Microhabitat preferences of benthic invertebrates in a New Zealand river and the development of in‐stream flow‐habitat models for Deleatidium spp.

Microhabitat preferences of seven groups of New Zealand benthic invertebrates (Deleatidium spp., other mayflies, cased caddisflies, uncased caddisflies, beetles, Diptera, and stoneflies) were investigated and habitat suitability functions for use with the instream flow incremental methodology (IFIM) developed for the predominant group, Deleatidium spp. All invertebrate groups except uncased caddisflies and Deleatidium spp. exhibited significant preferences for at least two of the three habitat variables (substrate, water velocity, and depth) when each habitat variable was considered independently. Significant relationships were found between invertebrate size and at least one habitat variable for all groups except stoneflies. Models of Deleatidium spp. abundance were poor ( r = 0.50–0.58) and generally predicted biomass better than numbers. The best models used all three habitat variables together with an index of the amount of periphyton. Deleatidium spp. abundance in the Waingawa River was most closely related to substrate composition followed by velocity and the amount of periphyton present.