Mysterious Green Swirls Spotted Off Antarctic Coast | Phytoplankton Blooms

These green swirls were spotted off the coast of East Antarctica on Feb. 27 by NASA's Terra satellite.

CREDIT: NASA image courtesy Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team

Late last month, a NASA satellite flying over East Antarctica spotted swirls of green off the Princess Astrid Coast that left experts wondering just what it was.

Such a pattern usually indicates a bloom of tiny plantlike organisms called phytoplankton, which form the base of the ocean food chain.

Such blooms are common along the Antarctic coast, but typically form in early December, in the austral spring, not so late in the summer season, according to experts consulted by NASA.

"It doesn't look like a phytoplankton bloom to me," Stanford University marine biologist Kevin Arrigo, who led NASA's ICESCAPE expeditions to the Arctic in 2010 and 2011, told NASA. "The spatial pattern resembles the sea ice too closely. It looks suspiciously like green sea ice. Plus, it’s very late for such a bloom in the Antarctic."