Picocyanobacteria are cyanobacteria that are part of the picoplankton, which is the fraction of plankton composed by cells between 0.2 and 2 μm.[1] Picocyanobacteria comprise the smallest photoautotrophs.[2]
Freshwater picocyanobacteria genera include Synechococcus, Cyanobium, and Synechocystis,[3] and marine picocyanobacteria genera are represented primarily by Synechococcus and Prochlorococcus.[4]