PHYTOPLANKTONDiversity of Algae

in the Plankton

• All are free-floating• All capture light energy by oxygenic photosynthesis • All use a suite of photosynthetic pigments that

includes Chlorophyll a.

Major Groups of Freshwater Phytoplankters

1. Blue-Green Algae- Cyanobacteria2. Green Algae- Chlorophyta3. Yellow-Green Algae- Xanthophyta4. Golden-Brown Algae- Chrysophyta5. Diatoms- Bacillariophyta6. Haptomonads- Haptophyta7. Cryptomonads- Cryptophyta8. Dinoflagellates- Pyrrhophyta9. Euglenoids- Euglenophyta

1. Blue-Green Algae=CYANOBACTERIA

• Chlorophyll a• Β Carotene• Xanthophylls• Billiproteins• No flagella• Photosynthate stored as cyanophycin

Filamentous Cyanobacteria

• Heterocystic Filaments– Anabaena

– Aphanizomenon

Filamentous Cyanobacteria

• No Cellular Differentiation– Oscillatoria

– Planktothrix

Colonial Cyanobacteria

• Microcystis

• Gloeocapsa

2. Green Algae=CHLOROPHYTA

• Chlorophylls a and b• Β Carotene• Xanthophylls• Paired, anteriorly-directed flagella• Photosynthate stored as starch

Volvocines

• Volvox

• Pandorina

• Chlamydomonas

Chlorococcalian Greens

• Scenedesmus

• Pediastrum

• Ankistrodesmus

• Oocystis

Desmids

Micrasterias

Cosmarium

Closterium

3. Yellow-Green Algae=XANTHOPHYTA

• Chlorophylls a and c• Β Carotene• Xanthophylls (dominant pigments)• Anteriorly-directed tinsel and posteriorly-

directed whiplash flagella• Photosynthate stored as oil• Eyespot within the chloroplast

Xanthophytes

• Ophiocytium

• Tribonema

4. Golden-Brown Algae=CHRYSOPHYTA

• Chlorophylls a and c• Β Carotene• Xanthophylls (dominant pigments)• Anteriorly-directed tinsel and posteriorly-

directed whiplash flagella• Photosynthate stored as chrysolaminarin and fat• Eyespot (if present) within the chloroplast• Walls often made of silica scales

Chrysophytes

• Dinobryon

• Synura

• Mallomonas

5. Diatoms=BACILLARIOPHYTA

• Chlorophylls a and c• Β Carotene• Xanthophylls (dominant pigments)• Flagella only in sperm of centrics• Photosynthate stored as oil or chrysolaminarin• Walls (called frustules) made of silica

Centric Diatoms

• Cyclotella

• Melosira

Radial symmetryFace usually with concentric regions

Araphid Pennates

• These are pennate but have no raphe. Common taxa include Diatoma and Fragilaria

Monoraphid Pennates

• Only one valve has a raphe (RV). The other is rapheless (RLV). Ex: Cocconeis

RV RLV

Other Monoraphid Taxa

• Planothidium• Achnanthidium

RV RLV

Symmetrical Biraphids

• Taxa are symmetrical in all three planes. Both valves have a raphe.

• Common genera include:– Navicula– Eolimna– Brachysira– Frustulia

Navicula

Eolimna

Brachysira

Frustulia

Assymetrical Biraphids

• Biraphids but are symmetrical in only one plane, often with a terminal pore field

• Common genera include– Amphora– Cymbella– Encyonema– Gomphoneis– Gomphonema

Amphora

CymbellaEncyonema

Gomphoneis

Gomphonema

Nitzichiods

• Raphe on marginal struts called fibulae. Striae across the valve without a break

Eunotids and Others

• Eunotids have raphes on the terminal ends of the valve

Pennate Plankters• Fragilaria

• Synedra

• Navicula

• Asterionella

6. Haptomonads=HAPTOPHYTA

• Chlorophylls a and c• Β Carotene• Xanthophylls (dominant pigments)• Paired anteriorly-directed flagella and a

haptonema• Photosynthate stored as starch

Chrysochromulina

7. Cryptomonads=CRYPTOPHYTA

• Chlorophylls a and c• Β Carotene• Xanthophylls (dominant pigments)• Paired anteriorly-directed flagella• Billiproteins• Photosynthate stored as starch

Cryptomonas

8. Dinoflagellates=PYRRHOPHYTA

• Chlorophylls a and c• Β Carotene• Xanthophylls (dominant pigments)• Posteriorly-directed whiplash and ribbon

flagellum around middle of cell.• Photosynthate stored as starch and oil

Dinoflagellates

• Gymnodinium

• Cystodinium

• Peridinium

• Ceratium

9. Euglenoids=EUGLENOPHYTA

• Chlorophylls a and c• Β Carotene• Xanthophylls• Anteriorly-directed tinsel flagellum with

paraflagellar rod (some with emergent recurrent flagellum)

• Photosynthate stored as leucosin

Euglenoids

• Euglena

• Phacus

• Trachelomonas