"We found that the isotopes of Fe(II) in the brines are shifted in a way that is consistent with this microbial process," said Anbar, who holds joint appointments in the School of Earth and Space Exploration and the Department of Chemistry and Biochemistry in the College of Liberal Arts and Sciences.
Even the earliest explorers noted the massive red stain at the snout of the glacier and speculated as to what may have caused it. Some guessed that red alga was responsible for the bright color. "In fact, the red color is a result of all that Fe(II) produced by bacteria," said Anbar. "When the Fe(II)-rich water reaches the surface, the Fe(II) reacts with oxygen in the air to make Fe(III) compounds that are sort of like rust. That's the source of the red color."
The microbes are remarkably similar in nature to species found in marine environments, leading to the conclusion that the populations under the glacier are the remnants of a larger population of microbes that once occupied a fjord or sea that received sunlight. Many of these marine lineages likely declined, while others adapted to the changing conditions when the Taylor Glacier advanced, sealing off the system under a thick ice cap.
In the paper, however, Mikucki and her colleagues argue that the creatures that survive under the Taylor Glacier are both far more exotic and far more adaptable than the early explorers thought.
Because the outflow from the glacier follows no clear pattern, it took a number of years to obtain the samples needed to conduct an analysis. Finally Mikucki obtained a sample of an extremely salty and clear liquid for analysis.
"When I started running the chemical analysis on it, there was no oxygen," she said. "That was when this got really interesting; it was a real 'eureka' moment."
|Contact: Nikki Staab|
Arizona State University