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Bacteria Survive Below Antarctica's 'Blood Falls'
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Bacteria Survive Below Antarctica's 'Blood Falls'

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Bacteria Survive Below Antarctica's 'Blood Falls'
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IRA FLATOW, host:

You're listening to SCIENCE FRIDAY from NPR News. I'm Ira Flatow. A bit later we'll be talking about a new play called "End Days." But first, a trip to the bottom of the earth. In Antarctica's Dry Valley, seeping out from the Taylor Glacier is a spot called Blood Falls. And I was fortunate enough to visit that glacier, oh, a while back, a few decades ago and did notice the strange red color that's running through the ice. And I was told back then that the red comes from algae living in the ice, but new research says something else.

This research says that the falls get their color from the iron-rich deposits that seep up from the salty darks of glacier pools far below the thick ice. And aside from giving the fall that blood red color, the iron is an energy source for an unusual community of bacteria. And they are able to survive in the cold dark climate right below, way down below the ice in Antarctica.

And joining me now to talk more about it is my guest, Jill Mikucki. She is a research associate in the Department of Earth Sciences at Dartmouth. She's also a visiting fellow at the Dickey Center for International Understanding and its Institute of Arctic Studies there. She joins us from Hanover, New Hampshire. Thanks for being with us today, Dr. Mikucki.

Dr. JILL MIKUCKI (Department of Earth Sciences, Dartmouth College): Thank you so much for having me, Ira.

FLATOW: You're welcome. Set the scene for us. Where in Antarctica are we?

Dr. MIKUCKI: Well, we're in the McMurdo Dry Valleys. I didn't know that you had done that. That's fabulous.

FLATOW: Way before you were born.

(Soundbite of laughter)

Dr. MIKUCKI: It's part of the two percent of the Antarctic continent that's actually ice-free. So it might not be exactly what you expect. You have these narrow-walled valleys, it's really brown, you have these large alpine glaciers coming into the valley. And then you have bright blue sky. Because when we were down there, it's summertime and so you have sunlight 24 hours. So Blood Falls really sticks out as this really visceral feature in the landscape.

FLATOW: Who named it Blood Falls?

Dr. MIKUCKI: I have not been able to track that down, and I've tried. It must have been one of the Navy pilots.

FLATOW: But it's been known for a 100 years almost.

Dr. MIKUCKI: Well, yeah. It was first discovered when Robert Falcon Scott's voyages to the Dry Valleys during the Heroic Age took place. And they took pictures of it and thought that the color was due to algae, but they never went up and actually sampled it.

FLATOW: And so how do you know that the color comes from iron? What's the iron connection here?

Dr. MIKUCKI: Well, researchers were always curious about this feature. So throughout the '50s, '60s, 70s, and '80s and into the '90s people have collected grab samples from the falls and looked at the chemistry of this outflow and saw that it was, in fact, iron oxides.

FLATOW: And where did the iron come from?

Dr. MIKUCKI: Well, it wasn't exactly sure where it came from, but it was presumed that it came from underneath the glacier. And if you look up the glacier walls there is iron-rich marble up on the side valleys that goes underneath the glacier.

FLATOW: And tell us about this collection, this conglomeration of bacteria that lived there.

Dr. MIKUCKI: So I was curious when I saw this iron as to whether or not there was life associated with it. It seemed to make sense to me. Whenever there seems to be some juicy energy, microbes will find a way to take advantage of it.

FLATOW: Especially colorful stuff. In Antarctica there is no color until something's living in it.

Dr. MIKUCKI: Absolutely. Right?

FLATOW: Yeah.

Dr. MIKUCKI: So, yeah, so we started collecting samples, and we detected viable cells. We looked at them under the microscope and there were cells there. So of course the next question was whether or not they were alive. So I tried to grow some of them on Petri dishes, was able to do that. So naturally the next question is, like, okay, what are they doing and how are they living?

FLATOW: Yeah. Did you discover where they came from?

Dr. MIKUCKI: Yes. So the next step then was also look at their genetic material and see, you know, who are they related to? What is their history? Can I build a family tree for these microbes? And so we did this by looking at a particular gene called the 16S rRNA gene - that acts as like a fingerprint or a dog tag for microorganisms. And we found that they were largely related to organisms that come from marine systems.

FLATOW: How do you get marine systems in the ice?

Dr. MIKUCKI: That's a good question. As you, you know, you know from being in the Taylor valley, it seems to contain its legacy of some of the climatic changes that that region has gone through.

FLATOW: Right.

Dr. MIKUCKI: Which is why it's so interesting to study this place. And during the past, during the pyacine(ph), when conditions were warmer and different, there was marine water. And the Dry Valleys - and instead of the desert landscape you see now - it was fjord lands. And so marine waters existed that far up valley. As conditions changed and the geology of the region changed, some marine waters became trapped and exposed at the surface until the Taylor Glacier advanced over them.

FLATOW: So you have this glacier sitting on top of a pool of marine water.

Dr. MIKUCKI: Mm-hmm. Well, the marine water has changed somewhat, but yes, that's where it came from.

FLATOW: And that's where the bacteria are living?

Dr. MIKUCKI: Yeah.

FLATOW: And so they are locked in the dark cold spot under the glacier?

Dr. MIKUCKI: Yes. So you can imagine it's very different from what they first experienced when they were in a marine setting, or the fjord or even when they were exposed at the surface. You know, now they're cut off from sunlight by 400 meters of glacial ice.

FLATOW: You know, this sounds very much like the moon Europa of Jupiter out there.

Dr. MIKUCKI: Or, yeah, or the ice caps of Mars even.

FLATOW: Yeah. So it's locked beneath some ice that the sunlight doesn't get to it, maybe there's living stuff under there.

Dr. MIKUCKI: Perhaps, yeah. And I think that, I mean, the Dry Valleys have always been a curiosity for people interested in understanding how life might exist on Mars, for example, because it's the closest in climate and temperature regime to Mars. This is our closest earthly analogue that we have.

FLATOW: So that's another good reason to study this stuff.

Dr. MIKUCKI: Yes, it's another good reason.

FLATOW: How diverse is the life forms that are in there?

Dr. MIKUCKI: Well, again, I haven't done an exhaustive measurement yet. But from initial characterizations it looks like there's about 17 unique types of organisms. And that estimate is probably low and that there's probably more like 30. So it's not as much diversity as you might find, for example, in a handful of soil, but surely it's more so than you might find in an acid mine drainage.

FLATOW: So there's really nothing bigger than bacteria living in - there are no fish around there…

Dr. MIKUCKI: Well, no. There's really just not enough energy to go around for some of the larger organisms.

FLATOW: And is the pool getting smaller? Is it changing in size as the ice moves?

Dr. MIKUCKI: That's a really good question. And that could be what's happening. But we really don't understand the hydrology of this system. And we haven't fully constrained or mapped this reservoir.

FLATOW: Tell us how you study it when you go down there. What do you do?

Dr. MIKUCKI: Well, I'm fortunate enough to go down as part of the United States Antarctic Program with the National Science Foundation. And so, I fly out there by helicopter, and we set up camp, and then I go - I usually take about a half hour ATV ride from our base camp in the field - and I monitor the falls. I look at changes in the chemistry of the surface. And I try to capture outflow depending on what's coming out of the glacier.

FLATOW: Do you drill down ever, right into the pool of water?

Dr. MIKUCKI: That would be great. That would probably be the next step. Again, you know, there's a lot of interest in understanding sub-glacial environments. They're one of the last unexplored frontiers on our planet. It's due to their difficulty in accessing them. But we have not been able to drill through this glacier yet. We're holding out for some, you know, advances where we can actually collect the sample aseptically or cleanly without contaminating it.

FLATOW: So you don't have the technology yet to take a sample out of it.

Dr. MIKUCKI: Well, it is being developed. So I think, you know, we want to, yeah.

FLATOW: You can't just lower a jar through a hole down there.

(Soundbite of laughter)

Dr. MIKUCKI: No, because then I'd introduce oxygen and everything else in there. I can hold a jar up, though, to the snout of the glacier and collect some samples that way. And that's pretty much how I've been doing it.

FLATOW: And that's it. That's good enough, I think.

Dr. MIKUCKI: Yeah. And it's really interesting when the brine first comes out when you collect it at the surface, it's clear and thick. And you can see, you know, see right through its clear liquid. And it isn't until it gets out to the surface that it actually becomes rapidly oxidized, and precipitates out all these iron oxides and actually stains the snout of the glacier.

FLATOW: Wow. You sound like another scientist with a really cool job.

(Soundbite of laughter)

Dr. MIKUCKI: Yes, I do love my job. And I also like recruiting new students, new polar scientists, so…

FLATOW: All right, well thank you for taking time to be with us today, and good luck to you.

Dr. MIKUCKI: Ira, thank you so much.

FLATOW: Have a good trip back to the ice.

Dr. MIKUCKI: Absolutely.

FLATOW: Jill Mikucki is a research associate in the Department of Earth sciences at Dartmouth College, talking about her trip to the Dry Valley.

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