36°/ooS great fluctuations occurred. However, the shrimp tested at 

 25°C were consistently efficient osmoregulators in the entire sa- 

 linity range. 



Blood chloride ion 



The temperature effect on chloride ion regulation was similar to 

 the osmoconcentration in brown shrimp acclimated at 25°C (Fig. 88), 

 32°C (Fig. 89), and 18°C (Fig. 90). The chloride ion regulatory pat- 

 tern in 2, 5, and 10°/ooS was similar in 25° and 32°C. The ion loss 

 was relatively less in these conditions than in 18°C. Temperature 

 effect was not significant on chloride regulation in 15 and 25°/ooS. 

 In 36°/ooS responses were similar at 25° and 32°C on the first day 

 of transfer. From the third day onward the animals from 32° and 

 18°C responded alike in 36°/ooS. 



Acclimation and testing in 32°C (Fig. 89) improved the ability 

 for chloride ion regulation in 36°/ooS over that of shrimp accli- 

 mated to 25°C and tested in 32°C. However, animals acclimated to 

 32 °C experienced considerable disadvantages in 36°/oo and 2°/ooS 

 when tested at 18°C. Temperature effect was not seen in 10, 15, 

 and 25°/ooS. The shrimp tested in 25°C and 32°C responded quite 

 similarly in all the salinities except in 5°/ooS. 



The chloride ion regulation improved considerably in animals 

 acclimated and tested at 18°C (Fig. 90). The acclimation also made 

 it possible to maintain nearly the same ion levels in 2, 5, and 

 10°/ooS as in 25°C, without the initial rapid loss. The ion regu- 

 lation of shrimp acclimated to 18° and tested at 32°C was not im- 

 paired much except in 2°/ooS where there was a rapid loss of chlorides 

 during the initial four hours. In 25 and 36°/ooS the ion regulatory 

 pattern was much the same in both 25° and 32 °C, 



165 



