Toxicity of an organophosphate pesticide (chloropyrifos) on a common Niger Delta wetland fish - Tilapia guineensis (Blecker 1862)
Chindah, A.C.; Sikoki, F.D.; Vincent Akpu, I.
Journal of Applied Science and Environmental Management 8(2): 11-17
2004
Document Number: 259979
The acute and sublethal toxicity of an organophosphate pesticide (Chloropyrifos ) on Tilapia guineensis juveniles was evaluated to determine its effect on the survival, body functions and heamatological values. The fish was exposed to varying levels of the toxicant (0.0125, 0.025, 0.05 and 0.1 mg/litre) using 96 h static bioassay to determine the median lethal concentration and median lethal time for the different concentrations. The mortality was found to increase with exposure and increase in concentration. The 96 h median lethal concentration was 0.002 mg/litre while the 96 h median lethal time of 56.2, 42.7, 31.1 and 18.2 h were recorded for 0.0125, 0.025, 0.05 and 0.1 mg/litre, respectively. The operculum beat frequency (F=Cal 6.89>P=3.49) 0.05 and Tail beat frequency (F=Cal 4.46>P (3.49)0.05) were significantly affected by the exposure. A sublethal exposure to various concentrations (0.0006, 0.00125, 0.0025 and 0.005 mg/litre) were observed to cause a progressive reduction in the number of leukocyte (F - Cal 15.4>P (3.01)0.05) and erythrocyte (F - Cal 14.39>P(3.01)0.05) of the fish. The reduction in leukocyte and erythrocyte number was significant indicating that the fish became anaemic. These conditions were more severe in higher pesticide concentrations.