Establishment of Daphnia lumholtzi (an exotic zooplankter) in the Illinois River Stoeckel, J. A., L. Camlin, K. D. Blodgett, and R. E. Sparks. 1996. Establishment of Daphnia lumholtzi (an exotic zooplankter) in the Illinois River. Note in Journal of Freshwater Ecology 11(3):377 379. Reprinted by U.S. Geological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, August 1997. LTRMP 97-R013. 3 pp. (NTIS #PB98-103112) ABSTRACT Daphnia lumholtzi, an exotic zooplankter, recently has become established in the Illinois River. This species was first detected at Illinois Rver Mile (IRM) 121.1 near Havana, Illinois, in June of 1995, and exhibited a peak abundance of 22.5/L in August. Population trends and densities in the Illinois River resemble those reported in lakes and reservoirs of the southeastern United States, suggesting D. lumholtzi is adaptable to lotic as well as lentic systems. Individuals were found at sampling sites as far upriver as IRM 195.9. KEYWORDS Daphnia lumholtzi, exotic zooplankter, Illinois River