Seagrass restoration
Restoring Posidonia australis seagrass meadows helps protect marine biodiversity, support fisheries, and keep our coasts healthy.
Posidonia australis is a long-lived seagrass endemic to southern Australia, forming extensive underwater meadows across the entire southern half of Australia, from Shark Bay (Western Australia) to Wallis Lake (New South Wales).
In southeastern Australia, Posidonia australis mostly grows in sheltered bays, estuaries and coastal lakes, where its meadows play a crucial role in coastal health – stabilising sediment, capturing carbon, and providing habitat for a wide range of marine life.
Once widespread, Posidonia australis meadows have declined sharply, particularly in urban estuaries such as Sydney Harbour, Pittwater, Gamay Botany Bay, and Lake Macquarie. Posidonia australis is now listed as endangered in several NSW estuaries, with losses driven by coastal development, poor water quality, and climate-induced marine heatwaves, as well as boating activities.
Restoration is critical because once damaged, Posidonia australis meadows recover extremely slowly, often taking decades to regenerate naturally. Restoration efforts across New South Wales now combine several complementary approaches:
Operation Posidonia – a citizen science program that collects naturally detached “beach-cast” shoots after storms and replants them into degraded areas, avoiding damage to existing meadows while engaging volunteers and local communities in restoration.
Project Restore – combines the Operation Posidonia approach to scale up habitat recovery in Sydney Harbour, combining seagrass and kelp restoration with biodiversity enhacement of artificial substrates to re-establish connectivity and regenerate whole seascapes.
Seeds of the Sea – a citizen-science project tracking Posidonia australis flowering and fruiting to understand reproductive patterns and explore future possibilities for seed-based restoration.
Together these programs bring together researchers, Indigenous Rangers, volunteers, and coastal communities to help re-establish one of Australia’s most valuable marine habitats.
Explore our projects
Operation Posidonia
Operation Posidonia is a restoration project where citizen scientists help to collect naturally detached “beach-cast” Posidonia australis shoots after storms, which then get replanted into damaged meadows. This community-led approach avoids harm to existing seagrass, supports recovery of an endangered habitat, and raises awareness about the importance of seagrass in protecting our coasts.
Project Restore
Project Restore is a collaborative initiative led via the Sydney Institute of Marine Science restoring Sydney Harbour’s marine habitats at scale, combining leading programs like Operation Posidonia and Living Seawalls to create a holistic, community-driven model for seascape restoration.
Seeds of the Sea
Seeds of the Sea is a citizen science initiative tracking the flowering and fruiting of endangered NSW seagrass Posidonia australis to guide seed-based restoration and help bring back lost meadows.
Get involved
You can help by reporting sightings of flowers, fruits, or seeds of Posidonia australis - whether you’re diving, snorkelling, or walking along the beach.
Visit our website to learn more, explore recent sightings, or get involved in community monitoring events.
