History of Freshwater Invasions in Illinois: Learning from the Past to Inform the Future

Rates of introduction and spread of non-native species continue to increase worldwide, with freshwater ecosystems highly impacted. Many non-native species crossed between the Great Lakes and Mississippi watersheds by traveling through waterways in Illinois. I assembled a comprehensive database of occurrences of aquatic non-native species (n=99) in Illinois inland waters. The arrival of non-native species accelerated since 1873. The Great Lakes Basin was the main source of established species into Illinois. From 1990-2012 the dominant vector was unintentional release of established species non-native to North America. Sixty of the 99 introduced species established. Eighteen established species had high or very high ecological impacts. Established species were more likely to be recorded, and first recorded, along the invasion corridor. Ten established species were recorded in >50% of counties while six species were found in one county. Because Illinois is a conduit of non-native species, it should be a priority for management.