How to know the freshwater benthic algae Maria

How to know the freshwater benthic algae Maria Kahlert a a m f b m a b d mm m

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 = cyano. BACTERIA – 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 (N 2 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) centric no raphe pennate raphe (slit in cell wall)

freshwater benthic algae Check next: • ‘Brown’ algae – Chrysophytes and ‘real’ brown algae Very 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 N 2 • 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