Michelutti Neal, McCleary Kathryn, Douglas Marianne S V, Smol John P
Paleoecological Environmental Assessment and Research Lab, Department of Biology, Queen's University, Kingston, Ontario, Canada, K7L 3N6.
Department of Earth and Atmospheric Sciences and Canadian Circumpolar Institute, University of Alberta, Edmonton, Alberta, Canada, T6G 2E3.
J Phycol. 2013 Feb;49(1):41-53. doi: 10.1111/jpy.12024. Epub 2013 Jan 11.
Arctic oases are regions of atypical warmth and relatively high biological production and diversity. They are small in area (<5 km(2) ) and uncommon in occurrence, yet they are relatively well studied due to the abundance of plant and animal life contained within them. A notable exception is the lack of research on freshwater ecosystems within polar oases. Here, we aim to increase our understanding of freshwater diatom ecology in polar oases. Diatoms were identified and enumerated from modern sediments collected in 23 lakes and ponds contained within the Lake Hazen oasis on Ellesmere Island, and compared with diatom assemblages from 29 sites located outside of the oasis across the northern portion of the island. There were significant differences in water chemistry variables between oasis and northern sites, with oasis sites having higher conductivity and greater concentrations of nutrients and related variables such as dissolved organic carbon (DOC). Taxa across all sites were typical of those recorded in Arctic freshwaters, with species from the genera Achnanthes sensu lato, Fragilaria sensu lato, and Nitzschia dominating the assemblages. A correspondence analysis (CA) ordination showed that oasis sites generally plotted separately from the northern sites, although the sites also appear to plot separately based on whether they were lakes or ponds. Canonical correspondence analysis (CCA) identified specific conductivity, DOC, and SiO2 as explaining significant (P < 0.05) and additional amounts of variation in the diatom data set. The most robust diatom-based inference model was generated for DOC, which will provide useful reconstructions on long-term changes in paleo-optics of high Arctic lakes.
北极绿洲是具有非典型温暖、相对较高生物生产力和生物多样性的区域。它们面积较小（<5平方千米）且出现频率较低，但由于其中包含丰富的动植物生命，因而得到了相对充分的研究。一个显著的例外是对极地绿洲内淡水生态系统缺乏研究。在此，我们旨在增进对极地绿洲淡水硅藻生态学的理解。从埃尔斯米尔岛黑曾湖绿洲内23个湖泊和池塘采集的现代沉积物中鉴定并计数硅藻，并与该岛北部绿洲外29个地点的硅藻组合进行比较。绿洲和北部地点的水化学变量存在显著差异，绿洲地点的电导率更高，营养物质及相关变量（如溶解有机碳）的浓度也更高。所有地点的分类群都是北极淡水记录中的典型分类群，来自广义曲壳藻属、广义脆杆藻属和菱形藻属的物种在组合中占主导地位。对应分析（CA）排序表明，绿洲地点通常与北部地点分开绘制，不过这些地点似乎也根据是湖泊还是池塘而分开绘制。典范对应分析（CCA）确定比电导率、溶解有机碳和二氧化硅是硅藻数据集中显著（P<0.05）且额外的变异解释因素。基于硅藻的最稳健推断模型是针对溶解有机碳生成的，这将为高北极湖泊古光学的长期变化提供有用的重建。
