Abstract
Metal and metalloid (hereafter simply 'metal') pollution is a growing global concern for both aquatic organisms and human health. Fishes are important in human diet, but they can also accumulate metals in their tissues. Therefore, it is important to monitor the concentration of metals in their muscle, and to investigate potential patterns of bioaccumulation and biomagnification. Here, we studied the bioaccumulation and biomagnification of chromium (Cr), nickel (Ni), arsenic (As), and lead (Pb) in three economically important fish species from Dalyan Lake (Türkiye): the grey mullet Mugil cephalus, the gilthead seabream Sparus aurata, and the European seabass Dicentrarchus labrax. To assess trophic transfer patterns, we combined metal and carbon and nitrogen stable isotope analyses. The trophic niches of the three species were differentiated, with D. labrax occupying a higher trophic position compared to the other species. We found significant interspecific differences in metal accumulation, especially due to different Pb, As, and Cr concentrations. The concentration of As was highest in S. aurata (2.07 µg/kg), intermediate in M. cephalus (1.49 µg/kg), and the lowest in D. labrax (1.06 µg/kg), possibly reflecting a greater exposure to polluted sediment in S. aurata. The concentration of the other metals were similar among species, ranging from 1.47 (S. aurata) to 1.58 (M. cephalus) µg/kg for Cr, from 0.51 (S. aurata and M. cephalus) to 0.56 (D. labrax) µg/kg for Ni, and from 0.25 (D. labrax) to 0.47 (M. cephalus) µg/kg for Pb. Despite no significant differences among species were found in its concentration, Cr showed evidence of biomagnification. The concentration of As, Ni, and Pb did not show biomagnification, but rather trophic dilution. This study demonstrates the value of integrating ecological tracers with contaminant analysis to better understand pollutant dynamics in aquatic food webs.