Independent Student Research Feature: Rachel Kahn

IMG_1424The independent research course is central to our semester long study abroad programs. During this course, our students conduct their own research project all the way from coming up with a question to presenting their results to the public. One of our Fall 2015 students, Rachel, was kind enough to share her perspectives and findings having completed the course.

What question(s) does your research address?
My research examined the effects of size and depth on pumping rate and filtering efficiency for a common species of marine sponge found in Bonaire (Aplysina lacunosa AKA convoluted barrel sponge).

IMG_1414Was it difficult to devise a research question?
It certainly wasn’t easy. I had a good start because my project was based on a past project by another CIEE student, but I still had the challenge of making the study my own and giving it direction. I remember when I was planning my project, I initially ended up with too many things to test and not a very clear idea of exactly what I was looking for. This was a little bit frustrating, but I managed to streamline it so that the direction I wanted to take the project was clear to me.

IMG_1449Was it difficult to devise the methods for your research question?
Devising my methods was not difficult, but actually executing them came with plenty of challenges. I think that one of the main lessons I’ve learned from being involved in scientific research is that it usually doesn’t work (at least not the first time). Every time I collected data, I found room for improvement. The difficulty came with making improvements when something didn’t work the way I intended. Also, every sponge is different so I had to adjust my approach for each sponge that I sampled.

Describe a typical day of data collection for your research project.
My data collection days always began with a dive. My buddy and I would carry all the gear we needed into the water with us (this included a mesh bag full of syringes and two slates among other things). During our dive, we would start by swimming down the reef slope to about 22 meters deep, then we would level off and swim until we saw a sponge of the right species. We would then use syringes to collect water samples from the outside of a sponge tube and at the opening where filtered water comes out. IMG_0749[2]For each sponge tube cluster, I selected three tubes from which to collect data. After collecting water samples, I would use a caliper and measuring tape to measure the size of the sponge tubes while my buddy collected a water sample from the water column at around the same depth as the sponge that I could use to measure food availability. Our last step was to take video footage that I could use to calculate the sponge’s pumping rate. I used a GoPro mounted on a slate to film the sponge tube’s opening. My buddy would then poke a needle through the sponge tube’s wall (this was not damaging to the sponge, I promise) and eject spurts of yellow fluorescein dye, which I caught on film as the sponge pumped them out. After collecting my data for a sponge in the deeper depth range, we would ascend to around 10 meters and find another sponge on which to repeat the data collection procedures. After the dive, I would take all of my water samples to the lab and measure their turbidity using a fluorometer so that I could calculate the percent reduction in turbidity between water before and after being filtered by the sponge. I would usually spend the evening analyzing my video footage of the sponge pumping the yellow dye and calculating the pumping rates.

IMG_0748What major difficulties did you have to overcome to complete your project?
One of the greatest difficulties I came across was getting the video footage to be easy to see. Yellow dye did not show up well on a white background. Neither did green food coloring… It took me a few tries before I landed on yellow dye against a dark background, which turned out to be quite successful.

What was the most fun part of your research project?
The most fun part of my research project was definitely the diving. Positioning myself in a way such that I could take my measurements and not touch surrounding coral proved to be an interesting buoyancy challenge, and I ended up hanging upside-down a lot of the time. It was also really fun to watch the sponge pump the yellow dye – it looked really cool.

IMG_0745Describe the general findings of your research project.
I found that larger sponge tubes have faster pumping rates, but sponges of all sizes have similar filtering efficiencies. I think this is because the filtering efficiency might depend more on the wall thickness of the sponge tube rather than the length, and I measured a relatively narrow range of wall thicknesses. Interestingly, I found that depth had no significant influence on sponge pumping rate or filtering efficiency. This makes sense because I also found that food availability was consistent across depths, so I wouldn’t expect sponges at different depths to use different filter feeding strategies.

Has the process of conducting an independent research project made you a better scientist?
I can say without a doubt that the process of conducting this research project has made me a better scientist. Going through the whole process of developing the project, conducting the research, writing the final paper, and giving the presentation has given me so much confidence. I feel more sure of myself and what I am capable of, which I think is a great foundation for my future research endeavors.

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