Québec-Océan, Département de Biologie, and Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, Québec, Canada.
PLoS One. 2011;6(11):e27492. doi: 10.1371/journal.pone.0027492. Epub 2011 Nov 9.
Increasing global temperatures are having a profound impact in the Arctic, including the dramatic loss of multiyear sea ice in 2007 that has continued to the present. The majority of life in the Arctic is microbial and the consequences of climate-mediated changes on microbial marine food webs, which are responsible for biogeochemical cycling and support higher trophic levels, are unknown. We examined microbial communities over time by using high-throughput sequencing of microbial DNA collected between 2003 and 2010 from the subsurface chlorophyll maximum (SCM) layer of the Beaufort Sea (Canadian Arctic). We found that overall this layer has freshened and concentrations of nitrate, the limiting nutrient for photosynthetic production in Arctic seas, have decreased. We compared microbial communities from before and after the record September 2007 sea ice minimum and detected significant differences in communities from all three domains of life. In particular, there were significant changes in species composition of Eukarya, with ciliates becoming more common and heterotrophic marine stramenopiles (MASTs) accounting for a smaller proportion of sequences retrieved after 2007. Within the Archaea, Marine Group I Thaumarchaeota, which earlier represented up to 60% of the Archaea sequences in this layer, have declined to <10%. Bacterial communities overall were less diverse after 2007, with a significant decrease of the Bacteroidetes. These significant shifts suggest that the microbial food webs are sensitive to physical oceanographic changes such as those occurring in the Canadian Arctic over the past decade.
全球气温的升高正在对北极地区产生深远的影响，包括 2007 年多年海冰的急剧减少，这种情况一直持续到现在。北极地区的大部分生命都是微生物，而气候介导的变化对微生物海洋食物网的影响，这些食物网负责生物地球化学循环，并支持更高的营养层次，目前还不得而知。我们通过使用高通量测序技术，对 2003 年至 2010 年期间从加拿大北极波弗特海（Beaufort Sea）的次表层叶绿素最大值（SCM）层采集的微生物 DNA 进行了随时间的变化研究。我们发现，总体而言，这一层已经变得更加淡水化，限制北极海域光合作用生产的硝酸盐浓度也有所降低。我们比较了 2007 年 9 月创纪录的海冰最小值前后的微生物群落，并检测到了所有三个生命领域的群落都存在显著差异。特别是真核生物的物种组成发生了显著变化，纤毛虫变得更加常见，而异养海洋鞭毛藻（MASTs）在 2007 年后占所回收序列的比例更小。在古菌中，早期代表该层古菌序列高达 60%的海洋 I 组 Thaumarchaeota 已经下降到<10%。2007 年后，细菌群落的总体多样性较低，Bacteroidetes 显著减少。这些显著的变化表明，微生物食物网对物理海洋变化很敏感，而这些变化在过去十年中一直在加拿大北极地区发生。
