Sequencing depth and diversity and dominance indices for the selected samples of cryoconite from Aldegondabreen

Table 5. Sequencing depth and diversity and dominance indices for the selected samples of cryoconite from Aldegondabreen. Abstract The aggregation of surface debris particles on melting glaciers into larger units (cryoconite) provides microenvironments for various microorganisms and metabolic processes. Here we investigate the microbial community on the surface of Aldegondabreen, a valley glacier in Svalbard which is supplied with carbon and nutrients from different sources across its surface, including colonies of seabirds. We used a combination of geochemical analysis (of surface debris, ice and meltwater), quantitative polymerase chain reactions (targeting the 16S ribosomal ribonucleic acid and amoA genes), pyrosequencing and multivariate statistical analysis to suggest possible factors driving the ecology of prokaryotic microbes on the surface of Aldegondabreen and their potential role in nitrogen cycling. The combination of high nutrient input with subsidy from the bird colonies, supraglacial meltwater flow and the presence of fine, clay-like particles supports the formation of centimetre-scale cryoconite aggregates in some areas of the glacier surface. We show that a diverse microbial community is present, dominated by the cyanobacteria, Proteobacteria, Bacteroidetes, and Actinobacteria, that are well-known in supraglacial environments. Importantly, ammonia-oxidizing archaea were detected in the aggregates for the first time on an Arctic glacier.表5. 阿尔达贡达冰川（Aldegondabreen）所选冰尘（cryoconite）样本的测序深度、多样性与优势度指数。 摘要：消融冰川表面的碎屑颗粒聚集形成更大的团聚体——冰尘（cryoconite），可为各类微生物及其代谢过程提供微生境。本研究以斯瓦尔巴群岛（Svalbard）的山谷冰川阿尔达贡达冰川（Aldegondabreen）为研究对象，该冰川表面可从多种来源获取碳与营养物质，包括海鸟聚居地。本研究结合地表碎屑、冰体与融水的地球化学分析、靶向16S核糖体核糖核酸（16S ribosomal ribonucleic acid）与amoA基因（amoA genes）的定量聚合酶链式反应、焦磷酸测序（pyrosequencing）及多元统计分析，以探究驱动阿尔达贡达冰川表面原核微生物生态的潜在因素，及其在氮循环中的潜在作用。高营养输入与海鸟聚居地的养分补给、冰面融水径流以及细粒黏土状颗粒的存在，共同促成了冰川表面部分区域形成厘米级的冰尘团聚体。研究表明，该区域存在多样性丰富的微生物群落，优势类群为冰面环境中常见的蓝细菌（cyanobacteria）、变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）与放线菌门（Actinobacteria）。尤为重要的是，本研究首次在北极冰川的冰尘团聚体中检测到了氨氧化古菌（ammonia-oxidizing archaea）。