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Icebergs are creating hot spots for life in Antarctic

Drifting ice plays host to new communities of plankton, fish, birds that may help absorb CO2.

June 22, 2007|Amber Dance | Times Staff Writer

The proliferation of Antarctic icebergs caused by rising temperatures is creating a vast ecosystem of plankton, krill and seabirds that may have the power to absorb some of the carbon dioxide that is driving global warming, scientists reported Thursday.

The researchers, led by oceanographer Kenneth Smith Jr. of the Monterey Bay Aquarium Research Institute, found that these new communities may cover a significant portion of Antarctic seas.

The ecosystems use photosynthesis to take carbon from the atmosphere and convert it into plant life and other forms of organic carbon that can be held in the ocean.

"I think it can be a substantial contribution" to reducing carbon dioxide levels, Smith said. "These things have been ignored forever."

As glaciers move across Antarctica, they accumulate nutrient-rich dirt and dust. When the glaciers break up, the resulting icebergs carry that material out to sea.

The researchers, who published their findings in the online version of the journal Science, analyzed two icebergs in the Weddell Sea, at the southernmost part of the Atlantic Ocean.

They found that soil and other organic matter from the icebergs provided nutrients and support for plankton and algae. Krill then fed on the plankton.

Scientists saw more seabirds, such as Cape petrels and Antarctic fulmars, near the icebergs than in the ocean. This iceberg-influenced zone extended over two miles into the ocean from the drifting ice.

Using satellite imagery, researchers counted 962 ice islands in an area of about 4,000 square miles near their study area. Based on their data, they estimate that 39% of the region could contain iceberg-influenced communities.

But the significance of icebergs in global carbon dynamics remains uncertain.

"While icebergs may be important on a local scale, I seriously doubt that their impact needs to be accounted for in global carbon budgets," said Kevin R. Arrigo, a geophysicist at Stanford University who wasn't involved in the study.

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amber.dance@latimes.com

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