AFA algae
Aphanizomenon flos-aquae
Aphanizomenon flos-aquae is a filamentous cyanobacterium that forms characteristic macroscopic colonies resembling tiny wood shavings or grass clippings floating in the water. It is globally distributed in eutrophic freshwater lakes and is known for creating dense water blooms. The species has the ability to fix atmospheric nitrogen within specialized cells called heterocysts, providing a competitive advantage in nitrogen-limited but phosphorus-rich environments.
Details
Oxygen production
Produces oxygen during photosynthesis, but leads to oxygen depletion during decomposition.
Habitat function
Provides habitat for associated bacteria and microorganisms within the colonies.
Nutrient uptake
High uptake of phosphates and fixation of dissolved nitrogen gas.
Food source for
Filter feeders in zooplankton, provided the colonies are small enough.
Human use
Used as a dietary supplement (AFA algae); health-wise controversial due to potential contamination with cyanotoxins.
Ecology
Ecological role
Primary producer and nitrogen fixer; mass blooms can stress ecosystems through toxin production and oxygen depletion.
Natural predators
Zooplankton (e.g., Daphnia), although the bundle shape provides some protection against grazing.
Competitor species
Other cyanobacteria such as Microcystis or filamentous green algae.
Ecosystem service
Input of biologically available nitrogen into the aquatic system.
Threats
None; benefits from anthropogenic eutrophication and climate warming.
Scientific profile
Profile
Distinguishing features
Possesses heterocytes for nitrogen fixation and akinetes (resting spores). Characteristic bundle formation of trichomes and gas vacuoles for buoyancy.
Reproduction
Asexual via fragmentation of trichomes (hormogonia formation) and germination of akinetes after resting periods.
Protection & threats
Status not on standard scale
Main threats
No threats; the species benefits from nutrient inputs and climate change (increasing water temperatures).
Conservation measures
No conservation measures; management focuses on reducing nutrient inputs to prevent mass developments.