Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy.
Limnology and Science for Life Laboratory, Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden.
Mol Ecol. 2018 Nov;27(21):4322-4335. doi: 10.1111/mec.14855. Epub 2018 Sep 26.
Temporal dynamics of bacterioplankton are rarely investigated for multiple habitats and years within individual lakes, limiting our understanding of the variability of bacterioplankton community (BC) composition with respect to environmental factors. We assessed the BC composition of a littoral and two pelagic habitats (euphotic zone and hypolimnion) of Lake Tovel monthly from April 2014 to May 2017 by high-throughput sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. The three habitats differed in temperature, light, oxygen and hydrology. In particular, the littoral was the most hydrologically unstable because it receives most of the lake inflow, the hypolimnion was the most stable because of its hydrologically sheltered position, and the pelagic euphotic habitat was intermediate. Consequently, we hypothesized different temporal patterns of BC composition for all three habitats according to their environmental differences. We applied PERMANOVA, nonmetric multidimensional scaling and source-sink analysis to characterize BC composition. Overall, BCs were different among habitats with the littoral showing the highest variability and the hypolimnion the highest stability. The BC of rainy 2014 was distinct from the BCs of other years irrespective of the habitats considered. Seasonal differences in BCs were limited to spring, probably linked to meltwater inflow and mixing. Thus, temporal effects related to year and season were linked to the hydrological gradient of habitats. We suggest that despite potential within-lake dispersal of bacterioplankton by water flow and mixing, local environmental conditions played a major role in Lake Tovel, fostering distinct BCs in the three habitats.
浮游细菌的时间动态很少在单个湖泊的多个生境和多年内进行研究，这限制了我们对浮游细菌群落（BC）组成随环境因素变化的理解。我们通过高通量测序 16S rRNA 基因的 V3-V4 高变区，从 2014 年 4 月到 2017 年 5 月，每月对多夫湖的沿岸和两个浮游生境（透光带和湖下层）的 BC 组成进行评估。这三个生境的温度、光照、氧气和水文学特性存在差异。特别是，沿岸带由于接收了大部分湖泊流入的水，因此水文条件最不稳定；湖下层由于其水文遮蔽的位置，因此最稳定；而浮游透光带生境则处于中间状态。因此，根据它们的环境差异，我们假设所有三个生境的 BC 组成具有不同的时间模式。我们应用 PERMANOVA、非度量多维尺度分析和源汇分析来描述 BC 组成。总体而言，BC 在生境之间存在差异，其中沿岸带的变异性最大，湖下层的稳定性最高。2014 年雨季的 BC 与其他年份的 BC 不同，无论考虑哪种生境都是如此。BC 的季节性差异仅限于春季，可能与融水流入和混合有关。因此，与年份和季节有关的时间效应与生境的水文梯度有关。我们认为，尽管浮游细菌可能通过水流和混合在湖泊内进行潜在的扩散，但当地的环境条件在多夫湖中起着主要作用，在三个生境中形成了独特的 BC。
