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-H](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.