Developing knowledge and tools to inform integrated marine management: Spencer Gulf as an Australian case study

Coastal and marine waters are becoming increasingly crowded. Besides fishing and aquaculture ventures there is also significant 
shipping and port development associated with new mineral and processing ventures, and potential for biosecurity risks. Other 
human activities operating in and around the sea also have potential to cause stress to marine and coastal habitats and the 
species they support. Understanding cumulative impacts of multiple activities remains a critical gap in marine management. Our 
aims were to generate a spatially explicit assessment of cumulative risk; examine current shipping traffic and determine how 
shipping pathways and number of ships are likely to change given proposed mining expansion and investigate potential changes 
to cumulative risk, as well as interactions with key fisheries and aquaculture activities, associated with changes in shipping. We mapped the spatial footprint and intensity of human activities occurring throughout Spencer Gulf, a large inverse estuary. We combined information from an ecological risk assessment using an expert elicitation process with the spatial intensity of threats 
to generate a spatially explicit assessment of cumulative risk. This map shows that the most-at-risk habitats occur in northern Spencer Gulf, near major industrial activities. Current shipping activities show that ships use clear pathways associated with bathymetry and future scenarios for shipping and port development suggest an increase in shipping traffic of 91-249% over current levels. Visualisation of shipping scenarios with the existing prawn and sardine fisheries suggest potential overlap of activities. Management solutions are required to avoid congestion in the narrow shipping paths of northern Spencer Gulf and to 
minimise the potential impacts and risks of increased disturbance on the Gulf environment and other industries supported by the 
Gulf.