Wrapping up the science

Today was our last day of field work. (We are scheduled to leave Escudero on Monday!)

Our main task was to take down an experiment we set up soon after our arrival. One of our questions is how moss influences the soil to provide a habitat for organisms. A main way moss can have that influence is by insulating the soil and protecting it from the harsh temperature fluctuations. Zoie, who was with us last year, wanted to measure that! She sent us with equipment to set up an experiment for her.

We set up an experiment where we ran thin wires that measure temperature (called thermocouples) into different parts of the moss. We had thermocouples at the top of the moss (the canopy), at the point where the moss and soil meet, and then an inch into the soil below the moss. That way we can measure whether the temperature changes differently across that small area of a moss tuft. We also put thermocouples into bare soil to see whether the temperature fluctuates differently under moss compared to without the moss coverage.

Those thermocouples are attached to a device that recorded temperature from each thermocouple every 5 minutes for a week. This is what they looked like when we installed them. If you zoom in, you can see the wires coming out of the box and into the moss.

We left them out for a week, but it has been very cold and and snowing a lot. So this is what the site looked like when we came back this morning:

So the wires going into the moss were now covered with snow!

We dug them out. When Zoie looks at the recorded temperature data, she will have an answer to the question!

Feliz cumpleaños, Angelica

Today is Angelica's birthday! 

Last night, we decorated the dining room so that she would wake up to a festive birthday celebration. In Antarctica, you can't just pop out to the store to buy decorations, so we had to make them from whatever we could find around the station. We made balloons from lab gloves, streamers from labeling tape, paper flowers from Kimwipes, and a birthday banner from absorbent pads! It was a group effort. We had to work hard to keep her from coming in to ruin the surprise!

This morning, we were greeted by a beautiful birthday sunrise over Fildes Bay!

The cooks made a beautiful birthday cake that we all got to enjoy. It's amazing what they can do with the meager ingredients we have down here!

So far, Angelica is having a great birthday. And, we all got to eat cake for breakfast!

Hannah's Best Day of Science, Ever

Yesterday was a banner day for Hannah!

First, she had the TRUE Antarctic field work experience! We were able to go back to Carlini to finish our transect from a few days ago. But... it was snowing the entire time!

First we find the moss, and then we count the species that are living there!

It is difficult to be a soil scientist when there's snow on the ground. We had to search for our plant and soil samples beneath the snow, all while getting snow blown in our faces! It was wet and cold, but we managed to complete all of the work! Success!

Dr. Becky and Hannah sampling under the snow.

After we completed our sampling, the Argentinians at the base were very kind and fed us a warm lunch. They even gave us each a super cool Base Carlini sticker! That was the first super fun extra thing to happen that day. Stickers are very popular in Antarctica, because they are a great, lightweight souvenir to trade with people. I gave Arizona stickers to the people at Carlini who helped us, and we received Carlini stickers!

On the boat ride home, we got to witness something special close-up. A large part of the glacier fell off into the bay. This is referred to as the glacier "calving", and it's how many icebergs are born. This is a regular occurrence in the mid and late summer, because as the temperatures warm during the season, the ice on the edge of the glacier starts to melt and crack. That makes the edges unstable and they start to break off. (The problem, of course, arises when the summers are warmer than they naturally would be, so you get more calving than would naturally happen. That's how we see the overall amount of ice decrease on the continent.) At first, we only saw small bits of ice roll out of the cave in the glacier. Then, suddenly, this happened:

That was very exciting, including the rapid retreat away from the big wave that was coming from the splash! At this point, the weather was better than the snowy morning of work, and we had a scenic journey back to Escudero. And, finally, as we were pulling into the dock at Escudero, who should come visit the boat but a leopard seal!

Leopard seals are one of several species of seal that live here, but they are the only species known to attack humans. They don't particularly want to hunt humans... really it's just that they have mistaken human divers for seals. The wet suit and flippers can make a human look an awful lot like a smaller seal that the leopard seals would normally prey on. They also eat penguins and other marine animals. Because their only predator is the orca, they are not generally afraid of anything on land and will follow boats with curiosity, occasionally sticking their head up above water to see what's going on. This one came right up to the boat to say "hi" to Hannah!

So, a couple of cool sightings, some rugged field work, and a new sticker. A good day! Today we have been busy in the lab processing the samples that we collected yesterday. And it's still snowing!

Revisiting Nelson

Today we went back to Nelson Island, which is "next door" to the island we're currently on.

Base Escudero is on King George Island off of the coast of the Antarctic Peninsula. It is a large island in a chain referred to as the South Shetland Islands. Nelson Island is the smaller one to the south of us. 

You can see in the map of King George Island that it is mostly covered by a large glacier. We are down in the red box. This part of King George Island is called Fildes Peninsula. You can see that there are many research stations on Fildes Peninsula, including Escudero where we are based.  (You can also see the peninsula to the east marked for Jubany Station. That is the old name of Base Carlini, where we were doing our transect in my previous post.) Just across the water at the bottom left corner of the map is Nelson Island, where we were today. It also has a glacier coving much of the island.

Last year, we sampled a successional transect from near the edge of Nelson's glacier towards the northern tip of the peninsula where the ecosystem is more developed. This year, we returned to collect some extra moss samples that will allow us to collect extra data about moss physiology. That way, we can understand how the moss functions as it develops from its young pioneer stages in early succession sites versus when it is more mature and developed during late succession. 

But why do we care so much about moss, specifically? Moss is the most abundant vegetation on the continent of Antarctica. There is a lot of it in the northern part of the Antarctic Peninsula, which has the slightly more hospitable climate and water is more available. In the desert regions of Antarctica, moss is only sparsely growing in some locations. But here in the South Shetland Islands and other nearby areas, we see quite a lot of it! This is the equivalent of our "tree canopy" like you'd see in a forest in the United States or Europe. 

Antarctica doesn't have woody plants. In fact, the only vascular plants are one species of grass and one species of pearlwort. Other than that... it's moss, algae, and lichens! So the reason we are so interested in moss is because of its major role as the main vegetation in Antarctica. The photosynthesis, and therefore CO2 uptake into the ecosystem is largely done by moss. The moss then becomes a food source at the bottom of the food web, and its decomposition recycles the carbon and nutrients that the moss takes up. The moss can help insulate the ground, retain water, and reflect light to protect the organisms that use it as a habitat. It can survive desiccation and wake up as soon as water is available again! It is an amazing plant! We will measure how the various species of moss differ in these physiological properties, how they help develop the soil during succession, and how that influences the organisms that live there. 

Succession gradients

 We've spent the past couple of days working on samples from a new field site. One of our main goals for this project is to measure plant and soil properties along a gradient of ecological succession from a receding glacier. Over the past two years of this project, we have measured transects from two different locations. Yesterday, we collected samples from a third transect.

To get to this new field site, which is a ways across the bay on another peninsula, we ride in boats. The presence of the glacier makes it impossible to walk across land to get to the peninsula, so we have to go by water! It is of course deadly if we fall out of the boat into the freezing Antarctic water, so to be extra safe, we have to wear big puffy suits and a lot of safety gear whenever we ride in boats. These big puffy full-body immersion suits provide both flotation and the ability to keep us alive in 5°C water for 1 hr. With the addition of big boots and water proof gloves, we are ready to go!

We traveled across Fildes Bay to another peninsula where one of the Argentinian bases is located, called Base Carlini. After some warm hospitality from the residents of the station, we hiked up into the moraines to find an early-succession site with only early pioneers of moss coverage. As you can see, it's not highly vegetated. There is moss and lichen on the ground, but it's fairly sparse... and partially covered by snow!

Dr. Angelica and Hannah measuring plant cover with cold hands!

Angelica and Hannah measured the resident plant community coverage while I sampled the moss and soil underneath it to bring back to the lab. It was a very cold day, and much of the moss was actually frozen! 

After spending an hour in our early-succession site, we started walking away from the glacier into a mid-succession site. We make the same measurements there to understand how the plants and soil change as they develop over the years of succession. This is called a "chronosequence": when we use space to represent different amounts of time. In other words, the trajectory of walking from close to the glacier away from it towards the coast is like walking through time from recently-exposed soil into older ecosystems that have been exposed for longer periods of time. Those areas that have been exposed longer have had more time to develop a more complex ecosystem. The moss and plant coverage there is much greater, and you can get large "carpets" of moss that look so lush and inviting!

A springtail's-eye view of a moss carpet.

We were about halfway done with the mid-succession sampling when we were told that the weather was getting worse, so we had to go home before it became unsafe to use the boat. We came back to Base Escudero where we have been processing the samples in the lab. We will hopefully be able to return later this week to finish sampling the mid- and late-succession sites! 

Lab time

We have continued to work diligently on our sampling. On Tuesday we collected samples from our transplant plots, and we have spent a lot of time in the lab processing them. 

First, we extract the invertebrates living in the soil. We do that in two ways. On the top shelf of the table in the photo, we have set up what are called Baermann funnels. A small amount of plant or soil gets wrapped in a tissue, then placed inside a funnel that gets filled with water. The small invertebrates that live in the water that is adhered to the soil or plant material then swim free in the water, but gravity pulls them down into the stem of the funnel. That is how we collect the nematodes and tardigrades that live in the plants and soil. Other larger invertebrates, like springtails and mites, don't live in water. We extract those using heat in Tullgren funnels. We wrap up some soil or plant material in gauze, and then place it inside of shiny funnels. To be space-efficient, we make those shiny funnels out of aluminum beverage cans. We place an incandescent lightbulb on top, which creates heat to dry out the soil and moss. By gradually turning up the heat, we make the soil more and more inhospitable to the invertebrates. Their natural behavior is to try to move deeper in the soil where it is still moist. But, instead of finding more soil... they find our funnel and drop into a sample container underneath.

We run those extractions for several days, so our transplant soils are still sitting on those funnels. While the extractions are taking place, we also preserve soils to measure the bacteria and fungi living in them. Those measurements will take place back at ASU, but first we have to properly preserve the microbes so that they do not degrade... or keep eating each other!

Using these data about the invertebrates and microbes, we can better understand how these plants help provide a habitat for the community of organisms as they are colonizing newly-exposed soil. The different growth forms of plants might provide better habitat than others, and some organisms might have preferences for particular plants.

It's lucky that we made it out on Tuesday to collect all of our samples, because the weather has been windy and snowy since then! We haven't been able to go too far from the station for any new field work. We quickly went out this morning to a nearby area to place some temperature sensors at one of our other field sites. 

It is beautiful in the snow, but cold! We cannot stay out for very long. That means we are spending a lot of time inside. I like to make sure my team stays fit during this time of inactivity by demanding they do pushups.

 (Just kidding! They were doing this by choice.)

We are hoping that tomorrow we can get out to our next major field site to collect more samples. If we cannot keep collecting samples, we will not have enough time to process them all before it's time to leave Escudero!

Straight on to field work!

 We finally made it to Base Escudero, our home in Antarctica for the next couple of weeks!

I haven't posted until now because we have been very busy! Because we were delayed by 3 days, we had to make up for lost time. The same day we landed on King George Island in Antarctica, we unpacked the lab and got organized to start our work. We did that until we couldn't stay awake any longer, and then went straight to bed! The next morning, we headed right out to check on our experimental plots!

We left the research station in the morning and walked to our main field site. We spent the day collecting the plant and soil samples. We only stopped briefly to eat a quick lunch... though it was a very cold lunch!

Dr. Becky, Hannah, and Dr. Angelica eating lunch with the Collins Glacier in the background.

We collected samples from our transplant experiment. In this project, we have planted some of the 'pioneer' species that first colonize the soil after a glacier recedes. We want to understand how the arrival of these plants alters the soil. The best way to do that is to add them to the soil and see what happens! 

Our hypothesis is that the presence of the plants will change the soil habitat that paves the way for organisms to move in. These organisms can then change the soil to make it possible for more plants to grow. So, we added the plants two years ago, and now we are measuring the changes in the organisms and soil habitat! We collected some of the plants and the soil underneath them to measure the bacteria, fungi, and invertebrates that now live there. We will also measure soil chemistry to see how the plants changed the habitat experienced by those organisms. We needed to collect the samples immediately and get them on the extractors in the lab, or else we wouldn't have time to get everything done in our remaining time here! 

Today, we have been busy in the lab processing these samples. We have to extract and preserve the organisms, and preserve the soil for the chemical analyses that we'll do back at Arizona State. It has been a busy couple of days! I will post more details when we have some down time. In the meantime, we will keep working to catch up!