River Murray Biological Monitoring Program
This project was initiated in 1980 after concern for river health emerged in the 1970s. During its 35 year history a number of different organisations have contributed to the project's unique database. The primary aim of this program is to sample and record the aquatic macroinvertebrate populations of the River Murray and its larger tributaries to provide a long-term biological record that complements existing physical and chemical data collected by the Murray–Darling Basin Authority.
The Research Centre for Freshwater Ecosystems collect and process samples twice a year and report annually to the Murray–Darling Basin Authority on the status and temporal shift of freshwater macroinvertebrate communities of the Murray River catchment. The Murray–Darling Basin Authority’s basin-wide environmental watering strategy which builds on the Basin Plan has a focus on achieving long term enduring environmental changes through a basin-wide perspective. The River Murray biological monitoring program provides an ideal mechanism to measure the success of environmental watering on instream biota of the River Murray system.
The objectives are to:
- provide long term baseline biological information for the rivers, collected using standardised methods to facilitate comparisons regionally and nationally.
- provide the basis for assessment of the health of the river ecosystems such that spatial and temporal patterns in river health can be assessed.
- provide biological data to inform reporting, standards and guidelines for management and policy decision making, and development and evaluation of water quality management strategies for rivers.
- maintain a voucher collection of preserved macroinvertebrate specimens as a reference for the conservation of rare and endangered aquatic species.
Macroinvertebrate data is used to determine:
- taxa richness (number of distinct taxa)
- abundance (number of animals)
- percentage composition (the number of animals in a taxon as a percentage of the total number of animals)
- EPT Index (number of Ephemeroptera, Plecoptera and Trichoptera taxa).
- Mulitvariate analysis of macroinvertebrate assemblages.
Monitoring currently occurs at 12 sites:
- 7 sites on the river Murray from site 800 at Biggara in the upper Murray Valley to site 814 at Woods Point, South Australia (2500 km downstream)
- 1 site on the Darling River at Burtundy to assess the influence of the northern basin streams
- 4 sites in the Mitta Mitta River sub-catchment (502–513) to monitor the effect of Dartmouth Dam on biological communities.
Principle coordinate ordination (PCO) indicating the change in the macroinvertebrate communities along the River Murray over time. The trajectories suggest homogenization of communities since 1980, with a slight shift back toward the earlier state following the flooding in 2010.
The River Murray biological monitoring project is unique; it covers over 2500 km of river length and has been operating since 1980. This project has been fundamental in describing the biodiversity of macroinvertebrate fauna, gauging the distribution of endangered species, evaluating the spread of invasive species, and determining the health of the rivers in response to climate, flow, water quality and river management changes.
Analysis of the data has revealed a substantial decline in biological health throughout the River Murray between 1996 and 2010; the period also referred to as the millennium drought. During this period species that are associated with poor water quality, habitat and flow conditions (typically considered ‘weedy species’) increased in diversity and abundance while sensitive species declined.
These data also provided valuable insight into the likely response of the Murray River fauna under predicted conditions of reduced water availability and elevated stream temperatures.
With more than 30 years of monitoring data prior to the implementation of the Basin Plan, this program is in a unique position to assess the biological responses to this major restoration program once it has been implemented. Two key areas for development are envisaged for the future, which will bring major benefits to the biological monitoring programs of the Murray–Darling Basin Authority, and the wider management/scientific community. One is to develop predictive modelling capabilities based on the biological and water quality monitoring programs. The other is the development of a deoxyribonucleic acid (DNA) database of the macroinvertebrate communities of the Murray–Darling Basin.