This image, captured by the MODIS on the Aqua satellite on May 31, 2009, shows a patch of bright water off the coast of Peru. The ghostly blues and greens are due to the presence of phytoplankton. The waters along the west coast of South America are some of the most biologically fertile in the world.
This is due mainly to the Humboldt Ocean Current—a very cold, deep current flowing from Antarctica past the southern tip of Chile and northward to Peru. Off Peru, the icy waters of the Humboldt Current upwell and bring a steady supply of sulfates and phosphates from the depths to the surface. With an abundance of these nutrients brought up to the surface, a wide range of tiny ocean organisms flourish and reproduce in great numbers. Among these organisms are diatoms, phytoplankton, and zooplankton—collectively, forming the foundation of the marine food chain.