One thousand ceramic razorfish shells have been buried in the seabed of waters off South Australia's Kangaroo Island to help encourage a threatened native flat oyster species to rejuvenate.
The Kangaroo Island Landscape Board has collaborated with a Tasmanian ceramicist to design and build a series of small-scale native flat oyster reefs in the Island's north coast waters.
Coasts project officer Alex Comino said the concept behind the reefs was to replicate what could already be found in the natural environment, and what native angasi oysters showed a preference for in the wild to attach themselves to in order to grow.
Ms Comino said ceramicist Jane Bamford was already on Kangaroo Island working on another conservation project when the board approached her.
"We were looking to create an artificial but biodegradable mimic of those razorfish and have them installed on our reefs," she said.
"Then Jane came along and the rest is history really."
Ms Comino says the shells, which protrude from the seabed, provide ideal substrates for micro and macro marine organisms to settle and grow upon.
New life at last
Due to overfishing by European settlers in the late 1800s, Ms Comino says angasi oysters have been lost, but larger populations have been found where razorfish are present.
"What they thought was an inexhaustible supply of oysters, they really believed they'd never see the end of them, were in reality completely exhausted within 100 years," she said.
Not only were the native oysters overharvested for consumption, but early settlers also dredged up the oyster shells to crush them down to make mortar.
"A lot of the roads and buildings that you see in Adelaide and some of the older cities around the southern coast of Australia have pretty much been built on old oyster shells," Ms Comino said.
Despite the millions of angasi larvae that float through Kangaroo Island waters each summer, Ms Comino says the absence of any substrate means many do not survive.
"Even when they do find somewhere to land —maybe it's on the jetty pylons or other infrastructure — they're generally picked off pretty easily by predators because they're just not very protected," she said.
The installation of the reefs was timed with the natural spawning season of the angasi oysters, with the first signs of life expected within months.
"In about two years, the oysters should be mature enough to produce their own spawn," Ms Comino
"So, hopefully, we'll see a self-sustaining reef where the oysters that have colonised the reef will start to have their own babies."
Over 1,000 handmade shells
Ms Bamford worked closely alongside the marine biologists to ensure the shells replicated natural ones.
"In a project like this you do quite a lot of research and start to have a look at the form, read all about it [and] try to understand what the ecosystem is," she said.
After making 100 ceramic prototypes to trial their forms in the marine environment, evidence showed the settled baby oysters, known as spat, were attaching to the moulds.
Ms Bamford eventually created 1,000 shells.
"Basically, I roll out a big slab of clay so it's got some sort of pressure on it to give it some strength and then I cut out those form shapes," she said.
"Each one of them is then slumped over a mould so it actually takes that concave form."
Ms Bamford said clay, once fired in a kiln, was the ideal material for the project as it was non-polluting, negatively buoyant and would not break down in a marine environment.
"They're actually held in place with something called liquefaction," she said.
"If you can remember being at the shoreline and digging your feet into the sand, and the sand is so full of water it almost sticks there, [that's liquefaction]."
Art meets science
While she's been working with clay for 27 years, Ms Bamford only recently started collaborating with scientific projects to support habitat and threatened species.
"About six years ago, I started working on a project with the CSIRO in Hobart making artificial spawning habitats for the spotted handfish," she said.
"From that experience, I realised there was an ability to work in conservation projects in clay and, since then, that's what I've sort of focused on."
Ms Bamford said the project was a group effort and it was a great experience working alongside Kangaroo Island locals, including those from the Kingscote Men's Shed who built terracotta tile modules that resembled dense razorfish beds.
"There's a lot of people who've had a small part and so it's really actually a community story," she said.
"It's a really incredibly beautiful thing to actually make a form for another species to land on."
