Offshore from Argentina, spring is in bloom. Massive patches of floating phytoplankton colored the ocean in November 2013. These microscopic, plant-like organisms are the primary producers of the ocean, harnessing sunlight to nourish themselves and to become food for everything from zooplankton to fish to whales.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this true-color image on November 26, 2013. The chalky blue swirls in the South Atlantic Ocean, as well as fainter streaks of yellow and green, are evidence of abundant growth of phytoplankton across hundreds of kilometers of the sea. These organisms contain pigments (such as chlorophyll) or minerals (calcium carbonate) that appear blue, green, white or other colors depending on the species.
The phytoplankton in this image are likely a blend of diatoms, dinoflagellates and coccolithophores. Near the coast, the tan and green discoloration of the water could be phytoplankton or it might be sediment runoff from rivers.
These phytoplankton help fuel one of the world’s best fishing grounds, particularly shortfin squid, hake, anchovies, whiting and sardines. The area known as the Patagonian “shelf-break front” is a crossroads of currents – Circumpolar, Brazil and Malvinas – where nutrients re carried in from southern waters or churned up from the edge of the continental shelf. Fish and squid congregate at the shelf-break especially in the spring and fall, because it is such a productive place for the growth of phytoplankton.