Is Catchment Imperviousness a Keystone Factor Degrading Urban Waterways? A Case Study from a Partly Urbanised Catchment (Georges River, South-Eastern Australia)
The extent of catchment impervious surface is recognised to be an important factor associated with the condition of urban freshwater streams. We tested the hypothesis that the degree of catchment imperviousness predicted the relative ecological condition of freshwater reaches within the network of streams and rivers in the partly urbanised Georges River catchment in temperate south-eastern Australia. The 2-year study involved two spring and two autumn assessments of water quality (chemical and physical) and ecological condition, using benthic macroinvertebrates, riparian vegetation and calculation of catchment imperviousness. The study revealed that highly urbanised streams had strongly degraded water quality and macroinvertebrate communities, compared to clean non-urban reference streams. We found three clear groups of sites with varying degrees of ecological condition, being categorised according to the level of catchment effective imperviousness (low <5.0 %, moderate = 5.0–18.0 % and high >18.0 %). Water pollution also varied according to these categories. A combination of two water chemistry attributes (total nitrogen and calcium), along with catchment imperviousness and riparian vegetation condition, were identified as being the factors most strongly associated with variation of macroinvertebrate communities. Based on our results, we recommend that protection of the ecological condition of streams should focus on not only water quality but also include catchment imperviousness and riparian vegetation condition.
KeywordsUrban stream syndrome Urban waterways Aquatic macroinvertebrates Water pollution Imperviousness
This study was supported by the Georges River Combined Councils' Committee, the NSW Government and Commonwealth Government. Community volunteers generously assisted with field work. All sampling was undertaken with permission of landholders and the NSW National Parks and Wildlife Service.
- ANZECC (Australian and New Zealand Environment and Conservation Council), & ARMCANZ (Agriculture and Resource Management Council of Australia and New Zealand). (2000). Australian and New Zealand guidelines for fresh and marine waters. National water quality management strategy paper no. 4. Canberra: Australian and New Zealand Environment and Conservation Council/Agriculture and Resource Management Council of Australia and New Zealand.Google Scholar
- APHA (American Public Health Association). (1998). Standard methods for the examination of water and wastewater (20th ed.). Washington, DC: American Public Health Association.Google Scholar
- Bowman, M. F., & Bailey, R. C. (1997). Does taxonomic resolution affect the multivariate description of the structure of freshwater benthic macroinvertebrate communities? Canadian Journal of Fisheries and Aquatic Sciences, 54, 1802–1807.Google Scholar
- Cairns, J., Jr., & Pratt, J. R. (1993). A history of biological monitoring using benthic macroinvertebrates. In D. M. Rosenberg & V. H. Resh (Eds.), Freshwater biomonitoring and benthic macroinvertebrates (pp. 10–27). London: Chapman & Hall.Google Scholar
- Chessman, B. C. (2003b). SIGNAL 2—a scoring system for macro-invertebrate (‘water bugs’) in Australian Rivers, monitoring river heath initiative technical report no 31. Canberra: Commonwealth of Australia.Google Scholar
- Cuffney, T. F., Zappia, H., Giddings, E. M. P., & Coles, J. F. (2005). Effects of urbanization on benthic macroinvertebrate assemblages in contrasting environmental settings: Boston, Massachusetts; Birmingham, Alabama; and Salt Lake City, Utah. American Fisheries Society Symposium, 47, 361–408.Google Scholar
- DEST, EPA, & WRDC. (1994). River bioassessment manual. Version 1.0, National River Processes and Management Program, Monitoring River Health Initiative. Canberra: Department of the Environment, Sport and Territories, Environment Protection Agency, and Land and Water Research and Development Corporation.Google Scholar
- Dunn, T., & Leopold, L. B. (1978). Water in environmental planning. San Francisco: Freeman.Google Scholar
- Gooderham, J., & Tsyrlin, E. (2002). The waterbug book—guide to the freshwater macroinvertebrates of temperate Australia. Melbourne: CSIRO.Google Scholar
- Hawking, J. H., & Smith, F. J. (1997). Colour guide to invertebrates of Australian inland waters. Identification guide no. 8. Albury: Cooperative Research Centre for Freshwater Ecology.Google Scholar
- Jansen, A., Robertson, A., Thompson, L., & Wilson, A. (2004). Development and application of a method for the rapid appraisal of riparian condition, River Management Technical Guideline no. 4. Canberra: Land & Water Australia.Google Scholar
- Krebs, C. (1989). Ecological methodology. New York: Harper Collins.Google Scholar
- Morgan, R. P., & Cushman, S. E. (2005). Urbanization effects on stream fish assemblages in Maryland, USA. Journal of the North American Benthological Society, 24, 643–655.Google Scholar
- Rosenberg, D. M., & Resh, V. H. (1993). Freshwater biomonitoring and benthic macroinvertebrates. New York: Chapman & Hall.Google Scholar
- Stranko, S. A., Hilderbrand, R. H., Morgan, R. P., Staley, M. W., Becker, A. J., Roseberry-Lincoln, A., et al. (2008). Brook trout declines with land cover and temperature changes in Maryland. Journal of the North American Benthological Society, 28, 1223–1232.Google Scholar
- Sydney Metropolitan Catchment Management Authority (SMCMA). (2012). Georges River. (http://www.sydney.cma.nsw.gov.au/georgesriver.html). Accessed 5 July 2012.
- Walsh, C. J., Leonard, A. W., Ladson, A. R., & Fletcher, T. D. (2004). Urban stormwater and the ecology of streams. Canberra: Cooperative Research Centre for Freshwater Ecology and Cooperative Research Centre for Catchment Hydrology.Google Scholar
- Walsh, C. J., Fletcher, T. D., & Ladson, A. R. (2005). Stream restoration in urban catchments through re-design stormwater systems: looking to the catchment to save the stream. Journal of the North American Benthological Society, 24, 690–750.Google Scholar
- Walsh, C. J., Roy, A. H., Feminella, J. W., Cottingham, P. D., Groffman, P. M., & Morgan, R. P., II. (2005). The urban stream syndrome: current knowledge and the search for a cure. Journal of the North American Benthological Society, 24, 706–723.Google Scholar