The 2-hectare reef is the second large-scale reef system to be developed in South Australia’s Gulf St Vincent to improve water quality and revive wild native oyster populations.
One of Adelaide’s most popular beaches, Glenelg was chosen as the location for the reef ahead of O’Sullivan Beach and Port Noarlunga after scientific advice and public consultation.
The project is a partnership between the South Australian Government, The Nature Conservancy and the City of Holdfast Bay and is being partially funded by a $1.2 million investment from the state government.
It follows the construction of the largest man-made oyster reef system outside the United States on the other side of the South Australian gulf near Ardrossan.
The 20ha Windara reef network was built in two stages in 2017 and 2018 and includes almost 160 individual reefs constructed of limestone boulders and seeded with more than 50,000 of endangered Australian flat oysters.
South Australian Minister for Environment and Water David Speirs said the Glenelg shellfish reef would also be constructed using a limestone reef base, with hatchery-raised Australian Flat Oysters (Ostrea angasi) deployed to re-create a living shellfish reef over the next several years.
He said more than 1500 responses were received during the community consultation stage of the selection process, reflecting the strong public support for the project.
“In the end Glenelg was chosen as it offers suitable environmental conditions as well as the opportunities for the community, with such good public transport and beach access to the area,” said Minister Speirs.
“Shellfish reefs were once common along sheltered nearshore areas of South Australia, however, from the late 1800s to mid-1900s the reefs suffered from the impact of overfishing, dredging, water pollution and disease.
“Aside from the recently completed Windara Reef off the coast of Ardrossan on the Yorke Peninsula, native oyster reefs are now near absent from South Australia’s waters.”
Oyster reefs are considered the temperate water equivalent to coral reefs in tropical waters. Australia’s southern coastline was home to thousands of kilometres of oyster reefs before European settlement. But dredging to remove substrate for lime production and the harvesting of oysters for food wiped out all the reefs except for one off the coast of Tasmania.
Adult native oysters can filter more than 100 litres of water a day and excrete a mucus-like substance that is rich in nutrients and provides food for small shellfish that in turn provide food for larger fish.
The Nature Conservancy in collaboration with the State Government will now refine the site to two hectares within the broader chosen five-hectare location.
TNC has been involved in dozens of shellfish reef restoration projects, chiefly in the United States and is considered a global expert on their establishment.
The Glenelg reef is part of The Nature Conservancy’s National Reef Building Project that aims to rebuild 60 reefs in six years across Australia.
If achieved, it will make Australia the world’s first nation to recover a critically endangered marine ecosystem. Other reef projects are located in Melbourne’s Port Phillip Bay, Western Australia and Queensland.
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