Seagrasses

Seagrasses are a group of flowering plants that live submerged in shallow coastal waters, unlike seaweeds which are algae. They form extensive underwater meadows in bays, lagoons, and estuaries around the world.

Seagrasses are true angiosperms adapted to marine life. They include several genera such as Zostera (eelgrass), Posidonia (posidonia), Thalassia (turtlegrass), Syringodium (manatee grass), Halodule, Halophila, and Enhalus. They grow with underground rhizomes and roots that anchor the meadow and allow clonal spread, while aboveground leaves capture light for photosynthesis.

Ecosystem services: They stabilize sediments, dampen waves, reduce coastal erosion, and increase water clarity by trapping particles. They are also highly productive, supporting diverse communities of fish, invertebrates, and algae. Seagrass meadows sequester significant amounts of carbon in sediments, contributing to blue carbon storage.

Requirements and threats: Seagrasses require clear, well-lit, shallow waters with soft, stable substrates. They are highly sensitive to turbidity, nutrient pollution, sedimentation, physical disturbance, and warming temperatures. Global seagrass meadows have declined in extent in many regions due to coastal development, anchors, dredging, and eutrophication.

Conservation and restoration: Efforts focus on protecting remaining meadows, controlling pollution, and restoring lost habitats through transplantation, seeding, and habitat rehabilitation. Mapping and monitoring are used to track declines and recovery. Because of their ecological importance, seagrasses are often prioritized in marine habitat conservation plans.