with the background temperature. Shrimp acclimated to 32°C were 

 adapted to 25 and 36"'/ooS faster than those acclimated to 18°C 

 background. Apparently the shrimp which were acclimated to 25° 

 and 32°C were able to adjust to high salinities at more or less 

 the same rates, as opposed to the slower rate of shrimp from 18°C. 

 In 5 and 10°/ooS, both 18° and 32°C acclimated shrimp showed sig- 

 nificant differences (P=0.001) with those from 25°C conditions; 

 but the differences were not consistent in all salinities (Table 

 22). This would indicate that the rate of acclimation to low 

 salinities was related to the background temperature. 



The rate of salinity adaptation in shrimp that were acclimated 

 to 18°, 25°, and 32°C was studied in 32°C (Fig. 116) and 18°C (Fig. 

 117). At 32°C the salinity adaptation to 25°/ooS from the three tem- 

 perature backgrounds proceeded at the same rate. In 15°/ooS shrimp 

 from the three temperatures did not show variations in their res- 

 piratory rates (Table 23) . In other salinities significant varia- 

 tions occurred in the acclimation process between the three groups. 



IVhen tested in 18°C the three groups of shrimp showed similar 

 rates of adaptation in 10, 15, and 25°/ooS; in the extreme sa- 

 linities 5 and 36°/ooS the shrimp exhibited significant differences 

 (Table 24). Among the three groups, the animals tested from 25° 

 and 32°C acclimation temperatures responded alike in their salinity 

 adaptation but they differed from those acclimated to 18°C. 



Irrespective of the acclimation or test temperatures, brown 

 shrimp in these experiments were adapted faster to control salinity 

 15°/oo and to the adjacent salinities of 10 and 25°/oo than to 2, 

 5, or 36°/ooS. Also the salinity adaptation proceeded at similar 

 rates between shrimp acclimated to 25° and 32 °C. 



248 



