Impact of high CO2 on the geochemistry of the coralline algae Lithothamnion glaciale

• Main Authors: Ragazzola, Federica, Foster, Laura C, Jones, C J, Scott, T B, Fietzke, Jan, Kilburn, M R, Schmidt, Daniela N
• Format: Dataset
• Language: English
• Published: PANGAEA 2016
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Benthos; Bicarbonate ion; BIOACID; Biological Impacts of Ocean Acidification; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Kattegat_OA; Laboratory experiment; Lithothamnion glaciale; Location; Macroalgae; Magnesium/Calcium ratio; standard error; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Plantae; Potentiometric titration; Registration number of species; Rhodophyta; Salinity; Sample ID; Single species; Species; Strontium/Calcium ratio; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.867382; https://doi.org/10.1594/PANGAEA.867382

Coralline algae are a significant component of the benthic ecosystem. Their ability to withstand physical stresses in high energy environments relies on their skeletal structure which is composed of high Mg-calcite. High Mg-calcite is, however, the most soluble form of calcium carbonate and therefore potentially vulnerable to the change in carbonate chemistry resulting from the absorption of anthropogenic CO2 by the ocean. We examine the geochemistry of the cold water coralline alga Lithothamnion glaciale grown under predicted future (year 2050) high pCO2 (589 matm) using Electron microprobe and NanoSIMS analysis. In the natural and control material, higher Mg calcite forms clear concentric bands around the algal cells. As expected, summer growth has a higher Mg content compared to the winter growth. In contrast, under elevated CO2 no banding of Mg is recognisable and overall Mg concentrations are lower. This reduction in Mg in the carbonate undermines the accuracy of the Mg/Ca ratio as proxy for past temperatures in time intervals with significantly different carbonate chemistry. Fundamentally, the loss of Mg in the calcite may reduce elasticity thereby changing the structural properties, which may affect the ability of L. glaciale to efficiently function as a habitat former in the future ocean.