The Fearsome Nematodes of the Dry Valley
Scientists look across the Mc Murdo Dry Valleys. (Peter Rejcek)
One of the driest places on Earth lies at the bottom of the world, the McMurdo Dry Valleys in Antarctica. A tiny worm is at the top predator in this desert, and scientists are subtly adjusting water and food levels to learn how food chains adapt to changing conditions. IEEE Spectrum's Glen Zorpette reports.
GELLERMAN: The McMurdo Dry Valleys are more like Mars than any place on Earth - and you have to go to the ends of the Earth to reach them. That's what Glen Zorpette did for IEEE Spectrum. Here's his report from the series: 'Antarctica: Life on the Ice.'
ZORPETTE: The Dry Valleys are among the most arid places on Earth. There's very little snow, and not a lot of ice except for some scattered glaciers. And yet inside the Taylor Valley where I was standing'
[SOUND OF WATER TRICKLING]
LEVY: And when I came down into Taylor for the first time and heard that water trickling, it almost brought a tear to my eye.
ZORPETTE: Joseph Levy is a postdoctoral fellow with Portland State University and the McMurdo Long Term Ecological Research group, also known as the LTER.
LEVY: After two months of not hearing any liquid water except for what we have in the pot, and this is just - I love it.
ZORPETTE: Levy knew exactly where that noise of trickling water was coming from.
LEVY: That's the sound of some old ice. That's water deposited 4000 years ago.
[SOUND OF WATER TRICKLING]
ZORPETTE: Up in the accumulation zone of one of the glaciers, apparently.
LEVY: And right now, when the sun shines during the peak summer, it melts, flows down over the frozen ground surface and out into the lakes. So that's why I'm really interested: the ground - it's this big unexplored source for water, for chemistry, for all the things that the LTER is interested in.
ZORPETTE: These little trickles of water sluicing their way through the Dry Valleys can mean the difference between dormancy and animation to some rather well-adapted creatures.
LEVY: The dominant predator here in the Dry Valleys is the fearsome nematode. It's a microscopic worm that eats both algae and also other microbes.
ZORPETTE: Are there nematodes unique to this area? Are there specific adaptations that you've seen with them?
LEVY: The nematodes - most of them are endemic, so they're from here and unique to here. They adapt to the subfreezing temperatures in the winter by drying themselves out, and as soon as the first trickle of water comes from either melting snow in the spring or a trickle of water off a glacier, or in my interest, the melting of permafrost and the wicking up of water, they snap into activity and start eating, respirating, multiplying, and living their lives in the summer.
ZORPETTE: Nematodes belong to a simple food web to which Levy and his team are making small experimental tweaks. They add some extra water here, some extra food there, and observe how food webs respond to a changing environment.
LEVY: And given that we're part of a larger food web, even just understanding how the nematodes adapt is telling us a little bit about how we adapt as a species.
ZORPETTE: Very few critters other than nematodes can live in the Dry Valleys. Take seals, for example. Rae Spain is a Raytheon employee who assists the scientists.
SPAIN: We have a lot of mummified seals up and down the valley. We're not really sure why they come up here. For some reason, they tend to go further and further up valley, which you're gaining altitude, and you're going over big lumpy rocks. It can't be easy travel, because they travel much better in water. And then they die, of course, because they're not going back to sea.
ZORPETTE: The seals will wander as far as ten or twelve miles away from the sea, hauling their blubbery bodies over rugged mountains and hills.
SPAIN: Long way for a seal. With little tiny flippers for feet. And then they don't - there's no bacteria here to break them down. So they just desiccate. They just dry out and then become a bag of bones with beef jerky around them.
ZORPETTE: Goes to show just how hostile the Dry Valleys can be. Still, Joseph Levy finds the Antarctic, and the Dry Valleys in particular, an endlessly rewarding habitat to explore.
LEVY: On those few occasions when the wind dies, and you're ten or fifteen miles from camp, you're the only soul in the valley, and it's absolutely breathtaking. The opportunity, though, to really study this place - to understand it, to get an appreciation not just of its surface beauty but how it's functioning and how it's changing with time - is really the great opportunity. It is a life-changing experience, and it's a very addictive place to do work. There's a lot of data here, and a lot of information, and it's critical because - as you can hear - it's melting out every day.
[SOUND OF WATER TRICKLING]
ZORPETTE: For Living on Earth, I'm Glenn Zorpette in the Taylor Valley in Antarctica.
GELLERMAN: Glenn's story comes to us from the IEEE Spectrum documentary 'Antarctica: Life on the Ice.'
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