EVALUATION OF THE HISTOLOGICAL AND HAEMATOLOGICAL IMPACTS OF GLYPHOSATE HERBICIDE ON THE AFRICAN CATFISH (Clariagariepinus) JUVENILES

ABSTRACT

This study was carried out to evaluate the histological and haematological impacts of glyphosate herbicide on Clarias gariepinus juveniles exposed to the toxicant. Tests were conducted over a 96 hours period after acclimation of test organisms for ten days in the laboratory. Initial range finding test was conducted to determine the concentrations of the toxicant to be administered on the test organisms prior to the definitive tests. The test organisms were exposed to five concentrations (0.0 ml/L (control), 10ml/L, 12ml/L, 18ml/L, and 22ml/L) of the toxicant. The 96 hours median lethal concentration was obtained at a concentration of 12ml/L.Histopathological changes on the gills of untreated fish showed normal architecture of the gill with parallel arranged gill filaments while the filaments of the gills of fish exposed to the toxicant suffered different levels of damages including hyperplasia of the epithelial cells, fusion of the primary and secondary lamellae of gill, shrinkage of the lamellae and oedema of the gill filaments. The liver of unexposed fish showed normal hepatocyte and sinusoid as well as the presence of central vein and bile duct.However, the liver of the exposed fish suffered degenerative changes and vacuolation of the hepatocyte and necrosis. Analysis of physico-chemical parameters (temperature, dissolved oxygen and pH) showed significant differences (P<0.05) in water quality variables relative to control. The temperature and pH value increases as concentration of the toxicant increases while dissolve oxygen decreases as concentration of the toxicant increases. Haematological evaluation showed an increase in the value of WBC and RDWC from 40.70 ×103µ and 8.00% in the T1(control) to 110.98×103µ and 8.75% respectively in the highest concentration. There was reduction in the red blood RBC from 2.49×106µ l in the control to 0.78× 106µ l. However, all experimental groups showed significant difference (P<0.05) in the 13 values acrossthewhite blood cell (WBC) and their differential counts, red blood cell and their differential counts, thrombocytes and other haematological indices, apart from PCT which show no significant difference(P>0.05).The study therefore, revealed that glyphosate exposure had toxic effect on Clarias gariepinus, juveniles.