Icebergs as oases of life

Biological productivity increased by 40 percent

Habitat iceberg © NSF
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Icebergs can not only sink supposedly "unsinkable" ships, they also play a crucial role in marine ecology. As scientists now report in Science, the seemingly hostile icebergs actually serve the marine food web as "hotspots" and significantly increase the productivity of the ocean.

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More than 11, 000 icebergs were included in a study by the National Science Foundation (NSF) in the Southern Ocean. However, the white giants not only bring ice from the edges of the pack ice surface and the glacier tongues into the sea, they also form true "islands of life". Because the ice also transports terrestrial material, including nutrient-rich, organic compounds on the open ocean. Here they are released by the slow melting of the icebergs and thus form a kind of floating "manger" for marine animals.

High and high densities of phytoplankton, krill and fish, as well as seabirds, circling and resting over the white colossi, are humming around and under the icebergs. The scientists have now discovered that this so-called "halo effect" - that is, areas where nutrients but also organism density are particularly high, extends more than three kilometers into the water. Overall, according to the researchers' calculations, icebergs in the Antarctic's Wedellmeer alone increase biological productivity by 40 percent.

The icebergs may therefore play a more important role in climate change than previously thought. Because the increased productivity also contributes to an increased binding of CO2 and thus acts as a buffer in the global carbon cycle. "This study opens up a promising horizon for polar ecology, " said Roberta Marinelli, director of the American Antarctic Research Program. "We hope to learn more about these unique ecological niches and their relevance to oceanic processes during the polar year." Display

(NSF, 25.06.2007 - NPO)