By most measures, Pavilion Lake is completely normal. A picturesque body of fresh water in British Columbia, carved out by a glacier some eleven thousand years ago, it has an ordinary pH, temperature, and mineral content. Yet the lake hosts a collection of bizarre structures that may someday help us detect past or current life on other planets. In the mid-1990s, scientists discovered microbialites at the bottom of the lake, luring researchers from NASA, the Canadian Space Agency, and a number of universities.
Microbialites are intricate carbonate formations that can be created by diverse microbial organisms. They look like coral, but without the tropical color schemes. In fact, microbialites are modern analogues for Precambrian reefs, which were some of the earliest indicators of life on Earth. Such structures were once common on the surface of Earth, but these days they are typically found only in extremely salty water. So what were microbialites doing in Pavilion Lake?
I came face to face with them while SCUBA diving alongside other scientists with the Pavilion Lake Research Project. In shallow waters, microbialites are small and resemble cauliflower. Up close, you can see individual sand-like grains. Some crumble like dirt between your fingers. As you dive deeper, the microbialites become larger and harder, and resemble giant artichokes.
Since 2004, scientists have been diving extensively in the lake. Yet SCUBA diving has its limitations. And so this year, for the first time, the Pavilion Lake Research Project brought in a pair of Nuytco DeepWorker submersibles to explore the lake.
Simply deploying the subs was a bold undertaking. Usually DeepWorkers are launched from enormous ships with the help of cranes. But with nothing but highway access to the lake, ships and cranes were not an option. Instead, we built a miniature barge, like a floating swing set. We lowered the subs by hand on chains, and divers guided them out from under the barge.
Twice each day pilots flew the submersibles over predetermined contours of the lake, taking high-definition video of the lake bottom. Using the ninety hours of video recorded, our goal is to create a high-resolution map of microbialite morphologies throughout the lake. Combined with ongoing biochemical experiments in the lake, our new knowledge of microbialite distribution will eventually help us see the big picture. We hope to piece together how these microbialites are formed, and why their structures are so varied.
