Zooplankton 265 



TABLE 6-6 Size of Predator and Prey Plus the Predation Coefficient for the 

 Interactions Shown in Figure 6-5 



1. K = predation coefficient, liters day" . 



2. Interactions are those shown in Figure 6-5. 



3. An underestimate, because at least half the copepodites were the non-predaceous 

 C. strenuus. 



Source: Modified from Dodson (1975). 



where N is numbers liter '\ M is Mg C per individual or egg, g is the 

 instantaneous growth rate, / is interval (days), T refers to survivors and E 

 to eggs produced. 



In the above formula, {N,—N,^i) is the mortality over a given time 

 period. Multiplication of mortality by the geometric mean of the biomass 

 (A/,) and by e '^' ' estimates the production of the animals lost by 

 mortality during that interval. The summation of production for each of 

 the intervals estimates total production of all animals not surviving to the 

 end of the summer. The production of animals that did survive to 

 adulthood is N tM t and the production of eggs is N eM e. 



The above formula holds for monovoltine fairyshrimps and calanoid 

 copepods that diapause as embryos. For Daphma and cyclopoid copepods, 

 subscripts are used for overwintering {A) and young-of-the-year (/) 

 generations. 



The cyclopoid copepods are monovoltine but enter diapause as near 

 adults. Thus, the J category shows much of the production. Also, the E 

 subscript now indicates the copepod stage. 



The total production of zooplankton in Pond C was approximately 1 

 mg C liter ' yr ' (Table 6-7) or 200 mg Cm' assuming an average 

 depth of 20 cm. Since sampling errors are unknown, and because the range 

 of estimates is not large (820 to 1400 ng C liter"' yr"'), we assume that 

 total zooplankton production was about the same each year. Estimates for 

 other ponds are given in Figure 6-8. 



