File:Spectacular Late-Summer Bloom off Newfoundland (MODIS).jpg

English: Splashes of spectacular turquoise tones colored the waters south of Newfoundland in late August 2023. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this true-color image of a widespread, late-summer phytoplankton bloom on August 25.

Phytoplankton are microscopic plant-like organisms that float in the waters in this region year-round in relatively small numbers. When conditions are right—enough sunlight, nutrients, and correct water temperature—phytoplankton can reproduce explosively to create massive blooms that can be seen from space.

There are many types of phytoplankton, each having unique characteristics including different pigments. While it’s not possible to know exactly what species is creating a bloom just from a satellite image, sometimes there are clues. For example, this image captures both bright milky-turquoise colors and a bloom that looks duller green. Although many blooms contain more than one species, it’s likely that each different color bloom is dominated by a different species.

Milky turquoise tones are most commonly caused by coccolithophores, a type of phytoplankton which contains outer scales made out of calcite. This chalky-colored substance gives a white tint to a bright blue bloom when coccolithophores are present in high numbers.

The most common species of coccolithophore found in this area is Emiliana huxleyi. A single E. huxleyi measures only about 5 microns across—1,000 times smaller than a grain of sand—so their numbers have to be incredibly abundant to create such large blooms.