Aerobiology over the Southern Ocean – implications for bacterial colonization of Antarctica

The Antarctic is experiencing drastic ecosystem change due to rapid and record warming. Understanding dispersal processes is paramount to assess the risks of microbiological invasions. Here, we analyze bacterial biodiversity in the circumpolar air above the Southern Ocean. This diversity had both local and global origins and presented from very low to very high Shannon biodiversity indices with consistent low richness, compatible with a scenario whereby samples are composed of a suite different species in very low abundances. However, only 4 of ASVs were identified in both Polar and non-Polar air masses, suggesting that the air mass over the Southern Ocean can act as a selective dispersal filter. Furthermore, air microbial diversity varied significantly with meteorological data, suggesting that regional bacterial biodiversity could be sensitive to changes in weather patterns. Future changes in weather patterns could, therefore, potentially alter the existing pattern of microbial deposition in the Antarctic