Shellfish such as oysters, mussels and razor fish, are filter feeders – they ‘sieve’ their food from the water. As natural ‘water filters’, they provide a wonderful ‘ecological service’ - helping clean up waterways.

Shellfish reefs are also important in protecting shorelines, especially as they are challenged by sea level rise. Reefs lock-up carbon and provide a foundation for a network (or eco-system) of other marine life.

While the Port River and Barker Inlet Estuary is home to numerous shellfish, the once plentiful native flat oyster, Ostrea angasi, is now found only occasionally in the Port River. Ostrea angasi has been classified as “functionally extinct’ not only in the Port River but throughout South Australia.

Restoring Ostrea angasi to the ecosystem and providing substrate for existing shellfish, will improve water quality, help stabilise shorelines, and enhance the ecology of the estuary.

Inspiration for our project is drawn from similar projects including the Billion Oyster Project in the Hudson River and the Elizabeth River Project.

Our project in the Port River is the first local, citizen science, shellfish restoration project in SA.

It is part of broader efforts to restore shellfish reefs, which once existed along 1,600 kms of the South Australian coastline.

Our three main strategies are to:

• Restore the native oyster Ostrea angasi to the Port River

• Provide substrate for reefs

• Develop reefs in areas where they can lessen the impact of storms and adverse weather events on the community

There is a lot of research and exploration in the project, because it hasn’t been attempted here before. So, we’ve been learning and experimenting, revising and documenting our efforts.

In November 2016, the project secured a $5K Community NRM Action Grant, enabling trials to begin with native oysters in baskets across six sites. Our sites include the pontoons of the Cruising Yacht Club and Royal SA Yacht Squadron and the wharves of the Australian Submarine Corporation and Flinders Ports.

Port Adelaide and the Lefevre Peninsula are experiencing sea level rise, land subsidence, tilting and erosion along the Port River. That all contributes to the area being one of the most vulnerable in SA to flooding and inundation.

Tide gauging in the Western Adelaide region has found sea levels to be rising at a rate of 2.06 millimetres per year and 2.08 millimetres per year at the Inner Harbour and Outer Harbour areas respectively.

Sea level rise could exacerbate exposure to non-climate specific threats such as land subsidence from natural causes and anthropogenic activities (e.g. landfill developments and large-scale groundwater extraction), and saline intrusion of aquifers.

Sea level rise is also expected to intensify storm surge events. These are events where sea levels rise significantly above normal tide levels for a temporary period of time. Presently, the mean sea level at Outer Harbor is 0.13 m below the Australian Height Datum (AHD). However, the 100-year ARI water level for Outer Harbor based on current mean sea levels is 2.4 metres above AHD. This means that under a high sea level rise scenario, storm surge events could cause tides to reach areas that are presently 2.4 metres above AHD.

AdaptWest, the Western Adelaide Region Climate Change Adaptation Plan, has identified the risks that we are seeking to address and the solutions that we are seeking to trial (i.e. Living Shorelines), amongst its Priority Adaptation Options.

While Living Shorelines have been implemented overseas for many years, the concept is not widely known in South Australia and there are no demonstration sites established. NSW refers to Living Shorelines as Environmentally Friendly Seawalls and since 2009 the NSW Department for the Environment has provided guidance for their development in NSW estuaries. Their design concepts, and projects implemented in NSW, can inform our projects.

A Living Shoreline strategy facilitates natural systems while providing improved protection (both engineered and natural). Climate change, including sea level rise and the potential increase in frequency and severity of storms, has placed an emphasis on shoreline protection. Unlike traditional means of shoreline armouring, such as rock walls and retaining walls, living shorelines offer a range of benefits well beyond erosion prevention and shoreline stabilisation.

Living shorelines use combinations of bio-engineered structures with elements of native aquatic plant and, and even animal, communities to provide the intended shoreline protection while also providing desirable green infrastructure and ecological benefits. They, like shellfish and seagrass restoration, help to counter the greenhouse effect by locking-up carbon in what is termed a ‘blue carbon ecosystem’.

Our project seeks to act on the risks and recommendations of AdaptWest by designing and constructing trial Living Shorelines.

Given the risks, from adverse weather events and flooding, to existing and proposed homes around the Inner Harbour, this is a priority area for Living Shorelines.

The Estuary Care Foundation applied in January 2017 to the National Disaster Resilience Program for a grant for two Living Shoreline trials. When those application were unsuccessful, the Foundation refined their plans and applied again to the NDRP for a new project, in the Inner Harbour. That application was submitted in July 2018.

The Foundation is grateful for the support, given by the Coast Protection Board, Renewal SA, City of Port Adelaide Enfield and DEW, for our efforts to promote these concepts and secure pilot project funding.

For information and updates on progress, see the Posts for Living Shorelines.

Seagrasses protect coastal infrastructure through wave reduction and retention of sediment, provide habitat for important fisheries, and are carbon sinks.

Seagrass meadows are an important component of the near shore marine environment of the Adelaide metropolitan area of Gulf St Vincent, where there are extensive subtidal beds of Posidonia (Tape weed), and Amphibolis (Wire weed). There are also extensive areas of Zostera (Eel grass) on the muddy banks adjacent to the mangroves in Barker Inlet and to the north, which also extend into the subtidal zone.

There has been extensive loss of seagrasses in the metropolitan region with significant changes to the marine ecology of the region. Restoring the natural seagrass beds will have major environmental benefits.

Of most interest to the Estuary Care Foundation are the intertidal and subtidal Zostera beds which, would have previously occurred throughout the Port River and Barker Inlet.

Improvements in water quality in the Port River and Barker Inlet are enabling the natural restoration of Zostera and encouraging restoration trials by the Foundation.

Qualitative observations by Assoc Professor Jason Tanner, SARDI in January 2017 indicated that Zostera had extended its range in the Port River, south of the Quarantine Station. He observed a thick band of intertidal seagrass almost all the way to AGL, and a few small patches in between the 2 AGL cooling water intakes. There was little seagrass on the mainland side, just a small pocket at Mutton Cove, which was then thick and healthy.

This significant news has encouraged the Foundation to establish three projects, two for seagrass monitoring and one for restoration.

Seagrass monitoring:

A volunteer team for monitoring from kayaks, along the western shore of Torrens Island, was formed in mid-2018, following kayaking instruction by Peter Carter and training by Jason Tanner. Foundation volunteers are involved in the monitoring and so too are volunteers from the Defence Shed, which is kindly lending kayaks to the program.

While the project has sought to utilise the methodology of SeaGrass Watch, there is considerable trial and error in establishing methods suited to our local circumstances.

The second monitoring program involves the deployment of two AusOcean rigs on either side of The Cutting at the northern end of Torrens Island. One rig is being deployed in the Port River, with the cooperation of Flinders Ports and the second is in the Barker Inlet. The locations were advertised in a Notice to Mariners (8/8/18)

Seagrass restoration:

In October 2017, the ECF applied for an NRM grant for a seagrass restoration project. Based on Dr Tanner’s advice, the shoreline just north of the Snowden’s boat ramp was chosen since it is quite wide and easily accessed and Zostera is not found there, having not yet progressed that far south.

In December 2017, the Foundation secured a $5K Community NRM Action Grant for seagrass restoration. Those funds provide coastal engineering advice while further funds, through a Coastal Participation Grant ($2,750) and the City of Port Adelaide Enfield ($700), provide project materials.

The seagrass restoration trial uses oyster shell in hessian bags, to protect translocated seagrass from wash, while also providing substrate for local shellfish to colonise the shells and form a low-level reef.

As a condition of our PIRSA Ministerial Permit, clean recycled shell is sourced only from SA oyster growers, for biosecurity reasons. The Foundation is sourcing bags and learning from OceanWatch in their trials in Sydney Harbour for shoreline protection.

For information and updates on progress, see the Posts for Seagrass Restoration.

Current activities of the Foundation, while community led, are informed by researchers and specialists who kindly make their expertise available to the Foundation.

Valuable expertise comes from community members who belong to organisations such as the Malacological Society and the Marine Life Society.

The Foundation hopes to profile the research, in the Port River and Barker Inlet, of our universities and research organisations.

The Foundation is keen to partner with research organisations to further investigate:

• Nature-based solutions to climate change

• Monitoring of key species including shellfish, fish, shorebirds, seagrasses, and mangroves

• Carbon sequestration from mangroves, shellfish, and seagrasses

• Filtering and reduction of stormwater to the Port River and broader Estuary

The Foundation will develop and promote project outlines for research and we are currently seeking interest in:

Thesis Proposal: Determination of Heavy Metals in Port River Bivalves, prepared by Michael Burrell, President, Malacological Society SA

The Foundation engages the community in understanding the Estuary as a living system.

Several high schools have participated in the Port River Shellfish Restoration Project and, as resources permit, the Foundation will involve high schools in STEM education involving water quality monitoring, oyster gardening, and habitat restoration.

The Foundation provides public speakers and organises public fora, to promote discussion of conservation and restoration, and the work of the Foundation.

Public meetings have been organised with international and national speakers on topics including coastal and aquatic restoration.

The arts can provide visual, sound, physical and other representations of nature, its challenges and restoration.

The Foundation has collaborated with local artists around the themes of our projects and welcomes further opportunities for engagement.

For information and updates on progress, see the Posts for Community Engagement.