Like plants on land, phytoplankton need sunlight and nutrients to bloom. The main source of ocean nutrients comes from cold, deep ocean water that wells up to the surface, called upwelling. The circulation of the ocean and atmosphere determine where nutrients upwell. Areas of upwelling, and thus phytoplankton productivity, include the subpolar gyres, along the equator, along the west coast of continents, along western boundary currents (e.g., Gulf Stream) and near islands. Other sources of nutrients to the ocean surface include run-off from land and atmospheric deposition of minerals (e.g., desert dust).