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
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Rice paddy nitrogen fixation
Nostoc balls
Odors and flavors-musty, moldy
Allergies
• Coloration of flamingoes and shrimp
Merismopedia
Nostoc balls
Oscillatoria
Spirulina
Microcystis
Rivularia
Lyngbia
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
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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
Dinoflagellates
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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
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General Structure
General Characteristics
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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
Ulothrix-’apple core’
Mougeotia-plates; can orient
Zygnema-stellate
Flagellated forms
Chlamydomonas
Eudorina
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 Algae
Note water color:
Brown: diatoms
Bluish green: blue-greens e.g.,
Microcystis or Oscillatoria
Bright green: Euglena-types, Volvox
Monitoring Algae (cont.)
Note water clarity:
Microscopic ‘cut grass’ --->Aphanizomenon
Algae
Remember . . . some algae is desirable!
Types:
• Single-celled/phytoplankton
– diatoms, greens, blue-greens
• Colonial/phytoplankton
– Euglena, Volvox
• Filamentous
– Spirogyra, Oscillatoria