Disentangling the drivers of bacterial and viral communities in the Southern Ocean

Climate change is driving unprecedented changes in both terrestrial and marine environments. The Southern Ocean, with its proximity to Antarctica, is a unique and ecologically critical region. While several studies have shed light on the ecology of macrofauna, comparative insights into microbial communities remain limited. In this presentation, I will discuss our recent work on Southern Ocean microbial communities using both amplicon and shotgun sequencing approaches. Our findings indicate that environmental factors such as temperature, salinity, depth, and water masses play a major role in shaping the diversity and functionality of these microbial communities, including viruses. I will highlight new insights into the biogeography of these communities and the impact of spatial variability on their composition. Using Marine Snow Catchers and our latest metagenomic data, we demonstrate the direct role of microbial communities in mediating carbon and nitrogen cycling. Our comprehensive gene and genome catalogue from the Southern Ocean reveals diverse consortia of microbial assemblages, including those with chemolithoautotrophic lifestyles. Collectively, these results underscore the central role of microbial communities in providing essential ecosystem services in the Southern Ocean.