tested at 32°C (Fig, 119c). Animals from a low temperature back- 

 ground (18°C) usually exhibited a sudden increase in oxygen con- 

 sumption when tested at higher temperatures. The rapid increase 

 occurred up to two hours, occasionally up to four hours, and in 

 rare instances longer. The magnitude of the initial increase in 

 the oxygen uptake was roughly in proportion to the difference 

 between the test and acclimation temperatures. The new steady- 

 state level was established above the level of the zero hour in- 

 terval and below the initial highest level. In brown shrimp that 

 were acclimated to and tested at the same temperatures 18 °C (Fig. 

 118a), 25°C (Fig. 119b), and 32°C (Fig. 120c), only insignificant 

 changes occurred between successive intervals. Salinity influence 

 was found in the oxygen consumption apparently in the absence of 

 temperature changes. In brown shrimp acclimated and tested at 

 25 °C oxygen consumption increased from a low in 15°/ooS to higher 

 levels in both lower and higher salinities (Fig, 119b). On the 

 contrary, in shrimp acclimated and tested at 32°C the oxygen con- 

 sumption was highest in 15°/ooS of all test salinities (Fig. 120c). 



Effect of Sex on Oxygen Consumption 



Comparisons of the mean oxygen consumption rates by male and 

 female brown shrimp in the various test conditions are shown in 

 Table 25, There were no significant differences in the respiratory 

 rates of the two groups of shrimp. In a few cases what were thought 

 to be individual differences showed up. It was concluded therefore 

 that sex had no effect on the metabolic rates of the shrimp tested. 



Behavio r and Survival in Salinities with Deviated Amounts of Cations 



The effect of deviated cations on the behavior and survival of 

 brown shrimp was studied in 15°/ooS (control) by altering the normal 



255 



