Download How to know the freshwater benthic algae

How to know the freshwater
benthic algae
Maria Kahlert
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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)
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:
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Hydrurus (golden)
Ophiocytium (green)
Tribonema (golden)
Vaucheria (green)
Pleurocladia (brown)
Hildenbrandia (brown)
freshwater benthic algae
Check next:
• Red algae
– Very few in freshwater
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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