Daily turnover of airborne bacterial communities in the sub-Antarctic

Colonization of remote ecosystems by new microorganisms poses a significant threat to the diversity and function of native microbial communities. In the polar regions, including Antarctica, airborne microbial communities are shaped by environmental and climatic factors, which are changing rapidly. However, the specific drivers of microbial community composition and diversity in these regions remain poorly understood. This study provides a comprehensive analysis of the daily microbial community heterogeneity of airborne bacterial communities over South Georgia, one of the largest and more remote sub-Antarctic islands and evaluates the influence of environmental factors, local ecosystems, and sampling methodology. Over two weeks, samples were collected from coastal and higher-altitude sites using different air samplers to capture spatial and temporal variability and assess sampling performance. Results indicate that the Coriolis Compact sampler, when run for longer durations, yielded higher diversity and richness, while the Coriolis Micro provided high-quality samples over shorter periods. In cold environments where liquid sampling is challenging due to freezing, the dry Coriolis Compact offers a viable alternative. Furthermore, Microbial communities exhibited rapid daily turnover, with up to 90% daily change, yet also identified a stable core microbiome comprising 10–20% of the community. Local ecosystems and host-associated taxa, particularly from the island’s abundant wildlife, strongly influenced airborne microbial composition, especially at the coastal site. In contrast, the high-altitude site showed greater variability and turnover, suggesting a stronger influence from long-distance microbial inputs. Finally, environmental factors, including wind direction, temperature, and precipitation, also shaped community structure. These findings highlight the dynamic nature of airborne microbiomes in the sub-Antarctic and the importance of monitoring microbial dispersal in polar regions, where environmental change could accelerate introductions with ecological consequences.