As lakes across the upper Midwest grow warmer year after year, cool-water species of fish are finding it harder to thrive. In Wisconsin, that trend is especially noticeable in struggling populations of walleye — important to many indigenous communities, a top target in the state’s sport fishery, and a popular item on many restaurant menus.

New research from University of Wisconsin–Madison scientists traces two tiny invasive species through their outsized effects on the water quality, algae blooms and toxic conditions in a Wisconsin lake.