Long term integrated biomarker responses in freshwater African catfish <i>Clarias gariepinus</i> exposed to a new brand of herbicide fluazifop-p-butyl

The study investigated the sublethal effects of Fluazifop-p-butyl (FPB) on the haematological, biochemical and oxidative stress changes in Clarias gariepinus. Juvenile C. gariepinus were exposed to FPB concentrations of 1.80, 3.50, and 7.10 mg/l corresponding to 5, 10 and 20% of 96 h LC50 value of FPB respectively for 21 days and allowed to recover for 7 days. The blood, liver and gills were removed and analyzed. Fish exposed to different concentrations of FPB showed significant decline in the values the pack cell volume, hemoglobin and red blood cells but the white blood cell values increased. The neutrophil values increased while the lymphocyte declined but the monocytes, basophil and eosinophil values remain unchanged. The liver and gill aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase significantly increased compared to the control. There were mixed trends in the values of glucose but total protein was reduced in both tissues of the fish. There was significant decline in superoxide dismutase, catalase and glutathione peroxidase while malondialdehyde, total glutathione, and glutathione reductase increased in both liver and gill of the exposed fish. Following the 7-day withdrawal, most of the observed parameters returned to normal values. The present study revealed that FPB is toxic to C. gariepinus juveniles and prolonged exposure could result to major health risks to aquatic organisms, hence, they should be carefully used.本研究探究了精吡氟禾草灵（Fluazifop-p-butyl，FPB）对革胡子鲇（Clarias gariepinus）的亚致死效应，具体考察其对该物种血液学指标、生化指标及氧化应激变化的影响。将幼龄革胡子鲇（C. gariepinus）分别暴露于浓度为1.80、3.50、7.10 mg/L的FPB溶液中21天，上述浓度分别对应FPB 96小时半数致死浓度（96h LC50）的5%、10%和20%，随后将其置于清水环境中恢复7天。采集实验鱼的血液、肝脏及鳃组织进行检测分析。结果显示，暴露于不同浓度FPB的革胡子鲇，其红细胞压积、血红蛋白及红细胞计数均显著下降，而白细胞计数则呈升高趋势；其中中性粒细胞计数升高，淋巴细胞计数降低，但单核细胞、嗜碱性粒细胞及嗜酸性粒细胞计数无显著变化。相较于对照组，暴露组鱼类肝脏与鳃组织中的天冬氨酸氨基转移酶、丙氨酸氨基转移酶及碱性磷酸酶活性均显著升高。血糖指标呈现混合变化趋势，但两种组织中的总蛋白含量均有所降低。暴露组鱼类肝脏与鳃组织中的超氧化物歧化酶、过氧化氢酶及谷胱甘肽过氧化物酶活性显著下降，而丙二醛、总谷胱甘肽及谷胱甘肽还原酶水平则呈升高趋势。经过7天的停药恢复后，绝大多数观测参数均恢复至正常水平。本研究证实，FPB对幼龄革胡子鲇具有毒性，长期暴露可能对水生生物造成严重健康风险，因此需谨慎使用该药剂。