Metabolic enzyme profile, behavioural changes and morphophysiological parameters of African catfish Clarias gariepinus juveniles in response to burnt waste tyres

Abstract

Water-soluble fractions (WSFs) of waste burnt tyres (WBTs) were tested on enzymatic activities, behavioural changes and histology of gills and liver of African catfish Clarias gariepinus juveniles for 96 h at 5.00, 10.00, 15.00, 20.00 and 25.00 g/L in a non renewable static bioassay. Water quality parameters of the experimental media showed significant (p < 0.05) decrease in pH and dissolved oxygen content and increased carbon dioxide and alkalinity levels compared to the control. The 96-h LC50 of WSFs of WBTs to C. gariepinus was calculated as 11.22 g/L. There were remarkable abnormal behaviours exhibited by the exposed fish as well as alteration in aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and lactate dehydrogenase activities in gills and liver in a dose-dependent manner. The exposure also led to changes in primary and secondary gill lamellar hypertrophy and hyperplasia, partial fusion of apical lamellar, cytoplasmic and nuclear degeneration of parenchyma cells, as well as cytoplasmic vacoulation, sinusoidal oedema and nuclear and periportal hepatocyte degeneration of the liver. Hepatomorphometry of the fish revealed significant (p < 0.05) increase in nuclear surface area as well as nuclear diameter of the hepatic cells. BWTs could be deleterious to aquatic biota including fish and could be adopted as biomarkers for assessing the quality of aquatic ecosystem.