Hydropeaking intensity and dam proximity limit aquatic invertebrate diversity in the Colorado River Basin

River biodiversity is threatened globally by hydropower dams, and there a need to understand how dam management favors certain species while filtering out others. We examined aquatic invertebrate communities within the tailwaters 0–24 km downstream of seven large dams in Colorado Basin western United States. quantified dominance, richness, abundance, biomass at multiple locations individual across basin identified biological community responses associated with operations distance from dam. found that each tailwater was dominated 3–7 taxa, accounting for 95% total abundance. Half these dominant taxa were non-insect, non-flying thus unavailable terrestrial consumers. Consistent previous studies, insects sensitive negatively hydropeaking intensity (magnitude daily flow fluctuations generation), which limits composition potentially quality food base. While abundance did not change increasing insect all increased, suggesting impacts are most acute immediately dams. Our results demonstrate experiencing support high abundances invertebrate, but diversity low.