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a. a. a. m. b. m. f. b. d. mm. m. How to know the freshwater benthic algae. Maria Kahlert. freshwater benthic algae. Check first: C o l o r: Bluegreen : bluegreen algae Green : green algae Yellowish-Brown : brown algae Diatoms Chrysophytes Brown algae Red : red algae
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a a a m b m f b d mm m How to know the freshwater benthic algae Maria Kahlert
freshwater benthic algae Check first: • Color: • Bluegreen: bluegreen algae • Green: green algae • Yellowish-Brown: brown algae • Diatoms • Chrysophytes • Brown algae • Red: red algae Be aware of exceptions!!!
freshwater benthic algae Exceptions in color: • Bluegreen red alga: Chroodactylon • Green ‘brown’ alga: Vaucheria • Green ‘brown’ alga: diatoms in bad shape • Red green alga: Haematococcus
freshwater benthic algae Check also: • Absence/presence of cell organelles: • Absence: bluegreen algae = cyanoBACTERIA • Presence: all other algae • Presence of siliceous cell wall (distinctly shaped ‘glass house’): diatoms
freshwater benthic algae Check next: • Bluegreen algae • Organization of thallus: • Coccoid • Filamentous • No branches • False branches • True branches • Presence/absence and place of heterocysts (N2 fixation) (only for the filamentous forms) • Length of cell
freshwater benthic algae Check next: • Green algae • Organization of thallus: • Coccoid • Single cell/colonies/coenobia • Filamentous • Not branched/branched • Chloroplast morphology: • Cup-shaped • Parietal (like a tapestry, middle of cell is vacuole) • Axial (in the middle of cell)
freshwater benthic algae Check next: • ‘Brown’ algae – Diatoms • Identification of living diatoms only grossly, must be prepared (see separate information) raphe (slit in cell wall) no raphe centric pennate
freshwater benthic algae Check next: • ‘Brown’ algae • Chrysophytes and ‘real’ brown algaeVery few in freshwater, very different: • Hydrurus (golden) • Ophiocytium (green) • Tribonema (golden) • Vaucheria (green) • Pleurocladia (brown) • Hildenbrandia (brown)
freshwater benthic algae Check next: • Red algae • Very few in freshwater • Heribaudiella • Chroodactylon • Audouinella • Batrachospermum
freshwater benthic algae Some algal terms • Cell organelles – cell content with a membrane inside the cell • Siliceous cell wall – cell wall outside cell in diatoms, made from glass • Heterocysts – special cells in bluegreens fixating N2 • Thallus – body of alga • Coccoid – ball formed thallus • Filamentous – hair formed thallus • Coenobia- cell cannot divide mitotically, after meiosis, the mother cells dies and relieves a certain number of identically shaped daughter cells, a finished colony