Seawater carbonate chemistry and physiological performance in the Coccolithophorid Emiliania huxleyi

• Main Authors: Xu, Jiekai, Sun, J, Beardall, John, Gao, Kunshan
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2020
• Subjects: Bottles or small containers/Aquaria <20 L; Calcification/Dissolution; Chromista; Emiliania huxleyi; Growth/Morphology; Haptophyta; Laboratory experiment; Laboratory strains; Not applicable; Pelagos; Phytoplankton; Primary production/Photosynthesis; Salinity; Single species; Type; Species; Registration number of species; Uniform resource locator/link to reference; Treatment; Growth rate; Growth rate, standard deviation; Cell, diameter; Cell, diameter, standard deviation; Chlorophyll a per cell; Chlorophyll a, standard deviation; Chlorophyll c per cell; Chlorophyll c, standard deviation; Carotenoids per cell; Carotenoids, standard deviation; Maximum quantum yield of photosystem II; Maximum quantum yield of photosystem II, standard deviation; Effective quantum yield; Effective quantum yield, standard deviation; Net photosynthesis rate per cell; Net photosynthesis rate, standard deviation; Calcification rate of carbon per cell; Calcification rate, standard deviation; Calcification rate/Photosynthesis rate, ratio; Calcification rate/Photosynthesis rate, ratio, standard deviation; Repair/damage ratio; Repair/damage ratio, standard deviation; Temperature, water; pH; pH, standard deviation; Alkalinity, total; Alkalinity, total, standard deviation; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Bicarbonate ion; Bicarbonate ion, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbon dioxide; Carbon dioxide, standard deviation; Partial pressure of carbon dioxide water at sea surface temperature wet air; Partial pressure of carbon dioxide, standard deviation; Carbonate system computation flag; Fugacity of carbon dioxide water at sea surface temperature wet air; Aragonite saturation state; Calcite saturation state; Potentiometric; Potentiometric titration; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. 2010; Ocean Acidification International Coordination Centre OA-ICC; Ocean acidification; Sea ice
• Online Access: https://dx.doi.org/10.1594/pangaea.930309; https://doi.pangaea.de/10.1594/PANGAEA.930309

While seawater acidification induced by elevated CO2 is known to impact coccolithophores, the effects in combination with decreased salinity caused by sea ice melting and/or hydrological events have not been documented. Here we show the combined effects of seawater acidification and reduced salinity on growth, photosynthesis and calcification of Emiliania huxleyi grown at 2 CO2 concentrations (low CO2 LC:400 μatm; high CO2 HC:1000 μatm) and 3 levels of salinity (25, 30, and 35 per mil). A decrease of salinity from 35 to 25 per mil increased growth rate, cell size and photosynthetic performance under both LC and HC. Calcification rates were relatively insensitive to salinity though they were higher in the LC-grown compared to the HC-grown cells at 25 per mil salinity, with insignificant differences under 30 and 35 per mil. Since salinity and OA treatments did not show interactive effects on calcification, changes in calcification: photosynthesis ratios are attributed to the elevated photosynthetic rates at lower salinities, with higher ratios of calcification to photosynthesis in the cells grown under 35 per mil compared with those grown at 25 per mil. In contrast, photosynthetic carbon fixation increased almost linearly with decreasing salinity, regardless of the pCO2 treatments. When subjected to short-term exposure to high light, the low-salinity-grown cells showed the highest photochemical effective quantum yield with the highest repair rate, though the HC treatment enhanced the PSII damage rate. Our results suggest that, irrespective of pCO2, at low salinity Emiliania huxleyi up-regulates its photosynthetic performance which, despite a relatively insensitive calcification response, may help it better adapt to future ocean global environmental changes, including ocean acidification, especially in the coastal areas of high latitudes. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2021) 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 by seacarb is 2021-04-07.