title: High wind speeds prevent formation of a distinct bacterioneuston community in the sea-surface microlayer.
abstract: The sea-surface microlayer (SML) at the boundary between atmosphere and hydrosphere represents a demanding habitat for bacteria. Wind speed is a crucial but poorly studied factor for its physical integrity. Increasing atmospheric burden of CO2, as suggested for future climate scenarios, may particularly act on this habitat at the air-sea interface. We investigated the effect of increasing wind speeds and different pCO2 levels on SML microbial communities in a wind-wave tunnel, which offered the advantage of low spatial and temporal variability. We found that enrichment of bacteria in the SML occurred solely at a U10 wind speed of ≤5.6 m s-1 in the tunnel and ≤4.1 m s-1 in the Baltic Sea. High pCO2 levels further intensified the bacterial enrichment in the SML during low wind speed. In addition, low wind speed and pCO2 induced the formation of a distinctive bacterial community as revealed by 16S rRNA gene fingerprints and influenced the presence or absence of individual taxonomic units within the SML. We conclude that physical stability of the SML below a system-specific wind speed threshold induces specific bacterial communities in the SML entailing strong implications for ecosystem functioning by wind-driven impacts on habitat properties, gas exchange and matter cycling processes.
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, Schleusenstraße 1, 26382, Wilhelmshaven, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Rahlff
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, Schleusenstraße 1, 26382, Wilhelmshaven, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Stolle
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, PO Box 2503, Carl-von-Ossietzky-Straße 9-11, 26111, Oldenburg, Germany.
authors.forename: Helge-Ansgar
authors.initials: HA
authors.lastname: Giebel
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, PO Box 2503, Carl-von-Ossietzky-Straße 9-11, 26111, Oldenburg, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Brinkhoff
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, Schleusenstraße 1, 26382, Wilhelmshaven, Germany.
authors.forename: Mariana
authors.initials: M
authors.lastname: Ribas-Ribas
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, Schleusenstraße 1, 26382, Wilhelmshaven, Germany.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Hodapp
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky-University Oldenburg, Schleusenstraße 1, 26382, Wilhelmshaven, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Wurl
mesh_terms: D001272:Atmosphere; D001419:Bacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D001454:Baltic States; D002245:Carbon Dioxide; D004269:DNA, Bacterial / Q000235:genetics; D017753:Ecosystem; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D014919:Wind
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D002245:Carbon Dioxide
keywords: Baltic Sea, pCO2; air–sea interface; bacterioneuston; enrichment factor; wind-wave tunnel