Testing the Biological Basis of a Stream Habitat Classification Using Benthic Invertebrates

The biological basis of a physical channel unit classification system for a warmwater stream was evaluated. We compared measures of benthic invertebrate communities in 11 channel units in three segments of the Jacks Fork River, Missouri, USA, in two different seasons. Within-group community similarity, as measured by Whittaker's percentage similarity, significantly increased by grouping the entire fauna into three flow habitat groups, and in most cases, community similarity significantly increased by further division into the 11 channel units. Community structure, measured as the ranking of abundance of fauna at the family level of taxonomy, was consistent for the same channel units from different segments of stream during the same season, as well as over time as measured by correlation analysis. Communities most consistent both spatially and over time were edgewaters, high gradient riffles, and races, while the least concordant faunas were from vegetated edgewaters, forewaters, and obstruction pools. Channel units did not maintain unique faunal relations over space or time when measured by the community-level measures of diversity, taxon richness, and abundance. We conclude that channel units have properties not found at other spatial scales and serve as an appropriate scale to coordinate interdisciplinary management goals and strategies.