Average 



w 



IT. 



I- 



z 

 < 



a. 

 o 

 o 



N 



m 



Z3 



Ploesomo hudsoni 



Kerotella canadensis 



Bosmina coregoni 



Epischura nevadensis 



I I I I I I I I I 



31 10 20 30 10 20 30 9 19 29 8 31 10 20 30 10 20 30 9 19 29 8 



Moy June July Aug. Sept. May June July i245 Sept. 



160- 



140- 



120- 



Ceratlum hirundinella Kellicottio longisplna 



100- 



8 



60 



40 



31 10 20 30 10 20 30 9 19 29 8 



I I I I I 



31 10 20 30 10 20 30 9 19 29 8 



May 



June 



July 



Aug. Sept. May 



June 



July 



Aug. Sept. 



I I I I I I 



Figure 5. --Seasonal variations in abundance of zooplankton by species from plankton tow 



data, Bare Lake, 1957. 



a No. 10 net, while those in the Colorado lakes 

 were collected with a Juday-Foerst plankton 

 trap. Pennak does not mention the possible 

 presence of a fish population in any of the 

 lakes studied, whereas Bare Lake has a 

 relatively large population of fish which ac- 

 tively crop the zooplankton population. This 

 factor, along with the longer growing season 

 and the higher rate of solar radiation in 

 Colorado lakes, indicates a higher level of 

 productivity in Bare Lake relative to the 

 Colorado lakes than is shown in the table. 



I 31 10 20 30 10 20 30 9 19 29 8 



z Moy Junt July Aug S«pt 



Figure 6. --Seasonal zooplankton abundance. Bare Lake, 

 1952 and 1957 (oblique tows No. 10 net). 



10 



