Bioaccumulation of chemical elements in grey seals (Halichoerus grypus) from the Baltic Sea

Abstract

Concentrations of Ag, As, B, Ba, Bi, Ca, Cd, Ce, Co, Cs, Cu, Dy, Er, Fe, Ga, Ge, Hg, Ho, K, La, Li, Lu, Mg, Mn, Mo, Na, Nd, Ni, P, Pb, Pr, Rb, S, Sb, Se, Si, Sm, Sn, Sr, Tb, Th, Tl, V, W, Y, Yb and Zn in the livers of grey seals obtained from stranded, hunted and by-caught animals from the Swedish and Polish Baltic coasts were determined by ICP-MS. Stable isotope analysis of δ13C and δ15N was applied to link chemical element concentrations to feeding preferences (pelagic vs. benthic) and trophic position of the seals, respectively. Isotopic ratios in the seals increased in seals from the north towards the southern Baltic Sea, with markedly higher isotopic signatures in seals inhabiting the Polish coast . Analysis of covariance revealed differences in chemical element concentrations between areas for As, B, Cu, Ni, Rb, Sr, Tl with most of these elements exhibiting higher concentrations in seals from the southern Baltic Sea. Additionally age related differences in concentrations of several trace elements were found. Silver, B, Bi, Cd, Co, Hg, Mo, Sb, Se, Sn, V and Zn and the rare earth elements (REE) were found to increase with age. The role of Se in detoxification of Hg was confirmed by high correlation between these two elements (r = 0.99, p < 0.0001). Significantly higher Se:Hg molar ratio were observed in yearlings compared to juvenile and adult seals . Several other elements also revealed statistically significant interrelationships, especially pronounced for the REEs.