Hazardous Effects of Heavy Metal Pollution on Nile Tilapia in the aquatic ecosystem of the Eastern Delta in Egypt

Introduction: Heavy metal pollution threatens the biodiversity and ecological equilibrium of the Nile River. This study investigates the impact of heavy metal pollution on aquatic animal as Nile tilapia ( Oreochromis niloticus ) in the Damietta branch of the River Nile and El-Rayah El-Tawfeeky in Benha city in Egypt. Methods: Fish and water samples were subsequently analyzed using inductively coupled plasma atomic emission spectroscopy (ICP-OES) revealing significantly higher concentrations of Mg, Cd, Hg, Cr, Cu, Ni, Pb, and Zn in fish muscle tissues collected from Damietta branch compared to El-Rayah El-Tawfeeky samples. Results: Histopathological examinations revealed noteworthy alterations in tilapia gill, liver, spleen, and muscle tissues, suggesting potential health risks. Gene expression analysis using Real time polymerase chain reaction (RT-qPCR indicated) significant changes in genes related to muscle growth (MyoD, IGF-1) and immune response (TNFa, IL6) in fish from Damietta branch relative to fish of El-Rayah El-Tawfeeky. Conclusion: The findings raise concerns about heavy metals bioaccumulation and potential health implications for consumers. The study underscores the significance of continuous monitoring, utilizing chemical, histopathological, and molecular tools as bioindicators for environmental protection measures against aquatic pollution.