LeBRASSEUR and KENNEDY: LAKE FERTILIZATION. II. 



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Figure 4.— Species counts (no./m^ in 50-m vertical hauls at Stations 1 and 2. (Points represent a 4-day running 

 mean, solid triangle indicates monthly mean, circle with dot indicates more than one sample with the same count. 

 Note: the numbers of organisms are shown on a logarithmic scale.) 



Table 4. — Copepod sex ratios. 



F/M Number of adult females/number adult males. 

 Fi'/Fi Number of adult females at Station 2/number of adult females 

 at Station I. 



September 14. In contrast there was a tendency 

 for Diaptomus females to be slightly more abun- 

 dant than males throughout the year. The only 

 period for which Diaptomus males were con- 

 sistently more numerous than females was from 

 June 22 to July 10. Included in Table 4 is the 

 ratio of the number of female copepods at Sta- 

 tion 2 to the corresponding number at Station 1. 

 Cyclops was the only species in which the fe- 

 males were as numerous or more numerous at 

 Station 2 than at Station 1. 



EGG PRODUCTION 



Counts were made of all readily identifiable 

 eggs; these consisted of eggs in the brood pouch 

 of cladocera and the egg sacks of Cyclops and 

 Diaptomus. Rotifer species were not examined 

 for eggs, while Epischura eggs were positively 

 identified on only one occasion from a horizontal 

 tow made at 1 m depth in August. It is possible 

 that Epischura eggs develop close to the surface 

 at depths of less than 1 m since they were not 

 found at other standard depths sampled between 

 1 m and 65 m. Also other data, not presented 

 here, indicate that the smaller size groups of 

 Epischura were found closer to the surface than 

 the adult stages. 



The data presented in Figure 5 show the ratio 

 of eggs per female for vertical samples collected 

 at Station 1 and Station 2. It was noted in Table 

 4 that maximum numbers of copepod females oc- 

 curred during the summer, June through Sep- 

 tember; Cyclops females were more numerous 

 at Station 2 than Station 1 and Diaptomus 



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