File:Phytoplankton Bloom off Iceland (MODIS 2019-07-12).jpg

English: Swirls of brilliant jewel-like colors swirled in the Atlantic Ocean off of Iceland in early July 2019. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of the summer phytoplankton bloom on July 7. Phytoplankton are plant-like organisms that live in these waters year-round in small numbers. Phytoplankton form the foundation of the marine food chain and, ultimately, support almost all animal life forms in the ocean. Like land-based plants, phytoplankton require sunlight, water, carbon dioxide and nutrients in order to grow. During the summer months in the North Atlantic, the main limiting factor to growth is the availability of nutrients. Whenever a strong low-pressure system passes overhead, or a strong shift in current patterns stirs up the water from below, nutrients that have settled toward the bottom of the sea are brought up near the surface. As a result, phytoplankton can quickly reproduce by the trillions, creating beautiful patterns of light blue and turquoise that can extend for hundreds or even thousands of kilometers—features easily seen by space-based sensors.