Influence of marine microbes on atmospheric organosulfur during an induced phytoplankton bloom in a large wave flume system

Ocean emissions are a major source of atmospheric gases that may influence Earth climate. However, the biological mechanisms underlying marine production of climate important gases are not well understood. Hence, it is important to further explore the role of marine microbes in the fluxes of trace gases between the ocean and the atmosphere and the drivers of theses dynamics. The link between marine emission of organosulfur gases and marine microbes was studied during SeaSCAPE (Sea Spray Chemistry and Particle Evolution Experiment) in Summer 2019. We followed microbial activities and gases’ concentrations (dissolved and headspace DMS and MeSH) during a 4-weeks phytoplankton bloom induced in a 13,000L sealed wave channel. Bacterial abundance and dissolved DMS increased when the phytoplankton bloom crashed. DMS emission patterns suggested potential bacterial utilization of DMS few days after the bloom collapsed. These results will be complemented with molecular biology analysis such as quantification of process-relevant functional genes to assess the role of the bacterioplankton in using and cleaving some algal metabolites (such as DMSP and isoprene) which may influence the fluxes of trace gases to the atmosphere. This is of particular importance to better constrain the biotic processes influencing sea to air exchange and the effect of biological emissions on atmospheric chemistry and radiative budget.