Warnings in the Water

Living most or all of their lives underwater, benthic macroinvertebrates can act as a warning sign for small but important changes in water quality. In a healthy stream, researchers like Jessica Cormier expect to find a large, diverse population of benthic macrovertebrates. In water that’s becoming polluted, however, more sensitive species will die out, while tolerant bugs will survive. An off-balance population like this can suggest the presence of toxic chemicals, excess nutrients or loose sediment running off the surrounding land.