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2011 Annual Science Report

VPL at University of Washington Reporting  |  SEP 2010 – AUG 2011

Stromatolites in the Desert: Analogs to Other Worlds

Project Summary

In this task biologists go to field sites in Mexico to better understand the environmental effects on growth rates for freshwater stromatolites. Stromatolites are microbial mat communities that have the ability to calcify under certain conditions. They are believed to be an ancient form of life, that may have dominated the planet’s biosphere more than 2 billion years ago. Our work focuses on understanding these communities as a means of characterizing their metabolisms and gas outputs, for use in planetary models of ancient environments.

4 Institutions
3 Teams
1 Publication
2 Field Sites
Field Sites

Project Progress

At the desert oasis of Cuatro Ciénegas in Coahuila, México, more than 300 oligotrophic pools can be found and a large number of endemic species of plants and animals. Recent results by Cerritos et al., (2011) showed that conductivity in this system is the environmental factor that explains the distribution of most of the microbial diversity. Phylogenetic reconstruction from their 16S rRNA sequences was performed for a sample of 150 isolates from the Churince hydrological system at Cuatro Cienegas. Only 17 sequences had a 100% match in the Gene Bank (NCBI), representing 10 well known cosmopolitan taxa. The rest of the sequences cluster in 22 clades for Firmicutes and another 22 clades for Actinobacteria, supporting the idea of high diversity and differentiation for this site.

Field trips to Cuatro Cienegas Basin were resumed in October and the drought that has affected the southern US had affected the hydrology of the fields sites. Several of the sites were almost dry. While this was not part of our original protocol, it is part of the environmental dynamics and we took samples from all our test sites and we are processing them in light of community constituency dynamics. Additional experiments will be performed in early 2012 as planned previously with the likelihood that the water table will resume its more standard levels. One addition to our sample protocol is to begin searching for nonstandard chlorophylls in a new collaboration with VPL Team member Bob Blankenship.

    Janet Siefert Janet Siefert
    Project Investigator
    Robert Blankenship

    Eric Boyd

    Objective 4.1
    Earth's early biosphere.

    Objective 4.2
    Production of complex life.

    Objective 5.2
    Co-evolution of microbial communities

    Objective 5.3
    Biochemical adaptation to extreme environments

    Objective 6.1
    Effects of environmental changes on microbial ecosystems

    Objective 6.2
    Adaptation and evolution of life beyond Earth