for National Geographic News
Looking for some lively action in the Antarctic? Check out an iceberg.
The oblong chunks of free-floating ice are hotspots for ocean denizens, a new study says.
Anecdotal scientific observations suggest marine plants, shrimplike crustaceans, and seabirds—big players in the ocean food chain—congregate on and around the chunks of ice.
Icebergs are proliferating in the Antarctic as rising temperatures shrink and split the continent's ice shelves, leading scientists to wonder what effect this has on the marine environment.
(See related: "Singing Iceberg Recorded in Antarctica" [November 29, 2005].)
A study in 2002 actually found Connecticut-sized icebergs in Antarctica's Ross Sea reduced activity of marine life there by 70 percent.
"That was catastrophically bad for the ecosystem," said Kevin Arrigo, a biological oceanographer at Stanford University in California who led the 2002 research.
But the new study, in which Arrigo did not participate, found the exact opposite around much smaller icebergs in the Weddell Sea, on the other side of the continent.
There melting icebergs release terrestrial nutrients into the sea, which allow tiny marine plants called phytoplankton to bloom.
Shrimplike crustaceans called krill congregate around the icebergs to feast on the plants, and seabirds flock in to eat the krill.
This thriving web of marine life extends out 2.3 miles (3.7 kilometers) from each iceberg and then dwindles.
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