Watershed urbanization affects macroinvertebrate community structure and reduces biomass through similar pathways in Piedmont streams, Georgia, USA

Abstract

AbstractWatershed urbanization affects stream macroinvertebrate communities via multiple pathways, including chemical stressors, physical scour, and indirect biological effects such as altered food availability. Different metrics may respond differently to urbanization and may be affected by different pathways. We tested whether macroinvertebrate biomass, community composition, and biotic integrity exhibited consistent responses to watershed urbanization and responded to the same stressors. We quantified macroinvertebrate community composition by biomass and density and estimated aggregate total macroinvertebrate biomass, biomass by functional feeding group, aggregate taxon richness, and biotic indices at 12 sites in urban, suburban, mixed-use, and rural watersheds in the upper Oconee River basin, Georgia, USA. Watershed-scale land use, physicochemical stressors, and biological covariates explained significant variation (∼85%) in community structure based on density or biomass across sites; all 3 groups o...