Impact of a Major Inflow Event on the Composition and Distribution of Bacterioplankton Communities in the Baltic Sea
Impact of a Major Inflow Event on the Composition and Distribution of Bacterioplankton Communities in the Baltic Sea
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DOI：
10.3389/fmars.2018.00383
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发表时间：
2018-10-26
影响因子：
3.7
通讯作者：
Jurgens, Klaus
中科院分区：
文献类型：
--
作者：
Bergen, Benjamin;Naumann, Michael;Jurgens, Klaus
主要的波罗的海流入（MBI）事件携带高盐水从北海到波罗的海中部，从而影响其环境条件和生物区系。虽然波罗的海的浮游细菌群落由盐度构成，但MBI如何影响细菌的组成和分布尚不清楚。2014年的特殊MBI将盐水和含氧水带入波罗的海中部的盆地，使微生物调查与该MBI的水文和建模研究联系起来。利用16 S核糖体RNA（rRNA）和16 S rRNA基因（rDNA）的序列数据，我们分析了浮游细菌群落组成的流入水，并在上升的前底层水站MBI达到。将细菌多样性数据与从先前非流入条件获得的相应数据进行比较。2014年MBI后细菌群落组成的变化主要在属水平上明显。一些特定的类群在流入的水中富集，与大的变化，rRNA/rDNA的比例表明不同的活动水平之间的水团。细菌群落在流入和上升沃茨的相对相似性，以及从流入模拟数值模型的结果表明，流入的水没有直接来自北海，但主要来自邻近地区在波罗的海。这表明，流入事件导致了波罗的海盆地之间的波罗的海水体的一系列变化和水体的逐渐混合。当底层水流入到缺氧的硫化物深盆地时，细菌群落组成发生了巨大的变化，导致以前缺氧的细菌群落上升，以Epsilonproteobacteria为主。因此，我们的研究MBIs对浮游细菌群落的影响突出了两个相关的基本机制，影响的分布，也可能在波罗的海的浮游细菌的活动：（1）连续稀释流入北海水与环境沃茨和（2）前底层水社区上升到更高的水层。
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 bottom water 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 bottom-water 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.