Drivers of recovery and degradation of riverine benthic macroinvertebrate communities: A nationwide analysis of time series

In response to the global freshwater biodiversity crisis this study examines the drivers, influencing recovery and degradation in riverine benthic macroinvertebrate communities across Germany. Utilizing the Asymmetric Response Concept (ARC), which posits that species tolerances to stressors, dispersal capacity, and biotic interactions are critical drivers in aquatic ecosystem recovery, we analyzed a comprehensive dataset from 1568 sites, sampled between 2004 and 2022. Our findings indicate that abiotic stress consistently influences ecological status in both recovery and degradation phases. Interspecific competition shows a stronger positive relationship with ecological status improvements during recovery phases than during degradation, underscoring its importance in the recovery process. Additionally, land use intensity has a nuanced impact: catchments with higher proportions of cropland and urban areas are more likely to recover, while forested catchments are more prone to degradation. This study supports the ARC and highlights the complex interplay of biotic and abiotic variables in shaping ecological outcomes, underscoring the importance of integrated management approaches in freshwater conservation and restoration efforts.