Phytoplankton
Phytoplankton are typically microscopic organisms that perform photosynthesis and form the base of almost all foodwebs in the ocean. They are a diverse community of organisms that includes important groups such as coccolithophorids, cyanobacteria, diatoms and dinoflagellates. Primary production by phytoplankton is the main driver for the biogeochemical cycles of the major elements (C, N, P, Si) in the ocean.