Where have the oyster reefs gone?
Threats to oyster reefs
Oyster reefs consist of clusters of living oysters and old shell. They can occur in the intertidal zone or be permanently submerged underwater.
During early European settlement, vast quantities of natural oyster reefs were harvested unsustainably for food and as a source of lime for use in construction. Increasing water pollution from upper catchments and disease also impacted the oyster reefs, and by the late 1800s they had all but disappeared in NSW.
In Australia, it is estimated that 99% of natural oyster reefs are ‘functionally extinct’, meaning they no longer play a significant role in ecosystem function. In NSW, wild oyster populations still exist in most bays and estuaries but at very low densities compared to the pre-European period.
‘Originally the oyster beds extended from Darling Harbour to the Flats in more or less quantities, but a few years back they became almost extinct from over-dredging’ NSW Inspector of Oyster Beds, 1877
Prior to the 19th century, oyster reefs were a common feature of NSW estuarine and coastal areas providing tremendous environmental benefits. Today, only a fraction of natural oyster reefs remain.
Why restore oyster reefs?
Extensive research continues to demonstrate the value of oyster reefs as habitat structures for biodiversity, fish production, water filtration, shoreline protection, and nitrogen fixation.
Looking abroad, international experience has shown considerable social and economic benefits of oyster reef restoration to local communities.
Oyster reef restoration provides a practical and effective means of rebuilding this lost habitat type and regaining environmental benefits while creating job and community involvement opportunities.
Oyster reef restoration efforts are increasing in NSW in recognition of the benefits that can be achieved. The first large-scale project for NSW is being launched in Port Stephens in January 2020.