Pla-Rabés Sergi, Hamilton Paul B, Ballesteros Enric, Gavrilo Maria, Friedlander Alan M, Sala Enric
CREAF , Cerdanyola del Valles, Barcelona , Spain.
Canadian Museum of Nature, Research and Collections , Ottawa, Ontario , Canada.
PeerJ. 2016 Feb 18;4:e1705. doi: 10.7717/peerj.1705. eCollection 2016.
We examined diatom assemblages from 18 stream and pond samples in the Franz Josef Land Archipelago (FJL), the most northern land of Eurasia. More than 216 taxa were observed, revealing a rich circumpolar diatom flora, including many undescribed taxa. Widely distributed taxa were the most abundant by cell densities, while circumpolar taxa were the most species rich. Stream and pond habitats hosted different assemblages, and varied along a pH gradient. Diatoma tenuis was the most abundant and ubiquitous taxon. However, several circumpolar taxa such as Chamaepinnularia gandrupii, Cymbella botellus, Psammothidium sp. and Humidophila laevissima were also found in relatively high abundances. Aerophilic taxa were an important component of FJL diatom assemblages (Humidophila spp., Caloneis spp. and Pinnularia spp.), reflecting the large and extreme seasonal changes in Arctic conditions. We predict a decrease in the abundance of circumpolar taxa, an increase in local (α-) freshwater diatom diversity, but a decrease in regional diversity (circumpolar homogenization) as a result of current warming trends and to a lesser extent the increasing human footprint in the region.
我们研究了来自欧亚大陆最北部土地法兰士约瑟夫地群岛（FJL）的18个溪流和池塘样本中的硅藻组合。观察到超过216个分类单元，揭示了丰富的环极地硅藻植物群，包括许多未描述的分类单元。按细胞密度计算，分布广泛的分类单元数量最多，而环极地分类单元的物种最为丰富。溪流和池塘栖息地拥有不同的组合，并且沿pH梯度变化。细弱羽纹藻是数量最多且分布最广的分类单元。然而，还发现了一些环极地分类单元，如甘氏矮羽纹藻、短颈桥弯藻、沙生藻属物种和光滑湿生藻，其丰度也相对较高。嗜气分类单元是FJL硅藻组合的重要组成部分（湿生藻属、美壁藻属和平藻属），这反映了北极环境中巨大且极端的季节性变化。我们预测，由于当前的变暖趋势以及该地区人类足迹的增加（程度较小），环极地分类单元的丰度将下降，当地（α -）淡水硅藻多样性将增加，但区域多样性将减少（环极地同质化）。
