Trophic transfer of heavy metals in the marine food web based on tissue residuals

Trophic transfer of metals has been well researched in aquatic food webs; however, most studies have examined the presence of metal residuals in the entire body of marine organisms and but not in specific tissues. In this study, we determined the concentrations of Cu, Cr, Pb, Zn, Cd, and Ni in various organs of 17 marine species, including crustaceans, gastropods, bivalves, and fishes, with different trophic levels (TLs), which were collected from the Liaodong Bay, China, in July 2019. Results showed that the liver, gill, and muscle tissues of marine species are ideal indicators for analyzing Cu, Cr, Pb, Zn, Cd, and Ni contamination in marine environments. When the entire bodies of these marine species were considered, a bio-dilution in Cu, Cr, Pb, Zn, Cd, and Ni was observed in the studied food web. In contrast, the metal tissue-specific bio-magnification in the entire studied food web showed different results. In the liver and gill tissues, negative correlations were found between the concentrations of cadmium and TLs, while copper bio-dilution was also observed in gill tissue. In the muscle tissues, Cu, Pb, and Ni showed bio-dilution and trophic magnification factors of Cu, Pb, and Ni ranged from 0.44 to 0.73. This study highlights the importance of tissue-specific considerations to obtain further accurate information on metal trophodynamics and trophic transfers in marine food webs, thereby enhancing the risk assessment of many elements in wildlife and human health.