Recent fish kills provide learning experience for environmental science students

Brazos River. Grace Everett | photo editor

By Gillian Taylor | Personal editor

Low dissolved oxygen levels in the Brazos River and Waco Creek have likely led to fish kills recently, and Baylor students used what they learned in class to help collect data from the site.

A kill fish is a localized mortality of one or more species of fish. It can be caused by multiple factors including low dissolved oxygen levels, fluctuations in water temperature, harmful algal blooms, toxins, pesticides, fertilizers, chemicals, disease , viruses, bacteria and parasites.

Professor Baylor and environmental toxicologist Dr Cole Matson said the cause of the Waco fish kills, which began in mid-October, is not officially known. However, he said that’s likely due to recent rainfall that ended a dry spell and flushed organic matter and nutrients into Waco Creek. The influx of nutrients, he said, could have fueled microbial growth in the water and consumed oxygen in the process. What was left were abnormally low oxygen levels and suffocating aquatic life.

Matson teaches a course called Field techniques for environmental sciences, in which it covers air, water, sediment and biota sampling techniques with an emphasis on aquatic systems. The class studies the factors that control dissolved oxygen in marine systems.

“When we found out there was a low dissolved oxygen event and fish kills were happening, we made it a learning experience for the class,” Matson said. “We decided to go out, study it, map it, find out how far it had gone and we did some nutrient analysis to try to figure out what could have caused this event.”

Pearland junior Anna Claire Brewer, a student in Matson’s class, said that although the circumstances were unfortunate, she was able to get real-life examples of what she is learning.

Brewer said in class they hypothesized how certain factors affect aquatic species, but with the Waco fish kill, students were able to see the effects in real time. They began their search just outside the Baylor Sciences Building in Waco Creek and began measuring oxygen levels.

“We saw a lot of dead fish, and the rest were coming up to the surface of the water because that’s where most of the oxygen was,” Brewer said.

Matson said the students went out on a boat to try to map the distribution of low dissolved oxygen levels. He said the course mainly focused on how oxygen levels change with depth.

Texas Parks and Wildlife collected portions of the students’ research, and Matson said he was delighted to have their work permanently saved.

Brewer said fish kills were a clear visual of the importance of environmental policies.

“We don’t know why fish kills occurred or why dissolved oxygen levels got so low,” Brewer said. “But it’s important to have people like Texas Parks and Wildlife, and policymakers like the EPA, to regulate environmental factors and prevent things like this from happening in the future.”

According to Matson, fish kills are typically acute events, so oxygen levels in Waco waters are “apparently recovered at this point.” However, he said there were significant mortality rates in the fish populations and it would take time for them to fully recover.

In his 11 years in Waco, Matson said there have been other occurrences like this, although it was the worst fish kill he’s seen here. He said that although the situation is unfortunate, he is proud of his students for playing a role in the data collection.

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