Stakeholder-supported restoration suitability modelling for oyster reefs in Sydney, Australia

Oyster reefs are one of the most imperiled marine habitats on earth, and are functionally extinct in Australia. Their ability to maintain ecosystem health and provide ecosystem services is highly valued, and there is growing initiative to restore oyster reefs, worldwide. Habitat suitability modelling has emerged as a powerful tool to guide site selection, a crucial component of restoration. Such models often use bio-physical parameters, but rarely consider conflicting estuarine uses or stakeholder-support, which are increasingly important in spatially complex, urbanised estuaries. This thesis took a holistic approach to suitability modelling, utilising available biological and physical spatial data and local stakeholder knowledge, to develop a stakeholder-supported restoration suitability model. Suitability models targeted native (Saccostrea glomerata and Ostrea angasi) oysters, whilst limiting proliferation of non-native Crassostrea gigas, and were produced for two highly urbanised estuaries, Sydney Harbour and Botany Bay in Sydney, Australia. When habitat suitability, estuarine conflicts, ecological connectivity and stakeholder-support were considered, 0.4-3.3% of each estuary was assessed as highly suitable for native oyster reef restoration. This holistic, data-driven approach to suitability modelling will guide pilot studies and site prioritisation, and may serve as a framework for future restoration modelling endeavours in other urbanised estuaries.