CHARACTERIZATION OF ENVIRONMENTAL FACTORS INFLUENCING AQUATIC CYANOBACTERIA DISTRIBUTION AT EL TATIO GEYSER FIELD, CHILE

El Tatio geyser field is located at 14,500 ft in the Atacama desert in northern Chile.The geyser waters are characterized by temperatures of 50-80°C, circumneutral pH, high arsenic concentration, and low total and dissolved inorganic carbon (DIC) content (as low as 2 ppm). The primary interest of this study is to identify associations between temperature and DIC, and their relationship to cyanobacteria abundance and distribution. Previous studies have shown that nutrient availability is one of the most important factors promoting aquatic bacterial mat growth, therefore DIC should have an impact on cyanobacteria mat growth and distribution at El Tatio. The nature and extent of the impact is unclear and hasn’t previously been investigated at the site.

This study focuses on a stream in the Upper Basin at El Tatio with two sources that flow together and mix downstream. Each source and the mixing zone all exhibit different temperature, DIC content, and observed cyanobacterial mat growth, and potentially exhibit different chemical signatures, as well. Temperature, pH, and DIC profiles will be made of the two sources and their downstream mixing zone, and a characterization of the changes in water chemistry and bacterial mat communities will be made along the length of the stream in order to identify the most important factors determining mat growth along the stream. Water and submerged bacterial mat samples were collected in the field, with pH and temperature measurements taken at the precise location of mat and water sample collection. In the lab, mat samples were analyzed for cyanobacteria pigment abundance, and water samples were analyzed for total organic and inorganic carbon content, arsenic content, and other major chemical constituents. DNA was extracted from mat samples from several locations along the stream, and amplification using PCR and sequencing of communities will be done to compare specific cyanobacteria as well as broader community signatures. Initial data and field observations suggest that there is a strong relationship between cyanobacteria distribution and temperature, and also suggest that the nature of the cyanobacteria-DIC relationship at El Tatio can be determined.