Aeolian dispersal of bacteria in southwest Greenland: their sources, abundance, diversity and physiological states

Abstract

The Arctic is undergoing dramatic climatic changes that cause profound transformations in its terrestrial ecosystems and consequently in the microbial communities that inhabit them. The assembly of these communities is affected by aeolian deposition. However, the abundance, diversity, sources and activity of airborne microorganisms in the Arctic are poorly understood. We studied bacteria in the atmosphere over southwest Greenland and found that the diversity of bacterial communities correlated positively with air temperature and negatively with relative humidity. The communities consisted of 1.3×103 ± 1.0×103 cells m-3, which were aerosolized from local terrestrial environments or transported from marine, glaciated and terrestrial surfaces over long distances. On average, airborne bacterial cells displayed a high activity potential, reflected in the high 16S rRNA copy number (590 ± 300 rRNA cell-1), that correlated positively with water vapor pressure. We observed that bacterial clades differed in their activity potential. For instance, a high activity potential was seen for Rubrobacteridae and Clostridiales, while a low activity potential was observed for Proteobacteria. Of those bacterial families that harbor ice-nucleation active species, which are known to facilitate freezing and may thus be involved in cloud and rain formation, cells with a high activity potential were rare in air, but were enriched in rain.

Air mass source determines airborne microbial diversity at the ocean-atmosphere interface of the Great Barrier Reef marine ecosystem

“…The fungi from continental sources displayed a similar though more variable trend of phylogenetic structuring although in ocean-derived samples this clustering was relatively weak indicating they were more randomly assembled. Overall our analyses support the hypothesis that long-range transport of microbial taxa in air results in differential recruitment and selection during transit over oceanic or continental surfaces [12, 16, 17].…”

Beyond the planetary boundary layer: Bacterial and fungal vertical biogeography at Mount Sonnblick, Austria

“…We and others used qPCR to measure bacterial numbers from air filters. Greenland air was reported to have 6.8 × 10 3 /m 3 16S copies (Šantl-Temkiv et al, 2018). In this study, values ranged up to 1.17 × 10 7 /m 3 for 16S rRNA gene copies in the May sample.…”

“…The phyllosphere contains 2.1 × 10 5 bacteria/cm² plant surface on average (Redford et al, 2010) and as one of the largest microbial habitats on earth, exceeds 10 8 per km² globally (Lindow & Brandl, 2003). Plant surfaces are highly productive emission sources of bioaerosols (Bowers et al, 2011;Šantl-Temkiv et al, 2018). This high emission potential is reduced by the size and weight of plant parts, and is a disadvantage for aerodynamic horizontal and especially vertical dispersal.…”

Variation of Ice Nucleating Particles in the European Arctic Over the Last Centuries

“…Results from the pollen analysis of the EUROCORE ice core show that the two samples (spanning 12.1 and 13.6 years) with the highest concentrations of Betula alba pollen occur in the same period where some of the highest and most variable N INP (−20 • C) are observed (Brugger et al, 2019). A further distinction between the continental biological species of the Arctic aerosol (Fu et al, 2013;Hicks & Isaksson, 2006;Moffett et al, 2015;Santl-Temkiv et al, 2018), which can also be ice active (Pummer et al, 2015), and the INP of marine origin (DeMott et al, 2016;Leck & Bigg, 2005;Schnell, 1977;Schnell & Vali, 1975, 1976Wilson et al, 2015), is not possible. The correlation plot in the SI ( Figure S6) shows no clear correlation between N INP at selected temperatures and concentrations of different chemical parameters for the Lomo09 ice core, preventing further statements about the nature of the INP.…”

“…A similar in-depth analysis is not possible for this study due to the comparatively low number of samples, but it was tested if N INP follows a lognormal distribution at eight selected temperatures (see SI Table S1 for the Lomo09 samples and Table S2 for EUROCORE. A further distinction between the continental biological species of the Arctic aerosol (Fu et al, 2013;Hicks & Isaksson, 2006;Moffett et al, 2015;Santl-Temkiv et al, 2018), which can also be ice active (Pummer et al, 2015), and the INP of marine origin (DeMott et al, 2016;Leck & Bigg, 2005;Schnell, 1977;Schnell & Vali, 1975, 1976Wilson et al, 2015), is not possible. Thus, long-range transport is a probable source for INP, which are ice active at lower temperatures.…”