Hindshaw R S, Lindsay M R, Boyd E S
1Department of Earth Sciences, University of Cambridge, Cambridge, UK.
2Department of Microbiology and Immunology, Montana State University, Bozeman, MT USA.
Polar Biol. 2017;40(9):1835-1843. doi: 10.1007/s00300-017-2106-3. Epub 2017 Mar 31.
Microbial eukaryotes are increasingly being recognised for their role in global biogeochemical cycles, yet very few studies have focussed on their distribution in high-latitude stream sediments, an important habitat which influences stream water nutrient chemistry. In this study, we present the first comparison of microbial eukaryotes from two different polar habitats by determining the abundance and taxonomic affiliation of 18S rRNA gene fragments recovered from four sediment samples in Svalbard: two from a glaciated catchment and two from an unglaciated permafrost-dominated catchment. Whilst there was no difference between the two catchments in terms of Rao's phylogenetic diversity (0.18±0.04, 1SD), the glaciated catchment samples had slightly higher richness (138-139) than the unglaciated catchment samples (67-106). At the phylum level, Ciliophora had the highest relative abundance in the samples from the glaciated catchment (32-63%), but only comprised 0-17% of the unglaciated catchment samples. Bacillariophyta was the most abundant phylum in one of the samples from the unglaciated catchment (43%) but phototrophic microbial eukaryotes only formed a minor component of the glaciated catchment samples (<2%), suggesting that in these environments the microbial eukaryotes are predominantly heterotrophic (chemotrophic). This is in contrast to previously published data from Robertson Glacier, Canada where the relative abundance of chlorophyta (phototrophs) in three samples was 48-57%. The contrast may be due to differences in glacial hydrology and/or geology, highlighting the variation in microbial eukaryote communities between nominally similar environments.
微生物真核生物在全球生物地球化学循环中的作用日益受到认可，但很少有研究关注它们在高纬度河流沉积物中的分布，而高纬度河流沉积物是影响河流水体营养化学的重要栖息地。在本研究中，我们通过测定从斯瓦尔巴群岛四个沉积物样本中回收的18S rRNA基因片段的丰度和分类归属，首次对来自两种不同极地栖息地的微生物真核生物进行了比较：两个样本来自冰川集水区，两个样本来自无冰川的永久冻土主导集水区。虽然在Rao系统发育多样性方面（0.18±0.04，1标准差）两个集水区之间没有差异，但冰川集水区样本的丰富度（138 - 139）略高于无冰川集水区样本（67 - 106）。在门水平上，纤毛虫门在冰川集水区样本中的相对丰度最高（32 - 63%），但在无冰川集水区样本中仅占0 - 17%。硅藻门是无冰川集水区其中一个样本中最丰富的门（43%），但光合微生物真核生物在冰川集水区样本中仅占一小部分（<2%），这表明在这些环境中微生物真核生物主要是异养型（化能营养型）。这与之前发表的来自加拿大罗伯逊冰川的数据形成对比，在那里三个样本中绿藻（光合生物）的相对丰度为48 - 57%。这种差异可能是由于冰川水文和/或地质的不同，突出了名义上相似环境之间微生物真核生物群落的差异。
