Spatial variability in Antarctic surface snow bacterial communities

We identify bacterial communities in Antarctic surface snow and evaluate cell viability, assess the presence of relic DNA, and determine the impact of human presence on otherwise pristine ecosystems. By sampling a transect from the South Orkney Islands to the Ellsworth Mountains, we characterize the surface microbiome of pristine Antarctic snow. Using presence/absence data, we observed a latitudinal change in microbial communities, notably with a decrease in alpha diversity at southern, more remote latitudes. Soil-related microorganisms dominated microbial assemblages, suggesting terrestrial inputs likely from aeolian transport. We identified indicator species within each location and, interestingly, northern sites harbored more endemic OTUs than southern samples, suggesting more variable and opportunistic communities in southern, more extreme systems. We also determined the impact of human presence on the snow microbiome by sampling the Lake Ellsworth deep field camp. While human presence has limited impact on the snow microbial communities across Antarctica, intense human activities, such as attempts to drill deep into the ice sheet, affect natural communities at specific locations. We recommend indigenous surface microbial communities are considered when forming plans for field activities that may affect their integrity.