Species-specific heavy metal concentrations of tuna species: the case of Thunnus alalunga and Katsuwonus pelamis in the Western Mediterranean

Abstract

Albacore Thunnus alalunga and skipjack tuna Katsuwonus pelamis are highly migratory species that are usually caught together in the Western Mediterranean. These species are top predators that are highly affected by the biomagnification process through the trophic chain. Bioaccumulation pattern of the main metal pollutants (mercury, Hg; lead, Pb; and cadmium, Cd) were analyzed in muscle tissues of 52 individuals (26 T. alalunga and 26 K. pelamis) of these highly consumed species in order to address two objectives: (1) compare the species-specific bioaccumulation between these large-pelagic species, and (2) assess the healthy properties of such valuable resources based on the trace metal limits established by the European Commission Regulation (ECR). Both generalized linear mixed models and redundancy analysis indicated a differential bioaccumulation between these two tuna species. While T. alalunga accumulates higher concentrations of Hg (0.1996 ± 0.0602 mg·kg-1 weight wet-ww), K. pelamis accumulates higher concentrations of Cd (0.0076 ± 0.0049 mg·kg-1 ww) and Pb (0.0031 ± 0.0017 mg·kg-1 ww). Size and trophic ecology support the differences detected in the bioaccumulation pattern. Heavy metal concentrations were below the tolerable limits considered by ECR (1, 0.1, and 0.3 mg·kg-1 ww for Hg, Cd, and Pb, respectively)