Seawater carbonate chemistry and photosynthesis of a coccolithophorid in a laboratory experiment

• Main Authors: Jin, Peng, Gao, Kunshan, Villafañe, Virginia E, Campbell, Douglas A, Helbling, E Walter
• Format: Dataset
• Language: English
• Published: PANGAEA 2013
• Subjects: Alkalinity; total; standard deviation; 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; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chromista; Description; Effective absorbance cross-section of photosystem II; Electron transport; absolute; cumulative; Electron transport rate; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gephyrocapsa oceanica; Haptophyta; Identification; Irradiance; Laboratory experiment; Laboratory strains; Light; Light absorption by phytoplankton normalized to chlorophyll a; Non photochemical quenching; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pacific; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.830526; https://doi.org/10.1594/PANGAEA.830526

Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400-700 nm) and ultraviolet radiation (UVR; 280-400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemical performance of a coccolithophore, Gephyrocapsa oceanica, grown under high, future (1,000 µatm) and low, current (390 µatm) CO2 levels, under regimes of fluctuating irradiances with or without UVR. Under both CO2 levels, fluctuating irradiances, as compared with constant irradiance, led to lower nonphotochemical quenching and less UVR-induced inhibition of carbon fixation and photosystem II electron transport. The cells grown under high CO2 showed a lower photosynthetic carbon fixation rate but lower nonphotochemical quenching and less ultraviolet B (280-315 nm)-induced inhibition. Ultraviolet A (315-400 nm) led to less enhancement of the photosynthetic carbon fixation in the high-CO2-grown cells under fluctuating irradiance. Our data suggest that ocean acidification and fast mixing or fluctuation of solar radiation will act synergistically to lower carbon fixation by G. oceanica, although ocean acidification may decrease ultraviolet B-related photochemical inhibition.