Effect of Acclimation and Test Temperatures 



Metabolic rates were changed greatly during salinity adaptation 

 depending upon the temperature background. The effects of change 

 between acclimation and test temperatures were shown comparatively 

 on the metabolic responses of shrimp acclimated at 18°C (Fig. 

 118a, b,c), 25°C (Fig. 119a, b,c), and 32°C (Fig. 120a, b,c). Com- 

 parisons were made between the metabolic changes occurring at the 

 1, 2, 4, and 10 hour intervals. These intervals were selected for 

 comparison because of the rapid initial changes. The responses 

 were compared with the control mean (zero hour reading) and with 

 the mean steady-state levels. 



Two major metabolic patterns were observed when the test tem- 

 peratures were different from acclimation. The first pattern was 

 characterized by a gradual decrease in the oxygen consumption from 

 the initial (zero hour) high level until a new steady state was 

 reached. In the second type there was a steep initial increase in 

 the respiratory level followed by a gradual decrease until a new 

 steady-state was attained. The first pattern of response was ob- 

 served generally when the test temperature was lower than the accli- 

 mation temperature as shown in Fig. 119a (acclimated at 25° and 

 tested at 18°C) and Figs. 120a and 120b (acclimated at 32°C and 

 tested at 18° or 25°C, respectively). In these cases the new 

 steady-state levels were lower than the control means. Animals 

 belonging to this category exhibited greater metabolic fluctuations 

 in low salinities 2, 5, 10, and 15°/oo during the ten hours after 

 transfer. Changes were, however, minimal in 25 and 36°/ooS (Fig. 

 119a and 120a, b) , 



The second pattern of metabolic responses was seen in shrimp 

 acclimated to 18°C and tested at higher temperatures of 25° (Fig. 

 118b) and 32°C (Fig. 118c) and in shrimp acclimated to 25°C and 



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