Marine organisms and their contribution to organic matter in the ocean

Abstract

The best estimates of marine biomass can be made for the algal component. Estimates of the biomass of small animals and bacteria both in the water column and the sediment remain beset with sampling and enumeration problems and, in the past, the contribution of the microfauna has often been ignored. Marine phytoplankton are the major source of organic matter in the oceans by means of photosynthesis but their contribution is not necessarily related to the size of the organism. In some instances the nanoplankton are the major contributors. Factors affecting distribution and production are discussed. The chemical composition of phytoplankton production and variation within it is less well understood. The amount, nature, variation, and mechanism of extracellular production, of algal spoliation during ingestion by herbivores, of algal autolysis and of herbivore excretory products is not well understood and neither is the relative contribution to the non-living “dissolved” and “particulate” organic carbon pools.