Ocean-Atmosphere Microbial Interactions in the Pacific Ocean
Marine-atmosphere microbial exchange plays a significant role in global nutrient cycling, gene transfer, and marine ecology, though mechanisms of flux are poorly understood. To better understand this process, we investigated the role of the sea-surface microlayer (SML) in mediating marine emissions of bioaerosols. We analyzed the 16S rRNA gene and transcript sequences from surface seawater (SW), SML, and marine atmosphere samples, collected across a gradient of latitudes between the North Gyre and Equator in the Pacific Ocean. Genomic signature varied diurnally and spatially in all environments, where the SW community is the most consistent and air the most variable. Interestingly, the SML genomic community variability clusters directly between SW and air, much like its environmental position. The 16S rRNA transcript signature, used as a proxy for microbial activity and viability, showed tight clustering in the air and SML suggesting selective control of the active microbial community in these environments compared to SW. Further, the transcriptional community composition in the air clustered between the SML and SW, pointing to viable non-SML-mediated exchange. Abundant taxa from air-associated and marine-associated phyla show a gradient of presence through the three environments of interest, suggesting an exchange of key organisms through the SML. This study contributes to improving clarity in the role of the SML in the exchange of marine bioaerosols, advancing our understanding of how microbial communities travel and best utilize their environment.