CLUTTER and THEILACKER; PELAGIC MYSID SHRIMP 



RESPIRATION 



A polarographic oxygen electrode (Kanwish- 

 er, 1959) was used in a closed system to measure 

 the respiration rates of Metamysidopsis. Both 

 temperature and oxygen were recorded contin- 

 uously on a strip chart. 



The experimental animals were taken from 

 large constant-flow holding tanks (temperature 

 14°. 17° C) and acclimated overnight at the tem- 

 perature used in the experiments (13.8°-18.1° 

 C) , to avoid the overshoot in oxygen consumption 

 described by Grainger (1956). They were then 

 washed in millipore-filtered seawater, counted, 

 and transferred to previously filtered seawater 

 in the oxygen electrode system. In each experi- 

 ment an attempt was made to use animals of a 

 limited size range. During the run they were 

 held within a 10- ml chamber, baffled at each 

 end with silk screen cloth of 282 /i mesh aperture 

 size. The water in the closed system circulated 

 through this chamber and then past the electrode 

 at a constant rate. The whole system was im- 

 mersed in a temperature-controlled water bath. 



Oxygen use by bacteria was measured by mak- 

 ing blank runs with the same water both befoi-e 

 and after each test run. Bacterial use amounted 

 to less than 2 ^c . Oxygen consumption by the 

 mysids was corrected for bacterial uptake. The 

 decrease in relative oxygen tension with time 

 was nearly linear in both the blank runs and the 

 test runs. 



The results of the respiration experiments are 

 shown in Table 2. Observed weight-specific 



Table 2. — Summary of respiration experiments on 

 Metamysidopsis. 



Figure 11. — Relation between respiration rate of Met- 

 amysidopsis and size at 16° C. The symbol if' rep- 

 resents respiration rate per dry unit weight (R/W). 

 The lines were fitted to the circle points by two sta- 

 tistical pocedures. The x points are values calculated 

 from published data on other species of Mysidae: 1- 

 Neo7nysis americana (RajTnont and Conover 1961) ; 

 2-Neomysis integer (Raymont, Austin and Linford 

 1966); 3-Hemimysis labornae (Grainger 1956). 



respiration rates (/tl Oj/mg dry weight hr) were 

 corrected for the initial percent oxygen satura- 

 tion and for temperature. In correcting for 

 temperature, a Q,o of 1.9 was used (Grainger, 

 1956). All values were corrected to 16° C, 

 which is about the median of the year-round 

 temperatures that occur in the natural environ- 

 ment of the mysids. 



The corrected weight-specific respiration data 

 are plotted in Figure 11 on log-log scales. The 

 symbol R' (Conover, 1960) represents the res- 

 piration rate per unit dry weight (R/W). The 

 average relationship between mean dry weight 

 and R' was estimated by two statistical pro- 

 cedures. First, a straight line was fitted to the 

 logarithmically transformed data by the median 

 procedure (Tate and Clelland, 1957). This gave 

 the relationship: 



or 



R' = 2.0 H'-o-3« 

 R = 2.0 (^"-ss 



^ Corrected for oxygen saturation level and corrected to temperature 

 of 16.0° C by using Qio = 1.9 (Grainger, 1956). 



where R = respiration rate in fi\ Oj/hr 



and W = mean dry weight in mg. 

 Second, a straight line was fitted to the logarith- 

 mically transformed data by the method of 



103 



