Age factor and proximate compositions of the muscle of Heterobranchus Bidorsalis exposed to graded concentrations of bonny-light crude oil

Abstract

Variations in the proximate compositions of three age groups of Heterobranchus bidorsalis exposed to graded concentrations of Bonny-light crude oil (BLCO) were investigated in the laboratory. The fish were exposed to 1.00, 2.00, 4.00 and 8.00 ml L -1 concentrations of BLCO for 4 days (toxicity) and 42 days (recovery) periods. Significant decreases (P < 0.05) in the crude protein (CP), ether extract (EE), ash (AS) and dry matter (DM) contents of the juvenile (JV), the yearling (YRL) and the adult (AD) fish were BLCO-concentration dependent. Lower CP values in the adult fish than in the juveniles or the yearlings implies that the crude oil compounds might have depleted the quantity of protein faster in the adults than in the juveniles or the yearlings. Significant decreases (P < 0.05) in the EE content of the fish muscle could be attributed to the harmful effects of petroleum-related aromatic compound (ACs) on animals. These ACs might have caused decreases in the muscle triglycerides of the total lipid (EE) content of the three age groups of the fish. Significant increases (P < 0.05) in the nitrogen free extract (NFE) of the fish muscle might have been due to the high energy demand imposed on the fish as a positive survival value under the condition of crude oil stress.