HISTOPATHOLOGICAL EFFECTS OF 2,2-DICHLOROVINYL DIMETHYL PHOSPHATE (DDVP) ON Coptodon zilli (GERVAIS, 1848) JUVENILES

Mabel O Ipinmoroti

Abstract


Abstract
Concerns have often been raised on the application of pesticides on croplands and the threats posed on aquatic organisms. These pesticides get to the aquatic system from runoff on croplands where there was excessive application and can be more pronounced in integrated fish farming systems. This study was designed to investigate the lethal concentration an agricultural pesticide; 2,2-Dichlorovinyl Dimethyl Phosphate (DDVP) on the physical and chemical properties of water as well as the liver, kidney, tissue and gills of Coptodon zilli juveniles. A total of 150 experimental fish of average length and weight of 6.2±0.32cm and 0.9±0.11g respectively were stocked at 1fish/litre in renewable culture tanks (43cm x 30cm) each containing 10litres of water. The bioassay media concentrations were 0mg/l (A), 0.33mg/l (B), 0.67mg/l (C), 1.0mg/l (D) and 1.3mg/litre (E) and each contained 0mg/l, 3.3 x 10-6mg/l, 6.7 x 10-6mg/l, 1.0 x 10-5mg/l and 1.3 x 10-5mg/l of active ingredient Dichlorvos DDVP (1000g/L) EC respectively with three replicates each in a Completely Randomized Design (CRD) experimental setup. Temperature, pH, Dissolved Oxygen (DO) and Chemical Oxygen Demand (COD) were measured before and after inclusion of the pesticide and significant differences (P<0.05) in mean concentration of DO and COD were observed. The experimental fish exhibited restlessness and uncoordinated movement and these behavioral characteristics increased with increased concentration of DDVP and time of exposure. LC50 for C. zilli juveniles after 96hours exposure was 0.39mg/l. Histological reports illustrated various alterations in the gills, liver, kidney and muscle of the exposed experimental fish while the control was normal. The result indicated that DDVP is highly toxic to C. zilli and must be applied to at recommended dosages for sustainability of the environment.

Keywords: Agro-chemical, C. zilli, Histopathology, Water Quality, Sustainability