Alterations in the Bio-membrane of Libyodrilus violaceus following Exposure to Crude Oil and Its Fractions

Abstract

We investigated changes in the lipid profile of clitellum and post-clitellum sections of earthworms (Libyodrilus violaceus) after exposure to different doses of crude oil (Bonny light blend) or its fractions for two-weeks. Two hundred and forty earthworms were assigned to four major groups of sixty earthworms each; one group was given deionized water and served as the control group and the other test groups were either exposed to whole crude (WC) or its water soluble fraction (WSF), or water insoluble fraction (WIF). Twenty animals in each test group were exposed to 0.1%, 0.2% or 0.3% contamination. The treated groups revealed a significant reduction (P<0.05), (1.71% - 28.29%) in the weight of earthworms when compared with those in the control group. Generally, the exposure of the earthworms to either whole crude oil or its fractions resulted in a dose dependent significant (P<0.05) reduction in the total lipid and total phospholipid content of both sections (clitellum and post clitellum) of the worms studied. We observed that the exposure of earthworms to crude oil or its fractions decreased phosphatidyl ethanolamine (PE), and phosphatidyl choline (PC) at different doses when compared with concentrations in control animals. There was also an increase in sphingomyelin levels in both the clitellum and post-clitellum sections of worms in the treatment groups at the different doses. These changes significantly affected the SGM/PC ratios. These changes in the phospholipid profile may have profound significance in the tolerance of earthworms to the toxicants in crude oil or its fractions. Physical and ionic characterization of the crude oil sample revealed that it contained unsafe levels of cadmium(7.50mg/l, 0.97mg/l, 11.54mg/l for WSF,WIF and WC respectively) and poly aromatic hydrocarbons (PAHs) (1.2926mg/l, 5.5871mg/l, 36.3665 mg/l for WSF, WIF and WC respectively).