Histopathological and ultrastructural perturbations in tilapia liver as potential indicators of pollution in Lake Al-Asfar, Saudi Arabia

摘要

Lake Al-Asfar (Al-Hassa, Saudi Arabia) is under threat from contaminants released through human activities such as agriculture and urban and industrial developments. In the present study, histopathologic and ultrastructural changes in liver of tilapia Oreochromis niloticus were analyzed to monitor the possible impact of pollution in Al-Asfar estuary. Heavy metals such as Ni, Fe, Zn, Co, Ba, Pb, and Cd were predominant in the lake water and far exceeded the interna-tional permissible limits. In fish samples, high prevalences of preneoplastic changes (50 %) and one case of cholangiocar-cinoma were revealed in liver tissues. Cytological damage in fish hepatocytes included glycogen exhaustion, deformation of nuclear envelope, heterochromatin condensation, mito-chondrial degeneration, vesiculation of rough endoplasmic reticulum, augmentation of smooth endoplasmic reticulum, and lysosomal proliferation. In conclusion, the observed bio-marker responses were potential indicators of health impair-ment or disease in field fish populations, although there was no direct proof of a simple cause-effect relationship. This is the first biological effect assessment in Lake Al-Asfar using tilapia as suitable target species.