Starry Stonewort
Nitellopsis obtusa
Starry stonewort is a large, perennial macroalga belonging to the Characeae family. It is characterized by robust, ecorticate (unarmored) stems and very long internodes that often appear grayish-green. A defining feature is the presence of white, star-shaped bulbils on the rhizoids, which facilitate vegetative reproduction. This species typically inhabits the deeper zones of clear, calcium-rich lakes, where it can form extensive underwater meadows.
Details
Oxygen production
High; contributes significantly to oxygen enrichment of deeper water layers.
Habitat function
Important spawning ground for fish and a refuge for macrozoobenthos.
Nutrient uptake
Very efficient uptake of phosphates from the water and storage within tissues.
Food source for
Important food source for waterfowl such as the Red-crested Pochard (Netta rufina).
Human use
Formerly used occasionally as fertilizer; today primarily relevant for ecological water quality assessment.
Ecology
Ecological role
Forms dense stands (charophyte meadows) that stabilize sediment, sequester nutrients, and provide habitat for micro-organisms.
Natural predators
Waterfowl, herbivorous fish, and some invertebrates.
Competitor species
Other charophyte species and vascular aquatic plants (e.g., Sago Pondweed) under increasing eutrophication.
Ecosystem service
Improvement of water clarity through nutrient sequestration and suppression of phytoplankton.
Threats
Eutrophication (nutrient input), mechanical disturbance by boats and anchors, sedimentation, and hydraulic engineering.
Scientific profile
Profile
Reproduction
Predominantly vegetative via the characteristic star-shaped bulbils on the rhizoids. Generative reproduction is dioecious via oospores, but is rare in many European populations due to the absence of one sex.
Protection & threats
Main threats
Eutrophication (nutrient loading), increasing water turbidity, mechanical destruction by boating and anchoring, and herbicide runoff.