Common needle diatom
Ulnaria ulna
The common needle diatom is a single-celled alga with a characteristic elongated, rod-shaped silicate shell. It belongs to the diatoms (Bacillariophyta) and often forms filamentous colonies or occurs individually. This species is distributed in almost all standing and flowing freshwater bodies worldwide and plays a crucial role as a primary producer. Its frustule consists of two valves that fit together like a box and exhibit fine pore structures.
Details
Oxygen production
Actively produces oxygen during the light phase through photosynthesis.
Habitat function
Colonizes stones, aquatic plants, and artificial substrates as periphyton.
Nutrient uptake
Efficiently absorbs nitrates, phosphates, and especially silicates for frustule construction.
Food source for
Serves as a primary food source for many benthic invertebrates and microscopic filter feeders.
Human use
Scientific use in water monitoring and paleolimnology for reconstructing environmental changes.
Ecology
Ecological role
Important primary producer forming the base of the aquatic food web and contributing to oxygen saturation.
Natural predators
Zooplankton (e.g., Daphnia), herbivorous snails, insect larvae (e.g., mayflies), and small fish.
Competitor species
Other diatom species as well as green algae and cyanobacteria competing for light and silicates.
Ecosystem service
Oxygen production, carbon sequestration, and nutrient filtration from the water body.
Threats
Heavy eutrophication, chemical pollution (herbicides), and extreme water turbidity.
Scientific profile
Protection & threats
Main threats
Extreme toxic pollution (e.g., herbicides), massive acidification, or extreme morphological degradation of water bodies (loss of substrate diversity).