The warm water is replaced by nutrient-rich cold water rising from the deep ocean in a process known as upwelling.
Under normal circumstances, permanent east-to-west winds known as trade winds blow westward along the equator in the Pacific Ocean, moving warm water from South America toward Asia, according to NOAA. The warm water is replaced by nutrient-rich cold water rising from the deep ocean in a process known as upwelling. The burst of nutrients from the depth drives seaweed growth and supports vast blooms of phytoplankton — microscopic organisms — which are a crucial energy source for large animal populations. As such, coastal upwelling regions are some of the most productive ecosystems in the world, supporting important fisheries.