The World of Nematodes

Last year, Breana joined the stream team to sample a reactivated stream channel, called the Relict Channel. If you missed it, you can read about the experience here. We wanted to sample again this year in order to get a second year of data for the project.

Last year was a cold summer, and the streams were not flowing very fast. This year is very warm, and the melt from the glaciers has increased and caused high flow in the streams. We were excited to collect data from two very different summer seasons to compare what the system is doing under drastically different environmental conditions.

Wormherders Karen, Nick, Bishwo and Breana, along with Ana from the Stream Team and Judit, an artist visiting Antarctica, hiked up to the top of the Relict Channel. Our intent was to sample the algae and sediments along the entire length of the stream, stopping in nine specific places along the way.

The algae in the stream can be found in large mats like this:

or in small patches, like this:

and it acts as a habitat and food source for nematodes, rotifers, tardigrades, and other even smaller organisms. Breana is especially interested in these animals, and how they respond to changes in the stream itself.

The water in the Relict Channel comes from the Von Guerard Glacier, which also feeds Von Guerard Stream. Look how tiny Nick is compared to the glacier!

From the top of the stream you can see the Commonwealth Glacier, which is on the other side of the lake. It’s so far away you can’t even see the camp, or the lake!

Karen’s job was to collect bits of algae and the sediment directly beneath them so that we could extract and count all the animals living in them. Breana’s job was to preserve algal samples in preservative (4% formaldehyde) for identification of diatoms.

This has to be done very carefully. Here you can see Karen sampling a large algal mat. The algae is fragile, and must be picked up carefully with tweezers and placed in plastic bags of water or preservative. You can see that she is wearing gloves and not touching the mat with her hands. She doesn’t want to disturb it too much!

Nick and Ana were in charge of collecting information on the stream: how wide is the stream? how far below the surface is the permafrost? what is the pH of the water? which nutrients can be found in this part of the stream? Here Ana tests the pH of the water, while Nick measures the depth to permafrost using a metal t-bar.

Bishwo’s job was to sample the dry soil near the stream for Uffe, who was hoping to use the soils for a later experiment. We do a lot of experiments back at home in Colorado using soil we collect from Antarctica.

Judit’s job was to keep detailed field notes. Writing down exactly what happens while sampling is very important, because our memories are unreliable when we try to remember the details of an experiment. She also took lots of photographs of our sampling efforts – she IS an artist, after all! Most of the pictures in this entry were taken by Judit.

But not this one! Judit asked to collect some algae, so that she could be a Wormherder, so Karen took this picture!

The water flow was really variable. In some places, the stream became very wide and shallow, with lots of algal mats. Here are Karen and Breana sampling in one of these spots.

Sometimes the stream became more like a pond!

In other places, the stream narrowed and became deeper. Here you can see that Ana and Nick are measuring permafrost, and they’re not very far apart at all!

Another important thing to notice about the picture above is how Nick is perched very carefully on the rock while he waits for Ana to read the permafrost measurement to him. That’s because he is trying to minimize his impact on the soil environment. When we walk in the Dry Valleys we crush the soil animals living under our feet, and our tracks are evidence of this disturbance.

Antarctica is so special we try not to leave too many footprints! If there are rocks, we hop from rock to rock. We also try to walk in the polygon cracks (large cracks left in the soil by natural processes) because we know that soil animals don’t like living there, so walking in the cracks is not as harmful to the soils. Some areas are unfortunately already heavily disturbed, but those places make an excellent spot for a nap after a long day of sampling!