We are a group of freshwater ecologists from the Biology Department at St. Catherine University in Saint Paul, Minnesota studying the effect of temperature and nutrient availability on metabolism and nitrogen fixation in geothermally active streams in the Hengill region of Iceland. This is a collaborative research effort with our partners from Montana State University, the University of Alabama, the University of Iceland, and the Institute of Freshwater Fisheries in Iceland. See links to our collaborators labs below.

Friday, December 14, 2012

Dry It, Weigh It, Roll It: Dealing with Algae Outside of the Stream

The frantic pace of the summer has subsided (somewhat) and we are back to the stability of a weekly schedule. With classes well under way, multitasking is the name of the game when it comes to finishing homework and still moving forward with our research. It really makes us appreciate our summer abroad for the freedom from distraction it provided.
A dried, weighed, and rolled algae sample
            As Jill mentioned in the previous blog, we are processing the dried algal samples we collected over the summer. I have finished rolling samples to be run on the isotope ratio mass spectrometer (IRMS) to determine the 15N/14N ratios, as well as the overall carbon and nitrogen content within each algal sample. This was a tedious process that involved measuring out micrograms of algae into a small tin capsule – mere dust under normal circumstances, but powerful data in our hands. This will allow us to determine how much of our 15N2 isotope got fixed and incorporated into biomass through the course of our field incubations in Iceland. Finally, we will get to see if this method worked like we thought it would.  Since we already have gas samples analyzed from the field, we know how much nitrogen fixation was occurring based on the acetylene reduction method. Comparing these results to the 15N isotope data will give us two measurements of nitrogen fixation rates and may help to illuminate the strengths and weaknesses of both methodologies.
Delor running a sample for P content
            In addition, I have been wrestling with another lab protocol that will tell us the phosphorus content in each of our algal samples. This has been challenging in the sense that we have to be sure that this method is giving us precise and accurate values. I have spent a great deal of of time practicing the techniques and various steps involved to ensure that we will be able to get the best results when we work with our actual samples.  Again, troubleshooting and problem-solving is key in our success – we need to intimately understand the protocols, equipment, and samples we are working with in order to achieve results that we can be confident in sharing with the world.
It has been interesting switching from large ecosystem scale field work to working with small scale microscopic lab procedures, like measuring nitrogen and phosphorus content in algae. Switching between moving big blobs of Nostoc around a stream to weighing miniscule amounts of powdered algae to determine their nutrient content presents its own challenges. The work is much more tedious and monotonous, but it still requires a high level of concentration to avoid sample contamination and ensure that the method works. It has been an exercise of both my patience and my chemistry techniques. I think I have found a balance between being so focused the work is frustrating and being absent-minded and making mistakes. I now look forward to my lab work as finals approach as a way to clear my mind in a more meditative fashion.
Delor pulling algal samples out of the muffle furnace for P analysis
   With Bayley’s presentation coming up we are beginning to meet our deadlines for this semester. We are all so proud of the work that we have done so far, and we are very excited to see how Bayley has synthesized our results and what she has to say about them! But this is by no means the end of our work, and there will be more to come next semester, including my upcoming presentation at the Society for Freshwater Science meeting!