One of the major problems affecting the ecosystem health is the exposure of heavy metals due to anthropogenic activities. These exposures may induce toxiogenetic damage and carcinogenesis in aquatic organism. DNA damage biomarkers for fish species detect genotoxic parameters for ecological risk assessment. In the present study, the effect of heavy metals (Cr, Cd, Cu, Fe and Mn) on DNA damage and oxidative stress of Clarias gariepinus was examined by Comet assay at Reference site and two different sampling sites of the Orontes River. Moreover, the relationship between DNA damage and physiological response to oxidative stress caused in C. gariepinus was investigated by sampling seasonal water and fish samples for one year. In this study, Cr, Cd and Cu in water column of Orontes River and the concentrations of Fe and Mn in liver tissue of C. gariepinus were highly exceed the maximum permissible limit set by EPA (1999, 2016) WHO (1989) and TEG (2012) that can cause adverse effects on environment health. SOD activities in liver tissues were significantly higher than those in muscle tissues. SOD, CAT activity and MDA levels of both Site 1 and Site 2 at Orontes River were higher than those of the Reference site. In result of the COMET analysis, the highest levels of DNA damage were found at gill and liver tissues in Site 2 (17.746 ± 1.072% T-DNA; 16.014 ± 0.710% T-DNA respectively) at Orontes river. A higher level of DNA damage in gill cells compared to liver cells was observed in all regions of the Orontes River. In Principal component analysis (PCA), the heavy metals Cd, Cr and Cu (in the water column) and MDA in liver and muscle revealed strong contribution to the observed DNA damage that were scattered opposite to each other’s along the principal components. Moreover, correlations between parameters revealed a positive significant relationship between Cd, Cr and Cu in water and DNA damage levels in C. gariepinus. Pearson correlation analysis detected a positive relationship between MDA, CAT and SOD and DNA damage levels in African catfish. Consequently, this study exposed genotoxic damage and oxidative stress of C. gariepinus due to metal pollution in Orontes River and lead to the better understanding of genotoxicty, oxidative stress and heavy metal relationships.

影响生态系统健康的主要问题之一是由于人为活动导致的重金属暴露。这些暴露可能会引起水生生物的产毒作用损害和致癌作用。鱼类的DNA损伤生物标记物检测遗传毒性参数以进行生态风险评估。在本研究中，通过彗星试验在奥龙特斯河参考点和两个不同采样点检测了重金属（Cr，Cd，Cu，Fe和Mn）对非洲胡子Cl（Clarias gariepinus）DNA损伤和氧化应激的影响。此外，DNA损伤与加拿大油茶的氧化应激生理反应之间的关系通过取样一年的季节性水和鱼样本进行了调查。本研究研究了奥龙特斯河水柱中的Cr，Cd和Cu以及gar.pina的肝脏组织中的Fe和Mn含量。其含量大大超过了EPA（1999，2016），WHO（1989）和TEG（2012）设定的最大允许限值，可能对环境健康造成不利影响。肝脏组织中的SOD活性明显高于肌肉组织中的SOD活性。Orontes河的站点1和站点2的SOD，CAT活性和MDA含量均高于参考站点。根据COMET分析的结果，在Orontes河的站点2的g和肝组织中发现了最高水平的DNA损伤（分别为17.746±1.072％T-DNA；分别为16.014±0.710％T-DNA）。在奥伦特斯河的所有地区，g细胞中的DNA损伤程度均高于肝细胞。在主成分分析（PCA）中，重金属Cd，肝脏和肌肉中的Cr和Cu（在水柱中）和MDA显示出对观察到的DNA损伤的强贡献，这些DNA损伤沿主要成分彼此相对分布。此外，参数之间的相关性揭示了水中的Cd，Cr和Cu与DNA损伤水平呈正相关。C. gariepinus。皮尔森相关分析发现非洲cat鱼的MDA，CAT和SOD与DNA损伤水平呈正相关。因此，本研究揭示了由于Orontes河中的金属污染而导致的C. gariepinus遗传毒性损害和氧化应激，从而使人们更好地了解了遗传毒性，氧化应激和重金属之间的关系。