Seawater carbonate chemistry and proportion of different dissolution levels in live juvenile Limacina helicina antarctica from the natural environment and ship-board incubations

• Main Authors: Bednaršek, Nina, Tarling, Geraint A, Bakker, Dorothee C E, Fielding, Sophie, Jones, Elizabeth M, Venables, H J, Ward, Peter, Kuzirian, Alan, Lézé, Bertrand, Feely, Richard A, Murphy, Eugene J
• Format: Dataset
• Language: English
• Published: PANGAEA 2012
• Subjects: Alkalinity; total; Animalia; Antarctic; Aragonite saturation state; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcification/Dissolution; Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coulometric titration; Dissolution level; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Incubation duration; Laboratory experiment; Limacina helicina; Mollusca; OA-ICC; Ocean Acidification International Coordination Centre; Open ocean; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; Percentage; standard deviation; pH; Phosphate; Polar; Potentiometric titration; Salinity; Scotia_OA; Silicate; Single species; Species; Station label; Temperature; water; Time point; descriptive; Zooplankton; Southern Ocean; Antarc*; Antarctica; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.833075; https://doi.org/10.1594/PANGAEA.833075

The carbonate chemistry of the surface ocean is rapidly changing with ocean acidification, a result of human activities. In the upper layers of the Southern Ocean, aragonite-a metastable form of calcium carbonate with rapid dissolution kinetics-may become undersaturated by 2050. Aragonite undersaturation is likely to affect aragonite-shelled organisms, which can dominate surface water communities in polar regions. Here we present analyses of specimens of the pteropod Limacina helicina antarctica that were extracted live from the Southern Ocean early in 2008. We sampled from the top 200 m of the water column, where aragonite saturation levels were around 1, as upwelled deep water is mixed with surface water containing anthropogenic CO2. Comparing the shell structure with samples from aragonite-supersaturated regions elsewhere under a scanning electron microscope, we found severe levels of shell dissolution in the undersaturated region alone. According to laboratory incubations of intact samples with a range of aragonite saturation levels, eight days of incubation in aragonite saturation levels of 0.94-1.12 produces equivalent levels of dissolution. As deep-water upwelling and CO2 absorption by surface waters is likely to increase as a result of human activities, we conclude that upper ocean regions where aragonite-shelled organisms are affected by dissolution are likely to expand.