Seawater carbonate chemistry and diatom silica production in the Southern Ocean

• Main Authors: Petrou, Katherina, Baker, Kirralee G, Nielsen, Daniel A, Hancock, Alyce M, Schulz, Kai Georg, Davidson, Andrew T
• Format: Dataset
• Language: English
• Published: PANGAEA 2019
• Subjects: Abbreviation; Alkalinity; total; Antarctic; Aragonite saturation state; Bicarbonate ion; Biogenic silica; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell biovolume; Chlorophyll a; Coast and continental shelf; Containers and aquaria (20-1000 L or < 1 m**2); Davis_Station_OA; Entire community; EXP; Experiment; Experiment day; Fragilariopsis curta; Fragilariopsis cylindrus; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Identification; Laboratory experiment; Maximum photochemical quantum yield of photosystem II; Nitrate and Nitrite; Number of cells; OA-ICC; Ocean Acidification International Coordination Centre; Other metabolic rates; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphorus; reactive soluble; Polar; Primary production/Photosynthesis; Proboscia truncata; Proton concentration; Pseudonitzschia turgiduloides; Registration number of species; Replicate; Salinity; Silicate; Silicification; Southern Ocean; Antarc*; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.914329; https://doi.org/10.1594/PANGAEA.914329

Diatoms, large bloom-forming marine microorganisms, build frustules out of silicate, which ballasts the cells and aids their export to the deep ocean. This unique physiology forges an important link between the marine silicon and carbon cycles. However, the effect of ocean acidification on the silicification of diatoms is unclear. Here we show that diatom silicification strongly diminishes with increased acidity in a natural Antarctic community. Analyses of single cells from within the community reveal that the effect of reduced pH on silicification differs among taxa, with several species having significantly reduced silica incorporation at CO2 levels equivalent to those projected for 2100. These findings suggest that, before the end of this century, ocean acidification may influence the carbon and silicon cycle by both altering the composition of the diatom assemblages and reducing cell ballasting, which will probably alter vertical flux of these elements to the deep ocean.