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Native angasi oysters in their millions once filled the waters of Coffin Bay on South Australia's Eyre Peninsula, filtering water, providing shelter for fish and preventing coastal erosion.
But the arrival of European settlers on the shores of the Eyre Peninsula in the 1840s signalled the death knell for the angasi oysters, which were dredged to near extinction within a century.
Now the community has banded together to revive the "ecological superheroes".
The early colony was built on the native oysters. (Supplied: Axel Stenross Maritime Museum)
Coffin Bay oyster farmer and local historian Lester Marshall said the demand for oysters was extremely high during early settlement.
"While the new colony here in South Australia was finding its feet with grain production, meat production and the rest of it, oysters were a really big high protein food source," Mr Marshall said.
"They just took so much out, and they didn't have time to recover and replenish the bay."
The early colony was built on the native oysters.
As well as eating them, settlers burnt them down to produce lime, which was used to construct some of South Australia's earliest buildings.
Depleted and forgotten
By the 1940s, the native oysters were considered functionally extinct in Coffin Bay and it wasn't until the 1990s that the Pacific oyster trade, for which the town is now known, officially kicked off.
However, the Coffin Bay community is working to right that historical wrong.
Pacific oyster farmer Lester Marshall comparing a pacific, left with the larger native angasi oyster, right. (ABC Eyre Peninsula: Amelia Costigan)
University of Adelaide researchers have joined forces with local conservationists for a three-year project to revive the native oyster population by constructing artificial oyster reefs around the bay.
Marine ecologist Dominic McAfee is leading the charge, following successful restoration projects elsewhere in SA.
He said oysters and native oysters were very important for the marine environment.
"I like to think of them as ecological superheroes because they are sort of the functional equivalent to trees in a forest or coral reefs in tropical seas," Dr McAfee said.
Dominic McAfee has pioneered successful oyster reef restoration projects around South Australia. (ABC Eyre Peninsula: Amelia Costigan)
"We've seen oyster communities essentially brought back from functional extinction within three years of reefs being constructed.
"That's a phenomenal outcome and really fills us with hope that if we have ongoing investment and support for this kind of work, we could repair large parts of the sea in a reasonable amount of time."
Dr McAfee is collecting data from "reefs" made of biodegradable bags full of shells from the sea floor, deployed around the bay to provide hard substrate for baby angasi to attach to and grow.
Once the oyster spat — oyster larvae that has permanently attached to a surface — settles on the old shells, they cement themselves and fuse with other oysters.
After two or three years, the structure they form resembles the extinct oyster reefs and provides the foundation for the reefs to bounce back.
Restoration reefs are filled with shell from the sea floor and placed in biodegradable bags. (ABC Eyre Peninsula: Amelia Costigan)
"What these oyster restoration projects have shown us is that with the right tools, knowledge and support from community and industry and government these projects can be quite successful in a short period of time," he said.
Declining ecosystem needs hero
Angasi oysters are powerful filter feeders that can filter the water of an entire estuary in a matter of days — hence their ecological superhero status.
New life on an oyster shell shows how oyster reefs provides shelter for fish and other creatures. (ABC Eyre Peninsula: Amelia Costigan)
Recent studies of Coffin Bay indicate a decline in water quality and ecosystem health due to nutrient run-off from the township and other activities.
"The water quality has been declining because of us — because of people — in the last 150 years and it's time to fix that," citizen scientist and scuba diver Manny Katz said.
Mr Katz has been deploying the restoration reefs around the bay and is monitoring their progress alongside Dr McAfee.
Coffin Bay's oyster industry has helped shape the town, (ABC Eyre Peninsula: Amelia Costigan)
Students from local high schools were given the opportunity to participate, gaining a scuba diving qualification along the way — and bringing the next generation on board is key to the ethos of the project.
"Teaching kids about environmental responsibility is crucial," Mr Katz said.
"These kids are going to be growing up, living in these communities and doing things that are directly impacting the environment on a day-to-day basis, whether that's going out fishing or just interacting with marine ecosystems, whether that be swimming, fishing or diving."
Manny Katz is helping the community participate in the oyster reef revival project. (ABC Eyre Peninsula: Amelia Costigan)
Survival shows resilience
The traditional owners of Coffin Bay, the Nauo people, trace their connection to the angasi oysters back millennia — as evidenced by ancient shell middens present in the area.
Nauo chair Michael Miller said the project to restore the native oysters was symbolic of their own survival journey.
"Once we were nearly annihilated and we've bounced back up. We're still here. We never went anywhere. Same as the native oyster population," Mr Miller said.
Baby angasi oysters grow on the hard surface of the old shell and eventually form reefs. (ABC Eyre Peninsula: Amelia Costigan)
"To be sitting in this place with shells that are 5,000-plus years old and to know that you're sitting in the same place as forefathers and ancestors … I'm getting goosebumps now even talking about it. It's really special."
The Nauo community were granted native title over Coffin Bay and surrounding areas in 2023, after a 32-year fight for recognition.
Nauo elder Brentan Weetra said he was pleased to see the community's efforts to bring back the native oyster population and protect the environment.
Brenton Weetra and Michael Miller say the native oyster revival project reflects their community's own survival journey. (ABC Eyre Peninsula: Amelia Costigan)
"I'm really connected to that place. It's a very sacred place for me," he said.
"We use it a lot, me and my wife and my kids, every time we come back home. It's nice to see people looking after the place."
The first year of the three-year project is nearly complete, and while it's early days, the team hopes to restore Coffin Bay to its former glory.
Lester Marshall believes it's the responsibility of the community to repair the legacy of destruction left behind by the early oyster industry.
"It took as a hundred and two years to stuff it up. I hope it doesn't take 102 years to fix it up," he said.