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Front. Microbiol. | doi: 10.3389/fmicb.2018.00357

Watershed-induced limnological and microbial status in two oligotrophic Andean lakes exposed to the same climatic scenario

  • 1Centro de Biotecnología, Universidad Católica del Norte, Chile
  • 2Departamento de Ciencias Geológicas, Universidad Católica del Norte, Chile
  • 3Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Spain
  • 4Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Chile
  • 5Smithsonian Environmental Research Center (SI), United States
  • 6Carl Sagan Center, SETI Institute, United States
  • 7Space Science Division, Ames Research Center (NASA), United States

Laguna Negra and Lo Encañado are two oligotrophic Andean lakes forming part of the system fed by meltwater from distinct glacial tongues of the Echaurren glacier in central Chile, which is in a recession period. The recent increase in temperature and decline in precipitation have led to an increase of glacial meltwater and sediments towards these lakes. Although the lacustrine systems are also hydrogeologically connected, the limnology of the lakes is strongly controlled by the surface processes related to the respective sub-watersheds and hydrology. Watershed characteristics (area and length, slope, lithology, resistance to erosion, among others) affect the chemical and physical characteristics of both lakes (e.g., nutrient concentration and turbidity). We studied limnological and chemical variables and performed 16S rRNA amplicon sequencing to determine the specific microbial signature of the lakes. The transparency, Chlorophyll-a, fDOM levels, and the total number of cells, revealed the different status of both lakes at the time of sampling. The predominant bacterial groups in both lakes were Proteobacteria, Verrucomicrobia, and Bacteroidetes. Interestingly, the contribution of phototrophs was significantly higher in LN compared to LE (13% and 4% respectively) and the major fraction corresponded to Anoxygenic Phototrophs (AP) represented by Chloroflexi, Alpha, and Betaproteobacteria. Multivariate analyses showed that the nutrient levels and the light availability of both lakes, which finally depend on the hydrological characteristics of the respective watersheds, explain the differential community composition/function. The abundance of a diverse photoheterotrophic bacterioplankton community suggests that the ability to utilize solar energy along with organic and inorganic substrates is a key function in these oligotrophic mountain lakes.

Keywords: Oligotrophic lakes, microbial communities, Glacial melting, 16S rRNA gene sequencing, Watersheed influence

Received: 21 Jul 2017; Accepted: 14 Feb 2018.

Edited by:

Justin R. Seymour, University of Technology Sydney, Australia

Reviewed by:

Levente Bodrossy, CSIRO Oceans and Atmosphere, Australia
Bonnie Laverock, Auckland University of Technology, New Zealand  

Copyright: © 2018 Echeverría-Vega, Demergasso, Chong, Serrano, Guajardo, Encalada, Parro, Blanco, Rivas, Moreno-Paz, Luque, Rose and Cabrol. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
PhD. Alex Echeverría-Vega, Universidad Católica del Norte, Centro de Biotecnología, Antofagasta, Chile, aecheverri@ucn.cl
Dr. Cecilia S. Demergasso, Universidad Católica del Norte, Centro de Biotecnología, Antofagasta, Chile, cdemerga@ucn.cl