Insect faunas of acidic coal mine drainages in Westland, New Zealand

Insect faunas at 10 stream sites affected by acidic drainage from abandoned coal mines were examined in North Westland. Stream water pH ranged from 2.6 to 4.2 and concentrations of dissolved aluminium and iron were elevated at all sites. Larval Ephemeroptera, Plecoptera, Trichoptera, Megaloptera, Coleoptera and Diptera were found at various sites, with species of Chironomidae (Diptera), Scirtidae (Coleoptera), Kokiriidae and Oeconesidae (both Trichoptera) below pH 3. The occurrence of caddisfly larvae belonging to four families at pH>3.6 is noteworthy and consistent with the hypothesis that many New Zealand stream insects are habitat generalists that tolerate a wide range of physico-chemical conditions.