Opposite Stonewort
Chara contraria
The Opposite Stonewort is a perennial macroalga that forms dense mats at the bottom of calcium-rich water bodies. It is characterized by its grey-green coloration and often pronounced lime encrustation, which gives it a rough texture. The species prefers nutrient-poor lakes and serves as an important indicator of high water quality. Through its growth habit, it contributes significantly to sediment stabilization and water clarity.
Details
Oxygen production
High, contributes significantly to oxygen saturation in the benthic zone.
Habitat function
Forms 'charophyte meadows' that serve as nurseries for fish and refuges for zooplankton.
Nutrient uptake
Very efficient phosphate uptake, which limits phytoplankton growth in the open water.
Food source for
Important food source for waterfowl such as the Red-crested Pochard (Netta rufina).
Human use
Historically used as calcareous fertilizer; today primarily of ecological significance.
Ecology
Ecological role
Primary producer that generates oxygen and stabilizes the lake bed; provides habitat for epiphytes and invertebrates.
Natural predators
Waterfowl, herbivorous fish, and various aquatic insect larvae.
Competitor species
Other stoneworts and, in case of eutrophication, filamentous green algae and higher aquatic plants (e.g., Potamogeton species).
Ecosystem service
Contributes to water purification through nutrient sequestration and prevents water turbidity by fixing sediments.
Threats
Eutrophication due to fertilizer runoff, mechanical destruction by boating or swimming, and herbicides.
Scientific profile
Profile
Reproduction
Predominantly sexual (monoecious) via oogonia and antheridia; asexual via bulbils on the rhizoids.
Protection & threats
Main threats
Eutrophication (nutrient input), mechanical disturbances (boating, bank stabilization), water turbidity, and herbicide use.