Final Week

by corbilm11

Last week was the conclusion of my summer internship at the Center for Ohio River Research and Education. The week began with a tour of Dr. McGregor’s mussel research lab. Dr. McGregor’s mussel lab is a unique state of the art facility that has all the necessary equipment to propagate mussel growth and development. There are small tanks for growing glochidia, small fish host tanks, mussel storage tanks, and algae tanks for growing food for the mussels. Dr. McGregor discussed how each system in his lab works. It was an interesting and informative tour that complimented his seminar that he gave the previous week.

We finished our habitat assessments and zebra mussel scraping on last Tuesday (August 5th). The habitat assessments were conducted at our upstream sample sites Z2 and Z1. We used the same methods as we used the previous week for Z4 and Z3. Once we finished the habitat assessments of our upstream sites, we performed zebra mussel scraping on the furthest upstream mooring cell. The zebra mussels were placed in 95% ethanol to preserve them for further processing in the lab. Before heading back to the lock house, we collected the remaining Hester Dendys as well. The Hester Dendys are part of an intern’s independent project. However, we assisted whenever we had extra time.

On last Wednesday (August 6th), we had a seminar with Dr. Erik Pilgrim about DNA barcoding and metagenomics applications for aquatic ecosystems. He uses these molecular genetic tools for environmental bioassessments and invasive species detection and monitoring. His goal is to provide quick and cost effective measures of aquatic biodiversity than previously possible. He intends to achieve his goal by using metagenomics. Essentially, metagenomics is genetic material recovered directly from environmental samples. For example, Dr. Pilgrim could take a kick net sample of benthic macroinvertebrates and grind them up, and sequence their DNA. The results would display all the macroinvertebrates that were present in the kick net sample.

We gave our final presentations on Friday (August 8th). We began by having five interns including myself present the PowerPoint presentation about our bioassessment of the Ohio River near the Zimmer power station. Our bioassessment presentation covered the results of our habitat assessment, physiochemical sampling, and fish collection. Once we finished our bioassessment presentation, the two interns that spearheaded our side DNA project presented a separate PowerPoint about our findings with the molecular work.
We presented our habitat assessment and physiochemical results first. We found that our upstream and downstream sites have a similar average depth, riparian area, and shoreline. By design, our four research sites are similar. It enables us to analyze the potential impacts Zimmer has on the Ohio River. For our habitat result, we found that research sites Z1, Z3, and Z4 are dominated by gravel substrate. Z2’s substrate consists mainly of fines (silt and clay). All four research sites lacked an abundance of boulders. For our physiochemical results, we compared our downstream sites to our upstream sites. There were no significant differences for pH, dissolved oxygen, and water temperature. However, there were significant differences for conductivity and secchi disk depth.

The next section that we presented was our fish results. We calculated the Ohio River Fish Index, number of species, individuals, and biomass for fish captured in our nets and electrofishing. The Ohio River Fish Index rates the health of a fish population. The minimum score is 13 and the maximum score is 65. Z1, Z2, and Z4 were rated as good scores, while Z3 had a fair score. In total, we sampled 32 fish species and 1,261 individuals.

Through our study, we found that the Ohio River around the Zimmer power plant meets water quality standards to support aquatic life. Our four study sites were comparable across all datasets including, physiochemical, habitat, and biological. However, there were a few notable exceptions:

• A higher proportion of fine substrate at Z2. This negatively affects the fish community in this area because benthic macro invertebrates tend to colonize structured substrates. Benthic macroinvertebrates are a primary food source for numerous fish species and they need structured substrate to colonize.

• Another notable exception is that we sampled higher abundance of fish downstream in our gill nets. This could be attributable to a tributary known as Big Indian Creek near Z4. This stream could be bringing nutrients and attracting fish to this area of the Ohio River.

• The next notable exception is that there was a significantly higher number of fish sampled upstream through electrofishing. This is because we sampled many mimic shiners upstream while electrofishing. However, it is not uncommon to collect a mass of minnows one night and none the next.

• The final notable exception is that there were significantly higher turbidity and conductivity levels downstream of the Zimmer power plant. The increased turbidity downstream could be due to high barge traffic, Big Indian Creek, recreational boaters near boat docks and ramps. We suspect that the increased conductivity is a consequence of suboptimal discharge from the Zimmer power plant.

Overall, this internship has been a great experience. I am grateful for the opportunity that I had to be a part of the long-term bioassessment of the Ohio River near the Zimmer power plant. I learned first-hand crucial big river sampling techniques and procedures. I was fortunate to spend almost every day working outside on the mighty Ohio River. Throughout this internship, I was able to work with multiple agencies and learn from professional researchers through their interactive seminars at the lock house. These collaborators include the Newport Aquarium, Duke Energy, Kentucky Fish and Wildlife Service, Cincinnati Museum Center, U.S. EPA, U.S. Army Corps of Engineers, ORSANCO, and other agencies. I would also like to thank Dr. Lorentz and all of my colleagues from this summer. Additionally, I am grateful of all the support that I have had throughout this internship.

Thanks for reading,
-Luke

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