Week Three

by corbilm11

Last week started similar to the previous week. However, the focus of last week was to collect tissue samples of fish species for DNA sequencing this week. On Monday morning, we put our gill nets and hoop nets out at our four sampling locations by the power plant. That evening, we checked our nets and recorded the lengths and weights of the fish that we caught. We also took tissue samples from each different fish species that we netted. This process of checking nets, recording lengths and weights, and taking samples for DNA sequencing continued for the rest of the week with the exception of Wednesday morning.

On Wednesday morning, thirty high school students came out to the Thomas More College Biology Field Station for an educational field trip. Before they arrived, Dr. Lorentz took us out electrofishing to collect fish to show them. While shocking, a five-foot paddlefish came thrashing to the surface and was gone in the blink of an eye! Paddlefish are prehistoric fish that have remained relatively unchanged for the past seventy five million years. However, they are not as common as they once were. When the students arrived, they were divided among the different intern groups for an hour each before rotating. The interns at the field station were able to instruct the students about their summer research projects. For instance, my intern group and I went with Dr. Lorentz and instructed the students how to boat electrofish, take water quality data, check a hoop net, and sample for zooplankton. We took two boats, Dr. Lorentz in the electrofishing boat and two interns and I in the second boat that focused on water quality, zooplankton sampling, and checking the hoop nets. The boat ride began with a short discussion of the importance of water quality and the meaning of each parameter. We also discussed the range of parameters a healthy river system should possess. Next, we let the students use the necessary tools to collect their water quality data and record their findings. We also encouraged them to make general observations about the current weather because the weather can significantly affect fish movement. When we checked the hoop net, they were all excited to see a longnose gar in the net.

On Wednesday afternoon, I went with Dr. Lorentz to take more students boat electrofishing. Dr. Lorentz informed the students of the importance of electrofishing. It is a widely used process and is one of the best methods to sample fish because it does not discriminate; it targets all fish species. Furthermore, it does not harm fish it only temporarily tetanizes them. Additionally, fish do not have pain receptors, so they cannot feel pain. While we were electrofishing at the confluence of a small tributary of the Ohio River, two silver carp came hurdling out of the water and one landed in a student’s net! This was an interesting revelation because silver carp are an invasive fish. These carp were used in ponds to reduce the algae and zooplankton. However, they first entered the Mississippi River when the farm ponds flooded. They eventually moved north into the Ohio River and are continuing to move north today. The controversy with silver carp (pictured below) is that they are detrimental to freshwater systems and they out compete native fishes such as the American paddlefish. Both of these fish have robust gill rakers used to filter out zooplankton, but when they are placed in the same system the silver carp will out compete the paddlefish.

 

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For the remainder of the week, we continued to check our nets, take tissue samples, and we volunteered for River Sweep and Paddle fest. We did not find any rare or unique fish in the nets this week. On Friday, we pulled the nets and once again began the tedious process of mending and pressure washing them. River Sweep was Saturday and I was in charge of driving a boat to transport volunteers to nearby sections of the Ohio River. This turned out to be a lot of fun and we were able to remove a decent amount of trash. In total, 21,000 participants volunteered for the Ohio River Sweep. The most interesting item that was found from the volunteers near the field station was an old wagon wheel hub that was estimated to have been from the late 1700s or early 1800s. On Sunday, the largest paddling event east of the Mississippi River occurred; Paddle fest. For this event, the U.S. Coast Guard closed commercial and powerboat traffic for an eight-mile section of the Ohio River from Coney Island to Cincinnati. Over 1,400 canoes and kayaks entered the river for this occasion. Unfortunately, I was unable to attend this event because I was out of town with a colleague.

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This week we will be performing DNA sequencing and boat electrofishing at night. We started the first few steps of preparing our tissue samples for sequencing today at the Cincinnati Museum Center. This consisted of taking our tissue samples and cutting them into smaller pieces to increase the surface area. Next, we used a micro pipet to insert a digestive buffer into each test tube. We added another agent and placed the test tubes at 60°C until tomorrow morning. This process creates a soup like mixture that exposes the DNA for extraction.

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Currently, I am preparing to go boat electrofishing tonight!

Thanks for reading,
-Luke

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