Sub-lethal effects of pharmaceutical effluent on tissues and organs of clariasgariepinus (Burchell, 1822)

Eleyele, Oluwabunmi Abigail (2016)



This study assessed the physicochemical parameters of pharmaceutical effluent and investigated its sub-chronic toxicity on the tissues and organs of Clariasgariepinus. It also investigated the histopathological effects of the pharmaceutical effluent on tissues and organs of C.gariepinus and alterations in biochemical indices of the fish as a result of the effluent toxicity. This was with the view to providing information on potential adverse effects of the effluent on C.gariepinus. Physicochemical parameters such as dissolved oxygen, temperature, pH, alkalinity, exchangeable anions and cations, total hardness and concentrations of five selected heavy metals (Cd, Cr, Cu, Fe and Pb) of the pharmaceutical effluent collected from a known pharmaceutical industry in Ilorin, Kwara State were evaluated. One hundred and eighty juveniles ofC. gariepinusprocured from the Fish Hatchery Unit, Department of Animal Science, ObafemiAwolowo University, Ile-Ife, which were acclimatized for one week in stock tanks were used for the toxicity assay. After acclimatization, a range finding test was carried out prior to the commencement of the definitive test. A static renewal bioassay procedure was adopted in which the test media was regularly renewed every 48 hrs at the set concentrations. Five juveniles of C.gariepinus were introduced into twelve different tanks containing gradient concentrations(0, 2, 4, 6, 8 and 10%) of the pharmaceutical effluent for the sub-chronic evaluation. This concentration was based on the median lethal concentration (LC50) determined using Probit analysis. After 21 days of exposure, two fishes per concentration were randomly selected, the tissues were removed and analyzed for histopathological changes and antioxidant enzyme (Superoxide Dismutase (SOD), Catalase (CAT), and Glutathione-S-Transferase (GST)) activitiesfollowing standard protocol. One-way Analysis of Variance (ANOVA) was used to compare the means of results obtained. The results of the physicochemical analysis of the effluent showed that the effluent was characterized by high alkalinity (118 mg/L), total hardness (131.34 mg/L), and dissolved oxygen (11.0 mg/L). However, the amount of Cd, Cr, Cu, Fe and Pb (0.01, 0.032, 0.10, 0.068 and 0.012 mg/L) respectively were below the national and international limits for fish culture.The LC50 value for the acute toxicity was 18.32%.Histopathological examination of the liver showed major changes which included hyperemia, cytoplasmic vacuolation and cirrhosis. The fish muscle analysis showed thickening andnecrosis of the muscle bundle at the low effluent exposure concentrations, while hyperplasia, fibrosis and intramuscular edema were observed in the fish exposed to high concentrations of the effluent. The gills in the fish showed cellular necrosis, cellular infiltration by inflammatory cells, epithelial erosion and lifting with effluent exposure. Also, the fin tissues showed disruption of muscle bundles, osteonecrosis, cartilage and epithelial degeneration with erosion and ulceration.Highest values of antioxidant enzymesSOD, 0.01 µmol/min/mg protein, CAT, 24.57 µmol/min/mg protein and GST, 56.73 µmol/min/mg proteinobtained in the liver of the test organism exposed to the effluent were significantly (p < 0.05) higher from the values obtained in the gill, fin and muscle of the effluent exposed fish. This study concluded that inspite of treatment, pharmaceutical effluent from a known pharmaceutical industry in Ilorin, was still a potent contaminant to juveniles ofC. gariepinus