Metal accumulation in sea urchins and their kelp diet in an Arctic fjord (Kongsfjorden, Svalbard)

Abstract

The Arctic marine environment is a significant repository of anthropogenic pollutants, including heavy metals (Bard, 1999;Muir et al., 1999;AMAP, 2002, 2005). Elevated concentrations of some toxic metals such as Hg, Pb, Se, and Cd have been reported from several marine birds and mammals (Ronald et al., 1984;Wagemann et al., 1996;Bard, 1999;Muir et al., 1999;Fant et al., 2001;AMAP, 2002, 2005;Dehn et al., 2006). Studies on metal accumulation in prey organisms in Arctic waters have been limited to some major pelagic species such as zooplankton and fish (Ritterhoff and Zauke, 1997;Dehn et al., 2006), despite the fact that a variety of prey organisms, including benthic invertebrates, constitute a major part of the diet for many Arctic marine mammals (Bustamante et al., 2004;Dehn et al., 2006, 2007). Several studies have already reported higher concentrations of Cd in Arctic seals that prey on benthic invertebrates rather than fish (Bustamante et al., 2004;Dehn et al., 2005).Sea urchins of the genus Strongylocentrotus have a wide geographic distribution, occurring in the North Atlantic, North Pacific, and Arctic Oceans (Bohn, 1979;Bazhin, 2002;Gagnon et al., 2004;Addison and Hart, 2004, 2005), including the Svalbard Islands, a key area in the Arctic Monitoring and Assessment Programme (AMAP, 1996). The green sea urchin S. droebachiensis is reportedly a key species on shallow rocky subtidal substrata in Kongsfjorden on West Spitsbergen, Svalbard (Hop et al., 2002;Kaczmarek et al., 2005;Beuchel and Gulliksen, 2008). Hop et al. (2002) reported that the coverage of laminarian kelps fluctuated widely in this location, and heavily grazed areas devoid of kelps were commonly associated with high densities of S. droebachiensis. This study aimed to assess the metal accumulation of the sea urchins Strongylocentrotus spp., and further to improve the understanding of metal transfer at lower trophic levels in Arctic marine ecosystems. Sea urchins (S. droebachiensis, S.