Differential biomarker responses and associated health risks in two pelagic fish species from the Mediterranean Sea, Egypt.

Coastal pollution poses a significant threat to marine ecosystem health and the safety of seafood resources, necessitating integrated approaches to assess its biological impacts. This study provides a comprehensive evaluation of pollution-induced effects on two commercially important pelagic fish, the omnivorous Sardinella aurita and carnivorous Scomber scombrus, from the polluted El-Mex Bay, Egypt. We analyzed the proximate composition, metal bioaccumulation, and a suite of biochemical and molecular biomarkers, including antioxidant enzymes (SOD, CAT, GST, GSH), lipid peroxidation (MDA), hepatic enzymes (ALT, AST), neurotoxicity (AChE), DNA damage (comet assay), and heat-shock protein (HSP70) expression. Distinct interspecific differences emerged. S. aurita showed higher protein content and stronger antioxidant enzymes, a pattern contrasting with S. scombrus. The latter accumulated more Pb and Hg, resulting in an elevated Metal Pollution Index (MPI), along with increased oxidative damage (MDA), hepatic stress, and molecular stress responses including HSP70 expression and DNA damage. This culminated in a substantially higher Integrated Biomarker Response (IBR) value for S. scombrus. Human health risk assessment indicated that the Hazard Index (HI) for both species exceeded the threshold (HI > 1), suggesting potential non-carcinogenic health risks primarily driven by Hg, while the Total Cancer Risk (TCR) was within permissible limits. This study highlights the importance of combining nutritional, biochemical, and molecular biomarkers for a comprehensive assessment of fish health and seafood safety, providing critical insights for environmental monitoring, consumer guidance, and coastal management strategies in polluted regions.