Changes in haematological characteristics of a bony fish, Tilapia guineensis (Bleeker, 1862), exposed to common pesticides in the Niger Delta Wetland, Nigeria

Abstract

This study is aimed at examining the effect of pesticide on a predominant fish in the Niger Delta of Nigeria. The effects of cypermethrin and chlorpyrifos on Tilapia guineensis juveniles were evaluated using haematological parameters (erythrocyte and leucocyte numbers and haematocrit) of the fish. The fish was exposed to varying sub-lethal levels of the two pesticides (cypermethrin and chlorpyrifos) at different concentrations (0.0006, 0.00125, 0.0025, and 0.005 ppm) for 8 weeks to assess the effects of the pesticides on haematological status of the fish. The erythrocyte, leucocyte, and haematocrit of T. guineensis exposed to sub-lethal concentrations of the two toxicants declined with concentration. The variations between treatments observed for erythrocyte, leucocyte, and haematocrit were significant for both pesticides. The variations between cypermethrin treatments were F = 9.63 >P = 0.45_0.05, F = 5.08 >P = 0.008_0.05, and F = 11.03 >P = 0.002_0.05 for leucocyte, erythrocyte and haematocrit, respectively. Chlorpyrifos showed similar trend of F = 5.89 >P = 0.040.05, F = 9.04 > P = 0.004_0.05, and F = 8.03 > P = 0.0009_0.05 for the same parameters. In addition, chlorpyrifos depressed concentrations of erythrocyte, leucocyte and haematocrit more than cypermethrin. Histological changes were observed in the erythrocyte of the fish. These conditions were more severe in the higher concentrations of the pesticide.

Ghana Journal of Agricultural Science Vol. 37 2004: 59-67