Seawater carbonate chemistry and photosynthesis and dark respiration of Thalassiosira weissflogii (diatom)

• Main Authors: Li, Futian, Fan, Jiale, Hu, Lili, Beardall, John, Xu, Juntian
• Format: Dataset
• Language: English
• Published: PANGAEA 2019
• Subjects: Alkalinity; total; Aragonite saturation state; Bicarbonate ion; Biogenic silica; per cell; Biogenic silica per surface area; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell biovolume; Cell surface area/cell volume ratio; Change; Chlorophyll a per cell; Chromista; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Laboratory experiment; Laboratory strains; Net oxygen evolution; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phytoplankton; Primary production/Photosynthesis; Registration number of species; Replicate; Respiration; Respiration rate; oxygen; dark per cell; Salinity; Single species; Species; Surface area; Temperature; water; Thalassiosira weissflogii; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.907928; https://doi.org/10.1594/PANGAEA.907928

Increasing atmospheric pCO2 leads to seawater acidification, which has attracted considerable attention due to its potential impact on the marine biological carbon pump and function of marine ecosystems. Alternatively, phytoplankton cells living in coastal waters might experience increased pH/decreased pCO2 (seawater alkalization) caused by metabolic activities of other photoautotrophs, or after microalgal blooms. Here we grew Thalassiosira weissflogii (diatom) at seven pCO2 levels, including habitat-related lowered levels (25, 50, 100, and 200 µatm) as well as present-day (400 µatm) and elevated (800 and 1600 µatm) levels. Effects of seawater acidification and alkalization on growth, photosynthesis, dark respiration, cell geometry, and biogenic silica content of T. weissflogii were investigated. Elevated pCO2 and associated seawater acidification had no detectable effects. However, the lowered pCO2 levels (25-100 µatm), which might be experienced by coastal diatoms in post-bloom scenarios, significantly limited growth and photosynthesis of this species. In addition, seawater alkalization resulted in more silicified cells with higher dark respiration rates. Thus, a negative correlation of biogenic silica content and growth rate was evident over the pCO2 range tested here. Taken together, seawater alkalization, rather than acidification, could have stronger effects on the ballasting efficiency and carbon export of T. weissflogii.