Date of this Version
THE PRAIRIE NATURALIST, Volume 37, No. 1, March 2005, pp 11-19.
A limnological assessment project by the University of Nebraska at Kearney and the Nebraska Game and Parks Commission collected weekly vertical zooplankton tows during May through September 2002 at Harlan County Reservoir in Nebraska. Beginning on 5 August 2002, the exotic Daphnia lumholtzi (Cladocera: Daphniidae) appeared at a density of 0.04 1.1 in one of fifteen standardized sampling stations. By 6 September 2002, D. lumholtzi was found in all fifteen stations at an average density of 2.17 ± 3.10 1.1 with a site maximum density of 11.43 1.1 • Length measurements of D. lumholtzi ranged from 0.80 mm to 5.66 mm with a mean length of 2.38 ± 1.107 mm. During sampling, the abundance of D. lumholtzi increased relative to the native Daphnia retrocurva from less than 1 % to greater than 45% of all zooplankton collected. Our finding represents the first account in a Nebraska water system of D. lumholtzi, a native of Africa, Asia, and Australia, and shows a northern expansion in the Great Plains of this exotic species.