There are many tools available to assess aquatic ecosystem and catchment health. These tools include in situ water quality measurements and analytical chemistry, macroinvertebrate composition, molecular techniques to investigate presence/absence of fauna and stress responses in target taxa. We trialled multiple tools in three catchments with different surrounding land use types in Victoria (i.e., urban, rural and agricultural), which were expected to be subjected to differing environmental stressors. The aims of the study were to investigate the health of the three waterways, identify the primary stressors, determine which tools were most suitable for each catchment type, and contribute to developing an assessment framework for waterway health and management prioritisation.
The same tools were used at each location in all three catchments and included in situ water quality measurements, chemical analysis of sediment, water and passive samplers, as well as ecotoxicity testing of sediment and water, in situ caged exposures (with the shrimp Paratya australensis) and macroinvertebrate community composition. In addition, a review of other available data was carried out prior to sampling to better understand the pressures on each catchment.
This approach was able to differentiate pressures at sites within catchments and between catchments. Results from the toxicity tests highlighted that sediment from the urban catchment had an impact on survival, growth and development of invertebrates, which was reflected in the chemistry and macroinvertebrate community composition data. Similarly, toxicity tests using sediment and water from the agricultural and rural catchments showed effects on the growth of macroinvertebrates and aquatic plants, and macroinvertebrate communities were impacted at some sites, but this was not reflected in the chemistry data. Habitat and flow are likely to be having an impact in the latter two catchments. The results of these studies and a potential assessment and management prioritisation framework will be discussed.