File:Phytoplankton blooms off of Argentina (MODIS 2019-12-19).jpg

English: Brilliant ribbons of green and milky blue highlighted the colorful waters off the coast of Argentina in mid-December, 2019. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of the stunning scene on December 14.

The swirls and ribbons of color mark areas where the ocean hosts large blooms of phytoplankton—microscopic plant-like organisms that live in these waters year-round and, when conditions are right, reproduce in huge blooms that can easily be seen from space. It’s no surprise to see such large blooms in this location, which is an exceptionally productive ecosystem. It’s here where the cool, nutrient-rich water from the Antarctic mixes with warm, salty water flowing south from Brazil. Where the two currents clash, the water becomes turbid and the churning waters bring additional nutrients from deeper reaches to the surface. Nutrients also flow into this region off the coast of Argentina after rains and from rivers along the coast. Thanks to the rich sources of nutrients, the mixing of currents, and plenty of sunshine, the waters of the South Atlantic off the coast of Argentina are a paradise for marine life, including a variety of fish and microscopic phytoplankton.

Each species of phytoplankton contain unique pigments. Chlorophyll and other pigments in these microscopic plants can give the water dark blue or green colors. Milky blue areas are often the result of the white, calcium carbonate (chalk) scales of organisms called coccolithophores reflecting light through the top layer of the ocean. Chlorophyll more typically appears green.