作者：Jiang, S., Zhang, L., Yang, J., Xu, Q., Altermatt, F. & Zhang, X.

Understanding how synthetic chemicals affect biodiversity is essential for informing ecological risk assessments and supporting global biodiversity targets. Yet, current risk assessments rely mainly on linear extrapolations from laboratory toxicity tests and rarely capture multifaceted biodiversity, particularly genetic diversity, at the watershed scale. We integrated high-throughput mass spectrometry and environmental DNA (eDNA) metabarcoding to assess cumulative chemical stressor impacts on multitrophic communities (protozoa, algae, fungi, invertebrate metazoan, and fish) across streams, rivers, and lakes of the 40,000 km(2) Tai Lake Basin, eastern China. A total of 132 chemicals were detected, and cumulative ecological risk thresholds were exceeded at >70% of sites, indicating basin-wide chemical stress. Spatial heterogeneity in chemical composition and ecological risk were strongly associated with land-use intensity, particularly agricultural and urban development. eDNA metabarcoding revealed that community composition and sequence diversity mirrored chemical stressor distribution across sites. Sites with higher chemical stressors exhibited reduced sequence diversity and increased community similarity, while taxonomic diversity remained stable. Structural equation modeling showed that chemical effects on beta diversity were mediated through reduced sequence diversity, with no significant direct effects. These findings underscore the need to incorporate sequence-based biodiversity metrics into ecological risk frameworks and develop biodiversity-informed thresholds for freshwater ecosystems.

理解合成化学品如何影响生物多样性，对于开展生态风险评估和支撑全球生物多样性保护目标至关重要。然而，当前的风险评估主要依赖于实验室毒性测试的线性外推，鲜有在流域尺度上捕捉多层面的生物多样性，尤其是遗传多样性。本研究整合高通量质谱技术与环境DNA（eDNA）宏条形码技术，评估了化学胁迫累积效应对中国东部四万平方公里太湖流域溪流、河流和湖泊中多营养级群落（原生动物、藻类、真菌、无脊椎后生动物和鱼类）的影响。共检出132种化学品，超过70%的位点累积生态风险阈值被超出，表明全流域存在普遍的化学胁迫。化学组成和生态风险的空间异质性与土地利用强度密切相关，尤其是农业和城镇开发。eDNA宏条形码分析显示，群落组成和序列多样性在各位点间的分布与化学胁迫因子分布格局一致。化学胁迫较高的位点表现出序列多样性降低和群落相似性增加，而物种分类多样性保持稳定。结构方程模型表明，化学品对β多样性的影响是通过序列多样性降低间接介导的，并无显著的直接效应。上述发现凸显了将基于序列的生物多样性指标纳入生态风险框架、并制定面向生物多样性的淡水生态系统阈值的必要性。

（来源：Environmental Science & Technology 2026 Issue 5  DOI: 10.1021/acs.est.5c09855）