638 



ANDERSON AND LENAT 



TABLE 5 



STATION AND STATION x MONTH INTERACTION AS INDICATORS 

 OF HOMOGENEITY BY ANALYSIS OF VARIANCE 



♦Explanation of symbols; 

 NS, not significant. 

 S5, significant at 5% level. 

 SI, significant at 1% level. 

 A, species absent in collection. 

 NI, not identified in year 4. 

 ?, insufficient data for test. 

 fStation column indicates whether or not the monthly densities of each species/group 

 varied significantly among stations for the year listed. 



^Station X month interaction column indicates whether or not the interaction term for 

 each species/group was significantly less in year 6 than in the year being compared. 



species was then tested between years. The taxa were then separated 

 into three groups. The first group was composed of nine taxa that 

 were considered stable over the 3-year period and therefore were not 

 detrimentally affected by power-plant operation: Keratella co- 

 chlearis, K. earlinae, Conochilus unicornis, Conochiloides spp., 

 Polyarthra spp., Tropocyclops prasinus, Bosmina longirostris, nauplii, 

 and cyclopoid copepodids. An increase in winter water-column 

 temperatures brought about by power-plant operation may have 

 been influential in causing the shift of Polyarthra spp. abundance 

 from the fall and spring of previous years to the winter in year 6. 



