Coastal upwelling - (n.)

Along many coastlines, especially at the western coasts of continents, there is a strong upward motion of cold deep waters called "coastal upwelling." Coastal upwelling is driven by winds related to the trade-wind system. Strong seasonal coastal upwelling occurs off the shores of California (whose cold water forces surfers wear wetsuits), Peru, northwestern Africa, Namibia, and in the Arabian Sea. The cold water coming from below the surface layer is rich in the nutrients nitrate and phosphate. The nutrients stimulate the growth of microscopic green algae called phytoplankton. These serve as food for small animals called zooplankton. The plankton is eaten by fish, mostly anchovies and sardines, which are in turn caught by bigger fish, sea lions, birds, and people. See also “productivity,” below. (Side note: whales off the coast of Namibia feed in the green upwelling waters, hence the name "Walvis Bay," given during the heydays of whaling.)