Benthic invertebrate fauna of an aseasonal tropical mountain stream on Bougainville Island, Papua New Guinea

Abstract

The benthic invertebrate fauna of Konaiano Creek, a small aseasonal mountain rainforest stream on Bougainville Island, Papua New Guinea, was studied over a period of 22 months. Konaiano Creek supported a diverse, mostly undescribed, fauna dominated by two closely related species of Simuliidae (55% of the total specimens collected) and two species of Hydropsychidae. Over 182 taxa were recorded, more than half of which were Diptera. Species richness in Konaiano Creek was quite high in comparison with that of similar streams in both tropical and temperate regions. There were 31 species of Trichoptera, but there were no Plecoptera, Mollusca, Psephenidae, or Megaloptera. Although many groups of marine origin such as Gastropoda, Atyidae, Palaemonidae and fish inhabited nearby coastal rivers, these animals were apparently unable to colonize high mountain streams because of the torrential, barren nature of the mid-mountain streams that sharply divide the headwater streams from the lowland rivers on Bougainville Island.