File:Spring Boom off South Africa (MODIS).jpg

English: On October 7, 2022, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of a colorful spring bloom coloring the waters off the west coast of South Africa. The jewel-toned swirls of stretch for hundreds of miles in the South Atlantic, roughly paralleling the coastline.

The colors are created by a floating mass of phytoplankton, which are microscopic plant-like organisms that live in these waters year-round in smaller numbers. When conditions are right—lengthening daylight, proper water temperature, and adequate nutrition—phytoplankton can reproduce explosively, creating massive blooms that are easily seen from space.

Such blooms are common in the coastal waters off southwest Africa where cold, nutrient-rich currents sweep north from Antarctica and interact with the coastal shelf. At the same time, the easterly trade winds push surface water away from the shore, allowing water from the ocean’s floor to rise to the surface, bringing with it iron and other material. The suffusion of nutrients from both the currents and upwelling water creates an environment where these tiny surface-dwelling ocean plants thrive in abundance.