Marine microbial ecosystems achieve community-level biogeochemical functions through the production, consumption, and exchange of bioactive molecules. While chemical currencies of microbial interactions, such as dissolved metabolites, represent a small fraction of the organic matter in the ocean, they disproportionately influence microbial physiology. Small bioactive molecules hence impact ecosystem functioning and the rates of biogeochemical reactions. In turn, the ocean’s physical and biogeochemical environment shapes macromolecular elemental composition and drives microbial evolutionary dynamics. Unraveling these complex processes critical to marine biogeochemical cycles requires novel multidisciplinary approaches combining ecological and evolutionary theory, large-scale modeling and simulations, and advanced analytical approaches including chemical and molecular biological technologies (‘omics). This session seeks submissions offering combinations of these techniques to address pressing questions at the intersection of microbial ecology/evolution and biogeochemistry, aiming to extract generalizable principles from marine environments across space and time. Studies focusing on all types of marine biomes are welcome, including high-latitude environments (e.g. sea-ice metabolites, trace metal ligands). Questions of interest include: under which conditions do microbial interactions become more or less prominent? What selective pressures shape the evolution of microbial interactions? How does the functional and taxonomic diversity of interacting marine microbes affect biogeochemical pools and fluxes?

• Marine Ecology and Biodiversity -