From: "Rich Gauszka" 

- But based on their findings and satellite imagery, scientists estimate the
icebergs may increase the biological productivity of the Weddell Sea by
close to 40 percent.-

http://news.yahoo.com/s/afp/20070621/sc_afp/scienceuswarmingicebergs_0706211830
21;_ylt=AokasZkbHAmghbyjz2MW1HtkM3wV

 CHICAGO (AFP) - The icebergs of the Southern Ocean around Antarctica, far
from being sterile chunks of floating ice, are "hotspots" of
activity that may play a role in global warming, oceanologists said
Thursday. Researchers who examined two mammoth islands of ice in the
Weddell Sea discovered the icebergs attract thriving communities of
seabirds above the waterline and a web of algae, krill and fish below.

These mini marine ecosystems may serve to draw down carbon dioxide in the
atmosphere and sequester it in deep ocean waters since the algae absorb
carbon from carbon dioxide through photosynthesis and then pass it up the
food chain.

"While the melting of Antarctic ice shelves is contributing to rising
sea levels and other climate change dynamics in complex ways, this
additional role of removing carbon from the atmosphere may have
implications for global climate models that need to be further
studied," said Ken Smith, an oceanographer at the Monterey Bay
Aquarium Research Institute (MBARI) in California.

It is too early to say how this phenomenon could affect the efficiency of
the Southern Ocean as one of the earth's carbon sinks, a natural depository
for human carbon dioxide emissions, Smith said.

But based on their findings and satellite imagery, scientists estimate the
icebergs may increase the biological productivity of the Weddell Sea by
close to 40 percent.

The number of Southern Ocean icebergs has increased in the last decade as
global warming has led ice shelves to shrink and split apart, but this is
the first time that scientists have studied the debris in such detail.

According to the study in the journal Science, Smith and his team examined
two icebergs in the Weddell Sea in early 2005, using a remotely operated
underwater vehicle equipped with cameras.

The objects were up to a dozen miles (20 kilometers) long and more than 120
feet (40 meters) high, with one extending nearly 1,000 feet under water.

The researchers found increased concentrations of marine and bird life, in
the form of phytoplankton, krill and seabirds such as Cape Petrels,
Antarctic Fulmars around the icy platforms up to a radius of two miles.

They attribute this "halo effect" to the fact that as the
icebergs melt, they shed accumulated terrestrial material
"fertilizing" the surrounding waters.

The run-off appears to be rich in iron, which stimulates the growth of
phytoplankton, the critical building block for the whole food chain.

"The Southern Ocean lacks a major source for terrestrial material due
to the absence of major rivers. The icebergs constitute a moving estuary,
distributing terrestrial derived nutrients that are typically supplied by
rivers in other areas of the oceans," said Timothy Shaw, a geo-chemist
at the University of South Carolina.

--- BBBS/NT v4.01 Flag-5