32°C continued for three hours instead of one hour as in control. At 

 18°C there was no change in the oxygen uptake from control (Fig. 

 121). Secondly, the survival rate was considerably lower at 25°C; 

 at 32°C there was a total mortality within the first day. Survival 

 rate was not affected at 18°C. At 32°C oxygen consumption in 25% Ca 

 was higher than the consumption in the control medium at the same 

 temperature. 



At 18°C the shrimp did not exhibit any marked changes in 25% Ca 

 from the control animals also tested in IS^C, either in deviation of 

 the stabilization period or in the steady metabolic level. The 

 steady-state level at 25°C was similar to that in the control con- 

 ditions (Fig. 121) , but the stabilization process took longer. Mor- 

 tality rate increased progressively with the temperature rise from 

 18°C. 



Eff-ect of total elimination of magnesium 



Oxygen consumption rates were determined at 18°, 25°, and 32°C 

 in 15°/ooS synthetic salt water with 0% Mg (Fig. 123). The respira- 

 tory rates during the immediate regulation were higher in 18° and 

 25 °C than in control shrimp tested at the same temperature. But 

 the rates at 32°C were similar to the rates in the control medium 

 at 32°C. 



Stabilization of the metabolic rates was faster at 18° than 

 in 25°C in the same test conditions. The new steady metabolic 

 level at 18°C was slightly higher than in control media 15°/ooS and 

 18°C (Fig. 121). The high oxygen consumption rate in 18°C was in 

 synchrony with the reported increased activity in the behavioral ob- 

 servations in the corresponding test conditions. Removal of magne- 

 sium affected the survival rate more adversely at 32°C than in 18° or 

 25°C. The shrimp survived in 32 °C for less than ten hours. During 



270 



