Yellowstone Lake is the foundation of the Yellowstone Ecosystem, providing key ingredients to a large and complex food chain that sustains many of the animals for which Yellowstone is so famous. Cutthroat trout are commonly thought of as the base of this food chain that includes otters, bald eagles, coyotes and grizzly bears. However, scientists’ views may be changing. The ecological underpinnings of this lake may have an unanticipated source deep below the surface — the Yellowstone volcano.
The hot springs and geysers in Yellowstone National Park are legendary; however, unseen to almost all eyes are the hundreds of hydrothermal features, including “vents,” below the surface of Yellowstone Lake. The northern region of the lake, in particular, is especially active, sitting about 5 km above the epicenter of the recent swarm of around 900 earthquakes that were recorded in December 2008 and January 2009. The vents are essentially pressure relief valves for the volcano, and, along with the tremors, are constant reminders of the energy trapped deep below.
One of the largest scientific expeditions ever mounted in Yellowstone is exploring Yellowstone Lake and its geothermal vents, seeking a better understanding of how this lake works.
Scientists from the Thermal Biology Institute and Big Sky Institute at Montana State University, the J. Craig Venter Institute in San Diego, the United States Geologic Survey, and Eastern Oceanics combine to form a multidisciplinary team that hopes to unlock the lake’s mysteries.
This group is particularly interested in examining how the vent emissions influence the lake’s food chain, and the MATBI (Molecular All-Taxa Biodiversity) study has yielded some startling discoveries. Yellowstone Lake is hardly “unremarkable” or a “simple ecosystem” as has been the prevailing view for nearly a century.
Chemicals and Gasses and Bacteria — Oh My!
Typically, photosynthesis energizes the food chain of freshwater lakes, allowing microbes to thrive, and that in turn feed zooplankton (tiny 
invertebrates that float freely throughout bodies of water) that young fish depend on for their first year of life. The scientific team has found that Yellowstone Lake is different — very different! As it turns out, in addition to solar energy, the geothermal vents on the lake’s floor release huge amounts of chemicals upon which bacteria thrive, and these bacteria are the key to converting the volcano’s chemical energy into life.
Using a Remote Operating Vehicle (ROV) — a submersible vehicle controlled by researchers on the boat — the scientific team has discovered vents that release incredible amounts of hydrothermal gases. For bacteria, these high-energy compounds are the equivalent of filet mignon. The molecular signature of these bacteria can be found throughout the lake but, as expected, appear to be enriched in the water columns above and around these vents.
Even more exciting, using state-of-the-art DNA sequencing techniques, the scientists have found that the microbial diversity supported by this lake exceeds anything yet documented in current scientific literature. Textbooks may have to be rewritten due to this groundbreaking study.
And it gets better. These same bacteria are sustenance for the zooplankton that are so essential to the survival of baby cutthroat trout — an important food source for grizzlies and other wildlife. While studying these vents, the scientific team frequently encountered clouds of zooplankton. Could this be key to helping fisheries biologists gain insight into the life cycle of the imperiled cutthroat trout?
After hatching from their eggs in the tributaries that feed Yellowstone Lake, these tiny fish seem to disappear. Where do they go for their first year of life? Do they seek out the vents and the rich zooplankton swarms they support?
Stay tuned. Exciting discoveries are sure to follow on the intricate connections between the better-known Yellowstone species and the microorganisms now being identified.
The MATBI Study is funded by a $1.1 million grant to the Yellowstone Park Foundation from the Gordon and Betty Moore Foundation. This grant has been matched by $959,000 in federal funds through the National Park Service’s Centennial Challenge.
Related links:
Watch a 6-minute video on the Yellowstone Volcano, Yellowstone’s Restless Giant
Yellowstone Volcano Observatory
By Christine Gianas Weinheimer
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