Meeting Abstract
Marine invertebrates in the Southern Ocean are considered to be at particularly high risk to ocean acidification (OA). Echinoderms are especially vulnerable because they use “high magnesium calcite” (>4% MgCO3) to construct their skeletal elements. Calcite comprised of high levels of magnesium is more soluble than either calcite or aragonite alone. The increased solubility of MgCO3 is compounded by the fact that the Southern Ocean has naturally low carbonate ion concentrations. As the saturation levels of calcite and aragonite in the Southern Ocean reach sub-saturation levels under ocean acidification, echinoderms will need to cope with both skeletal dissolution and the potential for increased energetic cost in producing and maintaining skeletal material. Representatives of the Echinoidea, Ophiuroidea, and Asteroidea (collected from a variety of biogeographic regions of Antarctica) were dissected and their skeletal elements powdered and analyzed for magnesium-calcite content using x-ray diffraction (XRD). Comparisons across the three classes of echinoderms, intra-specific comparisons among skeletal components, and comparisons across geographic regions will be reported. These data will provide the first analysis of MgCO3 levels in skeletal elements of echinoderms that occur south of -70 degrees latitude. The new information will facilitate future predictions about the vulnerability of Antarctic echinoderms to continued ocean acidification.
