Tiny Insects, Big Impact: Cedarville Study Explores Midges as Water Pollution Indicators

Water quality remains one of the most pressing environmental challenges in the United States, costing more than $35 billion annually in mitigation and treatment efforts. At Cedarville University, a team of researchers is exploring innovative solutions to monitor and prevent water pollution using an unexpected yet highly effective indicator: midges. 

Midges, small aquatic insects of the family Chironomidae, spend most of their life cycle as larvae in freshwater streams before emerging as non-biting adult flies. Because these larvae derive nutrients directly from their surrounding water, they can serve as indicators of environmental conditions. Cedarville faculty members and students are working to identify midges at the species level across Ohio, map their geographic distribution and determine their tolerance to varying stream conditions, including pollution levels. 

How midge species can help detect pollution in Ohio waterways

By analyzing which midge species are present — or absent — in specific waterways, researchers hope to use these organisms as biological tools to detect water quality problems, identify specific pollutants and highlight rare species and habitats that may require protection. 

“We’ve known for a long time that midges as a family are everywhere, but that as a species, they are not,” said Dr. Mike Mendel, professor of biology and principal investigator of the project. “Different species show up in different kinds of streams, and that’s where the real ecological story is.”

Different pollutants affect midge species in different ways

A wide range of water pollutants can affect midges, including low oxygen, excess sediment and metals such as copper and mercury. Because each species responds differently to these stressors, their collective presence can serve as a diagnostic tool for assessing stream health. 

“The beauty of midges is that different species are sensitive to different pollutants,” said Mendel. “That means a diverse group of midge species can give us insight into a wide range of water quality problems. In many cases, they may provide earlier and more precise warnings than traditional testing methods.”

Why biological indicators can be more effective than chemical testing

Monitoring aquatic life is widely recognized by environmental scientists as one of the most reliable methods for evaluating water quality. While chemical testing can be expensive and misleading, biological indicators can be a cheaper and more direct way of understanding environmental changes. 

“Every stream we visit tells a story,” said Abby Paulding, a junior biology major and student researcher on the project. “We note how wide it is, how fast it’s moving, how shaded it is and what the stream bed is like. Then, we look at which midges can live in those exact conditions.”

Cedarville student researchers collect stream samples across Ohio

After collecting and analyzing samples from streams across Ohio during spring seasons, researchers are building predictive models showing where specific midge species should occur.

“This leads us to the next question,” said Mendel, “why aren’t those species where we expect them to be? At that point, you can start tying absences to specific pollutants or environmental changes.”

Undergraduate biology research supports environmental protection and public health

As the project moves into the data analysis phase, it is contributing not only to environmental protection efforts but also to hands-on undergraduate education in the sciences.  

“It’s one thing to read a scientific paper and think, ‘Oh, that’s what they did.’ It’s another thing to be the one hiking to the stream and collecting samples,” said Paulding. “This research has helped me realize that I love both sides of the work — the muddy, hands-on field days and the careful hours at the microscope.”

By combining field research, data analysis and ecological modeling, the Cedarville team hopes to safeguard ecosystems and public health on a broad scale.

About Cedarville University

Cedarville University, an evangelical Christian institution in southwest Ohio, offers undergraduate and graduate residential and online programs across arts, sciences and professional fields. With 7,265 students, it is among Ohio's largest private universities and is ranked among the nation’s top five evangelical universities in the Wall Street Journal’s 2026 Best Colleges in the U.S. Cedarville is also known for its vibrant Christian community, challenging academics and high graduation and retention rates. Learn more at cedarville.edu.