Comparison of biotic index values for invertebrate collections from natural and artificial substrates

Abstract

SUMMARY. 1. We evaluated the use of a biotic index in a small mountain stream on the basis of collections of benthic macroinvertebrates from both artificial and natural substrates in years of above and below normal discharge.2. Invertebrate composition sampled from artificial and natural substrates exhibited inverse trends in density associated with discharge patterns.3. Biotic index values derived from artificial substrates provided a more consistent and accurate description of the water quality of a small stream between years of high and low discharge than did those determined from natural substrates.