الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
In recent years, there is wide spread use of atrazine and it is commonly monitored in groundwater and surface water. A study is needed to determine its effects on the aquatic organisms and its potential effects as an environmental contaminant. In this study, the half lethal concentration (LC50) of atrazine for female catfish, Clarias gariepinus (C. gariepinus) was calculated. Atrazine toxicity was evaluated through acute and chronic exposures of fish to 1/2 and 1/10 the calculated LC50 for 4 days and 6 weeks respectively. As well as, the evaluation of role of vit. E in preventing or alleviating the induced defects. Results showed that the LC50/96h was 13.75 mg/l. The effects of both acute and chronic exposures revealed clinical abnormalities which were manifested by loss of appetite, sluggish or restlessness swimming, rapid opercular movements and abnormal skin pigmentation in the form of faded skin. Moreover, the biometric parameters showed highly significant decrease in body weight and gonad weight but the liver weight of atrazine exposed fish was significantly increased. In addition, the results of absolute fecundity showed highly significant decrease in (T.R. Egg No.). The results also revealed a marked decrease in RBCs, Hb content, MCV, MCH, MCHC and WBCs. where as, significant increase in AST and ALT activities, creatinine, uric acid, glucose and serum cortisol levels were recorded. Furthermore, atrazine exposures were associated with an inhibition of cholinesterase activity. Marked decrease in estradiol, testosterone levels and total protein concentration in serum with a reduction in both albumin and globulin were also recorded. Results also showed a significant induction of oxidative damage in liver tissue as evidenced by increased level of lipid peroxidation (LPO) and reduced glutathione content (GSH). In addition, significant increase in the activities of catalase (CAT) and superoxide dismutase (SOD). The histopathological alterations of different organs of the exposed fish were recorded. Additionally, the supplementation of vit.E can reduce the incidence of growth retardation and can improve the haematological, biochemical and histological abnormalities in female catfish, C. gariepinus exposed to atrazine in relation to fish exposed to atrazine only. This may be related to successive reduction of the oxidative stress, caused by atrazine toxicity.
Keywords: Atrazine, Freshwater fish, vit.E, LC50, Clinical signs, Biometric parameters, Fish fecundity, Blood parameters, Biochemical parameters, Oxidative stress, and Histopathological changes.