AusRivAS: using macroinvertebrates to assess ecological condition of rivers in Western Australia

Abstract

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.

Are bioassessments based on the Reference Condition Approach (RCA) affected by 'rapid' approaches to sample collection and processing?

“…Although we did not evaluate cost and processing times, we would expect that live-sorting would be significantly faster. Smith et al (1999) found that the cost of laboratory sorted samples was about 20% greater than that of live picking, which was 40% faster than laboratory sorting. Other benefits to the live-sort approach include a reduction in the amount of material that is returned to the lab which is beneficial for hard to reach sites (Chessman, 1995), the need for less expensive equipment and less preservatives, all which benefit community groups (Campbell, 2007).…”

“…The under-representation of certain taxa in live-sorted samples has called into question the accuracy of this method and whether it can be compared with preserved and microscope-aided sorting (Smith et al, 1999;Humphrey et al, 2000;Nichols and Norris, 2006). However, the live-sort method has also been shown to collect more taxa than microscope sorting (Borisko et al, 2007).…”

Establishing microbial baselines to identify indicators of coral reef health

“…Biological indicators are a wellestablished monitoring tool for estuarine and freshwater ecosystems 25,26 and also find application in coral reef ecosystems 27 systems, which has led to holistic sampling efforts to establish the first microbial baselines for soils and marine environments. We argue that the establishment and ongoing assessment of such microbial baselines will be crucial to understanding microbial dynamics in response to broad ranging anthropogenic impacts.…”

Impacts of deep open drains on water quality and biodiversity of receiving waterways in the Wheatbelt of Western Australia

“…Macro-invertebrates have been selected as the key indicator group for assessment of the health of Australia's rivers using biological indicators under the National River Health Program (Smith et al, 1999). Macro-invertebrates are found in most habitats, generally have limited mobility, are easy to catch using standard collecting methods, and have a range of sensitivities to changes in water quality and habitats, and are thus good indicators of ecological 'health'.…”