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

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)

Dinoflagellates (Class Dinophyta)

• biflagellated –

•subtropics

• Ceratium, Peridinium - binary fission - sexual reproduction rare

•Pfisteria blooms in N.C.– Diane Burkholder

“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

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)

• 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-

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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

• 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

• Cladocera – dominant in freshwater, only important in estuaries - Podon spp. - preys on other zooplankton

•Other crustaceans – ostracods, cumaceans, mysids, some amphipods

•Protists

•Foraminifera - CaCO3 tests - pseudopodia

• usually <1 mm, spherical and spinose

• high latitudes - rounded (Globigerina)

• low latitudes – spinose , Globigerina ooze

• Radiolaria - <50 um to a few mm

• silica skeleton

• threadlike pseudopods - axopods

• some have symbiotic algae - zooxanthellae

• asexual reproduction by binary fission

• Radiolarian ooze

• 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

• 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

• 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

• 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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