Zooplankton of a swamp water ecosystem

The Great Dismal Swamp, located in southeastern Virginia and extending into northeastern North Carolina, is a unique ecosystem which has undergone severe alteration over the last 200 years due to agricultural, municipal and timbering development. The swamp is presently about 50% of its late 1700 size when George Washington commissioned the construction of the first of a series of drainage ditches that have subsequently reduced the swamp aquatic environs to a ditch network draining into Lake Drummond located near the swamp's center. The swamp waters are characterized by a brown color, high suspended organic matter, high acidity and low nutrient levels. This paper presents the first comprehensive study of the zooplankton assemblages of the Great Dismal Swamp.Zooplankton was collected for one year at 14 stations and was dominated by rotifers. Of the 84 species identified, 61 were rotifers, 18 were Cladocera and 5 were copepods. Many of the species collected were cosmopolitan and acid tolerant forms. Dominant lake rotifers included Polyarthra vulgaris, Conochiloides dossuarius, Keratella cochlearis, Trichocerca similis, Synchaeta longipes and Microcodon clavus. Dominant crustaceae included Bosmina longirostris, Diaphanosoma leuchtenbergianum, Mesocyclops edax, and Tropocyclops prasinus.Usually the ditch zooplankton was the same as that of the lake. Of the seven ditches studied, the most unique chemically and biologically were Interior, Washington, and Portsmouth. Measurable alkalinity was detected in Interior and Washington Ditches. Alkaline water rotifers such as Brachionus, Mytilina, Filinia, Notholca Platyias and Keratella earlinae were found in these ditches. The rotifer, Keratella valga, was only found from Portsmouth Ditch, during a period when water was flowing into the lake and it contained high nutrient levels.Research funded in part by the Virginia Academy of Sciences and the Center for Environmental Studies, Virginia Polytechnic Institute and State University.