Seawater carbonate chemistry and cell numbers during experiments with dinoflagellates, 2007

• Main Authors: Hansen, Per Juel, Lundholm, Nina, Rost, Björn
• Format: Dataset
• Language: English
• Published: PANGAEA 2007
• Subjects: Alkalinity; total; Aragonite saturation state; Bicarbonate ion; Biomass/Abundance/Elemental composition; Calcite saturation state; Calculated; Calculated using seacarb after Nisumaa et al. (2010); Caratium lineatum; Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chromista; Counted in Sedgewick-Rafter chamber; Density; mass density; Dinoflagellates; EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Hansen_etal_07/F2; Heterocapsa triquetra; Infrared gas analyser (ADC; MK3); Laboratory experiment; Laboratory strains; Light:Dark cycle; Measured; Myzozoa; PAR sensor LI-1000; LI-COR Inc.; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; pH meter (Sentron; Argus X); Phytoplankton; Prorocentrum minimum; Radiation; photosynthetically active; Salinity; Single species; Species; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.718214; https://doi.org/10.1594/PANGAEA.718214

The effects of dissolved inorganic carbon (DIC) on the growth of 3 red-tide dinoflagellates (Ceratium lineatum, Heterocapsa triquetra and Prorocentrum minimum) were studied at pH 8.0 and at higher pH levels, depending upon the pH tolerance of the individual species. The higher pH levels chosen for experiments were 8.55 for C. lineatum and 9.2 for the other 2 species. At pH 8.0, which approximates the pH found in the open sea, the maximum growth in all species was maintained until the total DIC concentration was reduced below ~0.4 and 0.2 mM for C. lineatum and the other 2 species, respectively. Growth compensation points (concentration of inorganic carbon needed for maintenance of cells) were reached at ~0.18 and 0.05 mM DIC for C. lineatum and the other 2 species, respectively. At higher pH levels, maximum growth rates were lower compared to growth at pH 8, even at very high DIC concentrations, indicating a direct pH effect on growth. Moreover, the concentration of bio-available inorganic carbon (CO2 + HCO3-) required for maintenance as well as the half-saturation constants were increased considerably at high pH compared to pH 8.0. Experiments with pH-drift were carried out at initial concentrations of 2.4 and 1.2 mM DIC to test whether pH or DIC was the main limiting factor at a natural range of DIC. Independent of the initial DIC concentrations, growth rates were similar in both incubations until pH had increased considerably. The results of this study demonstrated that growth of the 3 species was mainly limited by pH, while inorganic carbon limitation played a minor role only at very high pH levels and low initial DIC concentrations.