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Thursday, October 28, 2021

UC Davis graduate student investigates ancient life forms in Canadian lake

Like many children, as a 10-year-old Rebekah Shepard wanted to be an astronaut. Her involvement in the Pavilion Lake Research Project is bringing her ever closer to that dream, as she joined researchers from NASA in their exploration of the development of ancient life forms.

Shepard, a doctoral candidate in the department of geology, participated in the 10-day expedition conducted by the Pavilion Lake Research Project (PLRP) held from June 23 through July 3 in British Columbia, Canada. This year, researchers involved in the PLRP included representatives from both American and Canadian universities.

Our participants are made up of support staff and scientists. We have met most of our collaborators through conferences and word of mouth about the project,said Darlene Lim, NASA’s Principal Investigator of the PLRP, in an e-mail interview.

Shepard first became involved in the PLRP in 2005. Lim, whom she met through her connections at UC Davis, invited Shepard to join the expedition.

“[I’m] ridiculously lucky,Shepard said.Make great friends in life, that is my advice.

The PLRP is studying microbialite structures and microbial mats in British Columbia’s Pavilion Lake in order to understand microbialite development.

Microbialites are microbial mats that are literally rock hard. The suffixitemeans rock in this context,said Dawn Sumner, a professor in the UC Davis geology department and Shepards graduate adviser, in an e-mail interview.The microbialites in Lake Pavilion are microbial mats that have had the mineral calcite form within the microbial mats, turning them into rocks.

Researchers are investigating the relationship between microbial mats, which are living organisms, and the carbonate-based microbialite structures, Lim said.

We know [microbes] live on the surfaces and inside of the microbialites, especially those at mid-to-deep depths in the lake, but how they contribute to the shape and fabric of the structures, and whether those contributions leave behind signatures that might be preserved in the rock record are key questions were trying to answer,said Sherry Cady, a geology professor at Portland State University and researcher involved in the PLRP, in an e-mail interview.

The research conducted by the PLRP contributes to Shepard’s graduate work at UC Davis.

“[Microbial] mats are an entire chapter of my thesis,Shepard said. “People differ in [their] approach [to] Ph.D.s. I spend a lot of time working on projects.

Researchers are also studying the development of microbialites in Pavilion Lake in terms of their similarities with structures on other planets.

“What is most relevant to our current exploration of Mars is our ability to detect biosignatures in the Pavilion Lake microbialites,Lim said.This is proving complicated to do, but our methods and findings are relevant to our ability to detect biosignatures on other planets such as Mars.

“We want to know how to recognize signs of life in such structures should we find them in the ancient rock record here on Earth, or if we found similar structures on another rocky planet in our solar system,Cady said.

“[It is] hard to define life,Shepard said.If we are looking for life on Mars, how do we know if we’ve found it if we can’t define it?”

Unlike previous expeditions, this year the researchers used DeepWorker submersibles, created by Nuytco Research Ltd., in order to expand upon the research conducted by scuba diving.

With the submersibles, researchers were able to remain underwater for longer periods of time, as well as capture video of their dives, Lim said. The submersibles also allowed researchers to explore the length and depth of the lake in its entirety.

Used in addition to scuba diving, the submersibles provided a broader perspective of the lake, which complemented the more localized study conducted by scuba diving.

When we dive we are focused on discreet tasks and get very little time to ‘take it all in,Lim said.Context is so important in understanding an environment and with [DeepWorkers] we finally got that.

The use of the one-person submersibles created a research environment distinctly different from that of scuba diving.

“We were able to go down to any depth, sit, and take it all in – all in the comfort of a one atmosphere environment too,Lim said.

“Every time I had to come up I was sad,Shepard said.There is so much to look at. I felt like an astronaut.

This year’s expedition also partnered with NASA’s Spaceward Bound program to teach members of the academic community about the research conducted at Pavilion Lake.

Spaceward Bound is an education and public outreach effort to bring teachers and students firsthand field science experience. This summer we also piloted a SB program at the lake that saw 20 local teachers and students come and participate in a science activity. We intend to roll this out again next year with more teachers embedded in our science program,Lim said.

The PLRP, which organizes several expeditions per year, is scheduled to return to Pavilion Lake this fall.

We are definitely going back,Shepard said.I’m so excited. It’s finally what I want to be doing.

SARA JOHNSON can be reached at features@californiaaggie.com.

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