Biochemical and haematological responses in African catfish Clarias gariepinus following chronic exposure to NPK (15:15:15) fertiliser

Abstract

The indiscriminate use of inorganic fertilisers to boost plant productivity has resulted in negative consequences in aquatic ecosystems. The effects of chronic exposure to NPK (15:15:15) fertiliser at 0.40, 0.80 and 1.60 g l⁻¹ on the haematological and biochemical responses of Clarias gariepinus were determined under a static renewal bioassay for a period of 56 days in April–June 2013. There was a reduction in haemoglobin levels, mean corpuscular haemoglobin and haematocrit, while mean corpuscular haemoglobin concentration increased in exposed fish compared to the control. There was a significant difference (p < 0.05) between the levels of the parameters examined in exposed fish and the control. However, a mixed trend was observed in the leucocyte differentials. In addition, glucose, alanine aminotransferase and aspartate aminotransferase levels were significantly increased while protein levels were reduced (p < 0.05) in the plasma throughout the exposure period. Prolonged exposure of C. gariepinus juveniles to NPK can lead to physiological dysfunction in the fish.

Keywords: enzymes, fish, glucose, physiology, sublethal, toxicity