A whole-of-system approach to water management options for the region, to secure and sustain the health of the estuary.
Ecosystems suffering from low inflows
Located south-east of Adelaide in South Australia, the Coorong, Lower Lakes and Murray Mouth (CLLAMM) region is one of Australia’s largest estuaries. These ecosystems make up some of the best habitats for waterbirds in Australia and in recognition they have been added to the Ramsar List of Wetlands of International Importance (designated November 1985).
However, following a decade of limited River Murray inflows, the region became degraded, with significant declines in fish and bird numbers.
A new approach to management planning
The CLLAMMecology team developed a two-step approach to support future management interventions in the region.
Step one was to evaluate future climate and management intervention scenarios using a hydrodynamic model to predict future water level and salinity regimes, the two key ecosystem drivers in this region. These water level and salinity predictions can be made for the length of the Coorong (~110 km) at decadal or longer time-scales as a function of River Murray discharge over the Lower Lakes barrages, connection to the sea via the Murray Mouth, and Upper South East Drainage discharge.
Step two was evaluation of ecological responses to changes in water level and salinity. Several tools were developed, including models to evaluate the change in the distribution of key fish and bird species, of key habitats (such as mudflats), or of whole ecosystems.
New knowledge and tools for management in the region
The following outcomes were delivered:
Influence of water management on biodiversity
Datasets and models were developed to determine the aquatic conditions required to sustain biodiversity in the Coorong region of South Australia. They document historical and current distributions and abundances of key species in the Coorong, and the responses of key aquatic plants, aquatic bottom-dwelling invertebrates, fish and birds to changes in the aquatic environment.
Sustaining food webs within the region
New information was generated about nutrient cycles, primary production and trophic pathways in the Coorong region and how select groups of primary producers in the region were affected under different environmental conditions, in particular salinity and turbidity. Implications for species higher up the food chain, such as fish and birds, were also identified.
Our research has led to an improved understanding of the relationship between water management practices and the health, productivity and trophic dynamics of the region's ecosystem, with a view to improving practices.
Habitat changes under different water management scenarios
This project produced dynamic maps that show how habitats change with changes in water level, salinity, turbidity and other variables.
This allows the extent and quality of key habitats, such as the mudflats used by waders, to be predicted over time and under any flow scenario, enabling researchers and water managers to predict the impact of changes in management practices.
The future of the Coorong, Lower Lakes and Murray Mouth
We evaluated the longer-term status of the region under different potential climate and management scenarios as developed in consultation with stakeholders. We identified alternate ecosystem states that could occur in the Coorong under these different conditions.
- An Ecosystem Assessment Framework to Guide Management of the Coorong: Final Report of the CLLAMMecology Research Cluster
- Coorong, Lower Lakes and Murray Mouth: Knowledge gaps and knowledge needs for delivering better ecological outcomes
- Biogeochemistry of the Coorong: Review and identification of future research requirements
- An overview of the hydrodynamics of the Coorong and Murray Mouth: Water levels and salinity – key ecological drivers
- Hydrodynamic Modelling of the Coorong