Seasonal assemblages and short‐lived blooms in coastal north‐west Atlantic Ocean bacterioplankton

• Published in: Environmental Microbiology
• Main Authors: El‐Swais, Heba, Dunn, Katherine A., Bielawski, Joseph P., Li, William K. W., Walsh, David A.
• Other Authors: National Sciences and Engineering Researh Council of Canada, Canada Research Chairs Program, Canadian Institutes of Health Research, Bedford Basin Monitoring Program of Fisheries and Oceans Canada, Atlantic Computational Excellence Network (ACEnet), Tula Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: North West Atlantic
• Online Access: http://dx.doi.org/10.1111/1462-2920.12629; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1462-2920.12629; http://onlinelibrary.wiley.com/wol1/doi/10.1111/1462-2920.12629/fullpdf

Summary Temperate oceans are inhabited by diverse and temporally dynamic bacterioplankton communities. However, the role of the environment, resources and phytoplankton dynamics in shaping marine bacterioplankton communities at different time scales remains poorly constrained. Here, we combined time series observations (time scales of weeks to years) with molecular analysis of formalin‐fixed samples from a coastal inlet of the north‐west A tlantic O cean to show that a combination of temperature, nitrate, small phytoplankton and S ynechococcus abundances are best predictors for annual bacterioplankton community variability, explaining 38% of the variation. Using B ayesian mixed modelling, we identified assemblages of co‐occurring bacteria associated with different seasonal periods, including the spring bloom (e.g. P olaribacter , U lvibacter , A lteromonadales and ARCTIC96B ‐16) and the autumn bloom (e.g. OM 42, OM 25, OM 38 and A rctic96 A ‐1 clades of A lphaproteobacteria , and SAR 86, OM 60 and SAR 92 clades of G ammaproteobacteria ). Community variability over spring bloom development was best explained by silicate (32%) – an indication of rapid succession of bacterial taxa in response to diatom biomass – while nanophytoplankton as well as picophytoplankton abundance explained community variability (16–27%) over the transition into and out of the autumn bloom. Moreover, the seasonal structure was punctuated with short‐lived blooms of rare bacteria including the KSA ‐1 clade of S phingobacteria related to aromatic hydrocarbon‐degrading bacteria.