Colimitation of the unicellular photosynthetic diazotroph Crocosphaera watsonii by phosphorus, light, and carbon dioxide

• Main Authors: Garcia, Nathan S, Fu, Feixue, Hutchins, David A
• Format: Dataset
• Language: English
• Published: PANGAEA 2013
• Subjects: Alkalinity; total; Aragonite saturation state; Bacteria; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); 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; Carbon fixation rate; per cellular phosphorus; Cellular phosphorus; per cell volume; Coulometric titration; Crocosphaera watsonii; Cyanobacteria; Diameter; standard error; Figure; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Irradiance; Laboratory experiment; Laboratory strains; Light; log-phosphorus; Macro-nutrients; Nitrogen fixation rate; gross; per cell; North Pacific; 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; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.835394; https://doi.org/10.1594/PANGAEA.835394

We describe interactive effects of total phosphorus (total P = 0.1-4.0 µmol/L; added as H2NaPO4), irradiance (40 and 150 µmol quanta/m**2/s), and the partial pressure of carbon dioxide (P-CO2; 19 and 81 Pa, i.e., 190 and 800 ppm) on growth and CO2- and dinitrogen (N-2)-fixation rates of the unicellular N-2-fixing cyanobacterium Crocosphaera watsonii (WH0003) isolated from the Pacific Ocean near Hawaii. In semicontinuous cultures of C. watsonii, elevated P-CO2 positively affected growth and CO2- and N-2-fixation rates under high light. Under low light, elevated P-CO2 positively affected growth rates at all concentrations of P, but CO2- and N-2-fixation rates were affected by elevated P-CO2 only when P was low. In both high-light and low-light cultures, the total P requirements for growth and CO2- and N-2-fixation declined as P-CO2 increased. The minimum concentration (C-min) of total P and half-saturation constant (K-1/2) for growth and CO2- and N-2-fixation rates with respect to total P were reduced by 0.05 µmol/L as a function of elevated P-CO2. We speculate that low P requirements under high P-CO2 resulted from a lower energy demand associated with carbon-concentrating mechanisms in comparison with low-P-CO2 cultures. There was also a 0.10 µmol/L increase in C-min and K-1/2 for growth and N-2 fixation with respect to total P as a function of increasing light regardless of P-CO2 concentration. We speculate that cellular P concentrations are responsible for this shift through biodilution of cellular P and possibly cellular P uptake systems as a function of increasing light. Changing concentrations of P, CO2, and light have both positive and negative interactive effects on growth and CO2-, and N-2-fixation rates of unicellular oxygenic diazotrophs like C. watsonii.