Elizabeth Peterson's blog

This week was filled with results! I have had great success with the Nitric Acid digestions, and the lab now has permanent slides for the chironomid gut contents from June and July for all three collection sites! This is great because these results will be compared to Claudia's counts of the same sites to see how the environment compares to the chironomid diet. 

This week was a great week as I had my first really great result from the nitric acid digestions I have been working on. The nitic acid digestion is a procedure that allows us to digest the soft tissue of chironomids and other plant species leaving only diatom frustules. The end result provides clear and easily-identifiable diatoms from the chironomid guts. Our first nitric acid digestion trial with the May samples using a single chironomid did not provide good results. There were likely two problems with the first run.

This week was one of my busiest weeks at IEH. Now that I have collected all my chironomids from our various sampling sites, we need to begin our analysis projects. The first of these projects is the nitric acid digestion. However, before I can do any experiments, I need to clean the chironomids to make sure they don't have anything stuck to the outside of their bodies. Because we are doing a food web study, we only care about what is in the guts of the chironomids, so the cleaning step is critical.

This week started off with a whirlwind of sampling! I spent all of Monday sampling from our Welch Island and Whites Island sampling sites. It was very exciting to see the sites we collect from to obtain the samples I have been working with. Claudia worked with researchers from NOAA to collect samples, and I processed them out in the field, which was both exciting a somewhat scary because I was processing the samples alone and didn't want to do anything wrong. Fortunately, all the processing went smoothly, and we were able to get all the necessary information from both our sites.

Though this was a short week due to the 4th of July, it was a very busy and really fun week. On Monday, Claudia returned from her week off, and so I brought her up to speed on my project's progress. I then helped her prepare for our sampling trip to Camas to collect water and nutrient samples from the Columbia. I am definitely getting comfortable with the field work we are doing and really enjoy our time on site. After we got back from sampling, I helped to process the samples and analyze the nutrients.

This week I continued to photograph chironomids to prove that they were diatom free on the outside. Claudia, my frontline mentor, was out of town, so I was working indenpendently to get the pictures done, sort through more samples, and also prepare for a DNA extraction. Once again, because Chironomids are a new area of study for this lab, I needed to look through the literature to determine the best way to get DNA from a whole chironomid and how to ensure that diatoms in their guts would also have their DNA extracted.

            This week, I jumped into the project by beginning to sort through samples from the Columbia River for Chironomids. It took a day to get comfortable with sorting through all the detritus and other zooplankton to find the Chironomids, but I am now pretty good at finding Chironomids. The number of Chironomids found at each site varied a great deal. In the May Welch Island sample, I found 11 Chironomids. In the May Campbell Slough sample, I found about 30.

In the last few decades, the Columbia River has seen a marked decrease in salmonoid populations. The cause of this decline is unknown, but the installation of hydroelectric dams in the Columbia River has changed the water clarity and sedimentation patterns, resulting in a greater contribution by pelagic phytoplankton to river primary production. This caused the food web to shift from being a macrodetritus-based food web to a phytoplankton-based food web.