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PLANKTON Holoplankton: picoplankton- <2 u m - bacteria, prochlorophytes, cyanobacteria

PLANKTON Holoplankton: picoplankton- <2 u m - bacteria, prochlorophytes, cyanobacteria nanoplankton- 2-20 u m- diatoms, cocc., silic. microplankton- 20-200 u m - diat., dinoflagellates

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PLANKTON Holoplankton: picoplankton- <2 u m - bacteria, prochlorophytes, cyanobacteria

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  1. PLANKTON • Holoplankton: • picoplankton- <2 um - bacteria, prochlorophytes, cyanobacteria • nanoplankton- 2-20 um- diatoms, cocc., silic. • microplankton- 20-200 um - diat., dinoflagellates • Golden-brown algal line- Diatoms (Class Bacillariophyta)- Arctic, Antarctic, temperate and boreal, silica cell wall - frustule composed of hypotheca and epitheca

  2. Shapes: centric - radially symmetrical • pennate - bilaterally symmetrical • diatomaceous ooze >30-40% of total sediment composition • binary cell division • sexual reproduction does occur • gametogenesis - resulting zygote usually enlarges to form a large cell - auxospore • 0.5-0.6 doubling/day (Eppley, 1972)

  3. Dinoflagellates (Class Dinophyta) • biflagellated – • subtropics • Ceratium, Peridinium - binary fission - sexual reproduction rare • Pfisteria blooms in N.C.– Diane Burkholder

  4. “Red Tide”: • Gonylaux & Gymnodinium • toxins - paralytic shellfish poisoning • saxitoxin - accumulates in hepatopancreas of mollusks • interferes with Na transport - depresses synaptic function - within 12 hrs. of ingestion of bivalves human respiration is inhibited and cardiac arrest ensues

  5. Red Tides - associated with sudden influxes of nutrients, upwelling, turbulence, land-derived • Bioluminescence - Noctiluca • luciferin – luciferase reaction • endogenous circadian rhythm - max. at night • (Classes Haptophyta and Chrysophyta, Cryptophyta, Eustigmatophyta, Xanthophyta) – Chrysophyta – Chrysophyceae and Rapidophyceae; Haptophyta – Prymnesiophyceae (Coccolithophores) Cryptophyta - Cryptophyceae • spherical CaCO3 coccoliths; Phaeocysts - cold waters - produces poisonous acrylic acid (Guillard, 1971)

  6. Blue-green - Class Cyanophyceae - prokaryotes • Trichodesmium (Oscillatoria - nutrient-poor ocean gyres • Prochlorophytes (Prochlorophyceae) - may be important for food • chlorophyll b • Green Algal Line • (Chlorophyta and Euglenophyta) – includes Prasinophyceae (flagellated) and Chlorophyceae-

  7. Zooplankton: • Arthropoda – Crustacea (Copepods) - largest group of crustaceans • <1 nm to several mm • calanoid forms dominante • Calanus spp. • Particles trapped on maxillary setules - Acartia tonsa

  8. Calanus female may lay a 50-egg clutch (depending on food) • interval of 10-14 days • An equatorial deepening of depth distribution is known as tropical submergence - cold-adapted spp. • Euphausids – shrimp-like planktonic organisms, 2-5 cm length • Antarctic, red color (Astaxanthin) • Euphausia superba - feeds on diatoms

  9. Cladocera – dominant in freshwater, only important in estuaries - Podon spp. - preys on other zooplankton • Other crustaceans – ostracods, cumaceans, mysids, some amphipods • Protists • Foraminifera - CaCO3tests - pseudopodia • usually <1 mm, spherical and spinose • high latitudes - rounded (Globigerina) • low latitudes – spinose , Globigerina ooze

  10. Radiolaria - <50 um to a few mm • silica skeleton • threadlike pseudopods - axopods • some have symbiotic algae - zooxanthellae • asexual reproduction by binary fission • Radiolarian ooze

  11. Ctenophora - transparent, egg-shaped, 8 external rows of meridional plates, exclusively carnivorous • Pleurobrachaia • Mnemiopsis - larvae - eats zooplankton- failure of oyster larvae • gametes shed into water - newly formed embryo is a free-swimming larvae • SO4 - ions lost to enhance specific gravity

  12. Chaetognatha – chaetognaths normally shallow, but may occur in the deep waters • Arrow worms (Sagitta) - torpedo shaped • 4-10 cm in length • feed on copepods • hermaphroditic • eggs in water or attached • Annelida (Polychaeta) Tomopteris –paarpodia well-developed

  13. Coelenterata - Cnidaria • Scyphozoa - true jellies (Aurelia aurelia) • , feed on zooplankton • Siphonophores - floating hydrozoan colonies, nematocysts may be very large (Physalia, Velella) • Mollusca- (Gastropoda) pteropods – parapodia, thecosomes - sink to bottom • Pteropod ooze

  14. Subphylum- Urcochordata – Thaliacea (Salps) tunicates– and Larvacea • Salpa – solitary and Pyrosoma - colonial • feed on phytoplankton, fish larvae – using ciliary mucous net

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