Seawater carbonate chemistry and diatom Phaeodactylum tricornutum (CCMA 106) biological processes during experiments, 2010

• Main Authors: Wu, YaPing, Gao, Kunshan, Riebesell, Ulf
• Format: Dataset
• Language: English
• Published: PANGAEA 2010
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated; see reference(s); Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; partial pressure; Chlorophyll a; Chlorophyll a per cell; Chromista; Clark type oxygen electrode (5300A; YSI); Comment; DIC analyzer (AS-C3; Apollo Scitech); 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); Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.758214; https://doi.org/10.1594/PANGAEA.758214

CO2/pH perturbation experiments were carried out under two different pCO2 levels (39.3 and 101.3 Pa) to evaluate effects of CO2-induced ocean acidification on the marine diatom Phaeodactylum tricornutum. After acclimation (>20 generations) to ambient and elevated CO2 conditions (with corresponding pH values of 8.15 and 7.80, respectively), growth and photosynthetic carbon fixation rates of high CO2 grown cells were enhanced by 5% and 12%, respectively, and dark respiration stimulated by 34% compared to cells grown at ambient CO2. The half saturation constant (Km) for carbon fixation (dissolved inorganic carbon, DIC) increased by 20% under the low pH and high CO2 condition, reflecting a decreased affinity for HCO3- or/and CO2 and down-regulated carbon concentrating mechanism (CCM). In the high CO2 grown cells, the electron transport rate from photosystem II (PSII) was photoinhibited to a greater extent at high levels of photosynthetically active radiation, while non-photochemical quenching was reduced compared to low CO2 grown cells. This was probably due to the down-regulation of CCM, which serves as a sink for excessive energy. The balance between these positive and negative effects on diatom productivity will be a key factor in determining the net effect of rising atmospheric CO2 on ocean primary production.