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V. Alexander et al. 



hour incubation. The procedure chosen here was to set up a proportionate 

 relationship such that (insolation during incubation)H-(total daily 

 insolation) equals (primary productivity during incubation)^ (total daily 

 primary production). The errors are likely due to underestimations but the 

 total primary production due to phytoplankton was so small that it was 

 not worth attempting to obtain a more accurate measurement. 



If we assume a 100-day growing season and a mean depth of 20 cm 

 for the ponds, the 1971 production estimate was 1216 mg C m ~ ^ for Pond 

 B and 1024 mg C for Pond C. In 1972, Pond B had a production of 900 mg 

 C m "^ while in 1973 Pond C's production was 466 mg C. These estimates 

 agree with those of Kalff (1967a) for a nearby but different series of 

 Barrow ponds over a 2-year study (380 to 850 mg C m~^). Overall, these 

 are among the lowest values measured for phytoplankton production in 

 any body of water including other arctic lakes and ponds (Table 5-3). It is 

 obvious, however, that the maximum rates of photosynthesis per cubic 

 meter are quite high in the ponds. Therefore, the shallow depth and the 

 short growing season are the cause of the exceptionally low seasonal 

 primary production. Deeper lakes have lower rates per unit volume but a 

 much greater euphotic zone (up to 20 m or so in Char Lake) and a longer 



TA BLE 5-3 Phytoplankton Primary Production of Some A rctic Lakes 

 and Ponds 



