Australia’s biggest seagrass restoration project is happening in SA

Did you know?

  • Seagrass are marine flowering plants that evolved from land plants and adapted to marine life around 100 million years ago.
  • Around 40 times more animals inhabit seagrass than in adjacent bare sand
  • Eleven species of seagrasses are known to grow in South Australia covering an area of approximately 9,620 km2.
  • One hectare of seagrass is estimated to be worth more than $26,000 per year, making seagrass one of the most valuable ecosystems on the planet.
  • Per hectare, seagrasses can store up to twice as much carbon than terrestrial forests and play an important role in reducing global greenhouse gas emissions. There are potential long term blue carbon opportunities in seagrass restoration.

Explore

Take action

  • For boat owners: operate your boat in marked channels to prevent running aground and damaging your boat and seagrass beds. When in doubt about the depth, slow down and idle. If you are leaving a muddy trail behind your boat, you are probably cutting seagrass.

The South Australian Government is undertaking the largest seagrass restoration project in Australia through a $1 million New life for our coastal environment project to re-establish around 10 hectares of seagrass off the Adelaide metropolitan coast.

Seagrass meadows are very important to the nearshore coastal environment. They help stabilise the seabed by holding sand with their roots and reduce the waves and currents near the seabed with their leaves.  They also provide both food and habitat for marine life.

Over the last half century, around one third of seagrass along the Adelaide metropolitan coast has been lost.

While natural events such as storms can cause large-scale seagrass loss, the main cause of the initial seagrass loss was poor water quality resulting from drain discharge, stormwater run-off and effluent disposal.

Once destroyed, seagrass ecosystems do not easily recover as waves and currents erode the exposed seabed and inhibit regrowth.

Seagrass changes over time at Grange
Seagrass changes over time at Grange (view as PDF)

As seagrass is not easily able to re-establish in bare sand, the seagrass restoration project uses a technique developed in South Australia of placing hessian bags on the sea floor to hold seagrass seedlings in place. By the time the hessian decomposes, many seedlings are sufficiently established.

Trials are being undertaken in 2019 between Largs Bay and Hove, to identify suitable sites for large scale restoration work in 2020. It will take several years for the seagrass to fully establish. The restoration will be monitored to measure and report on progress over time.

Seagrass restoration project timeline
Seagrass restoration project timeline (view as PDF)

The project is being delivered by the South Australian Research Development Institute in partnership with our department and will inform future seagrass restoration work.