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Kirsti Marohn

Study: Chemicals affecting fish in Great Lakes rivers

Lake Superior, seen in Duluth.
Lake Superior, seen in Duluth.
Derek Montgomery for MPR News file

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Chemical compounds from human activity are affecting fish in rivers that feed into the Great Lakes, a new study shows.

These compounds, known as contaminants of emerging concern, come from a variety of sources including pharmaceuticals, personal care products, flame retardants and pesticides.

Some sites studied had levels of chemicals above those expected to cause adverse effects on fish, such as increased liver size and reproductive problems. Researchers studied sunfish from six Great Lakes tributaries and found many showed signs of stress.

More study is needed on the effects of the chemicals on fish reproduction, said Heiko Schoenfuss, a biology professor at St. Cloud State University who was one of the researchers. St. Cloud State students did the biological analysis.

The study was a joint project with the U.S. Fish and Wildlife Service, the U.S. Geological Survey and the Great Lakes Restoration Initiative. The results were published in the scientific journal PLOS One.

"The goal was really to understand the presence of chemicals flowing into the Great Lakes and the biological effects of those chemicals on the fish populations in the lakes that are important to the overall fish populations throughout the watershed," Schoenfuss said.

Data for the study was collected in 2013 and 2014 from 12 Great Lakes tributaries in Wisconsin, Illinois, Michigan, New York and Ohio.

Schoenfuss said researchers found chemicals at every site they studied, in both urban and agricultural areas.

"These are largely unregulated compounds," Schoenfuss said. "They are things we use in our homes and households every day — pharmaceuticals, personal care products, cleaning agents and so on. While some of them are being reduced in the concentrations by wastewater treatment plants, others really pass through them more or less unaffected."