Vertical profile of airborne microbial communities in the Southern Ocean atmospheric boundary layer

Recent aerobiological research has unveiled a vertically organized microbial ecosystem within the atmospheric boundary layer (ABL) of the Southern Ocean, distinct from traditional near-surface studies. Focusing on a low-orography coastal site on the Antarctic Peninsula, researchers examined microbial communities across both the lower and upper ABL, areas with minimal human disturbance.

Utilizing ground-based and aerial sampling, alongside advanced genetic and microscopic techniques, scientists assessed community composition, abundance, and morphology. The results revealed a consistent vertical stratification of airborne bacterial and eukaryotic communities, although some overlap indicated connections between different atmospheric layers.

The lower ABL displayed greater microbial diversity, homogeneity in community composition, and a strong dominance of marine-associated species, suggesting a strong influence from local sources and turbulent mixing. Conversely, the upper ABL exhibited reduced diversity but increased heterogeneity, with an enrichment of stress-tolerant, terrestrial, and plant-associated taxa.

This layer was more susceptible to atmospheric filtering, selective transport upward, and long-range atmospheric inputs. Furthermore, upper-layer samples featured higher microbial abundance and a prevalence of elongated cell morphologies, hinting at particle accumulation aloft and aerodynamic permanence. These findings establish the Southern Ocean ABL as a vertically stratified microbial habitat, organized into two partially decoupled sublayers.

Atmospheric dynamics appear to be key drivers in regulating microbial dispersal, maintaining ecosystem connectivity, and shaping biogeographic patterns within this unique environment.