "There is only roughly a fifth of the krill around
now that were around in the mid-70s. That is a substantial decline,"
he added.
-
- Krill, which measure about 6 cm in length and swim in
swarms, are important in the food chain. They feed on phytoplankton and
algae and in turn are eaten by fish, squid, sea birds, whales, some seals
and penguins.
-
- "We're already seeing some effects in certain
penguin
species at several sites in this area where krill are declining so
much,"
Atkinson added.
-
- Scientists had earlier suspected that stocks of krill
were dropping but the estimates were based on local surveys. The latest
figures, reported in the science journal Nature, are derived from data
covering 40 Antarctic summers between 1926 to 2003 that was gathered by
nine countries working in Antarctica.
-
- Atkinson and his colleagues also noted that as stocks
of krill have declined, the numbers of salps, jelly-like creatures, have
risen. But the species that eat salps are different from those that eat
krill.
-
- "We need to understand the mechanisms of these
ecosystem
interactions to be able to predict what is going to happen in the future.
The key thing is the climatic change at the Antarctic Peninsula. It is
this particular area that is warming up," he added.
-
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