What is seagrass and why is it important?
Seagrass is a flowering plant that grows underwater in shallow coastal seas. Seagrass meadows feed dugongs and turtles, shelter fish and store carbon. Australia has some of the largest seagrass areas in the world.
Unlike seaweed, which is a type of algae, seagrasses are true plants with roots, leaves and flowers. They evolved from land plants and returned to the sea millions of years ago.
Australia has more seagrass species than anywhere else, and huge meadows grow in Shark Bay, the Torres Strait, the Great Barrier Reef and South Australia's gulfs.
Under threat
Floods, cyclones, poor water quality and marine heatwaves can wipe out seagrass. In 2011, a marine heatwave killed a large share of Shark Bay's seagrass.
Seagrass helps trap sediment and keep water clear, which benefits nearby coral reefs. It also takes up nutrients that would otherwise fuel algae blooms.
Researchers and community volunteers are restoring seagrass by collecting seeds and planting shoots, with projects in Shark Bay, Western Port and Port Phillip Bay, and Adelaide's coast. Boaters can help by avoiding anchoring on meadows and using public moorings where available.
Did You Know?
A single seagrass plant in Shark Bay, discovered in 2022, covers about 180 square kilometres, making it the largest known plant on Earth.