A report on the results from a research cruise aboard the US Coast Guard Ice Breaker Healy last June and July appears in the June 8 issue of the journal Science. The two-year project, known as ICESCAPE, was funded by NASA.
In general, much of what's known about activity at the bottom of the marine food chain in the Arctic has been learned by studying what's happening in open water. That is partly because researchers tend to visit the Arctic in the summer, when sea ice retreats and exposes more open ocean. Moreover, satellites that can measure phytoplankton levels also can't detect what's happening under the ice.
But science, too, suggested that open water was the place to look. Phytoplankton need light, and historically, summer sea ice was thick and – at least early in the melt season – topped with a thick layer of snow. Less than 1 percent of the sunlight hitting the surface made it to the ocean surface underneath, says Don Perovich, a geophysicist at the US Army Corps of Engineers' Cold Regions Research and Engineering Laboratory in Hanover, N.H.
"I was sure that phytoplankton abundance would drop like a rock," Dr. Arrigo recalls.