Interactive effects of urban stormwater drainage, land clearance, and flow regime on stream macroinvertebrate assemblages across a large metropolitan region

Abstract

AbstractUrban impacts on streams are mediated by alteration of land cover and subsurface drainage. Understanding interactions of these 2 effects is critical for urban land and water management. We used boosted regression trees to analyze relationships between environmental predictors, including land-cover measures that indicate urban impacts, and Stream Invertebrate Grade Number Average Level (SIGNAL) or the occurrence of 60 macroinvertebrate families across the Melbourne (Australia) region. SIGNAL and 51 families were negatively correlated with attenuated imperviousness (AI). Twenty-four families exhibited a steep decline in probability of occurrence between 0 and ≤3% AI, consistent across the range of natural discharge (Q). Responses to attenuated forest cover (AF) were more variable among families (39 positive, 15 negative). AF had a less positive influence on SIGNAL at high than at low AI because the many (high SIGNAL-grade) families that were strongly negatively correlated with AI were likely to be a...