Seawater carbonate chemistry and particulate organic carbon accumulation of two Antarctic diatom species

• Main Authors: Heiden, Jasmin, Thoms, Silke, Bischof, Kai, Trimborn, Scarlett
• Format: Dataset
• Language: English
• Published: PANGAEA 2018
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Bicarbonate ion; 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; organic; particulate; per cell; Carbon/Nitrogen ratio; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chromista; Coast and continental shelf; Fragilariopsis curta; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Laboratory experiment; Light; Maximum photochemical quantum yield of photosystem II; Nitrogen; Not applicable; Antarc*; Antarctic; Southern Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.892795; https://doi.org/10.1594/PANGAEA.892795

Impacts of rising atmospheric CO2 concentrations and increased daily irradiances from enhanced surface water stratification on phytoplankton physiology in the coastal Southern Ocean remain still unclear. Therefore, in the two Antarctic diatoms Fragilariopsis curta and Odontella weissflogii the effects of moderate and high natural solar radiation combined with either ambient or future pCO2 on cellular particulate organic carbon (POC) contents and photophysiology were investigated. Results showed that increasing CO2 concentrations had greater impacts on diatom physiology than exposure to increasing solar radiation. Irrespective of the applied solar radiation regime, cellular POC quotas increased with future pCO2 in both diatoms. Lowered maximum quantum yields of photochemistry in PSII (Fv/Fm) indicated a higher photosensitivity under these conditions, being counteracted by increased cellular concentrations of functional photosynthetic reaction centers. Overall, our results suggest that both bloom‐forming Antarctic coastal diatoms might increase carbon contents under future pCO2 conditions despite reduced physiological fitness. This indicates a higher potential for primary productivity by the two diatom species with important implications for the CO2 sequestration potential of diatom communities in the future coastal Southern Ocean.