Hazardous effects of heavy metal pollution on Nile tilapia in the aquatic ecosystem of the Eastern Delta in Egypt

Heavy metal pollution threatens the biodiversity and ecological equilibrium of the Nile River. This study investigates the impact of heavy metal pollution on aquatic animals such as Nile tilapia (Oreochromis niloticus) in the Damietta branch of the River Nile and El-Rayah El-Tawfeeky canal in Benha City in Egypt.

Fish and water samples were collected from the Damietta branch and El-Rayah El-Tawfeeky during the fall of 2022. The concentrations of heavy metals in fish muscle tissues were analyzed using inductively coupled plasma atomic emission spectroscopy (ICP-OES). Histopathological examinations were performed on gill, liver, spleen, and muscle tissues, following standard histological procedures, to assess tissue damage and morphological alterations. Additionally, gene expression analysis was conducted using real-time polymerase chain reaction (RT-qPCR) to evaluate the expression levels of muscle growth (MyoD, IGF-1) and immune response (TNFa, IL6) genes.

Histopathological examinations revealed noteworthy alterations in tilapia gill, liver, spleen, and muscle, 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 the Damietta branch relative to fish of El-Rayah El-Tawfeeky.

The findings raise concerns about bioaccumulation of heavy, some of which surpass international safety limits, posing potential health risks to consumers. The study underscores the significance of continuous monitoring, utilizing chemical, histopathological, and molecular tools as bioindicators for environmental protection measures against aquatic pollution.