Empirical application of a framework for aquatic species conservation in Anthropocene rivers under changing conditions

We present an innovative framework for assessing fluvial aquatic species conservation under conditions of an impending regime shift using the case example of the Upper Colorado River Endangered Fish Recovery Program (UCREFRP). We assess the effectiveness of the program actions first, the ecoregional impact of the program second and the adaptive management paradigm in this context third, using mixed qualitative and quantitative approaches. Assessment of program effectiveness utilizes annual flow regime variability, and year-by-year summation of categories (hydrological, technological, ecological) of management interventions as predictive variables of abundance-based beta diversity indices of fish communities in six key Upper Basin sites. Results show that fish community beta diversity metrics are most responsive to hydrological and technological interventions such as e-flows through reservoir reoperation, and not on natural flow variability. Assessment of the program actions against the adaptive management paradigm uses a Resistance-Resilience-Transformation (RRT) scale. We find a backsliding from resilience-building actions to resistive strategies, where more transformative actions are required. Assessment of the effectiveness of the adaptive management paradigm shows that program policies and actions need to account more for compounded effects of multiple environmental and anthropogenic stressors to maintain the ecological health of the river into the future.