While our MAIN goal for the field season is to learn more about the effects of sedimentation on microbial mat shapes, there are many other questions that we are collecting data for, and many unanswered questions. Our day today illustrates some of these other questions, so I'll tell you about it.
We got ready for the day and headed out for what Sasha calculated would be the deepest part of the lake to collect water samples. The water in Lake Joyce is very stratified, forming horizontal layers that don't mix much – like salad dressing that's been sitting for a while. Each layer has its own density based on temperature and how salty the water is.
We drilled a 10 inch hole in the ice, and set up a small winch to lower our niskin bottle into the lake. A niskin is a bottle that opens at both ends. When it reaches the depth you want to sample, we send a weight down the line and when it hits the niskin, it snaps the top and bottom shut. Then we can crank on the winch and bring our samples up.
Tyler lowering the niskin into the drilled hole.
Megan and Anne took some of the samples for their work. They are microbiologists, and they're interested in learning more about similarities and differences between the microscopic communities at each depth. Anne also has samples from when she was here 4 years ago, so she can study how the community has changed over time. Megan and Anne took the samples back to the polarhaven tent to process for later. First, they filtered the microbes out, capturing anything larger that 0.2 micrometers (0.00002cm). After filtering them, they put them in chemicals that broke their cell membranes open so the DNA could be preserved for analysis later.
Megan and Anne studying microbe samples.
Tyler is analyzing water samples for isotopes, which occur because different atoms of the same element have different numbers of neutrons. Water flowing from Taylor Glacier has one isotopic signature, and water flowing from the alpine glaciers would have a different kind of isotopic signature. By knowing the ratio of isotopes in each layer of water, he can have an idea of where it came from and how the lake has changed over time as more of the alpine glaciers melt.
Along the way, there was a lot of problem solving that is typical of field work here. The niskin wasn't shutting when we thought it was, so we added weights to it, and yanked on it too. We also sent the drop camera in after it so we could SEE it shut. We also discovered that the filtering device that Anne and Megan were planning to use wasn't working, so they had to do much of that work by hand, which took longer.
Transferring water samples from the niskin to bottles.
All of the work that we did today will give us a better understanding of what's going on in the Lake Joyce system, from a biological, chemical and geological perspective. This will inevitably lead to more questions being raised, and more research!
Comments