Effects of crude oil and its fractions on the blood Monocytes and Lymphocytes of <i>Heterobranchus bidorsalis</i> juveniles

Abstract

The blood monocytes (MCs) and Lymphocytes (LCs) of Heterobranchus bidorsalis juveniles exposed to four concentrations (1.00, 2.00, 4.00 and 8.00 mL³) of crude oil and crude oil fractions for 4 days toxicity and 42 days recovery periods were studied. A control study without crude oil contamination was also used to compare the effects of these oil pollutants on the hematological parameters of the fish. It was observed that the higher concentrations of MCs and LCs during the 4 days toxicity period than during the forth nightly recovery periods was probably due to the physiological and/or immunological attempts by the fish to mobilise the body's defense mechanisms to mop up the xeno biotics crude oil compounds in the blood. Secondly, decreases in the values of MCs and LCs in fish blood during the recovery period (14-42 days) might be due to some physiological readjustments within the fish in response to improvement in the ambient water condition. Generally, the effect of exposing H. bidorsalis juveniles to the different concentrations of the oil pollutants resulted in significant differences (P<0.05; P<0.01) in the monocytic and lymphocytic components of the fish blood.

Key words: Heterobranchus bidorsalis, crude oil, Monocyte, Lymphocyte, Toxicity