High Arctic meromictic lakes are extreme environments characterized by cold temperatures, low nutrient inputs from their polar desert catchments and prolonged periods of low irradiance and darkness. These lakes are permanently stratified with an oxygenated freshwater layer (mixolimnion) overlying a saline, anoxic water column (monimolimnion). The physical and chemical properties of the deepest known lake of this type in the circumpolar Arctic, Lake A, on the far northern coast of Ellesmere Island, Canada, have been studied over the last 15 years, but little is known about the lake’s biological communities. We applied high-throughput sequencing of the V4 region of the 18S ribosomal RNA gene to investigate the protist communities down the water column at three sampling times: under the ice at the end of winter in 2008, during an unusual period of warming and ice-out the same year, and again under the ice in mid-summer 2009. Sequences of many protist taxa occurred throughout the water column at all sampling times, including in the deep anoxic layer where growth is highly unlikely. Furthermore, there were sequences for taxonomic groups including diatoms and marine taxa, which have never been observed in Lake A by microscopic analysis. However, the sequences of other taxa such as ciliates, chrysophytes, Cercozoa, and Telonema varied with depth, between years and during the transition to ice-free conditions. These seasonally active taxa in the surface waters of the lake are thus sensitive to depth and change with time. DNA from these taxa is superimposed upon background DNA from multiple internal and external sources that is preserved in the deep, cold, largely anoxic water column.
Keywords: Arctic, anoxic, climate change, meromictic, phytoplankton, polar lakes, protists
Citation: Charvet S, Vincent WF, Comeau A and Lovejoy C (2012) Pyrosequencing analysis of the protist communities in a High Arctic meromictic lake: DNA preservation and change. Front. Microbio. 3:422. doi: 10.3389/fmicb.2012.00422
Received: 14 August 2012; Accepted: 24 November 2012;
Published online: 20 December 2012.
Edited by:Linda Amaral-Zettler, Marine Biological Laboratory, USA
Reviewed by:Rebecca Gast, Woods Hole Oceanographic Institution, USA
Copyright: © 2012 Charvet, Vincent, Comeau and Lovejoy. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: Connie Lovejoy, Département de Biologie, Université Laval, Pavillon Charles-Eugène-Marchand, 1030 Avenue de la Médecine, Québec, QC, Canada G1V 0A6. e-mail: firstname.lastname@example.org