ABSTRACT
Pelagic production is characterized by fluctuations linked to hydrological conditions: this in turn is dependent on climatic conditions. Thus, in the Mediterranean during winter and early spring the genus Chaetoceros and ultraplankton make up the biggest proportion of plant production. While only a small proportion of the phytoplankton and the particulate wastes produced have positive buoyancy, most is likely to become sediment. Decomposition under bacterial action of dead phytoplankton and various zooplankton wastes to their basic mineral constituents is slow and waters rich in such nutrients are therefore usually at great depths. One particular type of primary producer is worthy of special attention because of its role in aquaculture; this consists of symbiotic dinoflagellates which participate in the feeding of the tridacnids by fixing carbon through photosynthesis; this can then be absorbed by the mollusc. This chapter shows that the primary production of the plants exceeds their consumption by herbivores.
