EPOW - Ecology Picture of the Week

Life on the Hot Edge

Thermophilic Extremophiles
El Tatio Geysers, Atacama Desert, Chile

Explanation:  Hands off!  You are standing on the edge of a bubbling, broiling hot springs, here at El Tatio Geysers in northern Chile, South America.  But what is this colored smudge on the edge of the steaming waters?

This is an amalgamation of thermophilic -- heat-loving -- life, mixed with colorful minerals.  

Studies have shown that the minerals consist of silica and travertine deposited by the waters that are saturated with silica and sodium chloride (see references at the end of this article).  

The life forms here, though, are the interesting part, at least to this biologist.  They consist of extremophiles, or life that thrives in extreme environments that would be hostile to most other life forms such as you and me.  These life forms here consist of cyanobacteria, green bacteria, and diatoms.  

In the main photo at top of this page, and in the closeup below, can be seen biofilms and filamentous microbial communities.  The filaments show as green and red threads along the light-colored mineral edges of the pool, and are largely species of the cyanobacteria genera Phormidium and Rivularia.

It is the microbes that play a key "ecosystem engineering" role here by providing the structure for silica nucleation, which means that they are the catalyst upon which silica bonds, forms, and grows into physical structures around these hot spring pools.  

And perhaps most important is that ancient remnants of hydrothermal outcrops have been discovered in Gusev crater on Mars.  And those outcrops most resemble the active hydrothermal vents and conditions here at El Tatio Geysers in Chile.  In a way, this is a bit of Mars here on Earth.  Might there be fossil evidence on Mars of ancient thermophiles such as cyanobacteria, green bacteria, and diatoms as found here?   

      
Steaming hot springs of El Tatio Geysers in the Atacama Desert
of northern Chile.  The Atacama resembles Mars in many other ways.
Might it signal that Mars once held -- still holds? -- robust
and hardy life forms clinging to extreme environments ... ?

  
Information:
     Barbieri, R., B. Cavalazzi, N. Stivaletta, and P. Lopez-Garcia.  2014.  Silicified biota in high-altitude, geothermally influenced ignimbrites at El Tatio Geyser Field, Andean Cordillera (Chile).  Geomicrobiology Journal 31(6):493-508.
     Fernandez-Turiel, J.L., M. Garcia-Valles, D. Gimeno-Torrente, J. Saavedra-Alonso, and S. Martinez-Manent.  2005.  The hot spring and geyser sinters of El Tatio, northern Chile.  Sedimentary Geology 180(4-5):125-147.
     Jones, B. and R.W. Renaut.  2006.  Formation of silica oncoids around geysers and hot springs at El Tatio, northern Chile.  Sedimentology 44(2):287-304.
     Renaut, R.W., and B. Jones.  2000.  Pp. 187-195 in: R.E. Riding and S.M. Awramik, editors.  Microbial sediments.  Springer, New York.
     Ruff, S.W., K.S. Campbell, M.J. Van Kranendonk, M.S. Rice, and J.D. Farmer.  2020.  The case for ancient hot springs in Gusev Crater, Mars.  Astrobiology 20(4):475-499.
     Ruff, S.W. and J.D. Farmer.  2016.  Silica deposits on Mars with features resembling hot spring biosignatures at El Tatio in Chile.  Nature Communications 7:Article number 13554.