Airborne bacterial populations in Miers Valley, McMurdo Dry Valleys, Antarctica
Understanding the sources and compositions of biological aerosols influencing an ecosystem is important for understanding ecosystem dynamics and for monitoring ecological change. Little is known about the importance of bioaerosol transport in shaping Antarctic ecosystems or how bacterial aerosols may influence sensitive ice-free regions of the content. In this study, high-throughput sequencing of 16S rRNA genes was used to assess the diversity of airborne bacteria at the valley floor and ridge of Miers Valley, Antarctica, during the 2009 austral summer. The Miers Ridge and Miers Floor samples were highly similar, as >90 % of the total sequences grouped into operational taxonomic units (OTU) common to both libraries. Firmicutes and Proteobacteria were dominant, while sequences grouping to the Actinobacteria, Bacteroidetes, and Cyanobacteria accounted for relatively minor proportions of the libraries. There was little evidence from the library compositions that the aerosols were influenced by local Antarctic soils or marine inputs from the Ross Sea, which was consistent with back trajectories that indicated the air masses arrived predominantly from the interior of the continent. As an initial survey, this work suggests that regional sources have the greatest influence on bacterial aerosols over the Antarctic Dry Valleys, and that the bacterial assemblages in air masses influencing the soils are largely non-invasive.