In animals acclimated to 25° and tested in 18°C the respiratory 

 rates were well below the normal level. In some of the salinities 

 the rates maintained no correlation with the osmotic or ionic gra- 

 dients. For instance the oxygen consumption in 36°/ooS was at the 

 same level as in 15°/ooS. In 2°/ooS the consumption was similar to 

 10°/ooS. However, in 5, 10, and 15°/ooS some kind of correlation 

 was sustained between the two responses as in 25°C. 



The salinity-related respiratory sequence of the shrimp accli- 

 mated to 18°C and tested in 25° or in 32°C more or less resembled the 

 pattern in animals acclimated at 25°C and tested in the same tempera- 

 tures. Nevertheless, in the test temperature of 18°C minor variations 

 appeared in the respiratory rates between the rest of the salinities, 

 except in 2 and 5°/ooS. At the same time, the osmotic and chloride 

 regulatory pattern did not change from the original. Consequently 

 there was no consistent correlation between the osmotic regulation 

 and the respiratory rates. 



In animals acclimated to 32° and tested at 18°, 25°, and 32°C 

 the oxygen consumption rates showed no relation to the osmotic or 

 chloride levels in the respective salinities. 



In animals acclimated and tested in 25°C the metabolic responses 

 were influenced mainly by the salinity changes. But in 18° and 32°C, 

 as a result of temperature influence the correlation between the oxy- 

 gen consumption and osmotic or chloride gradients disappeared. 



Potts and Parry (1964) observed that changes in metabolic rates 

 are, in most cases, much too large to attribute to energy expenditure 

 for ionic and osmotic regulation alone. They stated that increased 

 metabolic rates caused by salinity change were not confined to the 

 tissues involved in osmotic work. Therefore we are not certain that 

 the respiratory rates in shrimp reflect the energy spent to maintain 

 the osmotic or chloride gradients. 



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