A multiple-stressor syndrome approach to aquatic ecosystem management and restoration

Aquatic ecosystems are increasingly exposed to interacting anthropogenic and climatic pressures that jointly alter water quality, biodiversity, hydrological regimes, habitat structure, and ecosystem functioning. Although single-stressor approaches remain useful for regulatory monitoring and experimental control, they are insufficient for explaining real-world degradation, where pollution, flow alteration, habitat simplification, biological invasions, and climate extremes often co-occur. This narrative review synthesizes recent evidence on multiple stressors in aquatic ecosystems and proposes the concept of multiple-stressor syndromes as a framework for diagnosing recurrent clusters of interacting pressures across rivers, lakes, reservoirs, wetlands, floodplains, estuaries, and tropical freshwater systems. The review argues that stressor syndromes are not merely additive combinations of pressures; rather, they are context-dependent configurations shaped by land use, hydrological connectivity, geomorphology, climatic exposure, governance, and legacy disturbance. By advancing a syndrome-based framework, this review contributes to multiple-stressor research by shifting the focus from classifying interaction types alone toward diagnosing recurring stressor clusters, their dominant drivers, ecological mechanisms, response pathways, and management leverage points. This diagnostic framing complements existing work on additive, synergistic, and antagonistic effects by making multiple-stressor science more directly applicable to water-quality assessment, restoration prioritization, ecologiscal risk analysis, and adaptive water governance. The review highlights four key needs for future research and management: greater attention to underrepresented tropical and low-income regions, stronger integration of biological and functional indicators into water-quality monitoring, improved understanding of stressor timing and lag effects, and field-scale evidence on which stressor reductions generate measurable ecological recovery.