Primary Production
D1. Physical and chemical oceanography and marine meteorologyDefinition
Rate of synthesis of organic matter by photosynthesis or chemosynthesis.
Primary production is the rate at which phytoplankton and other autotrophs synthesize organic matter, mostly by photosynthesis, fixing roughly 50 gigatonnes of carbon a year in the ocean, about half of global photosynthesis. Net primary production sets the food available to the rest of the marine food web and the strength of the biological carbon pump. It is limited by light near the surface and by nutrients, especially nitrogen and iron, below the mixed layer.