Prokaryotes – Bacteria and Archea No membrane bound organelles Large surface area to volume ratio Asexual reproduction by binary fusion Single celled or colonial

Anaerobic metabolism – what’s going on in the hypolimnion of a stratified, anoxic lake? Chemoheterotrophs and Photohetertrophs – using active transport, more efficient at low nutrient concentrations Photoautotrophs – i.e. cyanobacteria (blue-green algae) Ecology Diapause – it may be that the dormancy is very important in bacteria

Cyanobacteria Prokaryotes (no nucleus or organelles) Blue-green Pigment = Chl a

Filamentous blue-green algae (Cyanophyta)

Protista – Protozoa and algae Eukaryotic (membrane bound organelles, nucleus, mitochondria, chloroplasts in photosynthetic protists) Single celled (although may be colonial)

Protozoa Also Giardia and Cryptosporidium Heterotrophic Protists Paramecium, amoebas, Euglena, Hydra

Photoautotrophic Protista – Algae Single celled or colonial Floating Phytoplankton Benthic algae Attached to surfaces (rocks, sediment)

Chlorophyta - Green Green-yellow green Pigment = Chl a and b Some have flagella

Chrysophyta Yellow green to golden brown Pigment = Chl a and c Some have 2 flagella

Chrysophyta (Golden-brown algae) Diatoms Brown to light green Pigment = Chl a and c Some have flagella Silica walls – composed of 2 frustules

Euglenophyta Pigment = Chl a and b All have flagella Eyespots Most are heterotrophic and autotrophic

Dinoflagellata Gray Pigment = Chl a and c Two flagella Some are highly toxic

Pfisteria

Reproduction - diverse Vegetative cell resistant cell (resting stage) Encystment Germination Asexual reproduction usually binary fission Sexual reproduction – possibly motile gametes or conjugation tubes

Fungi Yeasts Hyphae grouped into mycellium Chemoautotrophs (saprobic) Sexual and asexual reproduction

Ecological importance Breakdown of detritous Parasites on other aquatic organisms

Periphyton (or aufwuchs) – pond scum

A community of algae, fungi, bacteria