As cloud covered the Gulf of Maine, swirls of green and blue colored the waters of the Gulf of St. Lawrence in mid-July 2021. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired this true-color image on July 12. The Gulf of St. Lawrence is located in eastern Canada.
The jewel-like tones in the deep blue water are the result of a bloom of phytoplankton—microscopic plant-like organisms. These tiny organisms live in these waters year-round, but when conditions are right (correct water temperature, nutrients, and hours of sunlight), they reproduce explosively to create large blooms that can be seen from space. Because phytoplankton float near the surface of the ocean, they are carried with surface currents to form beautiful swirling patterns, such as seen here. Spring and summer blooms are common in these waters and usually fade by late summer.