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| Macquarie Marshes |
| Science informing adaptive management in the Macquarie Marshes |
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| The Macquarie Marshes is one of the largest and most significant wetland systems in Australia. Wetland communities (waterbirds, frogs, reptiles, fish, vegetation, invertebrates) in the marshes face a range of threats, such as upstream water abstraction from the Macquarie River and localised habitat degradation – threats that may be exacerbated by future climate change. At present, there is a general security allocation of 160 000 ML/yr for environmental flows and environmental flows purchased through Riverbank, but little is known about the specific responses of the biota to these flows. By quantifying these empirical relationships, this project aims to develop a decision support capability for the Macquarie Marshes that allows the evaluation of various environmental flow options at different temporal and spatial scales. The project forms a large research program in the system, which includes the modelling of hydrological processes, the mapping of floodplain inundation patterns, assessment of fine-scale productivity dynamics and assessment of earthwork structures that may impede flows. |
- Review existing knowledge bases and data sets relevant to environmental flow management in the Macquarie Marshes and the biotic communities found there.
- Construct a conceptual model of ecosystem ecology for the Macquarie Marshes.
- Describe, through a series of surveys and experiments, elements of the structure and function of waterbird, fish, vegetation and invertebrate communities and their food webs in the system.
- Develop empirical relationships between the biotic components (waterbirds, fish, vegetation, invertebrates and their food webs) and environmental flows.
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| Historical and recent data sets are being compiled to identify long-term changes to biota. A series of floodplain inundation maps have been prepared by DECC showing changes in inundation patterns that will be linked through historical and current data. |
| There are published records of waterbird communities observed in the Macquarie Marshes dating from the 1950s that indicate the Marshes were a significant breeding place for waterbirds. It was declared a sanctuary in 1955 under the Fauna protection Act, 1948. Detailed surveys (both ground and aerial) undertaken by CSIRO in the 1970s also recorded diverse and abundant waterbird communities with prolific breeding by colonial waterbirds. Surveys of colonial waterbird nests and broods in 1978 and from 1986 to 1996 show a strong relationship between the size of flood events and waterbird colonies, with both declining across time. This study was extended to examine records of 10 species of colonial waterbirds from 1986-2001, finding that breeding of most species was positively related to flow in the three months before breeding and triggered when flows were usually above 200,000 ML. The eastern Australian aerial survey has recorded waterbird species and numbers in the northern Marshes since 1983. This long term data shows a significant decline in waterbird species richness and abundance from 1983 to 2007. |
| Specimen record data have been obtained from the National Herbarium of New South Wales, and will also be requested from the Brisbane Herbarium. Vegetation survey data from Mike Brooker’s work with CSIRO and Paijman’s 1980 mapping is being collated and will be used to compare with present day survey results, along with vegetation information extracted from aerial photography. Literature on the water requirements of floodplain and wetland plants, as well as information on seed bank persistence is being collated and will be reviewed. |
| Fish data from historical accounts and recent surveys has been reviewed and will form the basis of a scientific publication outlining the probable pre-European condition of the Macquarie River catchment in general and the Macquarie Marshes in particular. A review of these data sets and the relevant literature will be used to outline the ecological needs of the fish community and to form a conceptual model of the influence of various flow scenarios on fish populations. Together, these papers will enable the formulation of thresholds of potential concern, suitable for incorporation in an adaptive management framework. |
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- NSW Department of Environment and Climate Change
- Natural
Heritage Trust
- Central West Catchment Management Authority
- Land & Water
Australia
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