Limnological characteristics of a South Australian intermittent stream, Brown Hill Creek

Abstract

Selected physicochemical features, litter input rates and the abundance and distribution of common invertebrates were studied in Brown Hill Creek, a small intermittent stream that flows annually for about 6 months near Adelaide, South Australia. Permanent pools had very highly coloured waters and long-term low oxygen levels in summer, apparently related to seasonality of litter inputs from Eucalyptus obliqua. The larvae of only two species of fully aquatic insect, Leptorussa darlingtoni and Lectrides varians (Trichoptera : Leptoceridae), remained in permanent pools once flow had ceased. A more diverse fauna, dominated by Riekoperla naso (Plecoptera : Gripopterygidae), was present during winter when the stream was flowing. Most of the more abundant insect species had extremely unusual life histories, including terrestrial egg deposition (Leptorussa darlingtoni and Lectrides varians), rapid larval growth at low temperatures (Riekoperla naso), and advanced ovoviviparity (Austrocerca tasmanica).