You are currently browsing the monthly archive for January 2007.
Lately, Ed and Breana have been very busy counting nematodes. Counting nematodes involves many hours in front of a microscope, searching a petri dish for soil animals. Then we count them! It sounds easy, but they are very wiggly, and that makes it more difficult.
Here is a movie of Scottnema lindsayae, a nematode that is native to Antarctica.
While the others jetted off the Ice, Ed, Breana and Abigail got to work setting up a new experiment to study the relationship between soil biodiversity and soil processes near Lake Fryxell. Soil processes include things like soil respiration, which represents the total activity of soil organisms, and the transfer of nutrients between organisms. These processes are carried out by a variety of organisms that inhabit the soil, including bacteria, fungi, protists, nematodes, tardigrades and rotifers, but we do not know how the composition of the soil community influences processes rates. For example, a simple soil community consisting of just bacteria and fungi may result in slower soil process rates than a more complex community consisting of bacteria, fungi, protists and various microscopic animals and this is what our experiment aims to investigate.
Soil was sterilized by exposing it to high temperatures and pressures, which kills all the animals and microbes. Then we placed the sterile soil in panty hose and buried it out in the field. We use to panty hose to contain the soil so we can find it again when want to see what has colonized the soil. Over the next three years we’ll collect the soil from the field site to see which organisms have colonized it and measure some biogeochemical properties, including soil respiration and the amount of different nutrients in the soil.
With a tear in our eye we said goodbye to Ross, Diana, Mike, Dorota and Byron, who all returned to the US (and reality). But before they left we took our 2007 soil team photo.
Diana, Ross and other members of the soil team visited two Antarctic valleys that have recently been named in their honor (Wall Valley and Virginia Valley, respectively)! These antarctic veterans have been working down here for 16 year and the valleys were named in recognition of their commitment to Antarctic research. Five soil samples were collected from each valley to see what’s happening biologically in each valley. Sadly (especially for Diana) we didn’t find any nematodes, but we’re hoping to continue the search next year.
During the same trip the soil team stopped off on top of Mt Falconer to collect samples from a soil transplant experiment. Soil from the valley floor and the top of Mt Falconer were swapped to study the effect of elevation on the animal community. Afterwards we headed to the valley floor to collect samples from the transplanted soil down there and bumped into two members of the Stream Team (Emily and Lee) and the Lake Hoare Camp managers (Rae and Sandra).
Diana, Ross, Byron and Mike continued on to Battleship Promontory, a large geologic feature in the Dry Valleys that (sort of) resembles a battleship. Battleship is one of the few places in the Dry Valleys were we find Geomonhystera sp., the rarest nematode species in this region. Some awesome helicopter flying by pilot Pandol meant they finally got to land at Battleship after three years of unsuccessful attempts.
On Sunday morning, a group of about 50 people was picked up by a Terra Bus. Those doing the full marathon were unloaded near Kiwi Scott Base and those running the half marathon were driven to the half-way point of the marathon to run back to the Scott Base. The route was simple and led through Willy Field to Pegasus (the airports), all on the highly packed snow. Everybody was enthusiastic as the weather was promising. But the weather can never be counted on here and surely just as the run started, the winds picked up and the clouds took over. Running the first leg of the marathon was relatively “easy”: the struggle was limited only to finding “highly” packed snow path (no success by any means). The way back (as the faces and hunched bodies of half marathoners indicated) was even harder, with headwinds of 25-30 knots testing everybody’s will. But wills of all were stronger than winds and cold. They all prevailed and crossed the finishing line.
This year marks the 50th anniversary of Scott Base, the New Zealand Antarctic Station, which is next door to McMurdo (the US base). To celebrate the occasion Scott Base was visited by several distinguished visitors, including Sir Edmund Hillary and the New Zealand Prime Minister, Helen Clark. As well as being the first person to scale Mt. Everest, Edmund Hillary was a keen Antarctic explorer and was a member of the party that founded Scott Base in 1957.
Diana, Byron, Dorota, Mike, Breana and Abigail attended the ceremony and met Edmund Hillary and Helen Clark, as well as the other visitors. Jeb and Ross were in the field and missed all the excitement. The next day Prime Minister Clark spent some time in our lab and we told her about soil ecology and she looked at nematodes down the microscope. Perhaps we have convinced her that nematodes are cool!
Diana hobnobs with PM Helen Clark and Sir Edmund Hillary at a dinner in McMurdo held in honor of our Kiwi friends.
Other photos of the historic trip can be viewd on our Flickr page!
The south side of Lake Hoare in Taylor Valley is the site of many of our former and current core LTER experiments. Today we needed to sample the Long Term Manipulation (LTM) experiment, the Elevational Transect experiment (ET) and the Algae experiment. The LTM experiment was set up in 1995 to investigate the effects of increased temperature, moisture, and carbon inputs. In 2005 the experiment was broken down, and we are sampling it now to determine whether or not the site is on a path to recovery.
Despite all our good intentions, our experiments have an effect on the landscape and the soil. Therefore, it is our hope that when we stop an experiment, the soil will return to pre-experiment condition. This may not always be possible. For example, in areas where people walk, paths are formed, and the abundance of nematodes that live on those paths can be less than half of the undisturbed population. That’s a significant drop in population size just from walking on the soil. Because of this, we treat the soil as carefully as possible and walk on established paths or in polygon cracks whenever possible.
The LTM and Algae experiments are close to the lake, so we marched down there to sample them. The Algae experiment is also an older experiment that included the addition of algae to plots as a natural nutrient input. We sampled this experiment to see if the addition of algae all those years ago had a lasting effect on the soil biology. When we arrived at the LTM plots, Ed noticed that the metal signs outside the plots were bent and worn by the wind.
The wind in the valley is so strong, especially in the winter, that we have to secure all of our scientific equipment with several bungee cords and metal stakes pounded into the ground. One year the wind was so bad it destroyed a food cache at one of the field camps. Food caches are stored in heavy wooden boxes and secured very tightly, but sometimes it’s not enough. Winds that blow down from the glacier are called “katabatic winds” and can reach speeds of 200 miles per hour. Combine high winds with unstructured Taylor Valley soil and you get a sandstorm. Definitely powerful enough to bend and “erase” a metal sign.
In the afternoon we sampled the ET experiment, a study of the differences in nematode populations at different elevations and sampling scales. Nematodes are so small, there could be totally different populations within several feet of each other, so the places we decide to sample from have to be picked very carefully. Also, the soil environment changes dramatically as elevation increases. Sampling for nematodes at low, medium and high (very high!) elevations at different scales (9 samples 5 meters apart v 9 samples 0.5 meters apart) gives us valuable information about the distribution and abundance of our Antarctic invertebrates.
For example, the A-plots are down by the lake, where the soil is wet, while the B-plots are both higher and drier. Nematodes that we find in the A plots but not the B plots may not tolerate dry soils very well, and vice versa. With this information we can predict which nematodes we can find in various soil environments. It also tells us a little bit about the life history and environmental requirements for different species of invertebrates. We hope to use this data to predict the effects of climate change on Dry Valley invertebrate species. Invertebrates are responsible for a large portion of the nutrient cycling in the Dry Valleys.
What will happen to the nematodes if the planet gets warmer or colder? What happens to nutrient cycling in Antarctica if worm populations increase or decrease? These are two of the many questions we are trying to answer down here at the bottom of the world.
Wednesday morning we awoke to some pretty bad weather in McMurdo: high winds, grey skies, and snow. In bad weather, helicopters will not fly, because they are small and vulnerable to high winds. Also, pilots will not fly into areas where they cannot see, so fog or low cloud cover will prevent access to areas by helicopter. After several weather related delays, Byron, Ed and Breana made it to F6 to apply treatments to plots in our Stoichiometry Experiment.
Ed and Byron hauled 30 carboys full of water across the landscape in order to apply the treatments. Each carboy weighed 25 lbs! In each jug of water is a combination of nutrients (C, N, P) that will help us to understand how nutrients affect soil processes here in the Dry Valleys. But first we have to put them on!
Precipitation, in the form of snowfall, is extremely low in the Dry Valleys, which is why the area is classified as a polar desert. It didn’t seem very desert-like when we out there! Breana tried to catch snow in her mouth while Ed was content to allow the flakes to pile on his parka.
The weather system was moving so fast, 30 minutes later it was sunny and blustery again. After a tough day in the field, we took some time to celebrate Dorota’s birthday! Here are current and former members of NREL: Rob Edwards, Diana Wall, Breana Simmons, Jeb Barrett, Dorota Porazinska, and Ed Ayres.
Ross, Diana, Jeb, Byron and Breana flew to the west lobe of Lake Bonney to set up the second set of plots for the Stoichiometry Experiment. Our Stoichiometry Experiment (SE) sounds very sophisticated and complicated, but really it’s very simple. We are adding combinations of carbon (C), nitrogen (N), and phosphorus (P) to the soil to see how it affects soil processes. Remember that in science you need to replicate your experiment (to prove that it works or doesn’t work more than one time in one place), and also have a control with which to compare your results. The design we came up with involves 56 plots in two lake basins; that’s a total of 112 plots! We will apply our treatements and take soil samples once every year. This year, we took our soil samples first, so that we know what the soil was like before we started our experiment.
This is a view of the Taylor Glacier, adjacent to the west lobe of Lake Bonney.
We were at Bonney setting up the SE with Ed and Dorota, who were sampling the last set of BEE plots. We are very careful when working in the Dry Valleys. We don’t want to disturb the soil more than we have to, so we try to use established paths for walking, and if there isn’t a path, we walk on rocks, not on the soil. Also, we try to keep our experiments modest in size to minimize the impact on the soil organisms.
We’ve been very busy setting up a new experiment and sampling our core LTER experiments. Ed and Dorota continued their crusade to sample the BEE plots at Lake Hoare while Byron, Jeb, Diana, Ross and Breana set up the first set of plots for the Stoichiometry Experiment (SE) at F6. We often split into smaller teams to get more than one sampling trip done in a day. In order to sample in the Dry Valleys, we have to fly there from McMurdo Station in helicopters. We spend a lot of time in helicopters, and our research could not be done if it weren’t for the hard work of all the pilots and heli-techs from PHI that fly us around to our field sites.
Because of the amount of wind a helictoper creates when it takes off and lands, anyone near the landing site must take precautions to hold on to lightweight items (like empty carboys or knit caps) and turn away to prevent getting blasted with sand.
Sometimes we get done with our work before the helicopter is scheduled to pick us up. Then we have to hunker down and wait. If it’s really cold, we wait in a big pile, and try to keep warm. It’s a very good time for sleeping, as long as someone listens for the helicopter. Usually the helicopter will radio ahead to tell you they are coming, but you can also hear them coming. The Dry Valleys are very quiet, so the sound of a helicopter carries for miles.
If you’re very lucky and the pilot is feeling generous, on the way back from the Dry Valleys they will take you along the ice edge to see penguins, seals and whales. This year the ice edge is very close to McMurdo, so it’s not a very long trip. In other years, the ice edge is so far away that it is nearly impossible to fly out there without causing delays in the helicopter schedule. The channel, formed by the icebreaker, is also very clear now, and there are rumors of whales “spy hopping” in the broken ice near McMurdo Station.