As you dine on locally-caught fish, you probably aren’t thinking of that old acrylic sweater or fleece jacket that you wear and wash frequently. But it turns out that they may be on your plate. Illinois-Indiana Sea Grant-funded researchers have found microplastic fibers that come from clothing and other sources in the water, in sediment and in fish in three major rivers that flow into Lake Michigan.

Loyola University Chicago biologists John Kelly, Tim Hoellein and Rachel McNeish are assessing levels of microplastic using a range of measures. As part of a larger study, they collected samples from the mouths of the Muskegon, Milwaukee and St. Joseph rivers seasonally over the course of 2016 and into 2017.

“We found that 99 percent of the microplastic is fibers, and microfibers are everywhere,” said McNeish, a post doc who implemented the project. “Much of what we found is acrylic, polyester, and polyethylene, which comes from plastic bags.” These plastics break down to microscopic size in the water due to physical abrasion, sunlight and freezing.

While water sampling is typically done using nets, the Loyola team also sampled water directly. “We started doing these grab samples, we just fill up a liter container and bring it back and filter it, and we found particles smaller than 300 microns, the pore size of the nets,” said Kelly. “The smaller you go, the more numerous the pieces of plastic there are.”

The three rivers in this study have provided insight into the effect of how we use the land on how much microplastic is in the environment, which was a key goal of this project.

The most northern river, the Muskegon, which flows through land dominated by forests had less microplastic than the other two rivers, as one might expect. Moving south to more populated and developed areas, are the St. Joseph River, in a farm-rich watershed, and the Milwaukee River, which sits in a mixed, urban and agricultural region. The researchers found that both agriculture and urban land uses contribute significantly to the abundance of microplastic in these Lake Michigan tributaries.

“Ultimately what we really want to do is predict what aspects of our development or features of the landscape pose bigger problems when it comes to contributing microplastic to the landscape,” said Hoellein. “And we need to understand where microplastic accumulates the most, because if we don’t answer those questions, we’re not really in a good position to come up with a solution or even address the problem.”

The researchers also sampled 74 fish from the shallow waters of these three rivers and 85 percent of them, including bass and other sportfish, contained microplastic in their digestive tract, averaging 13 particles. They found that the amount of microplastic in individual fish was not a reflection of how much plastic was in the water—fish from all three sites had similar numbers of microfiber in their digestive system.

How much microplastic shows up in one fish versus another can better be explained by looking at the food web. The researchers found that fish that eat insects and other invertebrates, which may already contain microplastic, have more fibers than those that eat plants.

“Microplastic is interacting with aquatic wildlife,” said McNeish. “Fish are consuming it—either actively eating it thinking its food, eating insects with microplastic in them or maybe just drinking water with microplastic. Or they may consume it through contact with sediment. In any case, microplastic is entering the food web.”

“And as these three rivers drain into Lake Michigan,” she explained, “the movement of microplastic can happen with the rivers’ currents, but also through the migration of animals.”

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🌊 Boost Your Great Lakes Literacy in 3 Easy Ways!1️⃣ Read the Great Lakes Literacy Principles2️⃣ Join a Sea Grant professional learning event3️⃣ Explore Great Lakes educational resources📬 The summer edition of the Center for Great Lakes Literacy newsletter supports all three—and more!Perfect for educators, environmental leaders, and curious minds.👉 Subscribe today and dive into a world of Great Lakes learning: https://conta.cc/3ZtrIKc or the link in bio.
Don’t miss this opportunity to enhance your teaching skills and connect with fellow educators! Join us for a two-day, water-themed workshop on August 8-9, 2025, at the Dunes Learning Center located in Indiana Dunes National Park. Open to all 5-12th grade formal and non-formal educators, this event offers a chance to explore the natural world, network, and receive exclusive access to the newest Project WET Educator’s Guidebook: Water in Earth Systems.The registration deadline is July 18th.Learn more at the link in bio.
📣 Aquaculture Teacher Workshop – June 2025🗓️ June 26–27, 2025📍 Purdue University – John S. Wright Forestry Center🕐 Starts June 26 at 1 PM | Ends June 27 at 4:30 PM🌿 Optional Pre-Tour: June 26, 10:30–11:30 AMExplore Aquaculture & Aquaponics in Action!Perfect for science teachers looking to bring hands-on, real-world STEM into the classroom.What’s Included:✔️ Facility tours at Purdue & nearby✔️ Build-your-own aquaponics system (FREE to take home!)✔️ Hands-on labs & classroom integration ideas✔️ $250 stipend for travel or classroom supplies✔️ Open to formal and non-formal educatorsLearn how aquaculture is a powerful tool for engaging students in science, sustainability, and food systems!Spots are limited – register early!Learn more at the link in bio.
IISG is hiring a part-time pollution prevention outreach assistant. IISG’s pollution prevention team addresses water quality issues affecting the Great Lakes coasts and the inland waters of Illinois and Indiana, specifically focusing on contaminants of emerging concern like pharmaceuticals, microplastics and marine debris, and PFAS. This outreach assistant will support the pollution prevention team by developing outreach activities and engaging with communities to share that knowledge.Learn more and apply at the link in bio.
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