| Summary: | The Series 4 Experiment, Aggregation of Thalassiosira weissflogii as a function of pCO2, temperature and bacteria, is made up of 2 phases. The Acclimatisation Phase and the Aggregation Phase. The Acclimatisation Phase has two components – The Carbonate System data and the Cell Counts Data. The Aggregation Phase also has two components – The Carbonate System + TEP data and the Sinking Velocity data. Note: For a complete list of measurements, refer to the supplemental document ' Series4_Field_names.pdf' . Increasing Transparent Exopolymer Particle (TEP) formation during diatom blooms as a result of elevated temperature and pCO2 have been suggested to result in enhanced aggregation and carbon flux, therewith potentially increasing the sequestration of carbon by the ocean. We present experimental results on TEP and aggregate formation by Thalassiosira weissflogii (diatom) in the presence or absence of bacteria under two temperature and three pCO2 scenarios. During the aggregation phase of the experiment TEP formation was elevated at the higher temperature (20ºC vs. 15ºC), as predicted. However, in contrast to expectations based on the established relationship between TEP and aggregation, aggregation rates and sinking velocity of aggregates were depressed in warmer treatments, especially under ocean acidification conditions. If our experimental findings can be extrapolated to natural conditions, they would imply a reduction in carbon flux and potentially reduced carbon sequestration after diatoms blooms in the future ocean. This research was supported by NSF Grant: OCE-0926711 2014-10-08
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