Antarctic octopod beaks as proxy for mercury concentrations in soft tissues

As the role of mercury is poorly known in Southern Ocean biota, the total mercury (T-Hg) concentrations were evaluated in upper/lower beaks, digestive gland, gills and mantle muscle of Adelieledone polymorpha and Pareledone turqueti, two of the most abundant octopod species around South Georgia. Beaks had the lowest T-Hg concentrations (A. polymorpha: [T-Hg]Upper = 27.2 ± 12.9 ng∙g−1 and [T-Hg]Lower = 27.5 ± 20.0 ng∙g−1; P. turqueti: [T-Hg]Upper = 34.6 ± 13.9 ng∙g−1 and [T-Hg]Lower = 56.8 ± 42.0 ng∙g−1), followed by gills and muscle. The highest values were recorded in the digestive gland (A. polymorpha: 251.6 ± 69.7 ng∙g−1; P. turqueti: 347.0 ± 177.0 ng∙g−1). Significant relationships were found between the concentrations of T-Hg in the beaks and muscle of A. polymorpha (T-Hg in muscle is 10 times higher than in beaks). This study shows that beaks can be used as proxy for T-Hg in muscle for some octopod species, and a helpful tool for estimating total Hg body burden from beaks.