Science  08 Jun 2012:
Vol. 336, Issue 6086, pp. 1218

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  1. Life Blooms Under Arctic Ice


    Once the Arctic ice begins to melt, life begins to bloom in the nutrient-rich waters of the Arctic Ocean—or so scientists thought. But life may not wait for the ice to retreat; scientists visiting the Chukchi Sea's continental shelf last July discovered a bright green bloom of phytoplankton—under ice more than a meter thick. Such blooms, which are invisible to satellites and scientists alike, suggest biological productivity in the region has been dramatically underestimated, the researchers note online this week in Science.

    Light was thought to be the limiting factor, says Kevin Arrigo, a biological oceanographer at Stanford University in California. It's dark under the ice, and phytoplankton, the photosynthesizing basis of a food chain that supports migratory species from Arctic terns to grey whales, require light to thrive.

    But Arrigo and his team noted many melt ponds on the surface of the Chukchi Sea ice. Thick ice simply reflects incoming sunlight, but melt ponds can transmit more than 50% of the light to the waters below, promoting under-ice blooms, he says. How long this has been going on is uncertain. But changes in bloom timing might not be good news for migratory animals still expecting to arrive just in time for peak productivity.