Tuesday, May 5, 2015

What do we do with the samples we ship home?

While we were in Antarctica earlier this year, we were able to do some of the analyses we need to measure on the soil we collected. However, we don't have the time or equipment to do everything we need, so all of our samples were boxed up and shipped back to Arizona.

I flew home on an airplane in mid-January, but my samples stayed at Rothera until one of the U.S. research vessels came to pick them up. The samples traveled by boat to the U.S. research station, then eventually on to Chile. From there, they were carefully packaged and flown to California. From there, they were carried on a truck to my lab at Arizona State University. I received many boxes that looked like this!
The soil samples were packaged with a lot of cryogenic material so that they remained frozen throughout the whole trip. They were immediately put into a -20°C freezer in my lab. Here are the samples, finally home-sweet-home!
Now that the samples have arrived, we are able to finish our analyses on the soil. It will take a long time to get through everything we need to measure, but we've already made good headway! Most of these analyses are being done by one of my students, Connor. The first analysis he's conducting measures the mineral forms of nitrogen in the soil. "Mineral forms" of nitrogen include ammonium (NH4+), nitrate (NO3-) and nitrite (NO2-). We want to know how much mineral nitrogen is in the soil, because those are the nitrogen compounds that plants and animals are able to consume. Here are some photos of Connor working hard in the lab to extract soils for nitrogen:
Connor mixes a big jug of potassium chloride solution.
Connor weighing soil samples into flasks for the extraction.

Connor filtering an extracted solution to remove the soil particles.

Friday, March 27, 2015

How water tracks influence soil biology: the results

You might remember the field work we were conducting a couple years ago on water tracks. (You can read more about them in my posts from October 2012.) Water tracks are a type of groundwater where water from melting ice trickles down through the soil and moves along the permafrost, kind of like slow-moving underground streams.
Water tracks are a common feature in the McMurdo Dry Valleys, but we actually don't know much about how they change the soil they're flowing through. The water they bring would of course be important for the soil organisms living in an otherwise very dry desert. But they also bring a lot of salt, which can mess with the osmotic balance of the organisms, making it hard for them to survive. (Just like how animals living in freshwater have a hard time surviving in the ocean.) We wanted to know what the net impact is of these water tracks on soil biology. Is life better for them in a water track, or does it harm them?

In December 2012, I collected soil samples from inside and outside of three different water tracks. Those soil samples were shipped back to Arizona State University, and we measured a lot of important chemical properties of the soil.We measured the pH, salinity, and nutrient levels. We also measured the "texture" of the soil, which refers to the size of the soil particles. In other words, is it very sandy soil or is it made of finer particles? We also measured the amount of bacteria and fungi in the soil, and how much CO2 is being respired from the soil.

Overall, we learned that water tracks can have a big influence on soil, changing the water availability (obviously), salinity, amount of carbon, and texture. Those changes in the soil relate to changes in the microbial biomass and the amount of CO2 respired from the soil. In the graphs to the left, you can see that position "A", which is outside of the water track, is drier and less salty. It also has a higher pH than the other positions inside the track.

Also, Position "A" outside the track respires more CO2 and has more bacteria living in the soil.

However, this is just for one of the water tracks. As it turns out, each water track was different, so we can't assume that they'll all change the soil in the same way. They might hinder the soil microbes, or they might promote them. That means that, if the climate gets warmer in the Dry Valleys and more water tracks appear, we can't predict exactly what will happen. Some water tracks will stimulate biology, and some will hinder it.

The citation for the paper publishing these results is:
Ball, B.A. and J. Levy. 2015. The role of water tracks in altering biotic and abiotic soil properties and processes in a polar desert in Antarctica. Journal of Geophysical Research: Biogeosciences.  120: 270-279.

Monday, January 19, 2015

Now that I'm home... some videos!

I made it back to Phoenix, Arizona last week according to schedule. It was a long journey, taking about 25 hours total. When I got home, I came down with a cold! (This is funny, since I was going from a cold place to a much warmer place. Night-time temperatures in Phoenix are warmer than day-time temperatures at Rothera!)

Now that I'm back home and have fast internet, I want to share some video clips with you that I wasn't able to upload from Rothera Station.

First, some wildlife! There were a lot of elephant seals around Rothera. Most of them are juvenile males, and they spent a lot of time bickering with each other (practicing for when they're adults that will want to rule a beach). When they weren't scuffling with each other, they were lying around looking lazy! Here's a video of some of their behavior. Be sure your sound is on so that you can hear them.
video

And some tinier wildlife! This is a video Uffe took when he found a crowd of springtails in a puddle. They're doing what's called "rafting". They hold onto each other in a bundle and float on water. We were often surprised by how many springtails we found at the sites!
video

A lot of our sampling sites were on nearby islands, and we took a boat to visit those sampling sites. Here's what it's like to be on a boat in Marguerite Bay, Antarctica:
video


Saturday, January 10, 2015

Back in Punta Arenas, Chile

After almost two months at Rothera Station, we have begun the journey back home. We flew from Rothera back to Punta Arenas, Chile.

While we are here, we are returning the cold-weather clothing to the U.S. Antarctic Program headquarters. We are also enjoying meals made out of fresh food, especially fruit and vegetables!

Soon, we will continue our journey home, and I will spend about 24 hours flying back to the U.S.

Tuesday, January 6, 2015

Wrapping up the Field Season

We've been spending a lot of time on the microscopes looking at our samples. We are interested in the invertebrates living in the soil. At Rothera, we've only been able to look at the larger invertebrates, such as Springtails and mites. The smaller invertebrates (the nematodes and rotifers) require higher power microscopes, so we will look at those from our labs at home.

Here's some of what we've seen:
Collembola, also known as Springtails
We've found a LOT of springtails. Many of the samples from the islands near Rothera have thousands of springtails in them! Here's what we saw in the field:
Springtails "rafting" in a puddle of water

There are also a lot of mites in the samples, but they are not nearly as numerous as the springtails.
Oribatid mites
Other than microscope work, for the past few days, Uffe and I have been packing up to leave. We are scheduled to leave Rothera in two days! We have carefully packed up our samples and science gear to be shipped home. The lab has been cleared out and cleaned up, and we've put away all of our field gear. The end of our season is near! On Thursday, we will hopefully be boarding the Dash 7 to return to Punta Arenas and begin our journey home.

Saturday, January 3, 2015

Shackleton’s Endurance

People have been coming to the Antarctic for over 100 years. I get to fly down on airplanes and live in heated buildings with electricity, telephones, and internet. 100 years ago, though, it was a lot tougher! The people that were first exploring the continent dealt with amazing challenges, often facing death, in the name of science and knowledge. They traveled to the Antarctica not on airplanes, but on ships sailing from their home countries. These ships were usually very thick and capable of handling the ice around Antarctica, but they did not have the modern metals and motors that we use in ice-breaker ships today! The ships were wooden and powered by sails and steam.

One of the famous men that led many of these expeditions was named Ernest Shackleton. One of his most famous journeys was along the Antarctic Peninsula, just on the other side of where I am now. Shackleton and his team of explorers traveled to Antarctica from Great Britain on a ship called the Endurance in 1914. What they endured is an incredible story!
The Endurance stuck in winter ice, from PBS
Their goal was to sail as far south as they could through the ice to reach land. They were then planning to march across Antarctica from the coast, through the South Pole, to the other side of the continent. It would have been the first Antarctic traverse ever.

The Endurance just before sinking, from Wikipedia
However, the Endurance got stuck in the ice. This often happens to boats traveling around Antarctica. The ice moves around on the tides and with the winds. (You’ve heard me talk about it blowing in and out of the bay near Rothera Station, blocking our boats.) If the pieces of ice wedge in too tightly, the boat cannot keep pushing through. If winter sets in, everything freezes solid, and the boat has to sit there until summer when it melts! Unfortunately, the Endurance got stuck, and the ice surrounding it kept getting squeezed together until it crushed their ship. The Endurance sank, and left the men stranded on the ice out on the ocean with nothing but their three smaller life boats (which were useless at the time, because of all the ice) and as much food and survival gear as they could carry.

Their goal then became to march across the ice towards land. They marched across ice, which was breaking apart beneath them, pulling their boats, food, tents… everything they needed to survive. At first they used their sled dogs to help pull their gear, but they slowly lost their dogs (to illness, fatigue, and human hunger.)
Man-hauling the life boats, from CoolAntarctica

Eventually they made it to the point where the ice was ending and they could use their boats. Their life boats were small, powered only by sails and rowing, and did not offer much protection from bad weather. They were not meant for long journeys through Antarctica! The best they could do in these boats was get themselves to an uninhabited island called Elephant Island (named for the elephant seals that lived there). Nobody knew they were there, but they needed to be rescued as soon as possible, because they were frostbitten, starved, sick, and running out of food. The only way to get help was to send a small party of people on one of the boats to the nearest whaling colony on South Georgia Island, across 800 miles of open Antarctic ocean during the winter! Only six of the explorers went on one of the life boats, called the James Caird. The rest of the crew remained on Elephant Island to wait out the winter, using the other two overturned life boats as shelter.

The men aborard the James Caird from Wikipedia
Amazingly, Shackleton and the few men who went on the James Caird made it through the 2-week journey through storms and the open ocean to South Georgia. However, because of the weather, the only place they could land on South Georgia was on the opposite side from where the colony was! They had to walk across the island, which was covered with glaciers and crevasses, and generally considered un-crossable by the whalers living in the colony. But they had no choice. They marched across, and miraculously arrived at the whaling station a few days later.

From there, they were able to use a whaling vessel to get them to Punta Arenas, Chile. The Chilean government lent them a ship that was able, after many attempts, to get to Elephant Island and rescue the starving, weather-beaten crew. The most amazing part of the story is not just that they were able to endure such harsh conditions and misadventures, but that not one single member of the Endurance’s crew died during the adventure. (Ironically, after returning home from such a death-defying journey, many of them enlisted in the army to fight in World War I, which was breaking out as they were leaving Great Britain, and several died on battlefields.)

Thursday, January 1, 2015

Happy New Year!

Welcome to 2015!

We had a great New Year's Eve. Our day began by visiting Leonie Island, which was our final sampling site. It's a very lush island, with a lot of healthy grass, moss, and algae. It provided great samples! In the picture below, you see the brown tufts of hairgrass, and the green carpets of moss and algae.
Two skuas at our sampling site on Leonie Island.
There are only two flowering plants in Antarctica, and they are both only found along the Peninsula. (Moss is a plant, but it's a bryophyte, not a flowering plant.) There's the hairgrass, which I've mentioned before. The second one is a pearlwort. We've sampled hairgrass from the other islands we've visited, but Leonie is the only place where we've found pearlwort this far south. We found the pearlwort, but not in large enough patches to be able to sample. (We don't sample if it mean we'd have to collect the entire plant, because that's too destructive to the environment.)
Antarctic pearlwort, Colobanthus quitensis
After a successful day of sampling in beautiful weather, we ended the day with a station celebration of the New Year. We had a BBQ down on the wharf, and ended the evening up on the hill where we rang in the New Year at midnight. Since we have 24 hours of daylight here, it was of course still light out at midnight. Here is the view from the hill at midnight. It was my first view of Antarctica in 2015!