Ocean acidification: Research on top of the world (video)

Short Note: Natural seasonal variability of aragonite saturation state within two Antarctic coastal ocean sites

Production of aragonite shells by many marine organisms via calcification requires adequate availability of seawater carbonate ions (CO₂), which is often represented by the aragonite saturation state of seawater: Ω=(Ca²⁺)(CO₃^2-)/λ, where λ is the solubility coefficient of calcium carbonate in the form of aragonite. Changes in Ω_arag are explicitly linked to rises and falls in oceanic partial pressure of CO₂ (pCO²) through alterations in equilibrium CO₂ chemistry in seawater. The coastal Southern Ocean ecosystem in particular, is most vulnerable to future declining Ω_arag via anthropogenic CO₂, uptake (Orr et al. 2005, McNeil & Matear 2008) since pteropods (aragonite secreting zooplankton) make up a large proportion of its biomass (Accomero et al. 2003, Hunt et al. 2008). Spatio-temporal variability in surface ocean Ω_arag is scarce for coastal Antarctic waters. Here, we report data on seasonal variability of Ω_arag from two independent Antarctic sites (Ross Sea and Prydz Bay).