30 



■ 



cr 



X 



d 



P20 



LU 



D 



—I 



< 



10 



..<N 



5 p.p.t. 



50p.p.t. 



100 p.p.t. 



150 p.p.t. 



200p.p.t. 



.87 



.89 



J 



10 



20 



30 



TEMPERATURE (°C.) 



Figure 28.-- The effect of temperature upon the respiration rates of brine shrimp nauplii at five salinities. 

 The numbers at the ends of the regression lines are the correlation coefficients for the lines. 



medium (fig. 29). When the QjQvalues for all 

 temperature-salinity combinations tested were 

 analyzed by an analysis of variance, tempera- 

 ture was found to be a highly significant factor 

 (P< 0,01), salinity was not significant, and the 

 temperature-salinity interaction was signifi- 

 cant at the P<0.10 level of confidence. The 

 influence of temperature was expected, since 

 temperature affects the rates of biological and 

 chemical reactions. The response of the brine 

 shrimp nauplii to temperature change appears 

 to be almost independent of salinity because 

 the patterns of Qjq values are similar for each 

 salinity. The only exception is at the salinity 

 of 150 p,p,t., at which QjQdecreased with in- 



creasing temperature. At present we have no 

 explanation for this difference in response to 

 temperature increase. 



The apparent differences in the available 

 data on the effects of temperature and salinity 

 upon the respiration rates of brine shrimp 

 nauplii may result in part from genetic dif- 

 ferences in the animals. There are many popu- 

 lations of brine shrimp throughout the world, 

 and each of these populations has a slightly 

 different habitat. Thus their physiological re- 

 sponses to changes in the environment, such 

 as changes in temperature and salinity, may 

 be different. This possibility makes it very 

 difficult to compare results of various inves- 



53 



