Alterations in hematological parameters of rainbow trout Oncorhynchus mykiss exposed to mancozeb

Rainbow trout reared in fresh water were exposed to a sublethal concentration of mancozeb (1/2 of LC50 = 1.1 mg/l) at 24 h intervals, for 3 weeks in tanks containing 780 1 water under natural light conditions with a constant flow (1.51 min(-1))of aerated dechlorinated tap water at 9-11 degreesC and with no recirculation. Approximately 2 cc venous blood was drawn from each subject (after weekly exposure) for the determination of hematological parameters, using heparin as an anticoagulant. Hematological parameters were investigated weekly. The findings of this study showed that mancozeb had some effect on the hematological parameters of rainbow trout. It was determined that the use of the pesticide caused a slight increase in red blood cell (RBC) numbers and a decrease in hemoglobin (Hb), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), packed cell volume (PCV), mean corpuscular volume (MCV) and white blood cell (WBC) levels. Significant decreases (P < 0.05) in Hb content and in MCH were observed during exposure to the pesticide. No significant differences were observed in the levels of RBC, MCHC, PCV, MCV and WBC (P > 0.05). The RBC/WBC level increased due to the decrease in WBC during the study.