Bacterial diversity and composition during rain events with and without S aharan dust influence reaching a high mountain lake in the A lps

Summary The diversity of airborne microorganisms that potentially reach aquatic ecosystems during rain events is poorly explored. Here, we used a culture‐independent approach to characterize bacterial assemblages during rain events with and without S aharan dust influence arriving to a high mountain lake in the A ustrian A lps. Bacterial assemblage composition differed significantly between samples with and without S aharan dust influence. Although alpha diversity indices were within the same range in both sample categories, rain events with A tlantic or continental origins were dominated by B etaproteobacteria, whereas those with S aharan dust intrusions were dominated by G ammaproteobacteria. The high diversity and evenness observed in all samples suggests that different sources of bacteria contributed to the airborne assemblage collected at the lake shore. During experiments with bacterial assemblages collected during rain events with S aharan dust influence, cell numbers rapidly increased in sterile lake water from initially ∼3 × 10 3 cell ml −1 to 3.6–11.1 × 10 5 cells ml −1 within 4–5 days, and initially, rare taxa dominated at the end of the experiment. Our study documents the dispersal of viable bacteria associated to S aharan dust intrusions travelling northwards as far as 47° latitude.