Comparison of the macroinvertebrate faunas of runs and riffles in three New Zealand streams

Abstract

The macroinvertebrate faunas of runs and riffles in three North Island streams were studied during February 1984. In all three streams, both habitats supported similar numbers of taxa and all species found in runs were also present in riffles. No more than two taxa in any one stream were exclusive to riffles, and of these, only the trichop‐teran Costachorema xanthoptera was exclusive to that habitat whenever it was found. In two of the streams (Rangitukia and Waitakaruru), the mean total densities of macroinvertebrates supported by runs and riffles were not significantly different. However, in Kiripaka Stream, higher total densities were found in riffles than in runs. Most of the taxa (63–68%) in each stream had similar densities in runs and riffles, but some (20–30%) were more abundant in riffles and a few (6–12%) were more abundant in runs. Of the nine major taxonomic groups recorded, only Ephemeroptera had consistently higher relative abundances in riffles than runs, whereas Gastropoda and Amphipoda had consistently higher relative abundances in runs. The distribution and abundance of macroinvertebrates are discussed in relation to environmental and biotic factors. The relevance of the data to invertebrate sampling programmes is also discussed.

Keywords:

• macroinvertebrates
• streams
• runs
• riffles
• New Zealand
• distribution
• abundance
• sampling