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DaveOrion · 09-17-2007, 04:50 AM

As I'm sure everyone knows, its not just the north pole, but Antarctica is melting as well. With the loss of the the sea ice, the loss of the krill that live under it is almost certain. Why should we care???

http://en.wikipedia.org/wiki/Krill

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Krill occur in all oceans of the world. They are considered keystone species near the bottom of the food chain because they feed on phytoplankton and to a lesser extent zooplankton, converting these into a form suitable for many larger animals for whom krill makes up the largest part of their diet. In the Southern Ocean, one species, the Antarctic Krill, Euphausia superba, makes up a biomass of over 500 million tons, roughly twice that of humans. Of this, over half is eaten by whales, seals, penguins, squid and fish each year, and replaced by growth and reproduction. Most krill species display large daily vertical migrations, thus feeding predators near the surface at night and in deeper waters during the day.

http://www.coolantarctica.com/Antarc...al_warming.htm

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Krill shortages

Studies (November 2004) have shown that stocks of krill in Antarctica have declined dramatically in recent years. The reason for this is likely to be a fall in the amount of sea ice in the winter months particularly in the Antarctic Peninsula region.

Krill numbers may have dropped by as much as 80% since the 1970's - so today's stocks are a mere 1/5th of what they were only 30 years ago. The decline in krill may in turn account for the decline in the numbers of some penguin species.

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, is one of the places in the world where there has been the greatest rise in temperatures due to global warming. This region has warmed by 2.5�C in the last 50 years (much more than the mean global rate), with a striking consequential decrease in winter sea-ice cover.

"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."

There are commercial implications as well as scientific ones. The Southern Ocean is a valuable fisheries resource, many of the species caught feed on krill. Thousands of tourists are also attracted to Antarctica to enjoy the spectacular wildlife, most of which feed on krill.

There has been previous speculation that krill stocks might have decreased, based on smaller more localized surveys over shorter time periods. This new finding comes from data from nine countries working in Antarctica who pooled their separate data covering 40 Antarctic summers, in the period between 1926 and 2003. This is the first time such a large-scale view of change across the Southern Ocean has been seen.

Another animal that feeds on the same phytoplankton food as krill, jelly-like colonial animals called salps that drift in the ocean currents have increased in the same time the krill have decreased.

This decline in krill will also make it more difficult for the great baleen whales to return to pre-exploitation levels following their decimation in numbers during the years from approximately 1925-1975.