Impact of a Major Inflow Event on the Composition and Distribution of Bacterioplankton Communities in the Baltic Sea
Laen...
Kuupäev
2018
Kättesaadavus
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Frontiers
Abstrakt
Major Baltic inflow (MBI) events carry highly saline water from the North Sea to
the central Baltic Sea and thereby affect both its environmental conditions and its
biota. While bacterioplankton communities in the Baltic Sea are strongly structured by
salinity, how MBIs impact the composition and distribution of bacteria is unknown.
The exceptional MBI in 2014, which brought saline and oxygenated water into the
basins of the central Baltic Sea, enabled the linkage of microbiological investigations
to hydrographic and modeling studies of this MBI. Using sequence data of 16S
ribosomal RNA (rRNA) and 16S rRNA genes (rDNA), we analyzed bacterioplankton
community composition in the inflowing water and in the uplifted former bottomwater at stations reached by the MBI. Bacterial diversity data were compared with
respective data obtained from previous, non-inflow conditions. Changes in bacterial
community composition following the 2014 MBI were mainly apparent at the genus level.
A number of specific taxa were enriched in the inflowing water, with large changes in the
rRNA/rDNA ratios indicating the different activity levels between of the water masses.
The relative similarity of the bacterial communities in the inflowing and uplifted waters as
well as the results from an inflow-simulating numerical model showed that the inflowing
water did not originate directly from the North Sea but mostly from adjacent areas in
the Baltic Sea. This suggested that the inflow event led to a series of shifts in Baltic Sea
water masses among the Baltic Sea basins and a gradual mixing of the water bodies.
Dramatic changes in the bacterial community composition occurred when the bottomwater inflow reached the anoxic, sulfidic deep basins, resulting in an uplifting of the
formerly anoxic bacterial community, dominated by Epsilonproteobacteria. Our study of
the impact of MBIs on bacterioplankton communities therefore highlights two relevant
underlying mechanisms that impact the distribution and possibly also the activities of
planktonic bacteria in the Baltic Sea: (1) the successive dilution of inflowing North Sea
water with ambient waters and (2) the uplifting of former bottom-water communities to
higher water strata.
This work was funded by the Deutsche Forschungsgemeinschaft (DFG) (projects JU367/15-1, JU367/16-1 to KJ and LA1466/8- 1 to ML). DH was supported by the European Regional Development Fund and the Estonian Research Council Mobilitas Plus Top Researcher grant “MOBTT24.” UG was supported by the BMBF project “Hydrodynamic observations and simulations of munition in the sea,” a subproject of the collaborative project “Environmental monitoring for the delaboration of munitions in the sea” (Grant No. #03F0747C).
This work was funded by the Deutsche Forschungsgemeinschaft (DFG) (projects JU367/15-1, JU367/16-1 to KJ and LA1466/8- 1 to ML). DH was supported by the European Regional Development Fund and the Estonian Research Council Mobilitas Plus Top Researcher grant “MOBTT24.” UG was supported by the BMBF project “Hydrodynamic observations and simulations of munition in the sea,” a subproject of the collaborative project “Environmental monitoring for the delaboration of munitions in the sea” (Grant No. #03F0747C).
Kirjeldus
Märksõnad
bacterioplankton, Baltic Sea, Major Baltic inflow, saltwater intrusions, RNA, DNA, articles