Donald Edward

Surber and kick sampling: a comparison for the assessment of macroinvertebrate community structure in streams of south-western Australia

Macroinvertebrate community 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 Sorensens and Czekanowskis 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.

Archaeochlus Brundin: a midge out of time (Diptera: Chironomidae)

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.

Botryocladius gen.n: a new transantarctic genus of orthocladiine midge (Diptera: Chironomidae)

A new genus of orthocladiine Chironomidae, Botryocladius (type species B. grapeth sp.n. from eastern Australia) is described and illustrated in all life history stages. All thirteen included species are described as new, six from eastern Australia (B. grapeth, B. brindabella, B. mdfrc, B. collessi, B. tasmania, B. australoalpinus), two from Western Australia (B. bibulmun and B. freemani), one from ephemeral streams in Australia (B. petrophilus) and four from Patagonian Argentina and Chile (B. edwardsi, B. glacialis, B. mapuche and B. tronador). All Australian species are known from at least pupal exuviae, most from adult males and several from larvae. In contrast, only B. edwardsi amongst Neotropical species is known from the adult male; all others are described from pupal exuviae. The immature stages are lotic in Australian permanent and temporary streams and Patagonian glacial streams and rivers, and lentic in Neotropical glacial‐fed and Australian subalpine lakes. Botryocladius appears to belong with a grouping centred on two formally undescribed taxa from Australia. The genus evidently demonstrates a vicariant distribution with at least two sister‐group relationships between South American and Australian taxa, providing a minimum dating for the clade of 38 Ma., with apparent absence from New Zealand indicating a maximum date of 80 Ma.

A systematic reappraisal of the Australian Aphroteniinae (Diptera: Chironomidae) with dating from vicariance biogeography

Abstract. The chironomid subfamily Aphroteniinae is revised for the Australian fauna. The larval‐based genus Anaphrotenia Brundin is synonymized with Aphroteniella Brundin, and Anaphrotenia lacustris Brundin with Aphroteniella filicomis Brundin, and all stages redescribed and illustrated. A second Australian species, Aphroteniella tenuicornis Brundin, has been reared and the larva is described and the pupa and male redescribed here.

Assessing river health in south-western Australia: comparison of macroinvertebrates at family level with Chironomidae at species level

In response to growing community concern about declining water quality in the Nations rivers and streams, the Australian Government established the National River Health Program (NRHP) in 1992. The first objective of the NRHP, to assess and monitor the ecological condition of Australian rivers, was met by the development of the Australian River Assessment Scheme (AUSRIVAS); a set of predictive models which use changes in assemblages of aquatic macroinvertebrates to rapidly bio-assess the ecological condition of the Nations rivers. AUSRIVAS is based on the British RIVPACS model, which uses aquatic macroinvertebrates as indicators of river health (WRIGHT et al. 1984, WRIGHT 1995) and has been successful in assessing river condition on a national scale (ARMITAGE et al. 1987). Cost-effective rapid bioassessment (RBA) is a priority of the NRHP. For this reason AUSRIVAS uses macroinvertebrates identified to family level, which is considered adequate for discrimination in RBA, and is less time-consuming than other approaches (MARCHANT et al. 1995, WRIGHT 1995, WRIGHT et al. 1995, BoWMAN & BAILEY 1997). Although based on RIVPACS, AUSRIVAS differs in that specific riverine habitats are sampled and processed separately. The change to specific habitat sampling was based o n HUMPHRIES e t al. ( 1996) an d PARSONS & NORRIS (1996). Habitat and bioregion-specific models were constructed following a series of standardised protocols. Firstly, Reference sites were classified into groups of sites with similar community composition, stepwise discriminant function analysis was then used to identifY environmental variables that best predicted the si tes to the correct group. The number of farnilies expected (E) to occur at a site was then calculated by multiplying the probability of a si te belonging to a classification group by the probability of a si te occurring in that group then summing the products. Only taxa with a probability of~50% of occurring at a si te were considered when calculating E values (SIMPSON & NüRRIS 2000).

The association of Glacidorbis occidentalis Bunn and Stoddart 1983 (Gastropoda: Glacidorbidae) with intermittently-flowing, forest streams in south-western Australia

Abstract The distribution of Glacidorbis occidentalis is considerably more widespread than previously recorded, occurring in streams throughout the northern jarrah forest, Western Australia. The species is largely restricted to forest streams with intermittent flow regimes and does not occur in lowland rivers west of the Darling Range. The association of this species with intermittently-flowing streams is atypical of the genus and cannot be attributed to differences in stream morphology or water chemistry. G. occidentalis is one of the most common gastropods in the intermittent streams of the northern jarrah forest though it rarely comprises more than a few percent of the total fauna. Adult snails oversummer in the stream bed and emerge shortly after the first winter flows. The species produces brooded young which appear to be released as veligers during the winter months.