Although the respiratory responses at normal temperature (25°C) 

 were influenced primarily by salinity, the test temperature had 

 exerted a greater effect in altering the response pattern. However, 

 when returned to 25°C, either from IS^C or from 32°C test conditions, 

 the experimental animals exhibited a tendency to resume the original 

 salinity response pattern. 



Interaction of Salinity and Temperature on Respiration 



In IS^/ooS the respiratory rates increased with temperature. But 

 it was not known how a simultaneous change in the salinity factor 

 would alter the temperature influence on respiration. This effect was 

 shown by reproducing the salinity-related metabolic response curves 

 of shrimp acclimated at 25°C (Fig. 112], 32°C (Fig. 113), and 18°C 

 (Fig. 114). 



The oxygen consumption of shrimp acclimated to 25 °C increased in 

 15°/ooS when tested at 32°C and decreased in 18°C (Fig. 112). The 

 differences were highly significant (P=0.001) between the three test 

 temperatures (Table 19). Such variations occurred consistently in 

 all salinities between 18° and 25°C. However, the situation was 

 different between 25° and 32°C. In salinities other than 15°/oo 

 there was no proportionate increase in the oxygen uptake when tested 

 at 32°C. Nevertheless, the respiratory rates between 25° and 32°C 

 showed significant differences in 10 and 25°/ooS, but not in 2, 5, or 

 36°/ooS. This was because in extreme test salinities 2, 5, and 56°/ooS 

 the animals failed to increase the oxygen uptake at 32 °C to above the 

 oxygen consumption levels in 25°C. 



In Fig. 113 the respiratory responses of shrimp acclimated to 

 32°C were shown. The animals exhibited more or less similar salinity 

 response patterns, except in 5°/ooS, like those acclimated and tested 

 in 25 C, In 5°/ooS the oxygen consumption increased with temperature 



236 



