Combined effects of CO2 and light on large and small isolates of the unicellular N2-fixing cyanobacterium Crocosphaera watsonii from the western tropical Atlantic Ocean

• Main Authors: Garcia, Nathan S, Fu, Feixue, Breene, Cynthia L, Yu, Elizabeth K, Bernhardt, Peter W, Mulholland, Margaret R, Hutchins, David A
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2013
• Subjects: Bacteria; Bottles or small containers/Aquaria <20 L; Crocosphaera watsonii; Cyanobacteria; Growth/Morphology; Laboratory experiment; Laboratory strains; Light; North Pacific; Other metabolic rates; Pelagos; Phytoplankton; Primary production/Photosynthesis; Single species; Species; Strain; Figure; Irradiance; Partial pressure of carbon dioxide water at sea surface temperature wet air; Growth rate; Growth rate, standard deviation; Diameter; Diameter, standard error; Carbon fixation rate, photosynthetic; Photosynthetic carbon fixation rate, standard deviation; Nitrogen fixation rate; Nitrogen fixation rate, standard deviation; Nitrogen fixation rate, gross/nitrogen fixation rate, netto ratio; Nitrogen fixation rate, gross/nitrogen fixation rate, netto ratio, standard deviation; Photosynthetic carbon fixation rate per cell; Nitrogen fixation rate, per cell; Nitrogen, particulate, accumulation, per cell; Nitrogen, particulate, accumulation, standard deviation; Nitrogen fixation rate, gross/particulate nitrogen, netto, accumulation rate ratio; Nitrogen fixation rate, gross/particulate nitrogen, netto, accumulation rate ratio, standard deviation; Salinity; Temperature, water; pH; pH, standard deviation; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Partial pressure of carbon dioxide, standard deviation; Carbonate system computation flag; Carbon dioxide; Fugacity of carbon dioxide water at sea surface temperature wet air; Bicarbonate ion; Carbonate ion; Alkalinity, total; Aragonite saturation state; Calcite saturation state; 15N2-tracer method; Potentiometric; Coulometric titration; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. 2010; Ocean Acidification International Coordination Centre OA-ICC; Pacific; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.835431; https://doi.pangaea.de/10.1594/PANGAEA.835431

We examined the combined effects of light and pCO2 on growth, CO2-fixation and N2-fixation rates by strains of the unicellular marine N2-fixing cyanobacterium Crocosphaera watsonii with small (WH0401) and large (WH0402) cells that were isolated from the western tropical Atlantic Ocean. In low-pCO2-acclimated cultures (190 ppm) of WH0401, growth, CO2-fixation and N2-fixation rates were significantly lower than those in cultures acclimated to higher (present-day 385 ppm, or future 750 ppm) pCO2 treatments. Growth rates were not significantly different, however, in low-pCO2-acclimated cultures of WH0402 in comparison with higher pCO2 treatments. Unlike previous reports for C. watsonii (strain WH8501), N2-fixation rates did not increase further in cultures of WH0401 or WH0402 when acclimated to 750 ppm relative to those maintained at present-day pCO2. Both light and pCO2 had a significant negative effect on gross : net N2-fixation rates in WH0402 and trends were similar in WH0401, implying that retention of fixed N was enhanced under elevated light and pCO2. These data, along with previously reported results, suggest that C. watsonii may have wide-ranging, strain-specific responses to changing light and pCO2, emphasizing the need for examining the effects of global change on a range of isolates within this biogeochemically important genus. In general, however, our data suggest that cellular N retention and CO2-fixation rates of C. watsonii may be positively affected by elevated light and pCO2 within the next 100 years, potentially increasing trophic transfer efficiency of C and N and thereby facilitating uptake of atmospheric carbon by the marine biota. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne et al, 2014) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation is 2014-09-01.