The phytoplankton Rhodomonas sp. CCMP 755 was grown semi-continuously in atmosphere controlled chambers at three different CO2 treatment concentrations; Ambient (400ppmv), Moderate (750ppmv), and High (1000ppmv). Cultures were diluted daily starting day 4 with pre-equilibrated media containing f/50 nutrients. Some of the culture removed was used to evaluate chemical parameters.
pCO2 Rhodomonas: Samples for total alkalinity were taken on growth days 1, 3, 5, 7, 9, 11, 12, 14 and 17 and preserved with HgCl2 and stored at 4° until analysis. Alkalinity was measured by gran titration using a Titrando 888, and 0.1 N HCl titrant, in a temperature controlled titration vessel. DIC samples were filtered through a 0.2 µm nylon syringe filter on the morning of the experimental day, then stored in airtight vials at 4°C until analysis within 60 days using an Apollo SciTech DIC Analyzer AS-C3 which incorporates the LI-7000 CO2/H2O Analyzer. Other parameters were calculated with CO2sys.
pCO2 Rhodomonas and long-term grazing by Gyrodinium: Samples for total alkalinity of pre-equilibrated media were taken on growth day 11 and from the Rhodomonas plus Gyrodinium grazing treatments on day16 and preserved with HgCl2 and stored at 4° until analysis. Alkalinity was measured by gran titration using a Titrando 888, and 0.1 N HCl titrant, in a temperature controlled titration vessel. DIC samples from the long-term grazing experiment were filtered through a 0.2 µm nylon syringe filter on the morning of the experimental day, then stored in airtight vials at 4°C until analysis within 60 days using an Apollo SciTech DIC Analyzer AS-C3 which incorporates the LI-7000 CO2/H2O Analyzer. Other parameters were calculated with CO2sys.