The interactions among the three variables 

 of radiation, salinity, and temperature also 

 caused significant changes in the nneasured 

 characteristics (table 6). The interactions of 

 radiation with salinity and radiation with tem- 

 perature caused signficant changes in IZ of 

 18 possible instances. Effects of the interaction 

 between salinity with temperature, however, 

 did not significantly alter any measured char- 

 acteristic during the 45 days of this study. The 

 interaction of radiation and salinity and tem- 

 perature had a significant effect on seven of 

 the nine measurements. Since interactions in 

 nature appear to be the rule rather than the 

 exception, these interactions possibly give 

 a better indication of changes in external form 

 than any one independent factor. 



Differences in Body Characteristics 

 After 45 Days 



Standard length and greatest body depth were 

 altered significantly by radiation, temperature, 

 and their interaction; weight and snout to vent 

 length similarly reacted to these factors except 

 that the main effect of radiation was not sig- 

 nificant (table 6). The main effect of radiation 

 was to cause a somewhat longer, deeper bodied 

 fish at the lowest radiation level of 0.83 rads/ 

 hour (table 7); an increase in temperature 

 generally caused a longer, deeper bodied, 

 heavier fish with a relatively longer snout to 

 vent length (table 8). 



Head length, eye diameter, and lengths of 

 the last dorsal spine, first dorsal ray, and 

 second anal spine were changed significantly 

 by temperature and by salinity (tables 8 and 9). 

 In general, the independent effect of these 

 two environmental factors resulted in relatively 

 larger body parts as temperature and salinity 

 levels increased, except for the effect of sa- 

 linity on eye dianneter. Here, the relative size 

 of the eye was larger at 10 p.p.t. than at 20 or 

 30 p.p.t. This difference may have been due to 

 a retardation in the rate of development of the 

 eye as it approached the asymptote of its 

 growth curve in relation to standard length of 

 faster growing fish at higher salinities. 



Table 7. --Table of means for the significant 

 effects of radiation after ^5 days of 

 exposure 



Table 8. — Table of means for the significant 

 effects of temperature after 45 days of 

 exposure 



**Slgnificant at 1-percent level. 



Table 9. — Table of means for the significant 

 effects of salinity after 45 days of 

 exposure 



*Significant at 5-percent level. 

 **Signif leant at 1-percent level. 



*Signif leant at 5-percent level. 

 **Signif leant at 1-percent level. 



The eye diameter, and the lengths of the 

 last dorsal spine, first dorsal ray, and second 

 anal spine were changed significantly by the 

 interaction between radiation and salinity (fig. 

 23). The general result was the same as that 

 for the main effect of salinity, i.e., as salinity 

 increased, body parts became longer. Once 

 again, the reaction of the eye was different. 

 This difference indicates that salinity was the 

 controlling factor in the interaction; radiation 

 merely acted as the modifier. 



43 



