Warming-driven coupling of functional and compositional stability under multiple stressors

Global change and anthropogenic activities are exerting multiple stressors on freshwater ecosystems, thereby impacting biodiversity and ecosystem functions. In this study, we evaluated the singular and combined effects of three common stressors (warming, nutrient enrichment, and insecticide exposure) on freshwater macroinvertebrate community characteristics and four components (resistance, recovery, resilience, and temporal stability) of the community's functional and compositional stability through a freshwater mesocosm experiment. Our findings reveal that warming temporarily enhanced the diversity of the macroinvertebrate community, while insecticides significantly affected community structure, though recovery was rapid. Warming further exacerbated the adverse effects of insecticides, whereas nutrients had comparatively minor impacts. Stability analysis revealed that nutrients and insecticides affected various aspects of compositional stability of macroinvertebrate communities by altering community structure. Notably, functional stability was more robust than compositional stability, which exhibited high dimensionality. Additionally, warming intensified the functional response, increased the dimensionality in compositional stability, and partially coupled functional and compositional dimensions by regulating community dynamics. Findings improve our understanding of how freshwater macroinvertebrate communities respond to multiple stressors and reveal the underlying mechanisms associated with stability in macroinvertebrate communities.