Patterns of air mass incursions from Southern Ocean play a role on microbial dispersions into West Antarctic Ice Sheet

Abstract The cryosphere microbiomes are mostly inoculated by airborne microorganisms, which can accumulate year by year over the accreted snow. The detection of sea salt, pollutants, volcanic glass and other lithogenic materials in the interior of the West Antarctic Ice Sheet (WAIS) is evidence of a continuous inflow of exogenous microparticles to that site. In this work we demonstrate, that, likewise, marine microorganisms follow same pattern and can be long-range transported through the Antarctic troposphere reaching out high latitudes. To evidence it, we constructed an excavated 2m-depth pit named “Criolab’ in the surroundings of the Brazilian Criosfera1 remote laboratory at WAIS to collect snow and firn samples for microbial diversity analysis, together with snow and airborne microparticle composition measurements. Origin of air masses reaching Criosfera 1 were inferred from air masses backward trajectories modelling. We found a discontinuous profile of microbial taxa abundances and diversity, which is likely a result of the air mass back trajectories changes that carried microorganisms from distinct Antarctic sources during an estimated period of 4 years. Our study indicates that different marine groups, such as SAR11, Idiomarina, and Nitrosopumilus, are shared between the WAIS snow and AP seawater communities, suggesting they are long-range transported over Antarctica. Considering their low and interspersed abundances, we postulate a pre- and post-depositional selection in the face of the extreme atmosphere and cryosphere conditions. Our observations have implications for the understanding of the aeolian dispersion patterns over Antarctica, indicating the importance of the marine microbiomes in seeding the interior of the continent.