AbstractsBiology & Animal Science

This thesis revealed Australian lakes to be richer in chironomid (Diptera: Insecta) species than was previously recognised. A methodology for the collection of chironomid exuviae from lakes was developed using a 12-month study of exuviae from a single lake, Lake McKenzie, Jervis Bay. The method is a rapid and effective way to produce an inventory of species living within a lake. In addition, a distinct biogeographical pattern was detected for chironomid species from a survey of chironomids from southern and eastern Australian freshwater lakes. Geographical location of the lake was more influential on the distribution of chironomid species than was the type of lake. The majority of lake dwelling chironomid species in this investigation were restricted to lakes within one of four geographic lake regions; Tasmania, south-eastern Australian mainland, Fraser Island or tropical north Queensland. A temporal investigation of chironomid exuviae was conducted on a pair of small upland Blue Mountain waterways. Abundance and species richness of exuviae exhibited diurnal patterns. A chemical and macro-invertebrate survey of zinc and sewage organic waste discharges to upland streams in the Blue Mountains detected marked ecological impairment. Macro-invertebrate families responded in different ways to the two different types of waste discharge. According to the family-level results, chironomid larvae responded negatively (reduced abundance) to the zinc pollution and positively (increased abundance) to the sewage pollution. Another major finding from this thesis was that chironomid species assemblages, in the streams surveyed, were strongly impaired by zinc-contaminated mine drainage and sewage effluent. This differed to the family-level larval results. This thesis provided the first Australian evidence that many chironomid species are intolerant of heavy-metal pollution. This research also revealed further evidence that many chironomids species are intolerant of sewage pollution. Doctor of Philosophy (PhD)