Prokaryotic biogeography across atmospheric, aquatic, and terrestrial ecosystems in the Mount Everest region

Abstract

The Mount Everest region encompasses one of the world’s most fragile cryospheric landscapes, comprising diverse and interconnected habitats across atmospheric, aquatic, and terrestrial ecosystems. Despite growing interest in high-mountain microbial ecology, basin-scale assessments remain scarce. Here, we conducted a microbial survey in the Rongbuk River basin (3699–7000 m a.s.l.), analyzing 677 samples from aerosols, snow, stream water, stream sediments, and soils via 16S rRNA gene amplicon sequencing. We identified 58,141 operational taxonomic units (OTUs) across 67 prokaryotic phyla, dominated by Pseudomonadota, Actinomycetota, and Bacteroidota. Elevational diversity patterns were ecosystem-specific: richness declined with elevation in aerosols and stream water, showed a U-shaped pattern in snow, peaked at mid-elevations in soils, and remained stable in stream sediments. Evenness and Shannon diversity, however, displayed distinct elevational trends and environmental determinants compared to richness. Community assembly was largely stochastic in snow, aquatic, and soils but strongly deterministic in aerosols. Source-tracking analysis revealed strong landscape-scale connectivity, with snow serving as a microbial vector linking atmospheric inputs to downstream ecosystems (contributing 1.4%–12.0%). Soils served as a potential microbial reservoir, harboring 42% of the unique OTUs and contributing 3%–11.8% of communities to other habitats. While stream water and sediments showed reciprocal exchange, aerosols remained largely uncharacterized in terms of their sources. Collectively, these findings demonstrate that although prokaryotic responses to elevation are ecosystem-specific, these habitats are ecologically interconnected across the high-mountain landscape, providing a comprehensive overview of the prokaryotic biogeography of the region.