The Capibaribe River provides water to a population of 1.7 million people in the Brazilian northeast, while receiving agricultural runoff and industrial and domestic effluents along its 280 km. The present study evaluated the ecotoxicity of surface waters along ten sites in rural and urban areas using zebrafish (Danio rerio) early-life stages and related it to water quality indices and chemical abiotic variables. Lethality rates, delays in embryo-larval development quantified by the general morphology score (GMS), and frequencies of developmental abnormalities were analyzed. A correlation was detected between zebrafish GMS and water quality index (WQI), sensitivity to domestic sewage contamination, and trophic state index, focused on eutrophication. These indices agreed in identifying a spatial pattern of smaller impact in terms of ecotoxicity, domestic sewage contamination, and eutrophication risk at three sites in rural areas (mean GMS 16.9), an intermediate impact at four sites with urban and agricultural influence (mean GMS 16.4), and greatest impacts at three more urbanized sites (mean GMS 14.9). Most frequent developmental abnormalities included noninflation of the swim bladder, delayed hatching, nonprotrusion of the mouth, blood stasis, and nondevelopment of pectoral fins. Toxic NH₃ concentrations varied spatially, with higher concentrations in urban sites; and blood stasis correlated positively with NH₃, suggesting a causal relationship. Polycyclic aromatic hydrocarbons were detected in both rural and urbanized sites, contributing to detected toxicity. The present study demonstrates the potential of zebrafish early-life stages as an ecotoxicological model that may contribute to a better understanding of surface water quality and ecotoxicity in tropical river systems. Environ Toxicol Chem 2021;40:3063–3077. © 2021 SETAC

中文翻译：

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巴西热带东北部卡比巴里贝河沿农村和城市地区地表水的污染和毒性

卡比巴里贝河为巴西东北部的 170 万人口提供水源，同时沿其 280 公里接收农业径流以及工业和生活污水。本研究使用斑马鱼 ( Danio rerio ) 评估了农村和城市地区 10 个地点的地表水的生态毒性。) 生命早期阶段并将其与水质指数和化学非生物变量相关联。分析了致死率、通过一般形态评分 (GMS) 量化的胚胎幼虫发育延迟和发育异常的频率。检测到斑马鱼 GMS 与水质指数 (WQI)、对生活污水污染的敏感性和营养状态指数之间存在相关性，重点是富营养化。这些指数在确定农村地区三个地点的生态毒性、生活污水污染和富营养化风险方面影响较小的空间模式（平均 GMS 16.9），在具有城市和农业影响的四个地点的中等影响（平均 GMS 16.4 )，并且在另外三个城市化地点的影响最大（平均 GMS 14.9）。最常见的发育异常包括鱼鳔不膨胀、孵化延迟、口不突出、瘀血和胸鳍不发育。有毒氨₃浓度在空间上有所不同，城市地点的浓度较高；血瘀与NH ₃呈正相关，具有因果关系。在农村和城市化地点都检测到多环芳烃，这有助于检测到毒性。本研究证明了斑马鱼生命早期阶段作为生态毒理学模型的潜力，可能有助于更好地了解热带河流系统的地表水质量和生态毒性。环境毒物化学2021；40:3063–3077。© 2021 SETAC