Friday, 01 July 2016 13:35

Glimpse of an Alien World, in Yellowstone National Park

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Published in Microbial Sciences

Yellowstone Figure 1Figure 1. Annotated relief map of Yellowstone National Park. Adapted from the NPS map collection.

A few weeks ago, on the night of June 10th, my brother Andrew and I were in Yellowstone National Park. We were in the middle of a 2,800-mile photography expedition that began in the desert of Capitol Reef National Park in Utah and ended in snowy Glacier National Park in Montana. This is the first article in a three-part series based on our trip. The series has two goals: to share our adventures as we find and photograph exceptional sites of microbial science, and, to celebrate the 100-year anniversary of the National Park Service. We’ll start now in Yellowstone. After all, it was the first national park in the world.

We had spent Friday evening spotting grizzly bears in the northeastern part of the park. After three days in Yellowstone, we were planning to head out towards Bozeman, Montana. But as the sun set over Lamar Valley, fading to a clear night sky, my brother saw the look in my eyes. We were headed back into the park. We couldn’t leave. When would be my next chance to photograph the Milky Way Galaxy over Yellowstone?

Yellowstone Figure 2Figure 2. Sunset at Lamar Valley, Yellowstone National Park, June 2016. Photo by: Scott Chimileski

So we drove back over Dunraven Pass, about two hours south to the Lower and Middle Geyser Basins. This is one of the largest regions of hot springs in Yellowstone—where many of the most colorful and well-studied microbial communities live.

I stood at midnight on the platform above Firehole Spring. The daytime cars and tourists were gone. A tiny red exposure signal on my camera was the only artificial light. I had been at the same exact spot 12 hours earlier, but there was more energy in the land now. Great Fountain Geyser erupted in the distance. Suddenly, all of the geysers in the area were erupting at once. It was surreal, like crashing waves, a thousand miles away from the nearest ocean.

During these moments of increased thermal activity, I heard a beat in the ground that vibrated through the wooden platform, in sync with huge bubbles released in the pool every other second.

Yellowstone Figure 3Figure 3. The Yellowstone Ecosystem has developed within one giant volcanic crater, or caldera. A system of magma chambers drives thermal activity at the surface. Image Credit: Hsin-Hua Huang. Source

In a very real sense, I had felt the pulse of Earth. I say this because the heat released by the over 10,000 thermal features in Yellowstone originates from an active supervolcano. An entire system of magma chambers lingers under northwestern Wyoming. In fact, much of this storied landscape exists within a 30 by 45 mile volcanic crater, blasted out during an apocalyptic eruption 630,000 years ago. If we go one step further back from the beat in the ground—the energy in the magma chamber beneath Yellowstone—it is ultimately generated by radioactive decay in Earth’s core, mixed with a bit of heat left over from the formation of the planet.

The blue color at the bubbling center of Firehole Spring is a result of scattered light. But as water flows towards the perimeter and slowly cools through a network of tributaries, more colors are produced by thermophilic microbes. Some of the most vibrant reds, yellows and oranges are carotenoid pigments produced by Synechococcus.

Photosynthetic cyanobacteria like Synechococcus form the foundation of complex multi-species microbial mats. Yellowstone’s microbial mats are diverse, reflecting the variable geochemistry, temperature, acidity or alkalinity of thermal features. These unique, macroscopic microbial food webs include species from all domains of life and challenge the way that we usually think about microbes.

S Chimileski Yellowstone Figure4aFigure 4. A bubble surges through Firehole Spring at night. Photo by: Scott Chimilesk

Over time, some microbial mats form hard structures called stromatolites. Without grazing animals at very high temperatures, microbial mats grow continuously in night and day cycles. As they thicken, layers beneath the surface literally turn to stone due to high levels of silica or calcium carbonate in the water, leaving a record of microbial activity. Analogous to trees in a forest, individual stromatolites are shaped through competition with other stromatolites within the local environment. In the example from Octopus Spring shown in Figure 5, we can only imagine which of the newly developing stromatolites will come to dominate this tiny patch of thermal stream.

In the end, we didn’t get to Bozeman until 3 AM that morning. But let me explain why these last photographs were worth it.

When we see the Milky Way Galaxy over Grand Prismatic Spring, we are looking at billions of stars. Among the stars are many Earth-like planets. We can’t see the colorful microbial cells in the foreground with our eyes, or details of far-off worlds within the galaxy. Yet here we have a glimpse of how life appeared for most of the history of Earth. And it’s the same kind of life likely to exist in the background, somewhere else in the universe.

Yellowstone Figure 5Figure 5. An orange and yellow field of stromatolites forming in a stream flowing from Octopus Spring. Photo by: Scott Chimileski











Yellowstone Figure 6Figure 6. Milky Way Galaxy over Grand Prismatic Spring. Photo by: Scott Chimileski












Last modified on Wednesday, 28 September 2016 15:46
Scott Chimileski

Senior Contributor Scott Chimileski is a Research Fellow in Roberto Kolter’s laboratory at Harvard Medical School and a member of the ASM Writer Team. Scott's research is focused on imaging biofilms and other microbial multicellular forms. He is a photographer, coauthor of the book Life at the Edge of Sight: A Photographic Exploration of Microbial World, and is currently spearheading several exhibitions on microbial life at the Harvard Museum of Natural History. You can find him on Twitter @socialmicrobes.