Swirls of jewel-toned colors marked a large bloom of phytoplankton in the Bering Sea off of Alaska. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Aqua satellite acquired a true-color image of the late-summer bloom on September 4.
Phytoplankton are tiny, plant-like marine organisms that thrive in cold water rich in nutrients. Like their terrestrial plant cousins, phytoplankton convert sunlight to energy, and the green chlorophyll that facilitates photosynthesis, combined with the blue of the sea water, often creates a brilliant blue-green colors as large colonies float of the surface of the ocean.
Blooms in the Bering Sea typically increase in spring, when nutrients and freshened water (from melting ice) are more abundant near the ocean surface. Then phytoplankton populations usually plummet in summertime after exhausting the nutrients in surface waters or falling prey to ocean grazers. By autumn, however, storms and cooler water allow nutrients to mix back to the surface, fueling more blooms.