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Plankton – Chapter 14

Ø Phytoplankton Ø Zooplankton Ø Review food webs Ø Motivation for studying plankton Ø How plankton are collected

Review: What is plankton? •  Plankton comes from the Greek word Planktos

that translates to “wanderer” or “drifter” •  Plankton include plant-like organisms and

animals that float, drift, or have feeble swimming abilities (insufficient for horizontal migration against currents)

•  Usually microscopic, but may be large drifting organisms, e.g., jellyfish

•  Phytoplankton - kingdom Protista - autotrophs, primary producers, utilize photosynthesis for energy

•  Zooplankton - kingdom animalia -heterotrophs (herbivores, carnivores and omnivores; primary and secondary consumers)

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Three main phytoplankton groups

Diatoms

Dinoflagellates

Coccolithophorids

Diatoms compose the most abundant phytoplankton group in the oceans, they come in two general varieties:

Centric (pillbox shape) Pennate (elongate shape)

Diatoms use silicate to make hard cell walls called ‘frustules’

ET: epitheca

HT: hypotheca

Diatoms may form chains…

What happens to diatoms when they sink to the aphotic zone? What adaptations help them remain in the euphotic zone?

Diatoms may form spines or setae

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© Jean-Marie Cavanihac 2001

Dinoflagellates are characterized by one or two whip-like flagella used to change orientation in the water (to increase light exposure).

Pyrocystis fusiformis

Dinoflagellates are often bioluminescent, for example:

Florida red tide organism: Karenia brevis

Dinoflagellates may cause red tides…

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Satellite image of phytoplankton in region where Florida red tides occur

Source: http://www.whoi.edu/science/B/redtide/rtphotos/flaczcs.gif

Target Study Area

See red tide news

Coccolithophorids: use calcium carbonate to form white “shells”

coccolith

Emiliania huxleyi

Black Sea, 2000

Alaska, 1999 E. huxlei blooms: coccolithophore blooms turn the sea milky white

Newfoundland, 1997

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(photo from SBI project, summer 2003)

In 1997, hundreds of thousands of Short-tailed Shearwaters died in the Bering Sea, probably due

to starvation. What happened?

Krill, food for the Short-tailed Shearwater

Zooplankton

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Important zooplankton phyla���(Kingdom Animalia)

•  Cnidaria - jellyfish, corals •  Mollusca - clams, oysters, snails (plankton as

larval forms) •  Arthropoda - copepods, crabs, shrimp (plankton as

larval and adult forms) •  Echinodermata - starfish, sand dollars, sea urchins

(plankton as larval forms)

Two primary zooplankton categories: ���

1. Holoplankton - planktonic throughout their entire life cycle (e.g., krill, copepods, chaetognaths)

2.  Meroplankton - planktonic for only a portion of their life cycle, invertebrate larvae (e.g., bivalves, starfish, barnacles); ichthyoplankton - fish eggs and larvae are also meroplankton

Photos courtesy of C. Guigand, RSMAS

Examples of holoplankton…

Farranula gracilis (copepod) with eggs

Eucalanus sp. female

Euphausiid (krill)

Chaetognath

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Examples of meroplankton…

Starfish larvae (echinoderm larvae)

Bivalve pediveliger

Gastropod veliger Crab megalop stage

1000 g C

100 g C

10 g C

1g C

Plankton are the basis for all fish life in the oceans, it takes a lot of plankton at the bottom of the food chain to feed a fish at the top.

dinoflagellate

carnivore 2

carnivore 1

herbivore Gen

erat

ion

time

Size

µm mm cm dm - m

days

weeks

months

years Zooplankton lifetimes and sizes in the pelagic ocean

zooplankton

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Copepods: crustaceans – usually the most abundant zooplankton (from Greek Kope=“oar”, Podos=“foot”, hence oar-footed, referring to their swimming legs) §  Herbivores, carnivores and omnivores §  Holoplanktonic: entire planktonic life cycle §  Migrate vertically day-night (see next slide)

Side view

Mr. Plankton

Night sunrise

http://jaffeweb.ucsd.edu/pages/celeste/Animations/