Data_Sheet_12_Warming, but Not Acidification, Restructures Epibacterial Communities of the Baltic Macroalga Fucus vesiculosus With Seasonal Variability.PDF

Due to ocean acidification and global warming, surface seawater of the western Baltic Sea is expected to reach an average of ∼1100 μatm pCO2 and an increase of ∼5°C by the year 2100. In four consecutive experiments (spanning 10–11 weeks each) in all seasons within 1 year, the abiotic factors temperature (+5°C above in situ) and pCO2 (adjusted to ∼1100 μatm) were tested for their single and combined effects on epibacterial communities of the brown macroalga Fucus vesiculosus and on bacteria present in the surrounding seawater. The experiments were set up in three biological replicates using the Kiel Outdoor Benthocosm facility (Kiel, Germany). Phylogenetic analyses of the respective microbiota were performed by bacterial 16S (V1-V2) rDNA Illumina MiSeq amplicon sequencing after 0, 4, 8, and 10/11 weeks per season. The results demonstrate (I) that the bacterial community composition varied in time and (II) that relationships between operational taxonomic units (OTUs) within an OTU association network were mainly governed by the habitat. (III) Neither single pCO2 nor pCO2:Temperature interaction effects were statistically significant. However, significant impact of ocean warming was detected varying among seasons. (IV) An indicator OTU (iOTU) analysis identified several iOTUs that were strongly influenced by temperature in spring, summer, and winter. In the warming treatments of these three seasons, we observed decreasing numbers of bacteria that are commonly associated with a healthy marine microbial community and—particularly during spring and summer—an increase in potentially pathogenic and bacteria related to intensified microfouling. This might lead to severe consequences for the F. vesiculosus holobiont finally affecting the marine ecosystem.

受海洋酸化与全球变暖影响，预计到2100年，波罗的海西部表层海水的平均二氧化碳分压（pCO2, partial pressure of carbon dioxide）将达到约1100 μatm，水温将升高约5℃。在1年内覆盖所有季节的4项连续实验（每项实验时长10~11周）中，研究人员针对非生物因子温度（较原位环境升高5℃）与pCO2（调整至约1100 μatm）的单一及联合效应，开展了针对褐藻泡叶岩藻（Fucus vesiculosus）表面附生细菌群落以及周围海水中细菌群落的测试。本实验依托德国基尔户外底栖微宇宙实验设施（Kiel Outdoor Benthocosm，基尔，德国）设置了3组生物学重复。在每个实验周期的第0、4、8以及10/11周，分别通过细菌16S（V1-V2区）rDNA Illumina MiSeq扩增子测序技术，对对应微生物群进行系统发育分析。研究结果显示：(I) 细菌群落组成随时间呈现显著变化；(II) 操作分类单元（operational taxonomic units, OTUs）关联网络内的OTU间相互关系主要受生境调控；(III) pCO2单一效应以及pCO2与温度的交互效应均未达到统计学显著性水平。然而，海洋变暖所产生的显著影响则因季节而异。(IV) 指示性OTU（indicator OTU, iOTU）分析共筛选出多个在春、夏、冬三季受温度显著影响的iOTU。在这三个季节的升温处理组中，研究人员观察到通常与健康海洋微生物群落相关的细菌数量逐渐减少，且尤其在春、夏两季，潜在致病菌以及与加剧微污损相关的细菌数量出现上升，这可能会对泡叶岩藻（Fucus vesiculosus）共生联合体（holobiont）造成严重影响，最终波及海洋生态系统。