Benthic invertebrate communities in permanent and temporary lentic habitats in New Zealand

S.A. Wissinger^1,2 and A.R. McIntosh². ¹Biology Department, Allegheny College, Meadville, PA 16335, ²Department of Zoology, University of Canterbury, Christchurch, NZ

Shifts in species composition of benthic communities in lentic habitats often occur along permanence gradients. The species replacements within taxa that underlie these shifts can reflect differences in tolerance to drying and/or in vulnerability to different top predators. In this study we compared benthic invertebrate communities in 1) lakes with fish, 2) lakes without fish, and 3) temporary habitats (wetlands, tarns) without fish on the South Island of New Zealand. Multivariate analysis revealed that community differences among lakes with and without fish were minor compared to differences between lakes and wetlands. Many of the dominant taxa in lakes (regardless of fish presence) were absent (e.g., odonates, caddisflies, Potamopyrgus snails) from wetlands. Invertebrate biomass in wetlands was dominated by epibenthic microcrustaceans (cladocerans and copepods), Diptera (mosquitoes and midges), Hemiptera (water boatman), and Coleoptera. The abundance and diversity of beetles was particularly striking compared to that in fish and fishless lakes. There was little evidence for species replacements within taxa between permanent and temporary habitats; i.e., wetland communities in New Zealand are composed of a subset of the lake fauna that can tolerate desiccation with egg banks (microcrustaceans), dispersal of aquatic adults (Hemiptera and Coleoptera), and/or rapid development and aerial dispersal (Diptera).