Along the shoreline of the low-lying town of Narooma on the New South Wales south coast, an award-winning initiative is creating a living, breathing barrier against erosion and rising sea levels.
Key points:
- A "living shoreline" in Narooma combines saltmarshes and oyster reefs to prevent coastal erosion
- The site is a first for adjacent intertidal and subtidal reefs in Australia
- The project protects the shoreline while boosting ecosystem biodiversity
The Wagonga Inlet Living shoreline project uses native plants, saltmarsh habitats and oyster reefs to secure and stabilise 400 metres of the bank along the foreshore, and diffuse potentially eroding wave energy.
Five years after the concept was first discussed in the area, conservation work at the site is complete.
Nature Conservancy Australia's south-east oceans coordinator Kirk Dahle said declining shorelines in Wagonga Inlet required "something bigger than just fixing an eroding seawall".
"Grey infrastructure such as seawalls work, but we often lose a lot of the environmental benefits that shorelines can have," he said.
"A living shoreline creates a self-healing and self-adapting shoreline that can then move with nature."
The living shoreline approach to managing erosion is gaining global momentum, but Mr Dahle said Wagonga was one of the first locations to incorporate many different habitat types, like shellfish reefs and saltmarshes, in one project.
Australia's 'forgotten ecosystem'
The project saw the creation of the first native angasi oyster reef in New South Wales and the first adjacent intertidal and subtidal reefs in Australia.
The intertidal reef is home to Sydney rock oysters near the surface, which are exposed to sunlight during low tides.
Growing six metres below the surface on the adjacent subtidal reef are angasi oysters — a species that occur very rarely naturally.
Fisheries manager for oyster reef restoration Jillian Keating said creating the two neighbouring reefs was "quite a landmark achievement".
Ms Keating says there is only one remaining healthy and substantial angasi reef in Australia, at St Helens in Tasmania.
"In the late 1800s, we all but lost all of our oyster reefs across Australia — 99 per cent are considered functionally extinct," she said.
"They're the forgotten ecosystem in Australia."
Creating the reef required oyster farmers in the inlet to donate old shells, which were crushed and deposited along the bottom of the inlet.
Thousands of oyster spat — the larval form of oyster — were planted on the reef by NSW's first Indigenous, commercially qualified dive team.
The oysters then began to feed on and filter phytoplankton, moving nutrients around the reef and increasing the productivity of the entire food chain.
"They do this amazing job to boost biodiversity and water quality," Ms Keating said.
Already, 15 species of fish have been seen in the subtidal reef, which Ms Keating said is similar to historic shellfish reef ecosystem populations.
Saltmarshes returning
More than 13,000 native plants have also been planted along the foreshore, transforming the patchy elements of a previous seawall into more than 3,000 square metres of saltmarsh.
Eurobodalla Shire Council natural resources and sustainability manager Heidi Thomson said the saltmarsh population around the inlet had declined three-fold since the 1970s.
"Reinstating some of that saltmarsh is going to help the entire estuary, not just to protect the foreshore, but by providing habitat," she said.
The innovation of combining both reefs and marshes to buffer wave energy saw the project receive an award for innovation at the 2023 Joint Coast to Coast and NSW Coastal Conference.
Community infrastructure such as a wharf, artwork and kayak access are still to be installed, but Ms Thomson said the council is already fielding requests from conservation groups around the country interested in the project.
"We hope it will take off in other parts of NSW and Australia," she said.