Plankton nanoplankton

Fig.1 Generalized pelagic food web [ 13]. The old view of a simple food chain vertical line in this figure) with phytoplankton (mainly diatoms) at the base, herbivorous mesozoo-plankton (mainly copepods) at the second trophic level, and planktivorous fish has been extended to a pelagic food web including nanoplankton (<20 pm), picoplankton (<2 pm), and their protozoan feeders lower left). Herbivorous tunicates and jellyfish as primary carnivores also play a role, as do mixotrophic flagellates. The main pathway of energy flow depends on the nutrient scenarios [13]. DOC=dissolved organic carbon, HNF=heterotrophic nanoflageUates. From [13] with permission of Kluwer Academic Press...

Classification of the plankton as a whole is often made on the basis of size (Fig. 1.9). The ultrananoplankton (or picoplankton) is composed almost entirely of bacteria, the nanoplankton of algae (phytoplankton), and the macro- and megaplankton of animals (zooplankton), mainly invertebrates. 

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