Stream blue-green alga
Microcoleus autumnalis
The stream blue-green alga forms extensive, dark green to black, leathery mats on the substrate of streams and rivers. It consists of filamentous trichomes that are often enclosed in a mucilaginous sheath and are photosynthetically active. Under certain environmental conditions, these mats can produce toxins such as anatoxins, which are dangerous to vertebrates. It plays an essential role in benthic nutrient cycling and as a primary producer in running waters.
Details
Oxygen production
Produces oxygen through oxygenic photosynthesis.
Habitat function
Provides microhabitat structures for bacteria and micro-organisms within the matrix.
Nutrient uptake
Efficient uptake of dissolved phosphate and nitrogen compounds.
Food source for
Benthic grazers in the running water ecosystem.
Human use
No direct use; relevant for health management during mass occurrences (toxin warnings).
Ecology
Ecological role
Primary producer; stabilizes the river substrate; serves as a carbon source in the food web.
Natural predators
Grazing invertebrates such as snails (e.g., Ancylus fluviatilis) and various insect larvae.
Competitor species
Diatoms, green algae, and other cyanobacteria of the genus Nostoc.
Ecosystem service
Oxygen production and contribution to benthic primary production.
Threats
Strong eutrophication, herbicide pollution, and extreme hydrological changes.
Scientific profile
Protection & threats
Main threats
Severe eutrophication (displacement by filamentous green algae like Cladophora), extreme low-water events leading to desiccation of riparian zones, and chemical pollution (herbicides).