Developing methods for oyster reef repair in Port Phillip Bay, Victoria

Oyster reefs were once a dominant structural and ecological component of estuaries around the globe. Studies in bay and estuarine systems worldwide have indicated that shellfish reefs provide important structural habitats for... [ view full abstract ]

Oyster reefs were once a dominant structural and ecological component of estuaries around the globe. Studies in bay and estuarine systems worldwide have indicated that shellfish reefs provide important structural habitats for a variety of invertebrate and fish taxa. Producing reef habitat for entire ecosystems, oysters act as ecosystem engineers, whilst providing a vast number of ecosystem services such as nutrient cycling, water filtration, sediment stabilization and carbon sequestration. Through centuries of intensive destructive fishing and more recently coastal degradation, these critically important ecosystems in many areas are now ecologically extinct. The major declines and ongoing threats to this habitat have stimulated projects aimed at their protection, enhancement and restoration.

We are developing best practice methodology for shellfish restoration in Australia. We are asking, how do we best construct these reefs to provide greatest opportunity for survival/success? Across two sites in Port Phillip Bay, we are utilising hatchery reared Ostrea angasi spat to ‘kick start’ natural reef redevelopment in Port Phillip Bay. We have deployed experimental plots designed to compare survival and growth of oysters deployed on different substrate and at different outplant ages. We will also compare natural shellfish settlement rates, predator densities, community biodiversity and biomass amongst treatments. Through this process we aim to identify limitations to restoration success in Port Phillip Bay including predation, water quality, sedimentation and natural seed availability. There is a long road ahead and in answering this question, we aim to create a best practice system for future restoration efforts.