Minor impact of ocean acidification to the structure of an Arctic sediment microbial community

Effects of ocean acidification on the diversity and structure of Arctic surface sediment bacterial and archaeal community was analysed in detail using 16S rRNA 454 pyrosequencing. Intact sediment cores were collected and exposed to one of five different pCO2 concentrations (380 (present day), 540, 750, 1120 and 3000 µatm) and RNA extracted after a period of 14 days exposure. Measurements of diversity and multivariate similarity indicated very little difference between pCO2 treatments. Only when the highest and lowest pCO2 treatments were compared were significant differences evident, namely increases in the abundance of the Halobacteria and differences to the presence/absence structure of the Planctomycetes. Members of the Planctomycetia also increased with increasing pCO2 concentration, particularly the Planctomyces, Schlesneria, Pirellula, Blastopirellula, Rhodopirellula and the Pir4 lineage, indicating that these groups may be able to take advantage of changing pH or pCO2 conditions. The modest response of the microbial communities associated with these sediments may be due to the low pore-water pH already experienced by sediment microbes or be a result of the high buffering capacity of marine sediments.

本研究详细分析了海洋酸化对北极表层沉积物细菌和古菌群落多样性与结构的影响，采用16S rRNA 454焦磷酸测序技术进行。采集完整的沉积物柱状样，并将其暴露于五种不同的二氧化碳分压浓度中（分别为380 µatm（现今水平）、540、750、1120和3000 µatm），在14天暴露期结束后提取RNA。多样性和多元相似性测量结果表明，不同二氧化碳分压处理之间的差异极小。仅在最高和最低二氧化碳分压处理之间进行了比较时，才出现了显著差异，即盐杆菌属丰度的增加以及浮游微生物门（Planctomycetes）的存在与否结构发生了变化。随着二氧化碳分压浓度的增加，浮游微生物门（Planctomycetia）的成员数量也相应增加，尤其是蓝藻菌属（Planctomyces）、斯莱尼尔菌属（Schlesneria）、皮雷拉菌属（Pirellula）、爆破皮雷拉菌属（Blastopirellula）、红光皮雷拉菌属（Rhodopirellula）和Pir4谱系，表明这些群体可能能够利用变化的pH或二氧化碳分压条件。与这些沉积物相关的微生物群落对变化的适度响应可能是由沉积物微生物已经经历的低孔隙水pH值造成的，也可能是由于海洋沉积物的高缓冲容量所致。