Australia-Wide Assessment of River Health: Western Australian AusRivAS Sampling and Processing Manual
S. Halse, M. Smith, W. Kay, M. Scanlon and J. Cocking
Departments of Conservation and Land Management
Monitoring River Health Initiative Technical Report Number 18
Environment Australia, 2002
ISBN 0 642 54885 4
About this Manual
Since European settlement anthropogenic effects on Australia's streams and rivers have been considerable. Sewage, detergents and agricultural run-off have altered nutrient balances and contributed to toxic algal blooms. Mine wastes have sometimes caused heavy metal pollution, acidification and sedimentation. Agricultural pest control has caused pesticides to enter waterways, while land clearing and deforestation have often caused sedimentation and salinisation. Other impacts include alteration of flow regimes through construction of dams, extraction of water for irrigation and thermal pollution from power plants. In addition, introduced biota have had deleterious effects on the ecological condition of rivers.
The degradation of Australia's rivers is widely recognised but, until recently, there was no coordinated effort to monitor or manage pollution and disturbance. The toxic blue-green algal blooms along 1000 km of the Darling river, New South Wales, in 1991 served to focus public and political attention on the condition of Australia's rivers, and following this, in December 1992, the Commonwealth Government announced a major new initiative to tackle the health and management of Australia's waterways. The initiative, known as the National River Health Program (NRHP) had three main aims:
- to monitor and assess the ecological condition of Australia's rivers,
- to assess the effectiveness of current management practices,
- to provide better ecological and hydrological data on which to base management decisions.
The NRHP has had two phases. The major component of the first phase, which commenced in 1993, was the Monitoring River Health Initiative (MRHI). The MRHI was a national program that used aquatic macroinvertebrates to assess the ecological condition, or health, of Australia's rivers. The primary aim of the MRHI was to develop models that predict the invertebrates likely to occur at an undisturbed site based on its geographic position and the habitat at the site. The predicted community is then compared with the actual community and the ratio of observed/expected families is used as a measure of ecological condition. The MRHI models are known as AusRivAS models (Australian River Assessment Scheme). AusRivAS is based on the British bioassessment system RIVPACS (River Invertebrate Prediction and Classification System), which also uses aquatic invertebrates and has been developed and refined during the past 15 years.
The second phase of the NRHP involved using AusRivAS models in the First National Assessment of River Health (FNARH). The FNARH commenced in 1997 and by late 1999 nearly 5000 sites throughout Australia had been biologically assessed. In Western Australia about 650 sites, throughout the State, were assessed, some several times in different seasons and years.
The rationale behind the use of macroinvertebrates as for river assessment is that they are highly sensitive to pollutants and changes in river flow and the condition of channels and floodplains. In addition, if the structure of the macroinvertebrate community is intact, it is likely that the important ecological functions of the river will be intact. Thus, bioassessment using macroinvertebrate communities provides the good measure of the ecological condition and health of a river.
From 1994-1997, the MRHI was administered by the Land and Water Resources Research and Development Corporation (LWRRDC), in collaboration with the Department of Environment, Sport and Territories (DEST). During 1998 Environment Australia (EA) took over the project with funding coming from the National Heritage Trust. While AusRivAS is an Australia-wide initiative being coordinated and funded by the Commonwealth Government, the program is being implemented by State and Territory Governments. The lead agency for the MRHI and subsequent FNARH in Western Australia has been the Department of Conservation and Land Management, with support from the Water and Rivers Commission.
Western Australian AusRivAS models are based on results of macroinvertebrate sampling at about 250 reference sites on rivers throughout the State. Reference sites were located, as much as possible, on undisturbed rivers, where an intact fauna and river ecology would be expected. In some regions, no such rivers occurred and least-disturbed sites were used as reference, although such reference sites were often discarded during the model-building process because of discrepancies in their fauna.