Phycology: The Study of Algae

• Some restricted to marine environment (reds and browns), some to freshwater

• Characterized by morphology, biochemistry, pigments, reproductive methods, food reserves

Photosynthetic Pigments

• Chlorophylls– Chlorophyll -found in all algae and

macrophytes; the primary pigment• Absorbance spectrum 660-665 nm and 430 nm

– Chlorophyll -only in chlorophyta, euglenophyta and charophyta;

• Absorbs about 435 nm and 645 nm– Chlorophyll c- accessory pigment

• Absorbs 630-635, 583-586, and 444-452 nm.

Accessory Pigments

• Carotenes- and are most common• Xanthophylls-derivatives of carotenes

– E.g., lutein, diatoxanthin, myxoxanthin, peridinin

• Biliproteins-almost exclusively in cyanophyta– E.g., phycocyanin, phycoerethryin

Cyanophyta (Blue-green algae)• are prokaryotic bacteria; date to 3.5 BYA• ~55% are blue-green• ~15% are never blue-green; others may be green, olive, red, purple,

black, or colorless• Store food as glycogen (iodine negative)• Never flagellate, but some can move (oscillate or glide)• Reproduction

– Sexual-not known– Vegetative-binary fission; fragmentation– Asexual

• Akinete-germinates directly• Heterocyst-may divide either directly to a trichome or to endospores which

‘germinate’ to a trichome• Presence of pseudovacuoles; gas-filled; affect buoyancy; may

shade other species

Cyanophytes (continued)

• Nutrition:– Mostly autotrophic, some saprophytic– 40 different kinds are N-fixers; all of these

have heterocysts; do well in N-poor environments

• Aphanizomenon Anabaena Nostoc

• Distribution-highly successful; terrestrial, aquatic, marine, epiphytic, on walls, soils, parasitic, planktonic; some can live at 80oC.

• Economic importance– Rice paddy nitrogen fixation– Nostoc balls– Odors and flavors-musty, moldy– Allergies

• Coloration of flamingoes and shrimp

Merismopedia

Nostoc balls

SpirulinaOscillatoria

Lyngbia

MicrocystisRivularia

Scytonema false branching

Diatoms

Centrales: centric diatoms

•Radial symmetry

•Striae composed of linear punctae

•May be single-celled like Cyclotella (above) or colonial: in filaments or like Tabellaria (above)

Pennales: pennate diatoms

Pennales• Bilateral symmetry• Many groups possess a raphe-these are motile;

some have a pseudoraphe• Generalization: pennate diatoms are more

common in eutrophic waters, centrics in oligotrophic waters;

Green Algae: Chlorophytes

Rhodophyta: Red Algae

• Eukaryotic• Pigments: chlorophyll a & b, phycoerythrin• Food storage: iodine negative starch• Cellulose cell walls• No flagellated cells• Many marine species often used as

thickeners due to their highly mucilaginous nature: agar, carageenans

Irish Moss (Chondrus crispus)

Porphyra (Nori)

Dulse (Palmaria palmata)

• Predominantly marine group

• Few FW representatives, especially locally

• Not necessarily ‘red’ in appearance

• Complex life cycles

Batrachospermum

Bangia atropurpurea

Characteristic of cool, clear streams

Dinoflagellates

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Dinoflagellates

• Photosynthetic, unicellular with flagella• Live in aquatic environments• Some are luminescent• Do not appear to be directly related to any other phylum• “Red tide” are “blooms” – fish, birds, and marine

mammals may die from toxins• DNA not complexed with histones

General Structure

General Characteristics

• Most are solitary• Most have two flagella of unequal length• Cellulose cell wall of plates; or naked• Ceratium-blooms color water brown, have

fish/septic odor

Ceratium

Red Tide

Red Tide

• In marine ecosystems, can cause paralytic shellfish poisoning (PSP)

Gonyaulax tamarensis

Pfisteria Noctiluca, sea sparkle

Brown algae

• Conspicuous seaweeds of northern regions

• Life cycle involves alternation of generations– Sporophyte – multicellular

and diploid– Gametophyte –

multicellular and haploid

• Not plants

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Chlorophyta: Green Algae

Cladophora

Branching filaments; often forms mats

Chloroplasts often distinctive to the genus

Spirogyra-spirals Mougeotia-plates; can orient

Ulothrix-’apple core’ Zygnema-stellate

Flagellated forms

ChlamydomonasEudorina

Pandorina

Volvox

Euglena

Chrysophyta: Golden Browns

• Eukaryotic• Pigments: chlorophyll a & b, carotenoids,

fucoxanthin• Food storage: chrysolaminarin, oils• Cell wall: cellulose• One or two flagella may be present

•Cluster of biflagellate cells

•Golden brown (not green like similar looking green algae)

•No division of labor between cells

Vaucheria

Dinobryon

•Constructs a cellulose lorica

•Diploid zygote can act as resting stage that can last for years

•Locally common

Factors affecting algal growth

Remember: they are plants!

•Amount of sunlight received: turbidity & water clarity

•require nutrients (fertilizers) P and N

•water temperature; some are seasonal; heat and chemistry

•sinking or flushing

•grazing

•competition from other plants for limited materials

Problems from Algae

Aesthetics: who wants a scum-covered pond?

Reduces water clarity

Taste and odor: from fish to pigsty

Mats clog propellers and cost you lures!

Swimming: aesthetics and safety

Can form rotting masses:

odor and oxygen problems

Monitoring AlgaeNote water color:

Brown: diatoms

Bright green: Euglena-types, Volvox

Bluish green: blue-greens e.g., Microcystis or Oscillatoria

Note water clarity:

Microscopic ‘cut grass’ --->Aphanizomenon

Monitoring Algae (cont.)

Algae

Types:• Single-celled/phytoplankton

– diatoms, greens, blue-greens

• Colonial/phytoplankton– Euglena, Volvox

• Filamentous– Spirogyra, Oscillatoria

Remember . . . some algae is desirable!