Lauren Rodgers, Rutgers University
The Approach: In my previous blog post I discussed the importance of iron in ocean ecosystems. Because so many living things rely on iron to live and grow, it is important for us to understand how iron cycles, as it enters the ocean, exits the ocean, and changes from one form to another. Zetaproteobacteria are marine bacteria that rely on iron to create energy for themselves, but in this process, they also turn dissolved iron into solid iron. So these bacteria make rust as they grow. Unfortunately, rust isn’t very good for other organisms, and the Zetaproteobacteria effectually remove iron from the ocean. But still, these organisms are one half of the iron cycle and therefore play an prominent role. With our research, we aim to determine whether these bacteria are present in Charleston’s estuaries, and extrapolate how they might be impacting the local iron cycle.
Now, you most likely have one thing on your mind: How are they going to study all of this!? From our lofty research aims, we must simplify those down to into bite sized goals so we can have a successful summer of sampling.
- Identify whether Zetaproteobacteria can be found in the sediments around Charleston.
- Measure the amount of Fe(II) and Fe(III) in the sediments
The first thing that we did in order to accomplish these goals is pick sampling sites. We wanted to sample the sediments for these Zetaproteobacteria, so we chose muddy regions close to tidal rivers that empty into the ocean. We wanted tidal rivers because Zetaproteobacteria live in salty waters, and these rivers mix with salt water from the ocean. We decided to look for these muddy regions along the Ashley River, Wando River, Stono River, and Cooper River, picking easily accessible sites far up the river where the water is fresher, midway down the river where the salt content is at a mid-range, and low down on the rivers, near the ocean, where the water is salty.
After identifying the sites that we wanted to sample at, we needed to figure out how to sample. We wanted to sample the mud at different depths, so we decided to use syringes to suck up the mud.
Once all of the samples were collected it was time to get back into the lab to analyze the data. In order to confirm the presence of Zetaproteobacteria we conducted PCR, which is a process that tells us if there was any DNA belonging to the Zetaproteobacteria in the samples.
To analyze the iron a ferrozine assay was conducted. In a ferrozine assay, different chemicals are added to the samples, which then turn different shades of purple depending on how much iron is present in them.
While we have already completed a lot of the data collection, we still have more to do. In the next few weeks we will focus on collecting the last few samples and analyzing them in the lab. Soon all of the results will be ready for interpretation!
I would like to thank my mentor, Dr. Heather Fullerton, for guiding me through this research. I would also like to thank the National Science Foundation for funding this research as well as the College of Charleston and Grice Marine Lab for their support.