Shedd Aquarium scientists researching impact of sewer overflows on fish in Chicago River
The heavy rain that soaked the Chicago area on Wednesday is being studied as part of a research project at the Shedd Aquarium, where scientists are examining how extreme weather impacts wildlife in the Chicago River.
Scientists are studying the long-term impact on fish when sewage ends up in the river after heavy rain.
Researchers at the Shedd Aquarium are putting tiny trackers inside fish living in the Chicago River to study them and the environment.
Scientists said it's work that's important as the environment fluctuates, with climate change bringing more rain our way.
"We have, at the moment, 100 fish that have tags within them, and those tags shout out a unique ID," said Dr. Austin Happel, a research biologist at the Shedd Aquarium.
Trackers about the size of Advil pills have been implanted in fish in the Chicago River to track their movement – carp, largemouth bass, and walleye. Researchers said aquatic ecosystems reveal a lot about the health of the environment and signal issues early, since they're more sensitive to change like climate change.
With changing weather, meaning more extreme weather and more rain events, sewer overflows present a unique issue for the Chicago River.
When heavy rains overwhelm the Chicago area's combined sewer systems, stormwater and wastewater can mix in the same pipe, and sewage can end up in the Chicago River. When that happens, fish leave the river and don't come back.
So while sewage overflows into the river are happening less frequently, the impact is long-term.
"That over a century of use and misuse has kind of built up, and so we can see that in what's called the sediment — the bottom of the river — that is contaminated with all sorts of heavy metals, or even organic waste, that has built up from sewage being dumped into it," Happel said.
The Shedd Aquarium's research project shows why it's important to bolster infrastructure to prevent sewage from getting in the river.
With more extreme weather expected moving forward, and the health of the Chicago River vital, Happel said, "if a system is super species-poor, we might see problematic events. Like maybe we will have a bunch more mosquitoes, or something like that, in the area."
"I'm trying to understand how do organisms live within this super-altered system, and how do we make their lives better? Because if restoration works here, it's going to work in any of those other cities that have the rivers flowing from an area into the city and back out," Happel said.
Researchers will tag 70 more fish in the Chicago River this spring.
