Surface Water Temperature Controls on Microbial Communities at the El Tatio Geyser Field, Chile

Extremophile community structure at geothermal features is predominantly controlled by temperature, a master variable that also influences the solubility of biogeochemically significant gases like O₂. Microbial communities at geothermal features display spatial variability related to thermal gradients created by the shallow flow from these features. This study investigates the community structures of chloroflexus, chlorobium, and cyanobacteria in relation to high-resolution temperature measurements at the El Tatio Geyser Field in northeastern Chile. The hydrothermal features at El Tatio release water at 86˚C (the boiling point at 4200 m), which can cool by 20˚C within 1 meter of the feature. These abrupt temperature gradients are remotely measured at an unprecedented scale using a thermal infrared (TIR) camera. TIR images were collected from 4 features with a thermal precision of 0.06˚C and spatial resolution of 1.5 mm². Color images were simultaneously collected and the dominant species are defined by their range of RGB values. Temperature and O₂ solubility maps are co-registered with the RGB color map in order to quantitatively correlate the different patterns of physicochemical parameters with microbial community structures. This study seeks to test and expand our knowledge of the relationship between microbial community structure and temperature. Moreover, we demonstrate the capabilities of ground-based thermal remote-sensing in high-resolution mapping of microbial communities and geothermal features.