BOZEMAN -- Bacteria may play a larger role in the melting of glaciers than previously suspected, according to a paper published by a recent Montana State University doctoral graduate.
A portion of Heidi Smith’s dissertation was published this month in the journal Nature Biofilms and Microbiomes under the title: “Biofilms on Glacial Surfaces: Hot Spots for Biological Activity.” Smith was a student in the Center for Biofilm Engineering and graduated in May with a doctorate from MSU’s Department of Land Resources and Environmental Sciences in the College of Agriculture.
Smith’s paper takes a close look at how glacial carbon – a food source for bacteria – moves out of the ice and into the environment. Smith examined how microbial communities organized in biofilms both consumed and emitted carbon, which may result in causing their host glacier to melt faster.
“Scientists are always trying to account for how much carbon is on the planet, how it might be utilized by biological systems, how it gets moved around in ecosystems and how it might end up in our atmosphere or oceans,” said Christine Foreman, Smith’s adviser and an associate professor of chemical and biological engineering in the MSU College of Engineering and the MSU Center for Biofilm Engineering.
“Heidi’s work is important because she’s among the first to get direct measurements of biofilms on glacier surfaces,” Foreman said. “Heidi has shown that biofilms transfer and cycle carbon and other nutrients in these systems, and are ecologically advantageous for the survival of organisms in these extreme environments.”
Understanding the quantities of carbon contained within glaciers, as well as how much carbon is being transferred to other ecosystems, could help scientists better model climate change.
The quality and quantity of carbon within glacial systems can affect the rate at which they melt, Smith said, through a chain reaction that begins when microorganisms consume glacial carbon. These organisms form a biofilm – a group of microorganisms that adheres to a surface – such as on sediment particles, located on the surface of the glacier. The biofilm ultimately impedes the ice mass’s ability to reflect sunlight.
“The glacier’s ability to reflect sunlight is important because if it’s darkened by biology or the accumulation of sediment, it causes more energy to be absorbed rather than reflected, thus increasing surface melt,” she said. “In other words, this biological process is hastening the melting of glaciers. It’s not that different from a rock on a glacier that absorbs the sun’s energy, heats up and melts the surrounding ice.”
Scientists have long known that organic carbon trapped for thousands of years in glaciers serves as a food source for microorganisms and is liberated as the ice melts.
However, Smith’s research shows that the fixation of inorganic carbon by microorganisms produces organic carbon that is rapidly used by neighboring microorganisms. “Fixing” inorganic carbon in this way is playing an important role in the lifecycle of these microbial communities on glaciers as they melt.
“We’ve shown that organisms capable of ‘fixing’ inorganic carbon are transferring carbon to nearby bacterial community members,” she said.
“It can be hard to convey the importance of microbes because people can’t see them, but they’re the most abundant organisms on Earth,” she added. “Microbes are also typically at the base of aquatic food webs, and are likely going to be the first to respond to changes in the ecosystem. In addition to the melt and altering the ecosystems of oceans through runoff from the glaciers, there’s also an increase in CO2, which contributes to the rising temperatures globally.”
While at MSU, Smith earned a competitive three-year NASA Earth and Space Science Fellowship and was a student associate with the MSU IGERT program in Geobiological Systems Science. She also attended the Woods Hole Microbial Diversity summer course in Woods Hole, Massachusetts, participated in an internship with the Max Planck Institute in Germany, spent four seasons conducting research in Antarctica and has mentored several undergraduate students.
Contact: Heidi Smith, email@example.com