Invasion of the exotic cladoceran Daphnia lumholtzi into North American reservoirs

Abstract

Daphnia lumholtzi, a large cladoceran native to Africa, Asia, and Australia, has recently invaded reservoirs of the southern United States. We examined its distribution, history of invasion, and population dynamics in Missouri reservoirs. Surveys detected the species in 7 of 112 reservoirs in 1992 and 11 of 119 reservoirs in 1993. Analysis of quantitative zooplankton samples from two reservoirs over a 7-year period indicated that D. lumholtzi first reached detectable densities in 1990 and persisted during 1991–1993. Population maxima typically occurred in late summer, with the species absent from the plankton during winter and spring. Based on its current distributional patterns, D. lumholtzi appears to be capable of colonizing most reservoirs in the southern regions of North America.