Download - Plankton Communities Plankton are free floating and weak swimmers whose position is determined by water movements- phytoplankton and zooplankton Nekton.

  • Plankton CommunitiesPlankton are free floating and weak swimmers whose position is determined by water movements- phytoplankton and zooplanktonNekton are strong swimmers who are able to determine the position regardless of the waters movements

  • Size Classification of Plankton

    Femtoplantkon - < 0.2 m Picoplankton - 0.2 to 2 m Nanoplankton - 2 to 20 m Microplankton - 20 to 200 m Macroplankton - 200 to 2000 m Megaplankton - > 2000 m

  • Size Classification of Plankton Femtoplankton mostly viruses Picoplanktonphototrophic bacteria and cyanobacteriaprochlorophytesheterotrophic bacteriachemoautotrophic bacteriaeukaryotic picoflagellates Nanoplanktonheterotrophic nanoflagellates (HNANs)small prokaryotic and eukaryotic phytoplankton Microplanktonprokaryotic and eukaryotic phytoplanktonheterotrophic flagellates and ciliatesmost small zooplankton and larvaeNote that the size relationship between bacteria and a ciliate is like krill is to a whale!

  • Plankton are usually separated into categories based on their size.

  • Community CompositionCome in all shapes and sizes (morphology and size limitations) single cells, chains, filamentssome are mixotrophic (both photo and heterotrophic)

    Major GroupsNon-MotileMotile (flagella)CyanobacteriaChlorophytesPrasinophytesDiatoms PrymnesiophytesCryptophytesDinoflagellatesEuglenophytesChrysophytes (coccolithophorids and silicoflagellates)Phytoplankton

  • Diatoms have heavy silicified (pectin and amorphous silica) frustules Are heavy than water, sink rapidly Usually the most abundant group (>80% of biomass) inestuarine and near-coastal waters

    PhytoplanktonFrom Sverdrup et al. 2004

  • DiatomsFrom PhytopiaChaetoceros debilisChaetoceros socialisDitylum brightwelliiThalassionema sp.Phytoplankton

  • PhytoplanktonDinoflagellatesHave 2 flagellaMany species are mixotrophicMost harmful algal species are dinoflagellatesFrom Sverdrup et al. 2004

  • From PhytopiaPhytoplanktonDinoflagellatesDinophysis sp.Protoperidinim divergens

  • Pfiesteria piscicida

  • MicroflagellatesPhytoplanktonFrom Miller 2004ChlorophyceaeCryptophyceaeChrysophyceaeHaptophytaPrasinophyceae

  • PhytoplanktonPicoplankton Are some of the smallest primary producers (0.2 2 m dia.) Were not discovered until the early 1980s Important contributors to oceanic primary production Are usually most abundant at the chlorophyll max in the open ocean Major groups areCyanobacteria (Synechococcus)Prochlorophytes (Prochlorococcus)

  • PicoplanktonDAPI DNA stainEpifluorescent MicroscopeUnder UV lightParticles contain DNADAPI DNA stainEpifluorescent MicroscopeUnder blue lightRed cells are ProchlorococcusYellow cells are SynechococcusBig yellow cell is a dinoflagellateFrom Kaiser et al. 2005

  • Prochlorophytes CryptophytesChl a + ca-carotenePhycobilinsChl a + bb-caroteneXanthophylls

  • In most estuaries, Nanoplankton have the highest biomass and primary production

    In oligotrophic habitats, Picoplankton have the highest biomass and primary production

    Occasional blooms of microphytoplankton occur under nutrient enriched conditions


  • Benthic Microalgae (microphytobenthos)Production: up to 2kg C m-2 yr-1Very high biomass: 0.1(?) kg C m-2Turnover (P/B): ~20(?)

  • Dinoflagellates: Naked and ArmoredCell densities up to 104-106 l-1 (Blooms)Coastal PhytoplanktonProduction: up to 0.5 kg C m-2 yr-1Low biomass: 0.02 kg C m-2HIGH Turnover (P/B): ~25Chl a + cb-carotenexanthophylls (peridinin)

  • Blue-green algaeTrichodesmiumN2 fixationHeterocystCell densities up to 101-103 l-1 (Blooms)Shelf-Oceanic PhytoplanktonProduction: up to 0.1 kg C m-2 yr-1Very low biomass: 0.003 kg C m-2VERY HIGH Turnover (P/B): ~40Chl ab-carotenePhycobilins (phycocyanin)

  • ~50% Production trapped on the continental shelf

  • Trends with distance

    Species composition varies with distance from land. Near-shore waters dominated by diatoms. Offshore waters have much higher percentages of dinoflagellates and coccolithophorids.

    Note: This picture can change with season and conditions.

  • CoccolithophoresCaCO3

  • ~50% spread over vast ocean

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