Bacteria recycle organic material to inorganic nutrients and also serve as a food source for micro zooplankton . A reduction occurs in the summer and a secondary bloom occurs in the fall . In stratified conditions inorganic nutrients can become isolated from the photic zone . Upwelling can then control productivity by delivering nutrients. Equatorial upwelling is the dominant feature in the central ocean.
Production is high in the coastal ocean and upwelling areas.
Ryther estimated a relationship between the primary productivity of an ecosystem and the yield of the fishery. For fish at the fourth trophic level there has to be three transfers and a 10 -3 reduction in productivity .