Hotspots of life surround drifting icebergs

WASHINGTON — Icebergs that break off Antarctica and drift away turn out to be hotspots of life in the cold southern ocean, researchers report.

Climate warming has led to an increase in the number of icebergs breaking away from the Antarctic in recent years, and a team of researchers set out to study the impact the giant ice chunks were having on the environment.

Turns out, the melting ice also dumps particles scraped off Antarctica into the ocean, providing a pool of nutrients that feed plankton and tiny shrimplike creatures known as krill.

Indeed, the researchers led by Kenneth L. Smith Jr., of the Monterey Bay Aquarium Research Institute in Moss Landing, Calif., found an increase in life forms surrounding a pair of icebergs they studied.

The abundance extended nearly 2 1/2 miles away from the drifting ice, they report in this week's online edition of the journal Science.

"Just as water-holes become 'hotspots' in the desert, drifting icebergs are like oases in Antarctic's ocean," helping promote life, said Russell R. Hopcroft of the Institute of Marine Science at the University of Alaska, Fairbanks.

It has been known that biological productivity is increased near the edge of an ice pack, Hopcroft said, but it's an aspect of floating icebergs that has not been previously considered. Hopcroft was not part of the research team.

Smith said he was surprised at the amount of sea life surrounding the icebergs, though "there had been anecdotal observations in the past of increased seabird abundance around icebergs."

By promoting life surrounding them, the icebergs also may have an impact on reducing the excess carbon in the atmosphere — at least somewhat countering the greenhouse warming that helped make them break free in the first place, Smith suggested.

"One important consequence of the increased biological productivity is that free-floating icebergs can serve as a route for carbon dioxide drawdown and sequestration of particulate carbon as it sinks into the deep sea," Smith said in a statement.

"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," he added.