Toxicity of an Organophosphate Pesticide (chloropyrifos) on a common Niger Delta Wetland Fish - Tilapia guineensis (Blecker 1862)

Abstract

The acute and sublethal toxicity of an organophosphate pesticide (Chloropyrifos) on the juvenile of Tilapia guineensis was evaluated to determine its effect on the survival, body functions and heamatological values. The fish was exposed to varying levels of the toxicant (0.0125mg/l; 0.025mg/l; 0.05mg/l and 0.1mg/l) using 96hrs 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 96hrs median lethal concentration was 0.002mg/l while the 96hr median lethal time of 56.2hrs; 42.7hrs; 31.1 hrs and 18.2hrs were recorded for 0.0125mg/l; 0..025mg/l, 0.05mg/l and 0.1mg/l 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 (0.0006mg/l; 0.00125mg/l, 0.0025mg\\l, 0.005mg/l) were observed to cause a progressive reduction in the number of leucocyte (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 leucocye and erythrocyte number was significant indicating that the fish became anaemic.These conditions were more severe in the higher concentrations of the pesticide.


Journal of Applied Sciences and Environmental Management Vol. 8(2) 2004: 11-17