OSCAR Student Investigates the Predator-Prey Dynamics Between Fish and Macroinvertebrates Tributaries to the Potomac River

As a member of the ecology team for the Potomac Environmental Research and Education Center’s (PEREC) summer OSCAR team project, my research goal is to investigate the predator-prey dynamics between fish and macroinvertebrates in two freshwater tidal Potomac River tributaries, Gunston Cove and Hunting Creek. This means, I examine the stomach content of 15 fish species known to inhabit both embayments in order to construct a food web for each location.

Due to variations in aquatic habitat types within the embayments (i.e., vegetated and non-vegetated), I use three different methods to collect my fish samples: fyke nets, seine nets, and otter trawls.

A fyke net is a passive collection technique in which fish are guided into a funnel shaped net by three leads, or guide nets. Once fish enter the funnel through narrow openings, they are unable to return to the outside of the net. The funnels on the fyke net are comprised of subsequently narrower openings that make exiting the net difficult for many fish. This method is implemented in heavily vegetated habitats where the submerged aquatic vegetation is so dense it is impossible to actively pull other types of net through.

The second method, seine nets, are an active collection technique in which two people extend a long net perpendicular to the shore and then drag it parallel to the shore for approximately 100 feet. This targets fish along the shoreline and can be used in vegetated and non-vegetated habitat. However, seine nets become very difficult or even impossible to use effectively once the vegetation reaches a certain density.

The third method, otter trawls, are another active collection technique in which a weighted net is dropped off the back of the boat and dragged at a constant speed for 5 minutes. Like the seine net, this method can be used in vegetated habitats to an extent. If there is too much vegetation, the trawl will become clogged or too heavy and will have to be reset, so it is best used in open water.
Once my fish samples are collected, I take them back to the lab to remove their stomachs for examination. I then sort the contents of their stomach into groups based on the lowest possible taxonomic level, which can be challenging if the organisms in the stomach have already begun to digest.

While there are published studies focused on the diet of many of the fish species I am studying this summer, none of the studies focus on populations in these specific tributaries of the Potomac River. The species found in these systems are unique, in a way, due to their close relationship with wastewater treatment plants upstream. These treatment plants feed nutrient rich effluent (i.e., discharge water) into the streams that then flow into these embayments. Adding additional nutrients to an aquatic system has the potential to influence the type of organisms that can live there.

I will use the organisms I identify in the fish stomachs to construct a food web, which will allow me to compare the diets of fish communities that reside in non-vegetated habitats, such as shorelines and open water, to the fish communities that reside in vegetated habitats, such as the submerged aquatic vegetation (SAV) beds.

Pursuing this question is interesting because in the 1980’s Gunston Cove was a hypereutrophic (i.e., very nutrient rich) system, due to the nutrient rich effluent released from the Noman M. Cole, Jr. Pollution Control Plant (NCPCP), which provided ample nutrient resources for phytoplankton algae to grow. Eventually, the algae became so abundant that it formed a thick green layer over much of Gunston Cove, which blocked the sunlight from reaching the streambed, preventing the growth of SAV. However, in an effort to reduce the occurrence of these harmful algal blooms, NCPCP reduced the amount of nutrients released in their effluent and after many years SAV beds began to reestablish (like they were prior to the 1980’s).

Now that nutrients, such as phosphorus (the first nutrient that was reduced in the wastewater effluent) and nitrogen, are better regulated, light is able to penetrate the surface and in turn SAV is able to grow. The food webs I construct will compare the potential impacts shifting from the historically non-vegetated habitat to the emerging vegetated habitat may have on the diets of fish in Gunston Cove and Hunting Creek.

As an Environmental Science student, I am very interested in the interactions that take place between organisms within an ecosystem. One day I hope to incorporate ecosystem modeling and spatial analysis into my own research, to investigate the potential impact factors such as climate change or invasive species can have on populations of aquatic species.

When I saw that Dr. de Mutsert was looking for a student to help construct a food web, I thought that this was a great place to start. Before I can create models to predict how stressors such as climate change or invasive species will impact an ecosystem, I must first understand how the species currently interact with their environment and surrounding community.

Now, I begin week seven of attempting to answer an unanswered question with high hopes and a long to-do list. I have spent many hours this summer on a boat collecting fish for my project, and macroinvertebrates for my partner’s, trolling the internet and library for resources on how to conduct a diet study and information on the history of the fish community in the Potomac River. More recently I have begun processing my 196 fish samples to try to understand what exactly is going on in the Potomac River (i.e., who is eating whom). The past six weeks have been spent collecting my fish samples and preparing the content in their stomachs to be examined.


With only two weeks left until our results are due to our advisors, it is now time I use our data to begin connecting the dots between the inhabitants of each embayment. The only thing standing between the coveted answer and myself are approximately 190 fish stomachs, but have no fear – I’ve come prepared with my microscope, tweezers, and coffee. Stay tuned to find out what happens next.

OSCAR Student Adam Schuman and the Peter Ritter Transcription Project

What got me interested in this was the opportunity to work with a professor outside of the classroom. I also got really excited about the daily work that I hoped I would be doing. In high school I transcribed some string quartets in my music theory classes and I really loved how I learned from transcribing. I got excited when I saw that this position was to edit and transcribe music. I love music theory and classical music but because I’m a music tech major I don’t have to take as many music theory classes as everyone else. To me this was a way to keep in touch with that side of music without taking classes for it.

I currently don’t see this experience directly helping my long term goals. I see this experience as something that can open up a career avenue post college. I am looking forward to adding the experience to my resume. I think it looks very good and can really help differentiate myself from other job applications.

On a weekly basis I am transcribing music from my phone or computer into Sibelius. Sibelius is the music notation software that the Ritter team is using. I would get through a certain amount of pages of music per day. The amount of pages depends on the size of each page and how legible the pages are. The challenges are not just putting in notes but paying attention to every bit of detail that’s on the manuscript. Translating what Peter wanted the music to sound like into my own edited edition. Later in the project the team began to work on posters. We divided up the work and each made a section of the poster for the presentation August 4^th.

Something that I discovered is how music changes and differs from the hands of a composer to an editor. An editor makes decisions that effects how a piece is performed. Hearing a piece that I edited is a very interesting experience because I imagine it sounded better when Peter’s musicians played it.

OSCAR Student Molly Kluck Researches Human Fetal fMRI

In my Sophomore year, I signed up for an introductory course on bioethics. It was taught by my now mentor, Andrew Peterson. The first class was about how fMRI has been used to detect sentience in patients that were previously thought to be in a vegetative state. I was sold. It was the next class, I think, that I went up to him and asked for more material. A few classes later, he asked if I’d like to meet him, and some other students he had “collected”, for a Neuroethics meeting. I agreed, and from there on, we’ve had several meetings where we look at ethical concerns involving the brain and share our work with each other. It was through this group that I became enthralled with the implications of the fMRI research being done on human fetuses.

As I look towards the future, I see myself staying proactively involved in matters of research that relate to human consciousness. I’m very interested in the how and when of its occurrence. My ultimate interest is in artificially intelligent machines and I think that in order to truly understand any type of consciousness these machines may have, that it is necessary to understand human consciousness.

On a weekly basis for my project on the ethics involving human fetal fMRI research, I mostly read a lot. The main focus of this project has been a paper that I will hopefully be submitting to the International Neuroethics Society’s annual meeting. As can be imagined, this has involved reading a lot of research articles that have been about how fMRI works, the noted effects on human bodies, bioethical articles that involve arguments surrounding the moral status of fetuses, and effects of common phenomena like heat and sound on a developing fetus. Writing and designing my poster was the other half of my weekly story.

As I have made it through this summer, my greatest discovery was that keeping an open and flexible mind is key to research. Especially research as subjective as an ethical analysis. It can be difficult to say what is wrong and what is right, but with an open mind and lots of research it is possible to find an answer backed up by science.

OSCAR Student Simone Hawkins and the Peter Ritter Transcription Project

I first became interested in the field of musicology and research while studying at NVCC Alexandria and would especially like to thank Professor John Kocur for his support and inspiration throughout my discovery of and consequent passion for music history, and neglected and virtually unknown/forgotten composers. As a transfer student to the B.A. Music program at George Mason University, I have been able to further my experience and skill in music research. Namely, my private study’s in period performance [practice] violin with June Huang has enabled me to increase my expertise in working with manuscripts (facsimiles) and being able to interpret music in a style appropriate to the composer’s intention. These experiences and the knowledge I gained from them helped prepare me for the extent of the research involved in the Peter Ritter project.

As opposed to doing research for my own personal interests, having the opportunity to do so in an academic setting as an undergraduate student is what immediately drew me to the Peter Ritter research project. And because music research is what I want to do after my undergraduate studies, being a part of this OSCAR summer group has given me hands-on experience in this field. This summer, I actually did something that I had not done before – I learned how to use the records at the Library of Congress and was therefore able to handle the physical manuscripts of some of Ritter’s music, which I later transcribed. Seeing the composer’s handwriting in person and turning the pages of the manuscripts made the research all the more exciting! All of my previous studies utilized online resources and databases, but I find that using the original music is more interesting and engaging because not only can you see markings and errors, which may not be visible in facsimile editions, but it also provides you the rare experience of working with primary sources.

OSCAR Student Chris Carlson Explores Different Methods of Perturbing Circuits to Transition Across Different Stable States

Working in Dr. Cressman’s lab has given me the opportunity to continue my research on non-linear dynamical systems. I initially became interested in Chua’s circuit as a sophomore while I was a lab assistant at the Krasnow Institute, where I produced simulations of the circuit. During the fall semester of my junior year, our focus was studying the fluctuation relation, a non-equilibrium theory, in the context of Chua’s circuit. With funding from the URSP, I have continued studying this system over the summer. Currently, we are exploring different methods of perturbing the circuit to transition across different stable states.

Unlike many-dimensional dynamical systems, Chua’s circuit is a simple chaotic circuit that only requires a few electronic components, thus making it easier to study in the lab. Chua’s circuit also has multiple simultaneous stable states, and can transition from one state to another. Our goal is to minimize the resources needed to move between states. We are exploring the different methods of transitioning by applying small perturbations of current in the circuit.

My work involves three main tasks: perturbing the circuit, perturbing the model, and comparing data from both the circuit and the model. I am also collaborating with professors from the mathematics department and using algorithms to predict and calculate stable and unstable directions in the system. One of the tools we use is called a Kalman filter, which is a predicting algorithm that helps us to forecast the system in real time. Additionally, we use the Kalman filter to verify and improve our model. The experiments we conduct in the model are replicated in the physical system. Data from both the model and circuit are then analyzed. From this data, we can improve on our approach to perturb the system.

In the future, I would like to pursue a master’s degree in engineering and focus on research. This project has given me a glimpse of what that entails. I believe that I have learned some skills, in the lab, that will help me with future academic and career goals. Above all, I have realized that scientific results come from hard work and persistence. I am grateful for the opportunity to contribute to science through my own work.