378 ZEEMAN AND GRUNEWALD 



Lake Michigan are relatively low, and temperature rises caused by the 

 power plant are not sufficiently great to exceed the thermal 

 tolerance limits of the organisms, even during the summer. Also 

 important is that this power plant does not have to use chlorine or 

 other biocide to maintain efficient heat exchange in the condenser 

 tubes. 



Estimates of size-fractionated productivity are important to our 

 understanding of aquatic ecosystems. Their utility will increase 

 further when our knowledge of size-selective grazing is improved. 

 Entrainment does not seem significant to phytoplankton population 

 changes at the Kewaunee Nuclear Power Plant, but conditions may 

 be different elsewhere. Changes in productivity of certain size classes 

 could have far-reaching implications to trophic structure. 



Multivariant analysis of variance, as demonstrated here, could 

 prove to be a useful tool in analyzing structural changes in 

 phytoplankton communities. The ability to analyze several variables 

 simultaneously adds new dimensions to ecological investigations 

 which have been neglected previously. These variables need not be 

 limited to productivity rates. Indeed, it might prove enlightening to 

 use other measurements (e.g., of adenosine triphosphate or chloro- 

 phyll a) in combination with productivity estimates. 



ACKNOWLEDGMENTS 



This research was supported in part by a grant to The University 

 of Wisconsin, Milwaukee, Department of Botany, from the Wisconsin 

 Public Service Corporation and by a research assistantship to Stephan 

 Zeeman from the Center for Great Lakes Studies, UWM. This study 

 was part of an M.S. thesis in botany by Zeeman. 



REFERENCES 



Allen, T. F. H., and S. Skagen, 1973, Multivariate Geometry as an Approach to 

 Algal Community Analysis, Br. Phycol. J., 8: 267-287. 



Bothwell, M. L., 1975, Studies on the Distribution of Phytoplankton Pigments 

 and Nutrients in the Milwaukee Harbor Area and Factors Controlling 

 Assimilation Numbers, Ph.D. Thesis, University of Wisconsin, Madison. 



Bremer, K. E., and D. G. Redmond, 1974, Phytoplankton Entrainment, in 

 Preoperational Thermal Monitoring Program of Lake Michigan Near the 

 Kewaunee Nuclear Power Plant: January— December 1973, Chap. 5, third 

 annual report prepared by Industrial Bio-test Laboratories for Wisconsin 

 Public Service Corporation, Green Bay. 



Brooks, A. S., 1972, The Influence of a Thermal Effluent on the Phytoplankton 

 Ecology of the Indian River Estuary, Delaware, Ph.D. Thesis, Johns Hopkins 

 University, Baltimore, Md. 



