New Article!! Watershed-Induced Limnological and Microbial Status in Two Oligotrophic Andean Lakes Exposed to the Same Climatic Scenario

fmicb-09-00357-g001
  • 1Centro de Biotecnología, Universidad Católica del Norte, Antofagasta, Chile
  • 2Departamento de Ciencias Geológicas, Universidad Católica de Norte, Antofagasta, Chile
  • 3Centro de Investigación Científica y Tecnológica para la Minería, Antofagasta, Chile
  • 4Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Madrid, Spain
  • 5Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, United States
  • 6Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Antofagasta, Chile
  • 7Carl Sagan Center, SETI Institute, Mountain View, CA, United States
  • 8Space Science Division, NASA Ames Research Center, Moffett Field, CA, 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 entering 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 physical and chemical variables and performed 16S rRNA amplicon sequencing to determine the specific microbial signature of the lakes. The transparency, temperature, turbidity and concentrations of chlorophyll-a, dissolved organic matter, nutrients 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.

ORIGINAL RESEARCH ARTICLE

Front. Microbiol., 05 March 2018 | https://doi.org/10.3389/fmicb.2018.00357

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