Using the red mullet, European hake, and common seabream as biomonitors of trace metal levels and associated health risks from the southwestern Mediterranean Sea

This study examines the accumulation of trace metals (Hg, Ni, Cu, and Zn) in the muscle, liver, and gonadal tissues of three benthic fish species (Pagellus erythrinus, Merluccius merluccius, and Mullus barbatus) collected from five coastal bays in Algeria. The study also evaluates the nutritional composition of these tissues by analyzing their protein, lipid, and carbohydrate content to better understand their implications for both ecosystem health and human consumption. The metals were present in the following order: Zn > Cu > Ni > Hg. Sediment-tissue transfer factors (TF < 1) indicate limited environmental bioavailability. Mercury, while biologically less essential, showed notable concentration in hepatic tissues. Nickel posed the greatest individual risk, with a target hazard quotient (THQ = 1.27) indicating potential health risks for children consuming M. barbatus. Cumulative hazard indices (HI) revealed moderate risk for younger consumers of P. erythrinus (HI = 1.39) and M. barbatus (HI = 1.72). Biochemical analysis showed significant variability among species: protein levels (9.69-36.80 %), lipid levels (7.33-45.67 %), and carbohydrate levels (0.70-16.24 %) differed among tissues and species. The energy content was relatively high (358 ± 89 kcal/g d.w. for P. erythrinus, 378 ± 67 kcal/g d.w. for M. merluccius, and 274 ± 23 kcal/g d.w. for M. barbatus). However, weekly intake recommendations based on the mercury exposure limit safe consumption to 350 g/week for children and 980 g/week for adults.