Macrobenthos 313 



TABLE 7-2 Equations Describing the Relationship between Respiration and 

 Size for Chironomus Larvae Represented in Figure 7-7 



Line 

 desig- 



Temp 



(Prosser 1973). Platzer (1967) has shown a similar response in tropical 

 Chironomus. In other experiments the Qio of unacclimated animals was 

 2.5 to 3.5 in the 5 to 15°C range and 2.0 in the 15 to 25°C range. A similar 

 pattern of decreasing Qxo at higher temperatures has been observed for 

 Chironomus sp. (Konstantinov 1971) and for stoneflies (Knight and 

 Gaufin 1966, Prosser 1973). Thus, the chironomids appear to adapt to 

 higher temperatures and keep their metabolic costs at a moderate level. 

 Yet, they stay active at 5°C and respiration increases with acclimation to 

 low temperatures. Respiration rates for fourth-instar Chironomus at 15°C 

 ranged from 1 .7 to 0.6 ^g C (mg dry wt) ' hr ', with rates decreasing as 

 larval size increased. Walsh-Maetz (1953) found a rate of 1.3 ^g C (g dry 

 wt) ^ hr ' (originally as 200 mm ^ (g fresh wt) " ^ hr ^ assuming 0. 1 5 g dry 

 weight per gram fresh weight) at 17°C for Chironomus larvae from 

 France, so the respiration of unadapted thaw pond Chironomus was not 

 notably different from other populations. 



Chironomid respiration per unit area can be estimated for any of the 

 ponds in which biomass and temperature are known by using the equations 

 in Table 7-2. Non-acclimated rates were used because temperature 

 fluctuated over a range of up to 10°C on many days. Mean daily 

 respiration was 3.5 times higher in 1972 than in 1971 because both 

 temperature and biomass were higher. Between 5 July and 16 August 1971 

 respiration was 630 mg C m " ^ or 1 5 mg C m ^ day ^ . Between 20 June 

 and 17 August 1972 respiration was 2950 mg C m'' or 52 mg C m"^ 

 day"' (Figure 7-7). 



Temperature Experiments 



In an experiment to determine the effect of temperature on growth 

 rates, Bierle grew Chironomus from egg masses at different temperatures. 

 At 5°, 10°, 15° and 25°C the eggs hatched in 14, 5, 3 and 2 days, 



