88 
Michael A. Mallin 
brownwater lake on a south Georgia barrier island. They found a sparse 
phytoplankton community dominated by Chlamydomonas sp., Melosira 
varians, and Peridinium pusillum. The zooplankton community 
maintained high densities and was dominated by Diaptomus floridanus , 
Polyarthra vulgaris , Keratella cochlearis, and Daphnia ambigua. The 
Great Dismal Swamp ecosystem in Virginia and northeastern North 
Carolina was investigated by Anderson et al. (1977). They found that 
the system was dominated by rotifers with high densities of Polyarthra 
vulgaris and Conochiloides dossuarius. Dominant crustaceans were 
Bosmina longirostris , Diaphanosoma leuchtenbergianum , Mesocyclops 
edax, and Tropocy clops prasinus. Casterlin et al. (1984) studied the 
algae of Lake Waccamaw, a large North Carolina bay lake, and found 
increasing eutrophication occurring. The North Carolina Department of 
Environmental Management has reported data concerning the mid- 
summer algae and chlorophyll of several coastal-plain lakes (NCDEM 
1984). The scarcity of plankton information about coastal-plain systems 
leaves mainly inland water systems for comparisons. 
SITE DESCRIPTION 
Sutton Reservoir (Catfish Lake) is a 445-ha impoundment located 
4.8 km northwest of Wilmington, N.C., adjacent to the Cape Fear 
River. It was constructed in 1972 to provide cooling water for the L. V. 
Sutton Steam Electric Plant, a 677-MWe closed-circulation, coal-fired 
generating facility operated by Carolina Power & Light Company 
(CP&L). The reservoir is U-shaped with a series of baffle dikes and has 
a mean depth of about 2 m and a maximum depth of about 12 m (Fig. 
1). It has a retention time of approximately 140 days, and the circulation 
time around the reservoir is about 4 days. Power plant discharge has 
caused midsummer reservoir water temperatures of 32 to 35 °C in 
recent years (CP&L 1986). 
The reservoir has no constant influent stream but receives intermit- 
tent makeup water from the Cape Fear River, particularly during the 
summer. The ionic composition of the water reflects the estuarine 
influence (Table 1). The lake is well oxygenated, well mixed, and 
circumneutral in pH (CP&L 1986). The fish community is dominated 
primarily by typical Southeastern freshwater species such as largemouth 
bass ( Micropterus salmoides ), gizzard shad ( Dorosoma cepedianum ), 
bluegill ( Lepomis macrochirus ), and several other sunfish. Estuarine 
influence is indicated by the presence of species such as mullet ( Muzil 
cephalus), flounder ( Paralichthys spp.), and blue crabs ( Callinectes 
sapidus ). Between 1972 and 1980 infestations of bladderwort ( Utricularia 
vulgaris ) were common in Sutton Reservoir, with growth dense enough 
in 1979 to cause a plant shutdown. Introduction of the redbelly tilapia 
