Sub-Chronic Toxicity Evaluation of Tannery Waste Water to <i>Clarias gariepinus </i>Juveniles

Abstract

This paper was conducted to investigate the sub-chronic toxicity of tannery effluents sourced from Challawa industrial estate Kano, Nigeria using Clarias gariepinus. The study covered physicochemical parameters, haematological, and biochemical stress enzymes assessments. The water quality results revealed mean value of Temperature (29.92±1.93oC), pH (8.14±0.85), DO (1.60±0.38mg/l), BOD (0.77±0.16mg/l), Salinity (7.75±0.60mg/l), Nitrate (1.19 ± 0.05mg/l) and Phosphate (16.48±0.85mg/l). After termination of 21 days sub-chronic test, haematological and biochemical changes analysed were generally considered significantly different (P<0.05) within the treatments. The haematological indices revealed a decrease and sudden increase in concentration of estimated values of PCV, Hb, RBC, MCHC and MCH, while WBC and MCV fluctuated. These may be attributed to stress, the duration of exposure and levels of pollutants in the effluent. Furthermore, oxidative stress enzymes followed an order of SOD > CAT > GSH. This could be due to level of pollutants in the effluent. The results of the data indicated tannery effluent to have a toxic effect on the experimented organism. The information calls for a more enrich toxicity testing that should involve wide range of organisms. It should entail reproductive aspects of the species, detail relationship and enhanced methodological procedures.