Phytoplankton are the plant-like organisms of the sea that carry out photosynthesis

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PHYTOPLANKTON

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WE CAN SEE

THEM

TOGETHER

IN THE

OCEAN

TROUGH

THE

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• Phytoplankton are the plant-like

organisms of the sea that carry out photosynthesis

• microscopic single celled organisms or

chains of single cells

• float in the upper areas of the world’s

oceans

• _{Spend all or part of their life history}

adrift in the water column

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Plankton: Defnitions

• _{Size classes}

Ultraplankton < 2 m

Nannoplankton 2-20 m

Microplankton 20-200 m

Macroplankton 200-2000 m

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Phytoplankton

• Pigments

– Often used to categorize phytoplankton

– All photosynthetic algae possess photosynthetic pigments.

• Chlorophylls - Chla in all algae; also b and c (absorb blue, red)

• Carotenoids - carotenes, xanthophylls (absorb blue, green)

• Phycobilins - pigment – bonded to proteins (absorb green, yellow, orange, red)

– Similar pigments usually indicates evolutionary relationships

• Special adaptations

– Flagellae

• _{motility (slight)}

Green Algae

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Major Taxa of the Phytoplankton

• _Prokaryotes

Blue-green algae (cyanobacteria)

Other eubacteria (purple sulfur bacteria) 

illuminated in anoxic zone (hydrogen sulfde accumulates

• _Eukaryotes

Chromophytes (Golden-brown algae)

Diatoms(Bacillariophyceae)

Prymnesiophytes

Chrysophytes, Cryptophytes Silicofagellates

Chlorophytes (Green algae)

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Cyanobacteria

• _{Includes many of the}

picoplankton, and

foaters (lagoon scum)

• _{Smallest and most}

abundant

phytoplankton in the ocean by far

• _Tropical

• _{Responsible for the}

majority of carbon fxation in the world’s oceans

• _{Many do Nitrogen}

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Diatoms (Bacillariophyta)

• _{Have silica shells}

appear in sediments

• _{Golden brown color}

• _{Coastal waters}

• _{Two forms:}

pennate, centric

• _{Some toxic}

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Diatom Skeletons (tests)

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Nitzschia pungens (domoic

acid)

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Coccolithophores

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Coccolithophorid bloom of

Newfoundland

SeaWiFS Project and ORBIMAGE

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Chlorophytes

• _{Green in color (a and b)}

• _{Rare in the ocean (most in fresh}

water)

• _{Can be motile (moving or capable of}

moving spontaneously)

• _{Related to higher plants and land}

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Dinofagellates

• _{Motile (2 fagellae), can have a test}

(cellulose-like)

• _{Many are toxic}

• _{Most red tides are dinofagellates} • _{All waters, esp. warm}

• _{Are also often symbionts of benthic and pelagic}

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Dinofagellates

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Pfesteria

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Gonyaulax

Paralyti

c

shellfs

h

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Dinofagellate Red Tide

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Dinofagellate Symbionts

• _{Many cnidaria}

(corals, anenomes) have dinofagellate symbionts called

zooxanthellae.

• _{Also many species}

of planktonic

protists (radiolaria, acantharia,

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Ceratium

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Dinofagellates

• _{Many distinct forms} • _{Diverse feeding}

strategies

• _{Some toxic forms} • _{Armored or}

unarmored forms

• _{Move by 2 fagella} • _{Complex life cycle}

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