Back at F6

We finally made it back to one of the penguin rookeries that we needed to visit. After two days of trying to get to Cape Crozier but being stopped by bad weather, we decided to try for Cape Bird instead. Ross and I made it there on Wednesday. Finally, we were able to get some more of our sampling done! We did the same time of sampling at Cape Bird as we did at Cape Royds. It is interesting to do this at different rookeries because each of the three rookeries we want to visit have different sizes of penguin colonies living there. Cape Royds has several thousand breeding pairs of penguins, and Cape Bird has about 25,000. Cape Crozier has over 100,000! That means that "high activity" will be different at each of the rookeries, and we'll be able to learn more about the influence of different levels of penguin activity than we would at just one site.

There was one very curious penguin at one of our sampling spots. It wanted to inspect everything we were doing. At one point it even pecked at the shovel I was using! Here it is approaching Ross to see what he's doing with that sample bag:

I learned something very interesting about Adelie penguins while I was there! They have spiny tongues! Penguins eat krill, which are small shrimp-like animals that live in the ocean. The spines on the Adelie's tongue helps them hold onto and swallow the little krill. Here's a photo of an Adelie tongue that I found online:

[photo credit: www.penguinscience.com]

So that's what I did yesterday. Today I am back at F6 for the next few days to finish up some projects in the Fryxell Basin. Let's hope the weather stays as beautiful as it is today!

There's more than just penguins here!

When people think of animals that live in Antarctica, they almost always think of penguins, seals, and whales. And, while those animals do live down here, they don't live on most of the continent. They only live in or near the water, and not on the actual continent (except for penguin rookeries, like I've shown you). But, there are animals that do live on the actual continent! You just can't see them, because they're microscopic. Most of our studies focus on how these animals respond to changes in environmental conditions and influence biogeochemical cycling. So, it's important for me to tell you more about them! 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!

Rotifers

https://en.wikipedia.org/wiki/Rotifer

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.

In addition to invertebrates like these guys, we also study microbes: the bacteria and fungi. These are more abundant in the soils than the invertebrates and have a larger role in the cycles we study. We look at the bacteria and fungi through our lab work and measuring CO2 flux. But, they aren't as cute to look at in a blog posting!

Waiting for a Helo... AGAIN!

We've been trying for the past two days to get to Cape Crozier, one of the other penguin rookeries we want to sample. But, bad weather strikes again! We haven't been able to make it. So, we've been spending our time processing samples in the lab.

It's very busy in the lab when we're all working. A lot of different things are happening at once. In this video, Uffe is in the laminar flow hood (in the back) weighing soil samples to be extracted for invertebrates, which he puts on the sink for Diana to process. She uses tap water to rinse the soil through a sieve and capture the invertebrates in a very small-mesh sieve. Zach is on the other side of the lab centrifuging samples, and every now and then he pops into view to bring Uffe a new sample. Once Uffe has poured soil into a beaker for invertebrate extraction, he then pours part of the sample into a sieve for me. I sieve the sample to remove all of the rocks, then pour the soil into a bag for storage. We'll take that bag of soil back to Dartmouth to measure chemistry. The rocks go into the waste bucket, and I wipe the sieve for the next sample. Meanwhile, Julia is measuring soil samples into tin cans for soil moisture. She keeps going to the fridge to get a new sample, weigh out 20 g, record the weight, then bring it back to the fridge. Jenn is just off-camera measuring pH and EC on her soil samples.


Hopefully we'll be able to make it to a rookery tomorrow!

Dr. Becky Meets her Hero in Antarctica

We've had a very special guest in town at McMurdo for the past week or two. Sir David Attenborough is down filming for his new nature series called Frozen Planet. This is the man who has narrated so many great nature series for the BBC. I grew up with The Trials of Life. You might know him from Planet Earth. You might not recognize his name or his face, but you know his voice, especially if you're my age. I have been SO EXCITED that he's here, because he is one of the inspirations behind me becoming a biologist. My sister and I have watched The Trials of Life over and over again since we were kids. Sir David's films make the many amazing aspects of our natural world so accessible and exciting to kids (and adults!), and he's been a major inspiration for most biologists my age.

So, I can't even tell you how excited I was when I actually got to meet Sir David last night!! I was able to tell him how big of an influence he has been and about what kind of research I do here in the dry valleys. Here's me with my hero:I also asked Sir David what he thought was the most amazing thing he's seen in Antarctica. His answer: the Trans-Antarctic Mountains. That's the mountain range that runs through the continent dividing it into an East and West half. It's one of the longest mountain chains in the world! Mountain ranges like the Trans-Antarctics are created through a process called "uplift", where two plates are pushed together, and the force of them being pushed together causes the contact point between the two plates to rise up. The presence of the mountains is what prevents the ice sheet from flowing in the valleys, creating the dry valleys where I work. Sir David thinks they're amazing because not only are they beautiful and created through such an amazing feat of nature, but because of the huge challenge they've posed for humans for over a century. When the early explorers were seeking the South Pole, they started from the Ross Sea (where I am) and had to attempt to cross through the Trans-Antarctic Mountains. Crossing these mountains posed a huge danger and required a large amount of hard work under grueling conditions for the early explorers, and frequently groups were stopped by the presence of the mountains. It's just one way that nature is more powerful than man!

So, last night was a very special moment for me. When I was a kid watching the Trials of Life on video, I never would've thought that many years later I'd meet Sir David Attenborough all the way in Antarctica!

Penguins Aren't Just Cute: They Influence Soil!

Yesterday, all four of us went to Cape Royds where there is an Adelie penguin rookery.

Adelie (pronounced uh-dell-ee) penguins are one of two species of penguin that are found in this area. (The other species is the Emperor penguin.) Adelies are fairly small penguins. You could easily fit one in your school backpack. They are easy to identify by the white ring around their eye. Adelies mate and nest in rookeries like this one on the rocky capes of Ross Island, which is made out of volcanic basalt. Adelies make their nests on the ground by creating a hollowed-out bowl and carrying lots of small rocks into it. Right now, the Adelies still have some chicks that they're taking care of. You can see one huddled underneath its parent in a nest in this photo, just to the right of center. Adelies nest on land, but they spend the rest of their time out on the sea ice, because they eat krill in the ocean. So, the open ocean isn't very far from this rookery. I'm standing very close to the edge of the cliff to take this picture, and the ocean wraps all the way around the peninsula. You can see it on the horizon at the other end of the rookery. Because they eat from the ocean, their guano smells very fishy. It is a smelly place to be!

We are interested in the soil at penguin rookeries because penguin guano is very high in nitrogen and phosphorus. Nitrogen and phosphorus are two key elements that we focus on in the dry valleys with many of our experiments (like the stoichiometry experiment where we add the solutions containing N and P). The soils at penguin rookeries are naturally very high in N and P because of all the penguin poo, which makes it a nice comparison to have for our experiment. I am interested in knowing how soil organisms and nutrient cycling respond to such high levels of N and P in Antarctica, so penguin rookeries are the place to find out!

We sampled soils from four different types of locations at the Cape Royds rookery. We sampled from soils in a nesting area (the areas that are really orangey pink from all of the penguin guano), areas outside nesting grounds but still highly trafficked by penguins (the gray areas in the photo), areas with very low penguin activity (just the occasional passer-through), and areas not trafficked by penguins at all. We took soil samples from these different locations, and we'll measure their chemistry and microbial community. The soil here is really hard and compacted from all of the penguin foot traffic. In this video, you can see how hard Ross has to dig to get a soil sample. Jenn was helping take samples by opening bags for Ross, and Julia was in charge of labeling. Meanwhile, I was documenting every sample location with my camera and by drawing maps, so that we would know exactly where every sample came from.


In addition to taking soil samples to measure chemistry, I also measured CO2 flux to estimate the amount of respiration coming from the soil organisms. Because there's so much more nitrogen and phosphorus, the respiration rates were about ten times higher here than they are in the dry valleys!I also took a lot of extra soil from these areas so that I can set up a miniature stoichiometry experiment in the laboratory and do similar fertilizations as the ones we're doing in the field. So now our lab refrigerator is full of stinky penguin soils that will be shipped back to Dartmouth!
I hope to visit two other penguin rookeries that are on Ross Island: Cape Bird and Cape Crozier. You can see on this map where they are in respect to McMurdo and Cape Royds. (The dry valleys are on the mainland about 70 miles to the west.) Hopefully I will be able to tell you more about other penguin rookeries in the coming weeks!

Measuring Biotic Activity

Today, Julia and I went to the Lake Bonney basin to take some measurements on the stoichiometry plots. This is the experiment I posted about a couple days ago, where we add carbon, nitrogen, and phosphorus to the soil to see how it influences soil organisms and nutrient cycling. We do this experiment at two locations: Lake Fryxell basin (where I posted from before) and Lake Bonney basin (where we were today). We use these two sites because they naturally have very different nutrient conditions. Bonney has a lot more nitrogen, and Fryxell has a lot more phosphorus. That means that the two sites might respond differently to the nutrient additions, which would be very interesting!

One of the ways we measure the response of the biota is by measuring carbon dioxide flux. When most soil organisms respire, they produce carbon dioxide (abbreviated CO2). Humans do this when we breath, too. We breath in oxygen and breath out CO2. Soil organisms, from bacteria to nematodes, also respire to produce CO2. By measuring the amount of CO2 coming out of the soil, we are measuring how much the soil organisms are respiring. We hope to see an increase in respiration when we add nutrients (specifically, more respiration when we add C and P to Bonney and when we add C and N to Fryxell).

After adding the nutrient treatments to the plots like we did a few days ago, we go back and measure CO2 flux. We do this using a machine called an Infrared Gas Analyzer (abbreviated IRGA. It is made by a company called LI-COR, so we usually call the machine the LICOR). Here's Julia learning to use the LICOR: This is a fancy, expensive machine (about $25,000 for the whole set-up) that nests over the soil and sucks air from the space just above the soil. That air is sent through the tubing to the yellow box, which contains the IRGA. The IRGA measures how much CO2 is in the air space above the soil and how much the concentration of CO2 changes over one minute. If the soil organisms are respiring, we will see an increase in CO2 in that air space at a certain rate, called the "CO2 flux". We hope to see a bigger flux rate when we add nutrients.

We finally had a day of nice weather in the field, so we were not delayed for once! We are back in the lab now at McMurdo processing more of our soil samples from these stoichiometry plots. We head back to the field on Thursday, hopefully to visit a penguin rookery!

Snowfall in the Dry Valleys

I've spent the past five days in the dry valleys. As you've heard, we were weather-delayed getting out there. Then weather delayed my team from meeting me there. Then, my team got stuck there with me and couldn't get back to McMurdo. There was a lot of snow!

That snow doesn't stick around long. We don't have to wait for warm temperatures to melt the snow in order to see it disappear. In the dry valleys, the air is so dry that the snow will sublimate: turn directly from solid (snow) to gas (water vapor) and disappear from our view. On Thursday morning, there was a little over an inch of snow on the ground, but it all disappeared that day even though the air temperature never got above freezing.

These are all photos of roughly the same scene behind our hut at F6, looking north at the Kukri Hills. Here it is at 9:00 in the morning with an inch of snow, while it was still snowing a little bit. You can't even see the mountains because the clouds are so low:

And at noon:

And at 2:30 in the afternoon:

And at 6:00 pm:

And 7:30 pm:

And by midnight, it was gone:

Similarly, another group here has a camera set up in a different valley, called Wright Valley, and are taking time-lapse photos of one particular area. You can see snow come and go over the course of hours! Click here to see it on YouTube.

We think that most of the snow turns into water vapor, but some of it does melt. That extra moisture in the soil will be really important for the organisms living in the soil that are usually water-deprived. To find out how much moisture was getting added, we decided to take soil samples under the snow as it was ablating. Every few hours, we scraped away the snow and took soil samples from the surface (0-2 cm into the ground) and just below the surface (2-5 cm into the ground). We'll measure the soil moisture of those soil samples to see how much water melts into the ground from the snow and whether it ever trickles down to lower depths in the soil.

Now that we're finally all back in the lab at McMurdo (but barely, we almost got stuck at Marble Point, the helicopter fueling station, for the night!), I spent the day weighing out samples for soil moisture. Tomorrow, I will know how much the moisture was influenced by the snow, and how quickly it disappeared!

Tomorrow, I'm heading to the field with Julia, Zach, and Bishwo to sample and treat the stoichiometry plots that are at Lake Bonney. It is supposed to be a day trip, though, so there shouldn't be any getting stuck.