EFFECTS OF POWER-PLANT OPERATION 

 ON THE ZOOPLANKTON COMMUNITY 

 OF BELEWS LAKE, NORTH CAROLINA 



TERRY P. ANDERSON and DAVID R. LENAT 



Department of Environmental Sciences and Engineering, University 



of North Carolina, Chapel Hill, North Carolina 



ABSTRACT 



The euphotic-zone zooplankton community of Belews Lake, North Carolina, 

 was studied over a 3-year period. Belews Lake is a 1500-ha cooling reservoir for a 

 2200-MW coal-fired power plant. This study included 1 year of preoperational 

 data and 2 years of postoperational data. A detailed examination of 19 taxa 

 showed that three species may have responded to power-plant operation. Two 

 warm stenotherms (Hexarthra and Ptygiira) increased in density, and an increase 

 in the winter density of Polyarthra was also noted. An analysis of variance 

 indicated that circulation of surface water by the power plant resulted in greater 

 spatial and seasonal homogeneity for most taxa. Other changes in the 

 zooplankton community appeared related to natural causes. 



A lake ecosystem is temporally heterogenous in terms of a large 

 number of physical and biological factors. Seasonal patterns in the 

 zooplankton community have evolved to take advantage of these 

 temporal changes, therefore reducing competitive interactions be- 

 tween species. Because of the marked seasonality of the zooplank- 

 ton, comparison studies are best made between periods of at least 

 1 year. We studied the zooplankton community of Belews Lake, 

 North Carolina, on a monthly basis for a period of 3 years and 

 compared the resulting data on a yearly basis. 



Considerable differences in the abundance of zooplankton are to 

 be expected when making between-year comparisons (Ricker, 1938; 

 Carlin, 1943; Edmondson, 1946; Hutchinson, 1967). Multivariant 

 analysis of zooplankton densities vs. environmental variables has 

 indicated that temperature and food concentrations are the most 



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