Liberation of Extracellular Products of Photosynthesis by Tropical Phytoplankton

Abstract

Using14C as a tracer in experiments of 2–3 h duration it has been demonstrated, both with individual species in culture and natural populations, that marine phytoplankton from tropical inshore waters releases products of photosynthesis insoluble extracellular form. The relative extent of this excretion varied between 1% and 20% of the total carbon fixed but on any particular occasion the amount of extracellular products was approximately proportional to the amount ofphotosynthesis which had taken place. An inverse relation-ship between relative extent of excretion and phytoplankton abundance as measured by chlorophyllα concentration was found, in agreement with the results of previous workers. The relative extent of excretion did not appear to be greatly different in brackish water of 12–3% salinity from that in ordinary sea water.