Triplicate 5 mL samples were preserved for flow cytometry with 0.5% glutaraldehyde (final concentration), incubated at 4\u00b0C for 10 min and frozen (-80\u00b0C) until analysis (within 2-3 weeks; Kemp et al. 1993). To calculate phytoplankton group abundances, 200 \u00b5l aliquots of fixed sample were added to a 96-well plate and run on a Guava flow cytometer (Millipore). Filtered seawater (0.45 \u00b5m) was run as a blank\u00a0and instrument-specific beads were used to calibrate the cytometer. Samples were analyzed at low flow rate (0.24 \u00b5l s-1) for 3 min. Three major phytoplankton groups were distinguishable based on plots of forward scatter vs. orange (phycoerythrin-containing, Synechococcus spp.) or red (pico- and nanoeukaryotes) fluorescence signals (Worden and Binder 2003).\u00a0
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Samples for enumerating bacteria were stained prior to running on the Guava in 0.5% v/v SybrGreen I DNA stain for 1 hour at room temperature in the dark.
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Mesocosm treatment for all HHQ experiments was as follows:
\nRedfield: N:P added in a 16:1 ratio during the first 3 days of the experiment, no shading
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HHQ treatments here are as follows:
\nHigh HHQ - 100 ng mL-1 (410 uM) added to triplicate 5L bottles.
\nDMSO control - equivalent (v:v) DMSO added to triplicate 5L bottles.
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\u00a0All bottles were incubated for 24h in a flow-through tank, that was shaded to mimic in situ conditions. Chlorophyll samples were taken at T0 and T24 for all experiments.
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Data were processed in Excel with statistics run in Excel, R, or Matlab.
This dataset includes flow cytometry measurements from HHQ experiments conducted during the MesoHux mesocosm experiment, May 2017, Bergen, Norway. Microbial mesocosms were spiked with 2-heptyl-4-quinolone (HHQ).
BCO-DMO Processing Notes:
\n- added conventional header with dataset name, PI name, version date
\n- modified parameter names to conform with BCO-DMO naming conventions