Macro-invertebrates, zooplankton and water quality variables were sampled at 33 wetlands near Perth, Western Australia, in January-February 1989. Wetlands were classified and ordinated using the invertebrate data. Correlations of environmental variables with the ordination were calculated and the importance of seasonality and geomorphology of the wetlands were investigated. The wetlands were also classified and ordinated using the chemical data. Analysis of variance was used to compare species richness, abundances of all invertebrates, macro-invertebrates, copepods and total phosphorus levels among groups. Six groups of wetlands were identified from the invertebrate data, two of which were outliers on the basis of very low pH and high salinity, respectively. The majority of the wetlands grouped on the basis of their degree of nutrient enrichment and colour. The analyses of chemical data gave similar groups. The coloured wetlands and least nutrient enriched non-coloured wetlands were identified as being closest to the probable state of wetlands prior to European settlement. The greatest numbers of rare species were found in wetlands from these two groups. Species richness was significantly higher in the moderately enriched wetlands than in any other group but decreased in the most enriched wetlands where abundances of invertebrates were highest. Changes in community composition among the groups of wetlands are discussed. The most highly nutrient enriched wetlands were dominated by cosmopolitan species with high abundances, whereas less enriched and coloured wetlands had species with more restricted distributions and lower abundances.

Two sets of data were used to evaluate the procedure for rapid assessment of rivers described by Chessman (1995): (i) 72 samples from four habitats at 27 sites on the Nepean River and tributaries; and (ii) 41 riffle samples from the Blue Mountains. In the Nepean system all the sites had moderate anthropogenic disturbance but none had gross organic pollution. There were, however, conductivity differences related to mixed sandstone and shale lithology. The sites differed widely in natural physical attributes such as stream order (2-6) and altitude (40-600 m). The Blue Mountains data included sites with little or no anthropogenic disturbance and sites greatly affected by organic pollution. There was again a wide range of altitudes (15-1000 m) but stream orders were more restricted (1-4). The occurrence of macroinvertebrate families was analysed using cluster analysis (TWINSPAN) and ordination (semi-strong hybrid multidimensional scaling). Relationships between the pattems observed, the SIGNAL biotic index, and physical and chemical data were investigated. The Nepean data showed that the sample size of 100 animals used in the rapid procedure was sufficient to reveal natural distribution patterns in the communities, and that SIGNAL was essentially independent of these pattems. In the Blue Mountains, water pollution had a greater effect on macroinvertebrate communities than the physical habitat, and SIGNAL distinguished sites with differing levels of pollution.