Oyster bag structures installed in Port River, Adelaide
On Monday, community volunteers from the Estuary Care Foundation installed their first 'living shorelines' in Port Adelaide.
The trial structures, composed of oyster shells in hessian bags, have been installed in the intertidal zone to protect transplanted seagrass behind them. Deliberately utilising only organic materials, it is intended that local shellfish will colonise the structures, and that the bags will naturally decay in time leaving new, intact shellfish reef structures behind. WRL has a research partnership with OceanWatch Australia, who first pioneered this approach of restoring oysters reefs within Sydney Harbour.
Prior to European settlement, naturally occurring shellfish reefs (oysters and mussels) were widely found in the Port River. However, since the 1800s these reefs and associated seagrass meadows have been significantly reduced due to dredging, reclamation and changes to water quality.
WRL assisted the Port River seagrass and shellfish restoration project by undertaking a coastal engineering assessment for the oyster bag structures. It was found that the design wave climate was generated by passing commercial tugs operating in the port (which is equivalent to 1 year average recurrence interval wind waves). Based on the results from previous full scale physical modelling tests in WRL’s three metre wave flume, it was concluded that the oyster bags are expected to remain stable under attack from these wave conditions.
Click here to learn more about WRL’s oyster reef restoration project.
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