"The" Number

We found algae!

We finally had some decent weather after days of rain and wind, and we were able to go out and make our first measurements of nitrogen fixation on the tiles associated with the channel temperature experiment. Algae (and all photosynthetic organisms) typically acquire their source of nitrogen from the soil and water around them, but some species, called cyanobacteria, are able to acquire it from the atmosphere. The species that can do this have an enzyme called nitrogenase that can break apart the two nitrogen molecules in nitrogen gas (N2), the most abundant gas in the atmosphere. They then use the nitrogen to build amino acids and other nitrogen containing molecules for growth. 



This summer we are planning to measure nitrogen fixation with three different approaches as a comparison of the methods, as well as to use them as a check against each other.  For

Chemical conversion of nitrogen fixation (left) and
how it compares to acetylene reduction (right).

our first sampling day, we only used one method, which is called the Acetylene Reduction Assay, or ARA. The ARA method involves making acetylene gas, which we do in the field using calcium carbide and water in a flask, and then collect the gas in either a balloon or syringe. We then inject the acetylene gas into gas-tight chambers with the algal samples and then take an initial and final sample of the gas in the chamber. During the incubation the algae in the chamber are breaking the triple bond between the two carbon atoms in acetylene to produce ethylene (see diagram), which is similar to the chemical reaction in nitrogen fixation (see diagram), and we are able to measure production of ethylene gas and use this as a measure of how much nitrogen the algae are fixing. 



Working on getting "the" number.

Over the years, the ARA method has been modified and refined for better results while still trying to keep the procedure fairly simple. This summer, we are collaborating with another project and we are measuring nitrogen fixation on tiles that have been colonized with algae.  As part of this effort, we had to modify the ARA method again for use with custom chambers that were built for the project. This came with several challenges that involved some creative thinking and problem-solving skills, which are essential skills to have when conducting research. The physical act of research is easy; going out in the field, collecting data using technical instruments, putting samples of water and algae into vials, and following previously thought out methods.  However, it is naive to think that’s all there is to research. As Jill always says, “It’s easy to get 'a' number, but more challenging to get 'the' number”. What she means is that it’s easy to go out into the field, spends hours collecting data, and reading numbers off of instruments, but the hard part is deciding what that number tells us, and if we used correct and precise methods for obtaining the actual number that represents part of the answer to our question. For example, when we are trying to figure out how to make gas-tight chambers we have to think like a gas molecule and really channel our inner Sherlock Holmes to make sure we are getting good data, but at the same time not be biased.

So far, our research has been really frustrating, impossibly complicated, and infinitely

Excited after a day in the field of
hiking and looking at algae.

rewarding. I love a good challenge and this research is important in helping us understand how whole ecosystems work, which we can then use to help gauge how they are going to be affected by human activity. There is still so much we don’t know about our world and the ecosystem services we depend on for survival. I am starting to see how easy it is to build an entire career’s worth of work in research. I feel invested and driven by curiosity and I am really looking forward to seeing where it takes me.