At 18°C the surviving shrimp in 2°/ooS failed to control the salt 

 loss. In view of the large osmotic fluctuations in 2 and 36°/ooS the 

 adaptation was considered incomplete. In 10, 15, 25, and to some ex- 

 tent in 5°/ooS, steady-state levels in metabolic and salt regulation 

 were reached within the first day. 



Our results indicated that the large juvenile brown shrimp can 

 be more readily adapted to 2 to 36°/ooS range by a direct transfer 

 at normal temperature 25°C than at 18° or 32°C. With a temperature 

 change from 25°C to 18" or 32°C the range of salinity adaptation de- 

 creased. At these temperatures, adaptation was possible to a nar- 

 rower range of 5 to 25°/ooS and more favorably to 10 and 25°/ooS 

 without heavy mortalities. Between 18° and 32°C salinity adaptation 

 proceeded more favorably at 18°C with fewer deaths. 



Temperature Influence on Osmotic and Chloride Regulation 



Although it was suggested above that at 25°C salinity adapta- 

 tion was possible to a range of 2 to 36°/ooS, the osmotic and chlo- 

 ride concentration levels in Figs. 101 and 102, respectively, indi- 

 cated that such adaptation became more effective to a 5 to 25°/oo 

 salinity range. In other salinities osmotic or ionic regulation 

 was less stable. Also the animals acclimated to 25°C withstood 

 better the temperature changes (18° or 32°C). 



The osmotic and chloride regulatory pattern of shrimp acclimated 

 to 18°C and tested in 18°, 25°, and 32°C appeared much the same as in 

 25°C acclimated shrimp. The only difference was that the low tempera- 

 ture acclimated animals were temperature-sensitive. The sensitivity 

 was determined from the compensatory responses noticed in the regula- 

 tory pattern toward the temperature change. This would result in the 

 wide separation of the response curves from each other. The shrimp 

 acclimated to 32°C were even more temperature-sensitive than others. 



282 



