312 



M. Butler etal. 



at 5°, 10°, or 15°C (±0.01°C) and the oxygen concentration measured over 

 at least two 30-minute periods with a YSI meter. 



The respiration of Chironomus was a function of temperature, larval 

 size, and acclimation period (Figure 7-7, Table 7-2). Larvae that were 

 moved to 15°C from pond temperatures of 7 to 10°C increased their 

 respiration greatly (non-acclimated in Figure 7-7); after 2 days larval 

 respiration was reduced by 40% (acclimated). The reverse occurred when 

 animals were transferred to 5°C. First, the rate was lowered, then 

 increased again by 25% after 2 days. This is Precht's type 3 compensation 



0.5 1.0 1.5 2.0 2.5 



Lorval Size, mg dry wt. 



3.0 



3.5 



FIGURE 7-7. Relationship between respiration and size 

 for Chironomus larvae at 15°C (A and B) and 5°C (C 

 and D) (top). Lines A and D represent nonacclimated 

 larvae, while B and C represent acclimated larvae. These 

 data were used to calculate the respiration rate ofchiro- 

 nomids in Pond B for 1972 (bottom). 



