<P> The major upwellings in the ocean are associated with the divergence of currents that bring deeper, colder, nutrient rich waters to the surface . There are at least five types of upwelling: coastal upwelling, large - scale wind - driven upwelling in the ocean interior, upwelling associated with eddies, topographically - associated upwelling, and broad - diffusive upwelling in the ocean interior . </P> <P> Coastal upwelling is the best known type of upwelling, and the most closely related to human activities as it supports some of the most productive fisheries in the world . Wind - driven currents are diverted to the right of the winds in the Northern Hemisphere and to the left in the Southern Hemisphere due to the Coriolis effect . The result is a net movement of surface water at right angles to the direction of the wind, known as the Ekman transport (See also Ekman Spiral). When Ekman transport is occurring away from the coast, surface waters moving away are replaced by deeper, colder, and denser water . Normally, this upwelling process occurs at a rate of about 5--10 meters per day, but the rate and proximity of upwelling to the coast can be changed due to the strength and distance of the wind . </P> <P> Deep waters are rich in nutrients, including nitrate, phosphate and silicic acid, themselves the result of decomposition of sinking organic matter (dead / detrital plankton) from surface waters . When brought to the surface, these nutrients are utilized by phytoplankton, along with dissolved CO (carbon dioxide) and light energy from the sun, to produce organic compounds, through the process of photosynthesis . Upwelling regions therefore result in very high levels of primary production (the amount of carbon fixed by phytoplankton) in comparison to other areas of the ocean . They account for about 50% of global marine productivity . High primary production propagates up the food chain because phytoplankton are at the base of the oceanic food chain . </P> <P> The food chain follows the course of: </P>

Zones of upwelling near the shores of land masses have high primary production because such zones