AUTHOR=Lionard Marie , Péquin Bérangère , Lovejoy Connie , Vincent Warwick F. TITLE=Benthic Cyanobacterial Mats in the High Arctic: Multi-Layer Structure and Fluorescence Responses to Osmotic Stress JOURNAL=Frontiers in Microbiology VOLUME=3 YEAR=2012 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2012.00140 DOI=10.3389/fmicb.2012.00140 ISSN=1664-302X ABSTRACT=
Cyanobacterial mats are often a major biological component of extreme aquatic ecosystems, and in polar lakes and streams they may account for the dominant fraction of total ecosystem biomass and productivity. In this study we examined the vertical structure and physiology of Arctic microbial mats relative to the question of how these communities may respond to ongoing environmental change. The mats were sampled from Ward Hunt Lake (83°5.297′N, 74°9.985′W) at the northern coast of Arctic Canada, and were composed of three visibly distinct layers. Microsensor profiling showed that there were strong gradients in oxygen within each layer, with an overall decrease from 100% saturation at the mat surface to 0%, at the bottom, accompanied by an increase of 0.6 pH units down the profile. Gene clone libraries (16S rRNA) revealed the presence of Oscillatorian sequences throughout the mat, while