June 2007 -- Icebergs have long gripped the popular imagination, whether as
relatively run-of-the-mill floating hazards that cause "unsinkable'
ships to founder or, more recently, as enormous breakaway pieces of ice
the size of states or small countries.
But, according to a paper published in this week's Science magazine,
scientists have discovered that these floating ice islands--some as
large as a dozen miles across--have a major impact on the ecology of
the ocean around them, serving as "hotspots" for ocean life, with
thriving communities of seabirds above and a web of phytoplankton,
krill and fish below.
The icebergs hold trapped terrestrial
material, which they release far out at sea as they melt. Scientists
have discovered that this process produces a "halo effect" with
significantly increased nutrients, chlorophyll and krill out to a
radius of more than 3 kilometers (2 miles).
Based on their new
understanding of the role of icebergs in the ecosystem and the sheer
number of icebergs in the Southern Ocean--the researchers counted more
than 11,000 in satellite images of some 4,300 square miles of
ocean--the scientists estimate that, overall, the icebergs are raising
the biological productivity of nearly 40 percent of Antarctica's
Weddell Sea.
Scientists also have begun to suspect, but argue
for additional study, that icebergs may also play a surprising role in
global climate regulation by removing carbon from the atmosphere.
The
National Science Foundation (NSF) funded research was conducted by
scientists from the Monterey Bay Aquarium Research Institute, the San
Diego Supercomputer Center, Scripps Institution of Oceanography, the
University of San Diego and the University of South Carolina.
As
manager of the U.S. Antarctic Program, NSF coordinates and provides
logistical support to all U.S. research conducted on the southernmost
continent. The White House Office of Science and Technology Policy has
designated NSF as the lead agency for the International Polar Year, a
global scientific deployment to the Polar Regions that began in March
2007.
NSF officials agreed that the new research may open a new
and productive field for ecosystem research at the dawn of the Polar
Year.
"This research establishes yet another promising horizon
for polar ecology," said Roberta Marinelli, organisms and ecosystems
program director for the U.S. Antarctic Program. "And as we progress
through the International Polar Year, NSF hopes to expand this work to
learn yet more about these unique ecological niches and their
significance to oceanic processes."
Source : National Science Foundation
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