Unité d'Ecologie, Systématique et Evolution, UMR CNRS 8079, Université Paris-Sud Orsay, France.
Front Microbiol. 2011 May 11;2:106. doi: 10.3389/fmicb.2011.00106. eCollection 2011.
Our knowledge about the microorganisms living in the high Arctic Ocean is still rudimentary compared to other oceans mostly because of logistical challenges imposed by its inhospitable climate and the presence of a multi-year ice cap. We have used 18S rRNA gene libraries to study the diversity of microbial eukaryotes in the upper part of the water column (0-170 m depth), the sea ice (0-1.5 m depth) and the overlying snow from samples collected in the vicinity of the North Pole (N88°35', E015°59) at the very end of the long polar night. We detected very diverse eukaryotes belonging to Alveolata, Fungi, Amoebozoa, Viridiplantae, Metazoa, Rhizaria, Heterokonta, and Telonemia. Different alveolates (dinoflagellates and Marine Alveolate Groups I and II species) were the most abundant and diverse in gene libraries from water and sea ice, representing 80% of the total number of clones and operational taxonomic units. Only contaminants and/or species from continental ecosystems were detected in snow, suggesting wind- and animal- or human-mediated cosmopolitan dispersal of some taxa. By contrast, sea ice and seawater samples harbored a larger and more similar inter-sample protist diversity as compared with snow. The North Pole was found to harbor distinctive eukaryotic communities along the vertical gradient with an unparalleled diversity of core dinoflagellates, largely dominant in libraries from the water column, as compared to other oceanic locations. In contrast, phototrophic organisms typical of Arctic sea ice and plankton, such as diatoms and prasinophytes, were very rare in our samples. This was most likely due to a decrease of their populations after several months of polar night darkness and to the presence of rich populations of diverse grazers. Whereas strict phototrophs were scarce, we identified a variety of likely mixotrophic taxa, which supports the idea that mixotrophy may be important for the survival of diverse protists through the long polar night.
与其他海洋相比，我们对高北极海洋中微生物的了解仍然很初步，这主要是由于其恶劣的气候和多年冰盖带来的后勤挑战。我们使用 18S rRNA 基因文库研究了高北极地区水柱（0-170m 深度）、海冰（0-1.5m 深度）和上覆雪的微生物真核生物多样性，该地区位于北极附近（N88°35'，E015°59'），在极夜的末期。我们检测到非常多样化的真核生物，属于鞭毛藻类、真菌、变形虫、绿藻、后生动物、根足动物、异鞭毛类和 Telonemia。不同的鞭毛藻类（甲藻和海洋鞭毛藻类 I 和 II 种）在水和海冰的基因文库中最为丰富和多样，占克隆和操作分类单位总数的 80%。只有污染物和/或来自大陆生态系统的物种在雪中被检测到，这表明一些分类群通过风和动物或人类介导的世界性传播。相比之下，海冰和海水样本比雪具有更大和更相似的样本间原生生物多样性。与其他海洋地点相比，极点沿垂直梯度具有独特的真核生物群落，其中核心甲藻的多样性无与伦比，在水柱文库中占主导地位。相比之下，在我们的样本中，典型的北极海冰和浮游生物的光养生物，如硅藻和甲藻，非常罕见。这很可能是由于在几个月的极夜黑暗之后它们的种群减少，以及丰富的各种食草动物种群的存在。虽然严格的光养生物很少，但我们鉴定出了多种可能的混合营养类群，这支持了混合营养可能对通过长极夜的多种原生生物的生存很重要的观点。
