Organic pollutants have the potential for long range transport, allowing them to reach all ecosystems, including the oceans. These pollutants interact with marine microorganisms, which serve as the foundation of marine food webs and global biogeochemical cycles. Although they are essential for understanding how anthropogenic pollutants affect the structure, function, and metabolism of these communities, marine microorganisms remain understudied due to methodological challenges.

The global introduction of synthetic organic compounds to the oceans has increased over the last century, and, despite the need for understanding the role of synthetic organic compounds in the marine environment, there are only the appropriate analytical procedures for a small fraction of them. Even though these contaminants of emerging concern (CECs) individually exist at ultra-trace levels, there are thousands of them in the environment, and only a few dozen are regulated. From urban coastlines, to remote polar oceans, anthropogenic contaminants such as OPs are introduced to the oceans through riverine and atmospheric transport. In the marine water column, OPs become part of the organic carbon pool as dissolved organic carbon (DOC). As DOC, OPs enter the biogeochemical cycles mediated by marine organisms, especially by microorganisms (0.2-2μm in size), which transform these chemicals either in the environment or in the body of host organisms. The resulting transformation product can be more toxic than the parent compounds, and can bioaccumulate as persistent pollutants.

The objective of this thesis will be to perform a state of the art comprehensive integrated assessment of the mutual impacts of CECs and marine microbial communities. This assessment will be conducted for coastal regions and open waters, principally by means of membrane polarity and single-cell approaches. Specific output objectives under the proposed line of investigation include:

• Development of new methodologies to asses single-cell resolution multiomics from complex marine microbial communities exposed to Ops.
• Investigation of relationships between changes in OP concentrations and environmental microbiome structure and function with OPs. This will include a feasibility assessment of microbiomes as high sensitivity biological indicators of OP impacts, as well their degradation potential.
• Advancement towards globally usable biological indicators of OP contamination effects as a new and efficient method of chemical water quality monitoring.
• Definition of environmental impacts of chemical pollution by OPs in ocean bodies and their physiological consequences in microbiomes at lipidomic levels.
• Accessible dissemination of science to the general public, including proactive outreach activities.