Toward a Generalized Ecotox-Criticality Framework for Targeted Aquatic Ecosystem Risk Assessment

The growing number and diversity of chemical contaminants threaten aquatic ecosystem integrity, yet conventional risk assessments often overlook food-web interactions and require extensive toxicological and ecological data. We developed the Generalized Ecotox-Criticality Framework (GECF), which reframes ecosystem risk assessment as a targeted dimensionality-reduction problem. GECF integrates food-web energy flux, ecological redundancy, and chemical-specific toxicity sensitivity to prioritize pollutant-specific nodal taxa for direct toxicity-data generation while retaining the complete ecosystem network. In the Baiyangdian case study, a cutoff sensitivity analysis supported the 80% relative criticality index (RCI) setting as a practical balance between response fidelity and testing burden. At this setting, nodal scenarios retained the principal ecosystem responses simulated by AQUATOX and yielded indicator-specific candidate ecological thresholds (ECO-thresholds) internally benchmarked against full-organism scenarios. Relative to the 14-taxon full-organism evidence set, the 80% RCI setting reduced the standardized weighted assay burden by 71.1%, the number of tested taxa by 69.1%, and the number of vertebrate test taxa by 66.7%. Additional analyses showed that nodal composition varied across chemicals and ecosystems and that candidate thresholds shifted under warming and nutrient-enrichment backgrounds. GECF provides a model-based decision-support approach for prioritizing toxicity-data generation and conducting scenario-dependent regional aquatic-ecosystem risk screening.