Mat-forming cyanobacteria
Cyanobacteria (benthisch)
Mat-forming cyanobacteria are prokaryotic microorganisms that develop dense biofilms on stones, sediments, or aquatic plants. These mats consist of filamentous structures (e.g., from the genera Phormidium or Oscillatoria) held together by mucilaginous sheaths and often exhibit dark, brownish, or blackish-green colors. They play a significant role in nutrient cycling but can release dangerous toxins such as anatoxins during mass developments, which are particularly life-threatening for dogs.
Details
Oxygen production
High during the light phase through photosynthesis.
Habitat function
Provides habitat for microorganisms but can damage benthic fauna through oxygen depletion during decay.
Nutrient uptake
Efficient uptake of dissolved phosphate and nitrate; some species fix atmospheric nitrogen.
Food source for
Only limited for specialized grazers due to toxicity and low digestibility.
Human use
No positive use; primarily known as a health risk in bathing waters and for drinking water resources.
Ecology
Ecological role
Primary producers and nitrogen fixers; they stabilize sediments but can disrupt the food web through toxin production.
Natural predators
Some benthic invertebrates (e.g., mollusks, chironomid larvae), though they can be inhibited by toxins.
Competitor species
Diatoms, green algae, and aquatic plants (macrophytes).
Ecosystem service
Oxygen production and nitrogen input into nutrient-poor systems.
Threats
Herbicide inputs and strong mechanical disturbances caused by extreme flood events.
Scientific profile
Protection & threats
Main threats
Extreme flood events (mechanical scouring), herbicide input from agriculture, severe morphological changes to water body structure, and extreme shading.