Dry Valley Wildlife

Most people think of Antarctica as being a big, cold, dead place. When you see photos of our research in the dry valleys, you don't see animals. But, there are animals there, in every single one of those pictures! You just can't see them, because they're microscopic. Here's some information about the main types of micro-organisms that live in Antarctic soils.

Nematodes
Also called roundworms, nematodes live EVERYWHERE in the world. You can find them in every biome in the world. They live in water, soil, ice, even in other animals! They are the most abundant animal in the world. In the dry valleys, we find more nematodes than any other animal. They are what our collaborators at Colorado State focus on studying. We have three main species that live here. The most numerous species, Scottnema lindsayae, is in the photo to the left.

Nematodes eat a lot of different things. Some, like the guy at the left, eat bacteria. Others eat fungi or algae, and some are even predators that eat other microscopic soil organisms. In the dry valleys, a predatory nematode is the top of the food chain! Though nematodes are small, they have a lot of very well-defined characteristics. Here is a very close-up picture of the mouth-parts of a bacterial-feeding nematode. They use those long branches on their mouths to scrape bacteria off of soil surfaces.

Rotifers
Rotifers also live in a lot of different environments, including fresh water, saltwater, soils, and other watery environments. A rotifer eats by waving the hairs around its mouth (at the top, in this picture) to catch things floating in the water. The moving action around their mouth looks kind of like a wheel, which is how they got the name ROTifer (like rotate). The "foot" (at the bottom of the picture) is to anchor the rotifer when it doesn't want to move.

Tardigrades
Tardigrades are also called water bears, and looking at the picture I think you can see why! They even have claws at the end of their feet, which you can see in this very close-up microscrope picture that Uffe took of a tardigrade foot. The claws let them hold on to something as they float through water or the water-filled spaces in the soil. Tardigrades eat with a stylet that they use to pierce animal and plant cell walls.

Tardigrades are able to live in a lot of extreme environments, and are found everwhere from the Himalayas to the ocean floor to Antarctica. They can withstand the pressure of a vaccuum, radiation, dehydration, and both incredibly high and low temperatures. There are even experiments that test tardigrades' ability to live in open space! In the dry valleys, they especially like to live in the moss and algae patches, where food and water are readily available.

The soil environment in the dry valleys is a very hard place to be an animal. There's not a lot of water, not a lot to eat, and it is very cold! Most of these micro-organisms have a special ability to help survive in such a harsh environment. They can go into anhydrobiosis, which essentially means they can freeze-dry themselves. They can push out all of their water and curl up, so that they don't freeze and die. Their metabolism drops to almost a stand-still! They can stay in anhydrobiosis for a very long time, and immediately wake up if water becomes available.

Part of our research looks at what animals are living in the soil. We want to know why they live in some places in the dry valleys, but not others. We want to know how nutrient cycles in the soil change when animals are there or not. So, we spend a lot of time on the microscopes looking at the animals we can extract from the soil. One of our team members, Byron, made this awesome video through the 'scope featuring three of our soil superstars: nematodes, rotifers, and tardigrades.



[Photos of each are from the linked websites: S. lindsayae, rotifer, tardigrade. Video by Byron Adams. Tardigrade foot photo taken by Uffe Nielsen.]

Tracer Experiment

Well, we finally made it out to the field. The weather at McMurdo has been very patchy. There's been snow and a lot of clouds. But, the weather out in the Dry Valleys has been very nice. So, once they finally had a short window of time to get us out, we left McMurdo and have been staying in the Valleys ever since in some beautiful, sunny weather. Katie and Elizabeth made it out to Lake Fryxell on Wednesday afternoon. Ross and I made it out to Lake Bonney on Thursday afternoon.

At Lake Bonney, Ross and I were working on an experiment that traced the movement of water from melting permafrost flowing over the soil. Permafrost is soil and rock in the ground that stays permanently frozen year-round. It usually is found below the soil surface in cold places like Antarctica and the Arctic. During the summer in the dry valleys, the permafrost will melt a little bit, causing wet patches to appear in the soil. You can see those darker, wet patches of soil in this picture at Bonney:Because it's been so warm this year, the permafrost below the soil has been melting a lot more than usual. At one of our research sites at Bonney, that meltwater has reach the surface (kind of like a spring you might find in the mountains in the US). There's so much meltwater that it ended up forming a stream that flows all the way down to the lake, straight through some long-term sampling plots we set up years ago! (Our team nickname in McMurdo is the Wormherders. Because the stream flows through one of our plots, it is called Wormherder Creek.) Instead of being upset that our plots are ruined, we're using the opportunity to learn about sources of water in the dry valleys and how they influence the soil.

On Thursday, we soil ecologists teamed up with a group of stream ecologists to study how the new Wormherder Creek interacts with the soil to influence soil chemistry and organisms. We added chemicals containing lithium and bromide high up on Wormherder Creek, and we followed how those chemicals moved down the stream and through the soil. There were two people at the top of the creek at the chemical injection site running the pump. Then, there were scientists stationed at regular intervals down the stream collecting samples every 5 or 10 minutes. I was stationed higher up on the creek with Uffe. In this video, you see Uffe labeling the bottle to take the next sample. That bottle gets dipped into the stream flow to be filled with water. You can see another scientist, Anna, further down the stream at the next station. You can also see how fast that meltwater is moving! It's a small creek, but there's a good bit of water in it! The tube next to the orange flag is called a piezometer, which is how we extract ground water from below the surface.

We collected a lot of surface water, ground water, and soil samples for several hours through the night. We will look for the presence and concentration of the chemicals we released high up in the stream so that we can follow how the water moved down to the lake. We will also measure the chemistry of the water and soil, and look at what kinds of organisms we find in various locations, to see how those important properties are influenced by the presence of Wormherder Creek. It was a loooong night, but we finished it!

After we left Lake Bonney late Thursday night, Ross headed to Fryxell to be with Katie and Elizabeth. I have been back at F6 (across the lake from the rest of the group) working on the stoichiometry plots that we treated last week. Hopefully I will be heading back to Lake Bonney tomorrow, but the weather does not look good in McMurdo, so the helicopters may not be able to come get me! Keep your fingers crossed, because I have samples to get back to the lab!

My bags are packed, I'm ready to go....

Because the Dry Valleys are so remote, we fly on helicopters to get there. Today we were supposed to fly to Lake Fryxell and Lake Bonney. But the weather is very bad for flying right now so we can't go anywhere. Helicopters only fly when the sky is clear and the wind is not blowing too hard. The helicopters here at McMurdo have lots of jobs to do, such as taking people to different places, delivering packages to field camps, and moving large pieces of equipment. Even though the helicopters have many jobs to do, safety is more important than everything else. So if the weather is bad enough, they all stay on the ground. Usually from the helicopter pad you can look out at the Ross Sea and also see the mainland on the other side. As this picture shows, you can't see much of anything this morning.

Last night we got a few inches of snow in McMurdo, even though it's the middle of summer!

We come down to Antarctic with plans to do lots and lots of scientific research, the weather is unpredictable. Sometimes we simply can't get out to our field locations and must wait for the weather to clear. So that's what we're doing today... waiting for better weather!

In and Back Out Again

Our final team member, Ross, arrived Saturday night. So, we are now a complete group of 4 from Dartmouth! Together, we've spent the past couple of days in McMurdo in our lab processing our samples.

Katie is working on a procedure called Chloroform Fumigation Extraction. For that, she is measuring the amount of carbon in the soil that is released after adding chloroform. Chloroform is a chemical that breaks open cells of living organisms (including people). So, if the carbon is released by the chloroform, it was released by the microbes living in the soil. Measuring the amount of carbon released by chloroform gives us an estimate of the microbial biomass living in the soil we are studying. Of course, Katie has to be careful not to breathe the chloroform herself. (Don't worry: when this picture was taken, she was already finished with the chloroform step!)
Elizabeth is busy picking all of the rocks out of her soil samples. The soils she is studying are very rocky, and the pebbles have to be removed before she can measure their chemistry. Doesn't that look like fun?!

We will be heading out to the field again tomorrow. We will be splitting up into two groups so that we can get more work done. Katie and Elizabeth will be going back to Lake Fryxell where we went the first week of our field work. Ross and I will be moving around all over the valley for the rest of the week. We'll be busy!

~~~~~~~~~~~~On another note~~~~~~~~~~~~~
Check out the awesome card I got in the mail yesterday, drawn by my friend Bob! Cedar waxwings like these live in the trees outside my office back at Dartmouth, so I put the card over my desk here in McMurdo to remind me of home.

Now where was that?

The plants and animals that live in the Dry Valleys are very small. Because they are so small, they are often difficult to locate, and even more difficult to find a second time.

This picture shows how closely you have to look to find the mosses that we study.

There are also no road signs pointing us in the direction of our research sites. We study certain spots in the field during one research season and try to get back to those same locations the next year. This is challenging because there are very few land features that we can use to remember a certain location and some things change from year to year. The streams are fed by melted snow, so they change depending upon how much snow falls during the winter and melts in the summer. This stream might have looked completely different last year, so finding a particular bend in the stream is nearly impossible.

Because of these navigational challenges, we use a GPS to help us find places in the Dry Valleys.
GPS stands for Global Positioning System. It uses satellites orbiting the earth that transmit signals, which enable GPS receivers to determine their current location. A GPS tells you your location in latitude and longitude coordinates. When we want to be able to find a certain spot again, we record the latitude and longitude coordinates so that we can later return to that exact location using the GPS.

Here's a picture of Elizabeth using a GPS to record the coordinates of a study site. If she wants to come back later, all she has to do is tell the GPS to find those coordinates and it will point an arrow in the direction we need to walk to get there. It also tells you distance.

A GPS isn't perfect. Sometimes we have a really hard time finding a spot using the coordinates a GPS gives us. It is often about 10 meters off, which is a lot when your study subject is only 1 centimeter tall. But the GPS is a very useful tool and we are very happy that it's in our scientific toolbox!

Stoichiometry

This morning, Katie and I flew to the Lake Bonney basin for another two days of field work.
While we are here, we will be working on a project that will tell us how the soil and soil organisms respond to nutrients added to the soil.

There are three main elements that are very important for life everywhere: carbon, nitrogen, and phosphorus. These nutrients are important for all organisms to grow and live. If one of these elements is in short supply, organisms cannot continue to grow. So, the amount of nutrients in the soil can be limiting to life. We want to know which of these elements are limiting to life in the dry valleys.

We have set up areas where we add carbon, nitrogen, and phosphorus to the soil. Each year, we add more of the nutrients and measure how the microbes and invertebrates living in the soil respond to the additions. We add the nutrients by dissolving sugar and salt in water, then pouring the water over the plots. Some plots get sugar water (for carbon), some get water with nitrogen or phosphorus salt added, and some get both sugar and salt. In this photo, Breana is adding some nutrient water to one of the plots.

We use the plastic cone to prevent the wind from blowing the water away before it reaches the ground. Or, you can be like Uffe and wear the cones as a hula skirt:
After we add the nutrients, we measure respiration to see how active the microbes are. We also measure the amount of nematodes in the soil and how the soil chemistry changes after the nutrients are added.

We've been working on this project for many years. So far, we have learned that carbon is most limiting to life in the dry valleys. Carbon in the soil mostly comes from photosynthesis by plants. Plants are able to take carbon from the air (as carbon dioxide) and turn it into forms usable by soil organisms. Because Antarctica is so cold and dry, there are not a lot of plants. We only have some mosses and algae that can photosynthesize, and they are only found near sources of water. Because there's not a lot of photosynthesis, there is not a lot of carbon added naturally to the soil. So, carbon is often the limiting nutrient in the dry valley soils, which is why we notice the biggest response in the activity of the organisms when we add carbon.

Nitrogen and phosphorus may also become limiting in the soil, if there is enough carbon for organisms to use. That is why we look at all three of the nutrients. We want to know how increases in all three nutrients might influence soil organisms. Which nutrient is most limiting might not be the same everywhere in the dry valleys, since the different areas have different geology. Hopefully this project will be able to tell us which nutrients are limiting in the different areas.

Katie and I are only at Bonney through tomorrow, then it's back to McMurdo to process our soil samples that we collect here. Hopefully, the final member of our team will arrive tomorrow. Ross's flight should be arriving tomorrow afternoon as we're returning from the field. Let's all hope that the good weather continues!

Happy New Year!

It is 2009 down here at McMurdo!

We returned from the field on New Year's Eve. We quickly unpacked and took care of all of our samples for the evening. Then, we were ready to celebrate the holiday!

The new year starts for us 18 hours earlier than the east coast of the U.S., so we celebrated New Years Day before most of the U.S. woke up to New Years Eve. Here's Breana (one of the postdocs working with us down here from Colorado State) demonstrating how to celebrate New Years, McMurdo style:

A New Year's tradition at McMurdo is a concert called Icestock. Different groups of people working here (that also happen to be musicians) form bands (to varying levels of success) . Most have only been playing together for a few weeks or months. A big stage is set up outside where each of the bands plays short sets for the crowd of dancing Antarcticans on New Years Eve. So that you can fully experience Icestock, here's a short clip of my favorite Icestock band called Sunday Britches:

To help us ring in the New Year, some people made really cool, big puppets out of random things you can find around McMurdo. They were built on backpack frames and paraded through the crowd of people listening to the live music. They were really creative!

That's how we celebrated the coming of 2009 down here in McMurdo. Today, we are back in the lab processing our soil samples from the field and getting ready to head back out tomorrow morning!