Can studying a tiny minnow help the entire Great Lakes basin? St Cloud State graduate student Chryssa King’s research may do just that. Looking at one fish species can provide information that benefits an entire ecosystem. Understanding the complex way contaminants in our lakes and streams affect fish and wildlife is one way we at the U.S. Fish and Wildlife Service conserve resources in the Great Lakes region. Our partnership with St. Cloud State University in Minnesota highlights the importance of bringing new information and insight to understanding how contaminants affect our surroundings.
King took on the challenge of studying how combinations of contaminants affect a common Great Lakes basin fish, the fathead minnow. King, who just completed her master’s degree with a thesis on her studies, was interested in whether certain types of chemicals, known as contaminants of emerging concern, played a part in biological changes to fathead minnows when combined with nitrates, a common substance found in agricultural runoff.
Contaminants of emerging concern include chemicals used in everyday products like soap and pharmaceuticals, which disappear down the drain and end up in our water supply. Impacts to fish and wildlife may include changes in reproduction, behavior, development and growth.
“Contaminants of emerging concern are chemicals in common, everyday products, such as personal care aids, prescription and over-the-counter medications, flame retardants and insect repellents,” said Stephanie Hummel, a contaminants biologist with the U.S. Fish and Wildlife Service. “Water treatment plants don’t remove these chemicals, so they eventually find their way into rivers and lakes. We’re interested to find out whether these chemicals have long-term, harmful impacts to fish and other aquatic life.”
The other target of King’s study, nitrates, are found in agriculture products like fertilizer, and they likewise end up in waterways and lakes. High amounts of nitrates can stress aquatic ecosystems by fueling too much algal growth, potentially leading to low levels of oxygen in the water. Understanding the adverse effects to fish from nitrates in combination with other chemicals is especially relevant in the Great Lakes basin because both urban and agricultural landscapes are so common in the region. Contaminants of emerging concern could place additional stress on fish in rivers and streams flowing into the Great Lakes, compounding problems associated with already high nitrate concentrations.
King chose to study fathead minnows because they can be used in a laboratory setting and testing results often can be applied to fish species of greater concern. King examined how nitrates, plus mixtures of different contaminants of emerging concern from both urban and agricultural lands affected the growth, development and behavior of fathead minnows. She studied impacts over several generations and across their life stages, from eggs to young to adult. While the effects are subtle, King’s findings suggest that exposure to nitrates, in addition to complex chemical mixtures, could lead to reproductive problems, like feminization of males. These effects varied across generations and fish sex. King’s findings also showed that these impacts varied depending on whether the chemicals were associated with agricultural or urban land use.
“The science of contaminants of emerging concern is complex, and our work to better understand it depends on piecing together all the information we can gather. Chryssa’s research is adding to that mosaic,” added Hummel.
Hummel said information from this and similar studies will help fisheries managers make decisions about how to best manage Great Lakes basin fish and wildlife resources with efforts like restoring stream habitat, pinpointing the best places and times for relocation or release of hatchery-reared fish, and monitoring.
