Biological alterations in fish fingerlings (Tilapia guineensis) exposed to industrial detergents and corrosion inhibitors

Abstract

The common cichlid (Tilapia guineensis) of the Niger Delta was exposed to lethal (6.25, 12.5, 25.0, 50.0, and 100 mg l−1) and sublethal (1.56 and 3.13 mg l−1) concentrations of Neatex and Norust CR 486 for four and twenty eight days, respectively. The rate of mortality, level of glycogen reserves in the muscle tissues, and bioaccumulation of surfactants were measured as the ecotoxicological end-point. Estimated 96-h LC50 values were 82.42 mg l−1 (Neatex) and 20.21 mg l−1 (Norust CR 486), indicating that Norust CR 486 was more toxic. The levels of glycogen reserves in muscle tissues decreased significantly (P<0.05) in fish exposed to sublethal concentrations of the chemicals compared with the levels in the control groups. The decreases in glycogen levels in the muscle tissues in the highest concentrations (3.13 mg l−1) were 67% (Neatex) and 75% (Norust CR 486). The percentage reduction correlated with the increase in concentrations of chemicals and exposure duration. Surfactant bioaccumulation in the gill, gut and muscle tissues of fish increased significantly with increasing concentrations. The absence of mortality and surfactant accumulation in the control group may be an indication that the observed effects on the exposed fish may have been due to the chemicals. This study demonstrates the lethal and sublethal effects of surfactant-containing industrial chemicals on mortality and muscle glycogen in Tilapia guineensis.