Windara, biggest reef restoration in southern hemisphere, at Gulf St Vincent, South Australia
Young Leather jackets fish schooling at the Windara Reef in Gulf St Vincent.
Image by Anita Nedosyko, The Nature Conservancy project manager
Windara, the southern hemisphere’s largest reef restoration, is being led by The Nature Conservancy in Gulf St Vincent in South Australia. The reef was built in 2017-18 by placing almost 10,000 tonnes of limestone boulders, each about the size of a soccer ball, to form 150 reefs across the 20ha area, about 1km off the coast of Ardrossan on Yorke Peninsula.
After first 30,000 mature native oysters were seeded in 2018, that number has reached 50,000 – with the ultimate goal of boosting it to seven million. The native oysters (Ostrea angasi) were seeded at eight months old, about egg-yolk size, and supplied by the South Australian Research and Development Institute. The juvenile oysters are likely to begin producing spat (offspring) at three years old. It is expected take seven years to create a fully functioning self-sustaining reef.
Oyster reefs are the temperate water equivalent to coral reefs. 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 harvesting of oysters for food wiped out all reefs except off Tasmania. Adult native oysters can filter more than 100 litres of water a day and excrete a mucus rich in nutrients that provides food for small shellfish that provide food for larger fish.
First dives to measure Windara reef’s benefits have revealed abalone, scallops, sea urchins, schools of leatherjackets, snapper, magpie perch and cuttlefish adding to its biodiversity. Hopes are for the reef to increase fish production to five tonnes per hectare a year including recreational fishing favourites such as snapper and King George whiting.
The project is a joint effort of the South Australian and Australian governments, The Nature Conservancy, Yorke Peninsula Council and Adelaide University.