In these animals the salt concentration levels decreased in tempera- 

 tures other than 32°C. Furthermore, the shrimp lost large amounts 

 of salts in salinities below 10°/ooS even in 32°C which was their 

 acclimation temperature. 



The chloride regulation in shrimp acclimated to 25°C was less 

 affected by temperature change within a salinity range of 5 to 

 25°/oo. Nor was this influence noticed in a 10 to 25°/ooS range 

 in animals acclimated to 32 °C. The low temperature acclimated 

 shrimp were, however, more temperature-sensitive in the chloride 

 regulation as were the 32°C acclimated animals in osmotic regulation. 

 Although chloride regulation usually paralleled the osmoconcentration, 

 variations occurred between the two responses depending upon test 

 temperature. 



Temperature Influence on the Steady-State Levels 



Conclusions made on salinity adaptation at 18°C exclusively on 

 the basis of respiratory rates may be misleading. At IS^C the res- 

 piratory rates dropped to very low levels within a few hours and re- 

 mained throughout. At 18°C these levels usually designated as the 

 steady-state levels appeared faster than in 25 °C in most of the sa- 

 linities. On the basis of these levels it is hard to conceive the 

 idea of faster salinity adaptation in 18°C than in 25°C. Moreover, 

 the appearance of steady metabolic and osmotic levels in 18°C at 

 different intervals provides conflicting evidence on the state of 

 salinity adaptation. 



Bulnheim (1974) studied the respiratory metabolism in the isopod 

 Idotea balthica from the Baltic Sea. The salinity in this area aver- 

 ages 15°/oo. The laboratory control salinity was 10°/oo. Habitat 

 temperature was not reported; but the isopods reproduced at 15°C 

 temperature in the laboratory which indicates its proximity to the 

 ambient conditions. The isopods transferred from 15 °C achieved 



283 



