A recent study suggests that Chicago's dirty water may be keeping invasive silver carp at bay. The fish, known for their ability to disrupt recreational boating and native ecosystems, have been unable to establish a population in Lake Michigan despite making it far up the Illinois River. Researchers point to several factors contributing to this phenomenon, including pollution, dams and locks, active culling efforts, and an electric barrier.

Source: https://www.popsci.com/environment/invasive-carp/