Every plant and animal has a unique genetic composition, which makes a lake like a bowl of DNA soup—every spoonful contains the combined DNA of the lake’s inhabitants. Scientists have recently begun using this environmental DNA, or eDNA, to identify the presence of organisms like amphibians and fish. Using eDNA to monitor hard-to-detect species can provide early warnings of invasion. ACES aquatic ecologist Eric Larson in the Department of Natural Resources and Environmental Sciences and his colleagues analyzed eDNA to successfully detect the presence of the highly invasive rusty crayfish in a dozen Wisconsin lakes.