Star-shaped conjugate alga
Zygnema
The star-shaped conjugate alga is a genus of filamentous green algae within the class Zygnematophyceae. It is recognized by its characteristic pair of star-shaped chloroplasts located in each cell, each containing a central pyrenoid. These algae often form dense, cotton-like mats in clean to moderately polluted standing and flowing waters or in bogs. Reproduction occurs sexually through conjugation, involving the formation of conjugation tubes between cells, which gives the group its name 'conjugate algae'.
Details
Oxygen production
High; contributes significantly to oxygen saturation in shallow water zones.
Habitat function
Serves as a spawning substrate for small fish and as a hiding place for zooplankton.
Nutrient uptake
Efficient uptake of nitrates and phosphates from the water column.
Food source for
Food source for aquatic invertebrates such as daphnia and aquatic gastropods.
Human use
No direct economic use; significant in limnological research and education.
Ecology
Ecological role
Important primary producer in aquatic ecosystems; provides oxygen and serves as a habitat for microfauna.
Natural predators
Various aquatic insect larvae, snails, and herbivorous fish.
Competitor species
Other filamentous algae like Spirogyra or Mougeotia, as well as higher aquatic plants during nutrient competition.
Ecosystem service
Carbon dioxide fixation, oxygen production, and contribution to the self-purification of water bodies.
Threats
Water eutrophication due to fertilizer input, herbicides, and the destruction of small water bodies.
Scientific profile
Protection & threats
Main threats
Eutrophication (leading to displacement by filamentous green algae like Cladophora), herbicide input from agriculture, and loss of bog habitats.