To collect our soil and plant samples, we use a corer. That's a piece of metal pipe that is in Hannah's hand in the photo below. That cuts out a piece of the plant, which we put in a small envelope. (Those are in the ziplock bags next to Hannah).
Then we scoop the soil from underneath it into a plastic bag. The plants and soil are taken back to the lab for analysis.
We will do most of our measurements on the samples back in the U.S. We have to spend our time in Antarctica collecting the samples and setting up experiments. We just don't have time while we're here to collect all the data on the samples! We will ship the soil home frozen at -20°C. Those temperatures would kill most of the microbes and invertebrates, though! We extract the organisms from the soil here in Antarctica before we freeze them.
In my lab at Arizona State University, I have special equipment to look at the invertebrates. But equipment is heavy and takes up a lot of space, and we can't bring it all with us. So, in Antarctica, we have to get creative!
This is how we extract arthropods like mites and collembola. We use heat created by light bulbs.
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| We use aluminum cans because they are smooth and shiny, which reflects the light from the bulb to keep it bright and warm inside the can. |
These arthropods like to be cool and moist. If the soil gets too warm or dry, they will crawl deeper into the soil where it is cooler. We use that behavior to get them out of the soil. Each of these cans has a soil sample inside of it. We then put a string of outdoor Christmas lights over the top. The heat from the light bulb warms up the soil. The arthropods try to move deeper in the soil... except there's no more soil. They fall through the funnel into our little bottle. Now we've trapped them out of the soil and can look at them under a microscope!
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| Each can has a soil sample wrapped up in a little piece of gauze. The heat from the lightbulb is what makes them want to move down into our funnel. |
Smaller invertebrates like nematodes and tardigrades don't respond to heat. These tiny invertebrates live in the water in the soil. To get them out of the soil, we use water and gravity.
Each of these funnels contains a small soil sample wrapped in a tissue. We fill the funnel with water, and the nematodes swim away from the soil to float in the water. But gravity wins! They sink down to the bottom stem of the funnel, and we will capture that water in a bottle.
At ASU, I have sturdy stands that hold our funnels. We needed to pack light, so I made stands here out of cardboard boxes. It is very fancy, don't you think? The samples sit in the funnels for 5 days. These small invertebrates do not move fast, so it takes time! We put our first batch of samples onto the funnels on Wednesday, which means in a few days, I should have some invertebrates to show you!
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