Photosynthesis and photorespiration in marine phytoplankton

Although in healthy, exponentially dividing cells of marine phytoplankton the bulk of carbon assimilation is via ribulose-1,5-bisphosphate carboxylase and the photosynthetic carbon reduction cycle, a significant proportion of carbon fixation may be by β-carboxylation, which does not represent a “C4 pathway” as found in certain higher plants.