Primary Producers in the Pelagic Zone: Phytoplankton

In the pelagic zone, primary producers are phytoplankton—microscopic, plant-like organisms drifting in the water column. They photosynthesize, converting CO₂ and water into organic matter and oxygen, forming the base of the marine food web for zooplankton, fish, and other organisms.

Major types include diatoms (silica cell walls), dinoflagellates (cellulose walls, flagella for movement), and coccolithophores (calcium carbonate walls). They thrive in sunlit upper layers, varying by season, temperature, and nutrients.