Australian River Assessment System: Improving AusRivAS Analytical Methods - DDRAM and E-Ball (Phase I Final Report)
S Linke, R Norris and D P. Faith
Cooperative Research Centre for Freshwater Ecology
Australian Museum, Sydney
Monitoring River Health Initiative Technical Report Number 27
Environment Australia, 2002
About this report
Bioassessment is gaining acceptance as a complement to traditional methods of measuring human effects on river ecosystem health, based on the measurement of physical and chemical variables. These traditional approaches are often inadequate to detect and interpret ecosystem damage (Reice and Wohlenberg, 1993). Bioassessment reveals "hidden impacts" such as new toxicants or changes in physical properties of the environment. Another advantage of bioassessment or biomonitoring is that long-term effects on the ecosystem, altering the community in both structure and function, can be studied. Further, disturbance can be detected after the cause of damage passed through the system (Ghetti & Ravera 1993).
Aquatic macroinvertebrates are the most commonly used indicator organisms (Resh & McElravy 1993) for several reasons. They are ubiquitous and diverse, allowing detection of a variety of perturbations in a range of aquatic habitats. Benthic macroinvertebrates have relatively long life cycles, compared to groups such as zooplankton and phytoplankton, making the temporal scale of the population response appropriate for pollution response (Rosenberg & Resh 1993). Technical advantages of using benthic macroinvertebrates include relatively inexpensive quantitative sampling, an acceptable working knowledge of their taxonomy and their response to environmental damage, as well as a range of established methods for data analysis. (Hellawell 1986, Rosenberg & Resh 1993).
The first use of benthos in lotic bioassessment dates back to the "Saprobien System" (Kolkwitz & Marsson 1909), an empirical approach that assesses sites by the tolerance of their invertebrate assemblage to organic pollution. A number of related analytical approaches have evolved. The Saprobien concept was revised and extended by European scientists (Kolkwitz 1950, Liebmann 1962, Sladecek 1965), although only the Netherlands and Germany currently use Saprobien Systems. Later, diversity indices (Shannon & Weaver 1949, Simpson 1949, Margalef 1958, Cairns & Dickson 1971) were widely adopted as measures of community structure and for environmental assessment (Hellawell 1986). Diversity indices have been heavily criticized, with Green (1979) calling them "answers to which questions have not been found" in his influential book about sampling design. Although many diversity indices are still in use, their importance is decreasing, opening the way for modern biotic indices (Cairns & Pratt 1993).
More recently, biotic indices based on taxon abundance data have combined the ecological sensitivity of the Saprobien System and the simple output of diversity indices (Reynoldson & Metcalfe-Smith 1992). the earliest such index is the Trent Biotic Index (Woodiwiss 1960, Persoone & De Pauw 1979). Biotic indices in current use are described by Armitage et al. (1983), Chessman et al. (1995, 1997), Hilsenhoff (1988) and Stark (1993). More extensive reviews of biotic indices are found in Washington (1984) and Metcalfe (1989).