Dataset: Series 3B: bubble expt NPQ raw

Experiments were conducted to investigate the impact of bubbling gas through cultures of Thalassiosira pseudonana CCMP 1014 grown in Multicultivator MC-1000 OD culture tubes. TP1014 stock cultures were maintained in artificial seawater (Kester et. al 1967), enriched as with f/2 media (Guillard 1975). For the experiment, 5 ml of the TP1014 stock cultures were inoculated into 75 ml of ASW in eight tubes. The tubes were incubated in a Multicultivator MC-1000 OD unit (Qubit Systems), at 25 deg C and 400 µmol photons * m-2 * sec-1, set at a 12:12 day:night cycle for four days. Three tubes had no aeration (T1, T2, and T3); three tubes were bubbled with air at 60 ml·min-1 through a 0.2 µm stainless steel “carbonating stone” (T4, T5, and T6); and two tubes were bubbled with air at 120 ml·min-1 through a 0.2 µm stainless steel “carbonating stone” (T7 and T8). Samples were collected from each tube at the start of the experiment (day-0), and 5 hours after the start of the light phase each day (i.e. at 24-hour intervals) after that for four days. Samples were always collected 5 hours after the start of the light phase.

Three ml of samples from the non-aerated (T1, T2, and T3) and the 60 ml·min-1 aeration tubes (T4, T5, and T6) were used for assessment of photochemistry using the Aquapen-C AP-C 100 (Photon Systems Instruments). Samples were placed in the dark at 25 deg C for a minimum of 30 minutes prior to measuring photochemistry. The NPQ1 protocol on the instrument was used for assessment of non-photochemical quenching in samples, and the LC3 protocol was used to generate light curves that provide measurements of photosynthesis rates. The NPQ1 protocol administers 5 light pulses over 60 seconds during actinic light exposure, followed by 3 light pulses over 88 seconds during recovery in the dark. The LC3 protocol involves measurements of baseline fluorescence and maximal fluorescence during 7 phases of 60 seconds each, with each phase representing a light intensity from 10 to 1000 μmol * m-2 * s-1. Blue light (455 nm) was used as actinic light in these experiments. Baseline measurements were made at 0.03 μmol * m-2 * s-1, Saturating pulses were set at 2100 μmol * m-2 * s-1, and actinic light pulses (for the NPQ1 protocol only) were set at 1000 μmol * m-2 * s-1.