Summary 1. AusRivAS (Australian River Assessment Scheme) models were developed, using macroinvertebrates as indicators, to assess the ecological condition of rivers in Western Australia as part of an Australia‐wide program. The models were based on data from 188 minimally disturbed reference sites and are similar to RIVPACS models used in Britain. The major habitats in the rivers (macrophyte, channel) were sampled separately and macroinvertebrates collected were identified to family level. 2. Laboratory sorting of preserved macroinvertebrate samples recovered about 90% of families present when 150 animals were collected, whereas live picking in the field recovered only 76%. 3. Reference sites clustered into five groups on the basis of macroinvertebrate families present. Using seven physical variables, a discriminant function allocated 73% of sites to the correct classification group. A discriminant function based on seven physical and two chemical variables allocated 81% of sites to the correct group. However, when the same reference sites were re‐sampled the following year, the nine variable discriminant function misallocated more sites than the seven variable function, owing to annual fluctuations in water chemistry that were not accompanied by changes in fauna. 4. In preliminary testing, the wet season channel model correctly assessed 80% of reference sites as undisturbed in the year subsequent to model building (10% of sites were expected to rate as disturbed because the 10th percentile was used as the threshold for disturbance). Nine sites from an independent data set, all thought to be disturbed, were assessed as such by the model. Results from twenty test sites, chosen because they represented a wide range of ecological condition, were less clear‐cut. In its current state the model reliably distinguishes undisturbed and severely disturbed sites. Subtle impacts are either detected inconsistently or do not affect ecological condition.

1. Streams of the northern jarrah forest,, Western Australia, were sampled at twelve sites from December 1981 to December 1982 to examine spatial and temporal changes in the structure of the macroinvertebrate community.2. The climate of this region is quite predictable by Australian standards and each year a hot, dry summer is followed by a mild, wet winter. Highest stream discharge occurs during winter (June-November) reducing to negligible flow over late summer and autumn (January-May). The low flows in summer were associated with warm water, lower dissolved oxygen, increased concentrations of cations and, in many cases, lower pH.3. Temporal changes in abundance, diversity and evenness indicated that the invertebrate fauna became dominated by a few taxa during the summer months. Major spatial and temporal changes in the composition of the fauna were detected by classification and ordination. Summer and winter faunas were identified at most sites and were clearly associated with the seasonal changes in the physical and chemical environment. This seasonaiity is not typical of stream systems previously studied in Australia. Large spatial differences also occurred over small distances among sites in two similar-sized forested catchments.4. Multiple discriminant analysis and stepwise multiple regression analysis showed that velocity and depth were highly associated with the observed temporal changes in the fauna, though other variables, including concentrations of cations and water temperature, were also important. Spatial differences were correlated with concentrations of cations which may simply reflect differences in the geologies of the catchments.

Macroinvertebratecommunity structure was compared in benthic samples taken by Surber and kick methods from a lotic system in south-western Australia. Eleven sites were sampled concurrently in winter, spring and summer 1987.Surber samples contained fewer individuals and more taxa, particularly those with a low frequency of occurrence. This was attributed to the lower surface area, but greater intensity of Surber sampling. It is proposed that the Surber method is more suited to taking cryptic and closely adherent taxa in sites with a highly heterogeneous substratum.Percentage similarity between paired Surber and kick samples was determined by Sorensen's and Czekanowski's coefficients, with mean values of 66% and 60% for June, 61% and 49% for September and 66% and 49% for December respectively. Ordination demonstrated a division of upland from lowland sites on axis 1, with a separation of paired-samples on axis 2. This pattern held across qualitative and quantitative datasets, with and without a downweighting on rare taxa. At each level of classification fewer paired-samples separated in qualitative than quantitative datasets.Kick sampling provided a substantial saving in costs over Surber sampling, particularly when qualitative data were utilised, making the method suitable for routine, biological monitoring. However, the initial use of replicated Surber sampling, particularly in areas that have not been previously sampled is recommended for environmental impact studies to detect rare taxa, that may be endangered.

-Fifty-six sites, representing 53 wetlands, were surveyed in the southern Carnarvon Basin in 1994 and 1995 with the aim of documenting the waterbird and aquatic invertebrate fauna of the region. Most sites were surveyed in both winter and summer, although some contained water only one occasion. Altogether 57 waterbird species were recorded, with 29 292 waterbirds of 25 species on Lake MacLeod in October 1994. River pools were shown to be relatively important for waterbirds, while many freshwater claypans were little used.At least 492 species of aquatic invertebrate were collected. The invertebrate fauna was characterized by the low frequency with which taxa occurred: a third of the species were collected at a single site on only one occasion. Patterns of occurrence were not strongly seasonal. Many undescribed species were found and many range extensions were. recorded, reflecting lack of previous aquatic invertebrate work in the region. The level of regional endemicity could not be assessed adequately, although it is probably comparatively low. In terms of their invertebrate fauna, five types of wetlands were distinguished: river pools, rock pools and larger flowing streams; seeps, springs and smaller creeks; freshwater claypans; birridas; and Lake MacLeod. Environmental factors to which invertebrates appeared to respond were ratio of calcium/ alkalinity, total dissolved solids, turbidity, colour, flow, longitude and nutrients, although some factors were inter-correlated.Additional surveys should find extra species of waterbird and, more particularly, aquatic invertebrate using wetlands of the southern Carnarvon Basin. For many invertebrates, occurrences are too sparse for effective protection of species within a nature reserve system and other mechanisms will be required to ensure their conservation. Comparison of site classifications based on waterbird, aquatic invertebrate and plant data showed patterns among sites identified using one element of the biota did not reflect patterns shown by other elements. This suggests that, until further work has identified an element that reflects the whole wetland community, as many biotic elements as possible should be surveyed.

Abstract. Archaeochlus, a plesiomorphic genus of Podonominae (Chironomidae), is revised and two new species (biko from Namibia and brundini from southwestern Australia) described. The systematic status of the genus and the tribe Boreochlini is reassessed. Biogeographic evidence, sustained by a fossil record, dates the genus at least to the Upper Jurassic. The ecology of early Chironomidae is suggested to be eurythermic and hygropetric rather than cold stenothermic in lotic waters.