During the summer of 2017, I taught a course on the ecology, geology, and cultural significance of the greater Yellowstone area. My students and I took a FLIR ONE® thermal camera and an iPad® loaded with Vernier Thermal Analysis® Plus app on a field excursion to Yellowstone to record thermal imagery of hydrothermal features. Below, a true-color image and a pseudocolor thermal image of one of Yellowstone’s most famous hot springs, Morning Glory Pool, are shown side by side. The thermal image clearly reveals a higher temperature near the center of the pool, where the water is deeper and fed beneath the surface by superheated water and a lower temperature near the shallower edges of the pool. The true-color image reveals a pattern of colors that correlates with the temperature gradient. The different colors are different species of thermophilic (heat-loving) bacteria that form thick mats and streamers in the pool.
These thermophiles flourish in hot water, even water over 80°C. One such thermophile is the bacteria Thermus aquaticus, which was discovered in Yellowstone in 1969 by Thomas D. Brock and Hudson Freeze. Thermus aquaticus is the source of a heat-resistant form of the enzyme responsible for synthesizing DNA called Taq polymerase. Discovery of Taq polymerase allowed development of polymerase chain reaction (PCR) DNA amplification technology, a cornerstone of modern molecular biology. Taken together, the thermal and true-color images reveal that each species of bacteria prefers a specific temperature band, which determines how close to the edge of the pool each species establishes itself.