Studies on Mortality and Histopathological Alteration on the Gills of Oreochromis niloticus Juveniles Following Exposure to Ethanolic Extract of Phramenthera capitata under Laboratory Conditions

Abstract

The study was conducted using two replicate (Batch A and B) for 96 hours under controlled laboratory conditions, with five different concentrations of the extract ranging from 0 to 40 mg/l. The results of the study revealed that the extract had a concentration-dependent toxic effect on the test organisms, with induced behavioural changes such as abnormal and uncoordinated swimming movement, restlessness, respiratory difficulties, and attempts at jumping out. The alterations of physico-chemical parameters of the test water were also observed, indicating the adverse effects of the extract on the aquatic environment. The 96 hours LC50 for Oreochromis niloticus was determine to be 22.124 mg/l representing a log-transformed concentration of 1.345 mg/l. This is the concentration where 50% of the test organisms is expected to die at the end of the 96 hours’ bioassay. The histopathological examination of the gills revealed pathological changes in the test organisms at concentrations of 20, 30, and 40 mg/l whereas no histomorphological changes was observed at 0 and 10 mg/l concentrations of the extract. The result of the present findings suggests that ethanolic extract of P. capitata had severe impacts on the test organisms resulting in mortality and gill damage.