Seawater carbonate chemistry and growth and chlorophyll, photochemical parameters, carbon fixation of diatom Phaeodactylum tricornutum

• Main Authors: Liu, Nana, Beardall, John, Gao, Kunshan
• Format: Dataset
• Language: English
• Published: PANGAEA 2017
• Subjects: Alkalinity; total; Aragonite saturation state; 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; intracellular pool; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chromista; Cumulative carbon fixation per cell; Effective quantum yield; Factor; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Identification; Initial slope of photosynthesis/dissolved inorganic carbon; Laboratory experiment; Laboratory strains; Light; Light capturing capacity; Light saturated maximum photosynthetic rate per cell; Light saturation point; Maximal electron transport rate; relative; Maximum photochemical quantum yield of photosystem II; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phaeodactylum tricornutum; Phytoplankton; Primary production/Photosynthesis; Registration number of species; Salinity; Single species; Species; Temperature; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.900658; https://doi.org/10.1594/PANGAEA.900658

Elevated CO2 is leading to a decrease in pH in marine environments (ocean acidification [OA]), altering marine carbonate chemistry. OA can influence the metabolism of many marine organisms; however, no consensus has been reached on its effects on algal photosynthetic carbon fixation and primary production. Here, we found that when the diatom Phaeodactylum tricornutum was grown under different pCO2 levels, it showed different responses to elevated pCO2 levels under growth-limiting (20 µmol photons/m**2/s, LL) compared with growth-saturating (200 µmol photons/m**2/s, HL) light levels. With pCO2 increased up to 950 µatm, growth rates and primary productivity increased, but in the HL cells, these parameters decreased significantly at higher concentrations up to 5000 µatm, while no difference in growth was observed with pCO2 for the LL cells. Elevated CO2 concentrations reduced the size of the intracellular dissolved inorganic carbon (DIC) pool by 81% and 60% under the LL and HL levels, respectively, with the corresponding photosynthetic affinity for DIC decreasing by 48% and 55%. Little photoinhibition was observed across all treatments. These results suggest that the decreased growth rates under higher CO2 levels in the HL cells were most likely due to acid stress. Low energy demand of growth and energy saving from the down-regulation of the CO2 concentrating mechanisms (CCM) minimized the effects of acid stress on the growth of the LL cells. These findings imply that OA treatment, except for down-regulating CCM, caused stress on the diatom, reflected in diminished C assimilation and growth rates.