Seegräsern

Seegräsern are seagrasses, a group of marine flowering plants that grow submerged in shallow coastal and estuarine waters. They are not true grasses, but have grass-like leaves and reproduce by flowers and seeds as well as by spreading through underground rhizomes.

Seagrasses comprise several genera, including Zostera (eelgrass), Posidonia, Cymodocea, Halodule, Syringodium, Thalassia, Enhalus, and Amphibolis. They occur in temperate and tropical seas around the world, from sheltered bays to coastal lagoons, at depths where light can reach the seabed. Distribution varies by species, with some adapted to clear, sandy bottoms and others to muddy substrates or higher salinity.

Ecologically, Seegräsern form extensive underwater meadows that support high biodiversity. They stabilize sediments, reduce coastal erosion, and improve water quality by filtering nutrients. The dense root and rhizome networks trap and bind sediments, while the leaves and canopies provide habitat and feeding grounds for fish, crustaceans, and invertebrates. Seagrass meadows are important sinks for carbon, storing carbon in their rhizomes and the underlying sediments, a service often referred to as blue carbon.

Threats to Seegräsern include physical damage from boating, dredging, and trawling; nutrient pollution and eutrophication leading to algal overgrowth; sedimentation and turbidity reducing light penetration; and climate-related changes such as warming and sea-level rise. Restorations, legal protections, and improvements in water quality have shown success in some regions, though seagrass recovery can be slow and site-specific.

Seegräsern are indicators of coastal ecosystem health and are valued for their ecological services, biodiversity support, and contributions to shoreline resilience.