Joint SOLAS Bergen Mesocosm Experiment

This project will unify a number of individual projects within the current NERC SOLAS directed programme that are investigating the microbial processes controlling the production and consumption of atmospheric trace gases in the sea surface microlayer (SML). This is the interface through which climatically important trace gases such as CH4, N2O, CO, DMS, methyl halides and VICs must pass in order to be released to the atmosphere and/or taken up by the oceans. Microbes that both consume and produce these gases in the SML thus exert major controls on their biogeochemical cycles. The processes which regulate the activities of these microbes are poorly understood but can be directly addressed within UKSOLAS through generating a robust dataset including chemical and biological parameters under carefully defined experimental conditions. Although both SML sampling for biological and chemical components and measurements of SML gas exchange are now routinely possible through the work of the participating research groups, what is now needed is a coherent unifying approach that enhances the scientific deliverables of these ongoing UKSOLAS projects. The Bergen mesocosm facilities afford a unique opportunity for this; they will enable UKSOLAS scientists to generate a robust dataset for experimental analysis and modelling since it will be possible to follow SML microbiology, chemistry and trace gas transfer under carefully defined conditions throughout the course of a phytoplankton bloom, when several important trace gases will be produced and/or consumed microbially. This cannot easily be achieved on ocean-going cruises since the unpredictability of weather and sampling regimes often precludes the unified approach to measuring and sampling that we propose (see work plan). The outcomes of this work will provide valuable statistically-valid datasets for a number of UKSOLAS projects which are generated on large scale (rather than just in laboratory-based experiments) under defined experimental conditions. This will allow us to define the importance of microbes in the transfer of climatically important gases from the oceans to the atmosphere, a central aim of UKSOLAS.