Seagrass teams saving natives
A team of ‘underwater gardeners’ is working to stem the decline of an endangered seagrass.
The seagrass Posidonia is fast disappearing from Australian waters, knocked out by the traditional block-and-chain boat mooring which scars the sea floor as the winds and currents change, creating a halo of destruction.
“Posidonia australis is a slow-growing seagrass that likes to live in the same beautiful sheltered bays where us humans like to live, build our houses and moor our boats, so the building of marinas, coastal development, pollution and dredging has caused its decline,” UNSW marine ecologist Associate Professor Adriana Vergés said.
“Posidonia is a foundation species which provides habitat and food for lots of different animals; it’s also known as a nursery habitat which supports many juvenile species essential for fisheries to thrive.
“Without seagrasses, a lot of emblematic species like seahorses, as well as many species we like to eat, such as blue swimmer crabs, cuttlefish and snapper, would decline from our estuaries.”
Posidonia is also important for carbon capture and storage: the seagrass, when healthy, can store more than 30 times more carbon than rainforests.
Unfortunately, the plant is disappearing from six estuaries in NSW and is on a path to extinction in the next 15 years.
Operation Posidonia aims to restore seagrass to estuaries where it is endangered, in conjunction with replacing traditional swing moorings with environmentally friendly ones, also known as EFMs.
The project is a collaboration between UNSW Sydney, the Sydney Institute of Marine Sciences, the NSW Department of Primary Industries – Fisheries and The University of Western Australia.
Only 18 months after its launch, the project is yielding positive results in Port Stephens where a trial is underway with help from community volunteers.
Operation Posidonia’s “Storm Squad” has already collected more than 1500 Posidonia shoots at Port Stephens.
Storms naturally detach Posidonia from the sea floor and the shoots wash ashore.
The volunteers pick up the shoots which are still living and store them at submerged stations for the project’s “underwater gardeners” – the scientists – to take and replant.
Dr Vergés says it is important that Operation Posidonia had the twin aims of restoration of the endangered seagrass and the removal of the problem: traditional swing moorings.
“It’s difficult because moorings are owned by individuals and there is no strict regulation asking owners to have certain types of environmentally friendly designs,” she said.
“So, this project is partly about encouraging people to use a different mooring design that does not damage the seafloor.
“What we hope to do with this project is to show how this can lead to solutions and the recovery of lost habitats.
“We hope that will inspire mooring owners to become part of the solution and switch to an EFM.”
An EFM has no heavy chain and is usually made from a buoyant, synthetic material which hovers above the sea floor without drag.
Operation Posidonia’s “Look After Your Bottom” campaign aims to raise awareness about the issue.