Trace metals in skeletal calcite of echinoderms from the Barents Sea

This study investigates the skeletal accumulation of selected elements (Al, Ag, As, Ca, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Pb, Sr, Zn) in echinoderms inhabiting Barents Sea, an area impacted by human activities from northern Norway and Kola Peninsula, known sources of metal pollution. The primary aim was to have insight whether metals incorporation in the skeleton of Arctic echinoderms is regulated physiologically by the organism or influenced by abiotic environmental conditions (expressed as distance from the source of metal pollution). Metal concentrations were analysed in 17 species from four echinoderm classes: Asteroidea, Ophiuroidea, Crinoidea and Echinoidea. The results revealed species-specific accumulation patterns for most metals, indicating a strong biological control over metal incorporation. In crinoid Heliometra glacialis, a negative correlation between body size and skeletal concentrations of Al, Fe, Mg and Mn was observed. This correlation was ascribed to age-related metabolic traits and a likely mechanism for removing foreign metals from the skeletal calcite. The relationships between environmental factors and metal accumulation patterns were less clear. However, higher concentrations of Al, Fe, Mg, Mn and Pb were found in suspension feeders collected near glaciers, which were potential sources of suspended material. Asteroids exhibited particularly high concentrations of Cu, Fe, Cr, Hg compared to species from the other regions, suggesting that their calcified skeletons may serve as storage mechanisms to prevent toxic effects in other body parts. These observations confirm that biologically-mediated processes predominantly govern metal bioaccumulation in Arctic echinoderms.