X 



J. IS 



Vo ♦►' 



»-7 



z 



"J *►' 



'*o %*■' 



Figure 24.— Exploration of the interaction surface formed by (a) the standard length, (b) the ratio of wet weight 

 to standard length, (c) the ratio of standard length to greatest body depth, and (d) the ratio of standard length 

 to snout- vent length of pinfish exposed to three levels of temperature and three levels of radiation for 45 days. 



these three factors plus the three-way inter- 

 action between radiation, salinity, and tem- 

 perature had become the significant controllers 

 of length. According to this finding, it took 

 an accumulated dose of 577 and 890 rads in the 

 two irradiated groups for radiation to have a 

 significant effect on length. A table of means 

 (table 10), for the main effects of temperature 

 (the only consistently significant factor) at 

 each sample time shows the change in length 

 at each temperature over 45 days. 



Ecological Implications 



Relatively few studies have been concerned 

 with low levels of chronic radiation as an in- 

 fluence in the marine environment. Levels as 



low as 0.50 and 0.41 rads/hour of chronic 

 cobalt 60 irradiation caused no observable 

 effects on eggs and alevins of the anadromous 

 Chinook salmon, Oncorhynchus tshawytscha , 

 and coho salmon, O. kisutch, respectively. 

 They spawn their eggs in fresh water, and the 

 alevins migrate to sea to grow to adulthood. 

 There also have been relatively few studies 

 that describe the effects of acute radiation in 

 the marine environment. We found that the tol- 

 erance of the mummichog to acute radiation 

 doses is altered by salinity and temperature. 

 Radiation levels required to kill 50 percent of 

 a population of animals (L,D-50) have been 

 established for several marine and estuarine 

 species by this laboratory. Postlarval pinfish 

 were shown to have an LD-50 50-day value of 



45 



