Small Ponds, Big Impacts: CFL Researchers Explore Urban Ponds to Better Understand Human Influence

by Madelyn Anderson – Fieldwork comes in many forms. Some researchers spend their days wading through Wisconsin’s wetlands, looking for bugs in local rivers, and boating through Lake Mendota, the birthplace of limnology in North America. 

But other scientists are at work right in your own backyard or neighborhood park. 

PhD candidate Jessica Briggs is spending her summer investigating urban ponds in Madison and Middleton. Working in Dr. Grace Wilkinson’s lab, Briggs and her team of curious undergraduates sample eight sites each week. Four of them, Tiedeman’s, Strickers, Forebay, and Lake View West serve as “core” ponds, providing crucial information to the project.  The other half, Elver, McKee, Orchid Heights, and Lakeview function as volunteer sites, relying on community science to help collect data. 

A woman surrounded by plants on the shoreline of a pond.
Mercedes Hernandez-Natera processes water samples taken from a pond. Photo: Madelyn Anderson.

Each week Briggs and her crew profile their ponds, recording water temperatures, dissolved oxygen and pH levels, and even the amount of people present in the area. 

My research interests focus on carbon and nutrient cycling in aquatic ecosystems with high levels of anthropogenic influence,” Briggs said. “I want to understand how human activity changes how aquatic ecosystems are functioning – both directly through processes like urbanization and indirectly through climate impacts.”

Small bodies of water provide a direct look into Brigg’s questions, allowing her to paint a picture of their ecosystem metabolism and greenhouse production rates. While these bodies of water might be small in surface area, they’re large in impacts. 

“All of our ponds are slowly starting to move toward hyper-eutrophic, or extremely nutrient rich, levels due to human influence,” said undergraduate technician Emily Ledin. “And due to human-driven climate change, storms are also increasing, which affect their contents. So we’re studying these two factors that are likely to intensify with time.”

A woman holds two large syringes containing water samples.
Emily Ledin with samples collected on her study ponds. Photo: Madelyn Anderson

Team member Mercedes Hernandez-Natera described just how quickly these ponds’ profiles can change after a storm – or group of people – moves through. 

“The first time I visited what I thought was my favorite site, everything was lush and clear,” said Hernandez-Natera. “But when we came back, it was littered with trash and a thunderstorm had washed decomposing animals and things over [to shore].” 

This contrast leaves the researchers with more queries. 

“When it rains, we are focused on seeing what in the water is diluted versus what is enriched,” said Briggs. “Is the storm increasing or decreasing that parameter?” 

For example, Ledin and Hernandez-Natera donned waders and nets on an early Monday morning, tracking chlorophyll levels at one site as the daylight trickled in. By nightfall, the sun was replaced by a storm, washing runoff from local neighborhoods, factories, and farms into the pond. 

When they returned later in the week, their data revealed a difference. 

Chlorophyll is usually flushed and decreases initially (after a storm) but then growth is promoted and increases, resulting in a peak days later,” said Briggs. 

While Brigg’s and her team still need time to analyze how these trends move and what they mean, one thing is clear: humans make an impact. And that matters because these small ponds are part of the larger watershed that feeds into our lakes. Whatever happens in them ends up downstream. So, next time you contemplate the wonders of limnology on the lake, remember that a lot of what’s going on in our waters starts in your own backyard.