Phytoplankton

The phytoplankton - principal source of primary nutrition Produces organic matter through photosynthesis Contribute to about 95% of primary production in the oceans and supports the secondary production (zooplankton) and tertiary production (fish, shellfish, mammals, etc.) About 5,000 phytoplankton have been identified in aquatic ecosystem

Diatoms  Common forms of centric diatoms are Coscinodiscus, Chaetoceros, Biddulphia, Skeletonemia, Thallassionema, and Bacteriastrum, Thalassiosira, Navicula, Triceratium Some common pennate diatoms are Pleurosigma, Gyrosigma, Rhizosolenia, Thalassiothrix, Thalassionema and Nitzschia

Dinoflagellates Are next to diatoms Abundant in trophical water producing red tides The genera of Peridinium and Ceratium are most commen in the plankton Common unarmored (“naked”) representatives of dinoflagellates are Gymnodinium, Cystidinium, and Glenodinium

Common armored dinoflagellate species are Peridinium, Ceratium, Dinophysis, and Goniaulax etc. Non-photosynthetic species - Noctiluca. Sp. Certain species produce a poison – PSP Red tide is by Goniaulax sp. and Gymnodinium brevis. Noctiluca scintillans exhibit bioluminescence

Coccolithophores Are one-celled marine plants that live in large numbers in the upper layers of the ocean Abundant in the sub-trophical areas and also live in most subpolar regions. Importatent forms - Dicrateria, Phaeocystis, Coccolithus, Prymnesium etc.

Silicoflagallates Phytoflagellates are algae Abundant in phytoplankton Important forms are Dictyoche, Distephanus, Chromulina etc.

Blue-green algae   Are the hard, simple algae Chief primary producers of organic matter Trichodesmium sp species are tropical, dominant in warm seas and forms blooms Green algae The green algae are unicellular and colonial flagellates, often colonial, commonly found in fresh water. Trichodesmium sp

ZOOPLANKTON Are heterotrophic plankton except bacteria and viruses Size range from 2 µm (flagellates) to several meters (jellyfish) Adaptation to a pelagic mode of existence – holoplankton Larval forms present temporarily in the plankton are called meroplankton

The holoplankton includes – foraminiferans, radiolarians, siphonophores, ctenophores, pelagic polychaetes, copepods, cladocerans euphausids, chaetognaths, pteropods, salps etc. Whereas meropkankton - the drifting larval stages of numerous littoral and benthic species such as polychaetes, barnacles, decapods crustaceans, echinoderms, molluscs etc. Fish eggs and fish larvae - ichthyoplankton