Capabilities: Freshwater Macro-Invertebrate Monitoring1

Fresh Ben Aquatic invertebrates are sensitive to change in flow regime, water quality and habitat condition. They are consequently frequently used as biological indicators of waterway health, and to assess impacts on freshwater ecosystems. The diversity, composition and abundance of macro-invertebrate communities provide a general measure of the ecological health of waterways.

The better the water quality and habitat condition, the greater the biodiversity of macro-invertebrate communities. In addition, the presence or absence of certain species can be directly attributed to water quality. Some species are extremely tolerant of pollution, and there is a gradient of tolerance that ranges up to those that are extremely sensitive.

The taxonomic composition of macro-invertebrate communities is often used to determine the 'health' of waterways. The SIGNAL (Stream Invertebrate Grade Number ' Average Level) Index was developed by the National River Health Program as a tool for the bio-assessment of water pollution. Each type of macro-invertebrate has a grade number between 1 and 10 based on their sensitivity to various pollutants. Plecoptera (stoneflies), Ephemoptera (mayflies), and Trichoptera (caddisflies) species are particularly sensitive to disturbance. These insects are known as the PET group and are frequently used as a measure of ecosystem health, with typically more PET families in sites with good habitat and water quality than in degraded sites. The trophic structure and diversity of macro-invertebrate communities are also used to evaluate ecosystem health.

Macro-invertebrates have been selected as the key indicator group being developed for the bio-assessment of the health of Australia's streams and rivers under the National River Health Program.

FRC has been involved in a range of studies using freshwater macro-invertebrates as indicators of ecosystem health. Recent projects include:

  • Toowoomba Bypass Macro-invertebrate Survey, Main Roads.

    FRC Environmental was commissioned to undertake a freshwater macro-invertebrate survey at seven sites nominated along the proposed alignment of the Toowoomba Bypass road. The SIGNAL 2 index and number of families were calculated, and stream health assessments were undertaken for each site.
  • Investigation of the Environmental Impact of Cooling Water Blowdown at Tarong Power Station; Austa Electric.

    This study investigated the residual concentrations of contaminants in the waters and sediments of the power stations impoundments and the receiving waterway (Meandu Creek). Sampling of benthic biota was also undertaken. The impact of discharge on the biota of impoundments and receiving waters was assessed using a variety of statistical analyses.
  • Fin-fish and Macro-invertebrate Survey of Cooroy Creek, Cooroy, Noosa Council.

    The planned expansion of the Cooroy Waste Water Treatment Plant required the design and conduct of a fin-fish and macro-invertebrate survey for the Cooroy Six Mile Creek system. The survey focused on the detection of possible rare and endangered species; and the use of C and N isotopes to trace the source of nutrients in both water and plant tissue. An assessment of the current level of effluent-related impact was completed and recommendations made relating to water quality and effluent treatment.
  • Pioneer River Fish and Macroinvertebrate Survey, Mackay Hinterland, Qld. Dept. Natural Resources.

    The proposed raising of Kinchant Dam, and the predicted consequences for down stream flows, required an assessment of the finfish and macro-invertebrate fauna of the Pioneer River downstream.
  • O'Connell River Weir and Lethebridge Off-Stream Storage EIS, Nth Queensland Cane Farmers.

    The proposed construction of a weir on the OConnell River and an offstream storage on Thompson Creek required an EIS. FRC undertook a comprehensive description of the waterways aquatic flora and fauna (including benthic macro-invertebrates), and an assessment of the significance of the waterways to recreational fishing. The impacts of construction and operation were assessed for each storage, and recommendations for environmental management provided. An assessment of the need, and appropriate design, of a fishway for the proposed weir was an integral component of the study.
  • Cedar Grove Weir EIS, Logan River, Dept. Natural Resources.

    The proposed construction of a weir above the tidal reaches of the Logan River required an environmental appraisal of the rivers aquatic macrophytes, freshwater macro- invertebrates and fin-fish. FRC undertook field surveys, including a netting program to characterise the rivers aquatic flora and fauna, and to assess their sensitivity to the impacts of altered stream flow, altered habitat, and water quality. FRC also contributed to an EMP designed to minimise and mitigate the impacts of weir construction and operation. The need for a fishway to be incorporated into the weir

    • 1 FRC also offers expertise in the assessment of estuarine invertebrate communities: see Capability Statement 'Marine and Estuarine Invertebrate Monitoring'.

    2 ANZECC & ARMCANZ 2000, Australian and New Zealand Guidelines for Fresh and Marine Water Quality, National Water Quality Management Strategy, Australian and New Zealand Environment and Conservation Council & Agriculture and Resource Management Council of Australia and New Zealand.