Seasonal connectivity of microbes and carbohydrates between ocean, atmosphere, and cryosphere in Kongsfjorden (Svalbard, Arctic Ocean).

The coupling between ocean and atmosphere across the strong seasonal gradients in the Arctic is poorly understood. Here, we explored the microbial and glycobiological connectivity between the surface microlayer, the underlying seawater, snow, and aerosol particles in Kongsfjorden (Svalbard, 79°N) during autumn and spring. The marked overlap between marine and atmospheric microbiomes illustrates considerable sea-air transfer, linked to seasonally distinct environmental communities. For instance, Polaribacter and Formosa were aerosolized during the spring bloom, compared to Colwellia in autumn. Air-mass histories and microbial source tracking revealed a greater marine contribution in autumn, whereas spring aerosols were shaped by stronger winds and the cryosphere. Aerosol particles nonetheless contained numerous unique taxa, including Actinomycetes and Planctomycetia. Linking bacterial, microeukaryotic, carbohydrate, and meteorological dynamics established an overarching perspective across seasons and habitats, identifying five distinct ecosystem states. Genome-sequenced bacterial model isolates, representing key environmental populations, encode adaptive traits such as carotenoid and ectoine biosynthesis, linked to niche specialization and atmospheric transfer. Time-series records from the nearby Fram Strait revealed that many aerosolized taxa are core microbiome components; shaping ecology and biogeochemistry across the wider Arctic.