How to know the freshwater benthic algae
description
Transcript of How to know the freshwater benthic algae
aa
a
m
mm
mm
b
bf d
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 algaeCheck 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
pennatecentric
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 algaeSome 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