Kurt Waibel '19

Summer Research Scholar with Robert Humston, Biology and Environmental Studies, Summer 2017

The goal of our research project was to create detailed food webs of three separate rivers in the Virginia watershed. These food webs of the Dry River, the Tye River, and Ramsey's Draft will provide us with valuable insight on the effects of smallmouth bass movement into ecosystems that are historically home to native brook trout.

This summer was mainly focused on the collection of organisms that make up the food webs of these ecosystems. Several days a week we would drive out to each of these sites and use sein nets to collect macroinvertebrates that make up the primary consumers, detritivores, and occasional secondary consumers of the ecosystem. Once sufficient representations of the main feeding groups were collected from all of these macroinvertebrates we switched our focus to the fish that occupy these rivers. We employed electrofishing techniques to efficiently collect over 500 individual fish, ranging from bottom-feeders (suckers) to top predators (smallmouth bass and brook trout). Electrofishing required strapping a 40lb pack containing a battery to the back of two members of our six-man team. Each pack enabled the team member to place an anode and a cathode into the stream in order to create an electrical field; stunning any fish and allowing the other members to net them. Any fish caught were immediately placed in oxygenated holding tanks in order to limit the chance of accidental losses. Once enough fish were collected from each site, we began taking the data we needed. For our target species, each fish was anesthetized, measured for length, had a section of the anal fin clipped for isotope analysis, and were allowed to recover before they were released.

After our team had completed our field work for the summer, we spent numerous hours back in the lab organizing and analyzing the data we had collected. For all of the macroinvertebrates that our team had collected from each site, we were first tasked with identifying each one down to the family (species if possible) using microscopes. Then, each macroinvertebrate was counted, dried, and crushed so that they could be placed in labelled vials. As for the fin clips we had collected over the course of the summer, these were dried and placed in vials in the same manner that the macroinvertebrates were.

The final stage of our project will be the stable isotope analysis conducted over the course of the upcoming school year. By measuring out small amounts of each of our data points (both macroinvertebrates and fin clips), we are able to use the mass spectrometer to analyze the isotopic ratios of the various organisms in the different streams. This final stage of our research will allow us to put together a composite food web of the three different streams by using the isotopic compositions of the organisms present. These isotopic ratios will determine what ecological niche each species occupies and will help us determine whether the presence of invasive smallmouth bass is detrimental to native brook trout populations or not.

For other opportunities, view the Geology Department's Summer Research and Internships page