Extremities:  Geology and Life in Yellowstone and Implications for Other Worlds

OCTOPUS SPRING - 1 - Hot Water

Octopus spring is a "classic" low-sulfur, low carbonate hot spring. Dr. Dave Ward (Montana State University) led our visit and sample collection at Octopus — he and his colleagues are the experts on its microbial mat communities.

Octopus Spring Overview
Source of Hot Water

Octopus Springs. Hot water, >90C, comes up in the small pool to the right of the main, blue pool. Part of the water leaves immediately in the stream to the right, where we collected the pink streamers. The rest spills over in to the large blue pool, and then flows out to the upper right where we collected the microbial mats.
The spring itself. The hot water comes from the dark shadowed hole at the bottom of this pool. Its flow surges every 5 minutes or so, with lots of bubbles. Water flows to the right from here into the channel in the image below.
Octopus Spring photo 3
Octopus Spring photo 4

Bubbles at lower right show where the water comes up into the pool. The white deposits are silica sinter (=spring deposits). They grow out over the pool, and are fragile. Every year, several Park visitors step on and break through sinter like this, and are severely burned (poached).

Pink microbial filaments first appear in this channel ~2 meters downstream from the bubbling pool. We measured T = 83C, pH = 8 (slightly alkaline), and very little sulfur. The filaments contain the bacteria Aquifex and Thermotoga. The live by using oxygen from the air to oxidize hydrogen gas or formate (a small organic molecule) from the spring water. I.e., they respire aerobically (O2 from air) and are chemolithotrophic (draw their nutrients from inorganic chemicals).

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Copyright Allan Treiman, LPI.
Updated 11/15/02.
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