Seawater carbonate chemistry and particulate organic particles during a semicontinuous batch culture experiment with Trichodesmium IMS101, 2007

• Main Authors: Barcelos e Ramos, Joana, Biswas, Haimanti, Schulz, Kai Georg, LaRoche, Julie, Riebesell, Ulf
• Format: Dataset
• Language: English
• Published: PANGAEA 2007
• Subjects: Alkalinity; total; Aragonite saturation state; Automated segmented-flow analyzer (Quaatro); Bacteria; 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; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Carbon per cell; Chlorophyll a per cell; Counting; Cyanobacteria; Determined by acetylene reduction assay using a gas chromatograph; EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; Experimental treatment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gas chromatography (EURO EA Elemental Analyser; EUROVECTOR); Laboratory experiment; Measured; Nitrogen; Nitrogen fixation rate; per cell; Nitrogen per cell; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Other metabolic rates; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate per cell; Phosphorus; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.716818; https://doi.org/10.1594/PANGAEA.716818

Diazotrophic (N2-fixing) cyanobacteria provide the biological source of new nitrogen for large parts of the ocean. However, little is known about their sensitivity to global change. Here we show that the single most important nitrogen fixer in today's ocean, Trichodesmium, is strongly affected by changes in CO2 concentrations. Cell division rate doubled with rising CO2 (glacial to projected year 2100 levels) prompting lower carbon, nitrogen and phosphorus cellular contents, and reduced cell dimensions. N2 fixation rates per unit of phosphorus utilization as well as C:P and N:P ratios more than doubled at high CO2, with no change in C:N ratios. This could enhance the productivity of N-limited oligotrophic oceans, drive some of these areas into P limitation, and increase biological carbon sequestration in the ocean. The observed CO2 sensitivity of Trichodesmium could thereby provide a strong negative feedback to atmospheric CO2 increase.