Glacier “bleeds” proof of million-year-old life-forms
16 Apr 2009
Gushing from a glacier, rust-stained Blood Falls contains evidence that microbes have survived in prehistoric seawater deep under ice for perhaps millions of years, a new study says.
The colony of microscopic life-forms may have been trapped when Antarctica‘s then advancing Taylor Glacier reached into the ocean 1.5 to 4 million years ago.
What’s more, the tiny organisms’ feeding habits apparently give the falls their shocking color.
Blood Falls, Scientists Jump
For decades researchers have been intrigued by Blood Falls, which incongruously spills from one of the driest parts of Antarctica, the aptly named Dry Valleys.
“The Dry Valleys are all brown,” said study leader Jill Mikucki of Dartmouth College.
“You might see some white ice and blue skies—and then here’s this bright red waterfall. It invokes a lot of curiosity.”
Survival Strategy for “Snowball Earth”?
Mikucki and colleagues captured and analyzed a bit of the extremely salty, iron-rich liquid—which seems to be concentrated seawater—fresh from Taylor Glacier. In the samples were tell-tale proteins apparently from microbes.
Since their capture millennia ago, the microbes seem to have been completely isolated. Under 1,300 feet (400 meters) of ice, they catch no sunlight, required for photosynthesis, and have no source of outside food.
The only thing keeping the microbes alive, the study says, is their ability to generate energy from chemical reactions with sulfur and iron.
Iron is one thing in abundance beneath Taylor Glacier. Ground out of rocks by the creeping glacier and further broken down by the microbes, the mineral gives Blood Falls its surprising hue. (Related: “Rust-Breathing Bacteria: Miracle Microbes?”)
The water also carries the specific fingerprint of the sulfur-rich compound sulfate—a carryover from when the water was part of the ocean—the study found.
“This same creativeness in getting energy might be found elsewhere,” and might have been helpful during difficult times, such as an ancient period known as snowball Earth, Mikucki said.
During this phase, around 700 million years ago, the whole planet seems to have been periodically covered with a thick layer of ice, and the oceans were likely rich in iron.
Findings to be published in tomorrow’s edition of the journal Science.