Contribution of extracellular production by nannoplankton to ¹⁴CO₂ fixation in a tropical estuary

Abstract

During a 12-month investigation in Dona Paula Bay (Goa, India), nannoplankton (passing through a 60 µm mesh) was found responsible for almost 100% of CO₂ fixation except during 3 months. In February 1975 and January and February 1976 chain-forming net phytoplankton was dominant. Extracellular fixation in the <i>in situ</i> incubated samples varied from 0 to 22.1 mg C m^-3h^-1 (0 to 40% of particulate fixation). In January and February 1976 per cent extracellular release was higher in filtered than in unfiltered samples. No difference was found in these groups during the other months of study.