Long-range atmospheric processes facilitate global dispersal of microorganisms, with significant implications for Earth’s ecosystems functioning and global health. While traditional aerobiological studies have focused on low troposphere aerosols, assuming airborne communities are primarily influenced by neighbouring ecosystems, our study challenges this perspective. We analysed nearly three decades of aerosol particles present in rainwater samples collected at a mountain site located in South Europe (Iberian Peninsula, NE Spain). Coupling this data with analyses of high troposphere air mass provenances and genetic data of topsoils from North Africa and from a global public bacterial database, we revel a persistent influence of desert microorganisms from North Africa in Southern European sky. Remarkably, desert-derived microorganisms dominate even in rain originating from the Atlantic Ocean, despite sea spray being the largest source of global aerosols. The frequency of dust outbreaks, altitude reached, and long residence times of fine-sized particulates are postulated as critical factors that significantly shape the long-range and persistence of aerial assemblages, while air mass provenance playing a secondary role. Our findings highlight the profound and long-lasting impact of desert aerosols on terrestrial ecosystems, calling for further exploration of intercontinental aerial connections with deserts and drylands elsewhere, and the ecological implications of desert immigrants on worldwide ecosystems.
How to cite: Cáliz, J., Menéndez-Serra, M., Triadó-Margarit, X., Avila, A., and O. Casamayor, E.: Microorganisms from North African deserts persist in Southern Europe’s atmosphere, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18628, https://doi.org/10.5194/egusphere-egu25-18628, 2025.