Bioaccumulation of heavy metals in economically important fish and a parasitic nematode (Hysterothylacium sp.) from Mersin Bay, north-eastern Mediterranean Sea: implications for human health

Context The discharge of heavy metals into freshwater and marine environments is a serious environmental concern globally. Aims The objectives of this study were to determine the distribution of heavy metals in economically important fish species (Merluccius merluccius, Sardinella aurita, Sparus aurata) and the parasitic nematode, Hysterothylacium sp., from the Mersin Bay, and to evaluate potential human health implications. Methods Fish samples were collected to determine metal (aluminium, Al; chromium, Cr; manganese, Mn; iron, Fe; cobalt, Co; nickel, Ni; copper, Cu; zinc, Zn; cadmium, Cd; lead, Pb) concentrations and evaluate potential health risks. Key results The study results showed that only S. aurata was parasitised by Hysterothylacium sp. Additionally, the mean metal concentrations were found to vary between 1.54 and 2.00 mg kg−1 wet weight (WW) for Al, 0.20–0.45 mg kg−1 WW for Cr, 0.08–0.25 mg kg−1 WW for Mn, 1.26–5.36 mg kg−1 WW for Fe, 0.006–0.014 mg kg−1 WW for Co, 0.11–0.27 mg kg−1 WW for Ni, 0.13–0.23 mg kg−1 WW for Cu, 1.70–2.47 mg kg−1 WW for Zn, 0.001–0.002 mg kg−1 WW for Cd and 0.03–0.05 mg kg−1 WW for Pb, for the unparasitised fish samples. Additionally, findings of this study showed that the metal concentrations in nematodes were 4–14 times higher than those measured in the fish samples, suggesting high bioaccumulation of metals in the parasites. Conclusions Screening-level risk indices indicated potential human health concerns associated with carcinogenic Ni and Cu in the studied fish species from Mersin Bay.