An ecological typology of the rivers of New South Wales, Australia
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NO FULL TEXT AVAILABLE. Access is restricted indefinitely. ----- There is a need for an ecological classification scheme for rivers to facilitate natural resource management in New South Wales (NSW). One way of doing this is to define river types based on reference condition and multi-attribute data from river sites. 322 reference sites were selected across NSW, Australia which has a surface area of 801,428 km² and population of approximately 6.8 million. These were selected to represent all major river types across the State. Environmental data and macroinvertebrate samples were collected from all of these sites. In addition, wherever possible, I compiled likely lists of fish species for each sites from a database containing records of fish collected from rivers across NSW. I used diatom data from relatively undisturbed river sites in eastern NSW. I determined multivariate patterns in the abiotic and biological data using ordination and classification methods and defined river types for each of these attributes. Then, using classification trees, I identified major thresholds in elevation and mean annual rainfall. Using these thresholds, together with boundaries of major river basins, I defined regions for each typology that contained as few river types as possible. Then I constructed two classification trees for each region for each typology. One of these trees only used immutable variables: maximum distance from source, elevation, slope, latitude and mean annual rainfall. The other classification tree used all variables measured including water quality data, substratum cover and modal river width. In all I defined 10 abiotic, 8 macroinvertebrate edge, 5 macroinvertebrate riffle, 6 fish and 3 diatom river types. I wrote identification keys for all these except for the diatom river types using the immutable variables. One of the primary areas of application of the river typologies is in the prioritisation of rivers for conservation action. I explored this in the Hunter region by mapping the macroinvertebrate edge and fish river types, calculating the total length of rivers in each type and determining how much of this was within protected areas. I used this to determine criteria for prioritisation of land units within the region. I then divided the region into smaller subcatchments and ranked these subcatchments using the river type priority criteria. This prioritisation may be used as a factor in region prioritisation for conservation action alongside assessments of catchment condition, threats, special ecological values and recovery potential.
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