Aquatic hyphomycetes
Aquatic hyphomycetes (Ingoldian fungi)
Aquatic hyphomycetes, or Ingoldian fungi, are a specialized ecological group of fungi that play a key role in the decomposition of leaf litter in streams and rivers. They colonize submerged leaves and wood, producing enzymes that break down complex polymers such as cellulose and lignin. Their spores (conidia) often possess characteristic shapes, such as tetraradiate or sigmoid structures, which facilitate attachment to substrates in flowing water. These fungi are essential to the aquatic food web as they improve the nutritional quality of detritus for macroinvertebrates.
Details
Identification
Microscopic conidia typically featuring tetraradiate (four-armed) or sigmoid shapes; mycelium grows within plant tissue.
Diet
Saprotrophic; decomposition of organic matter, especially cellulose and lignin from terrestrial leaf litter.
Overwintering
Activity persists even at low temperatures just above freezing.
Ecology
Ecological role
Primary decomposers; they convert indigestible leaf litter into protein-rich biomass, making it available for shredding macroinvertebrates.
Natural predators
Aquatic invertebrates (e.g., amphipods, stonefly larvae) that consume the colonized leaf litter.
Competitor species
Bacteria and other aquatic fungi (e.g., oomycetes).
Ecosystem service
Nutrient cycling in water bodies, self-purification of streams by breaking down organic loads.
Threats
Water pollution, pesticide runoff, global warming, and the loss of riparian vegetation.
Scientific profile
Profile
Distinguishing features
Characteristic conidia shapes: tetraradiate (four-armed, e.g., Articulospora tetracladia) or sigmoid (S-shaped, e.g., Anguillospora longissima) to facilitate attachment to substrates in turbulent water.
Habitat
Clean, well-oxygenated, turbulent streams and rivers (lotic habitats).
Reproduction
Predominantly asexual through the production of conidia underwater; sexual stages (teleomorphs) are rare and often terrestrial.
Protection & threats
Status not on standard scale
Main threats
Water pollution, loss of riparian buffer zones, channelization of streams, and climate change (rising temperatures).
Conservation measures
Preservation and restoration of natural riparian vegetation, reduction of diffuse nutrient inputs, and restoration of lotic ecosystems.