628 



ANDERSON AND LENAT 



• Cyclopoid Copepods 



O Tropocyclops prasinus 



A Mesocyclops edax — 



it >f ai-i-frp ft|0|-ar<y> >f a 



d 



111 

 O 



0' — I — I — I — 1*1 I 'I * I ' I — I — r 

 JASONDJ FMAMJ J ASONDJ FMAMJ JASONDJ FMAMJJ 



1973 



4- 



1974 



+ 



1975 



4- 



1976 



Fig. 4 Seasonal distribution of seven species of zooplankton from 

 Belews Lake. Data plotted from mean euphotic-zone density, all 

 stations. 



Seasonal curves for the major zooplankton taxa are given in 

 Figs. 4 to 7. Statistical analyses and relative abundances of these taxa 

 are given in Table 3, and they are discussed in detail in the following 

 paragraphs. 



The taxa may be divided into three groups on the basis of 

 changes between years 4 and 6: stable, declining, and increasing. 



Stable Taxa 



Six taxa showed no significant difference between years 4 and 6 

 (at a 5% level) and were considered stable: Keratella cochlearis, K. 

 earlinae, Bosmina longirostris, Polyarthra spp., nauplii, and cyclopoid 

 copepodids. We think that Tropocyclops prasinus was also stable 

 over this period, although it was not identified to a species level until 

 year 5. It exhibited a warm season peak in July and June of year 5. 



