Swirls of bright blue and dull green floated in the waters off the coast of Argentina in early January 2020, each marking a bloom of phytoplankton. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Aqua satellite acquired a true-color image of the blooms on January 5, 2021.
Phytoplankton are tiny, plant-like organisms that float near the ocean surface and turn sunlight and carbon dioxide into sugars and oxygen. In turn, they become food for the grazing zooplankton, shellfish, and finfish of the sea. They also play an important role in the global carbon cycle, taking carbon dioxide out of the atmosphere and sinking it to the bottom of the ocean.
Phytoplankton live in these waters year-round and, when conditions are right burst into explosive reproduction, creating large blooms which can be easily seen from space. This part of the South Atlantic Ocean, off the coast of Argentina and north of the Falkland Islands, presents a favorable environment for blooms of this kind. It here that warm waters from the south-flowing Brazil Current mix with the north-flowing branch of the Antarctic Circumpolar Current. This turbulent mixing brings nutrients up from the bottom as well as moderates temperature, creating prime conditions for phytoplankton growth and reproduction.