BISHOP ET AL.: OXYGEN CONSUMPTION OF BROWN SHRIMP 



« ^2.7 g ?. aztecus 



» «6.7 g P^. aztecus 



900 r 



Line of Isotonicity 



J 1 1 1 I 



600 800 



1000 



200 400 



600 



800 1000 



900 



< 



z 



a: 



Z 800 



700 



600 



500 



T=28 C 



900 



800 



700 



600 



500 



200 



400 



600 



800 



1000 



200 



400 



600 



800 



1000 



EXTERNAL MEDIUM (mOsm) 

 Figure 2.— Mean hemolymph osmolality (mOsm) of 3.7 and 6.7 gPenaeus aztecus vs. temperatures at 18°, 23°, 28°, and 33° C. 



may complicate the ideal of testing uniform sub- 

 jects under similar conditions. In addition, the ef- 

 fects of spontaneous activity often mask any dif- 

 ferences of metabolism resulting from the effects 

 of osmoregulation, size, temperature, etc. In the 

 present study, attempts to eliminate molt-stage 

 differences were made by testing a minimum of 

 seven pairs of shrimp. Because integumental 

 changes occur at least 70% of the time between 



successive molts for decapods (Passano 1960), the 

 testing of only intermolt, acclimated animals 

 would have been nearly impossible. Most of the 

 shrimp tested, however, should have been in a 

 stage other than immediate premolt, and newly 

 molted shrimp were not tested. Therefore it is as- 

 sumed that most of the test animals were at a molt 

 stage that affected the total oxygen consumption 

 relatively little. 



747 



