Pelagic and Near-shore Plankton Communities 
of a North Carolina Coastal Plain Reservoir 
Michael A. Mallin 
Department of Environmental Sciences and Engineering, 
University of North Carolina at Chapel Hill, 
Chapel Hill, North Carolina 27514 
ABSTRACT.— The plankton community of Sutton Reservoir, an 
estuarine-influenced cooling reservoir in the coastal plain of North 
Carolina, was sampled monthly throughout 1985. Phytoplankton 
densities were low to moderate and dominated by the Chlorophyceae 
and Cryptophyceae, with chlorophyll a values indicating a mesotrophic 
state. The zooplankton community was unusual compared with other 
area reservoirs and reflected the estuarine influence of the lower Cape 
Fear River and the reservoir’s geographic location. Crustacean 
zooplankton were dominated by Diaptomus dorsalis, Eurytemora 
affinis, Daphnia ambigua, and Bosmina coregonv, and the rotifers were 
dominated by members of the Brachionidae. Zooplankton densities, 
which exhibited a bimodal peak, were high relative to area reservoirs 
and dominated by rotifers. Biomass was comparatively low and 
dominated by crustaceans. Correlation analysis indicated a strong, 
inverse relationship between crustacean zooplankton and phytoplank- 
ton, and zooplankton grazing is suggested as the primary controlling 
force in phytoplankton temporal population dynamics. 
Sutton Reservoir, in New Hanover County, North Carolina, is one 
of several water bodies located in the coastal plain of the southeastern 
United States. These systems comprise both man-made reservoirs and 
natural lakes (the Carolina bays). Most of these systems are very 
important to wildlife, particularly migratory waterfowl; and bay lakes 
often contain rare or endemic species (Sharitz and Gibbons 1982). 
Sutton Reservoir is ecologically interesting in that it is subject to 
both chemical and biological influence from the lower Cape Fear River 
and displays characteristics of both fresh and brackish waters. The 
objectives of this study were to describe the zooplankton community of 
this unusual ecological system, compare the pelagic and near-shore 
communities, discuss the relationship of the zooplankton community 
with the reservoir’s chemical and physical characteristics and phyto- 
plankton, and compare the Sutton Reservoir zooplankton with those of 
other Southeastern systems. 
Little has been reported in the literature regarding the plankton 
communities of coastal-plain lakes and impoundments. Stoneburner 
and Smock (1980) reported on the plankton community of an acid, 
Brimleyana No. 15:87-101, January 1989 
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