Figure 2.--Oysters, which can be seen through the clear sides of a modified "Lund" trough, are held in individual com- 

 partments and can be fed selected diets of radioactive foods. In such a system, an oyster's preference for certain 

 species of phytoplankton can be accurately determined, along with its ability to digest and utilize them. 



the Pacific. Radiobiologists believed that fis - 

 sion products would be of chief concern. Be- 

 cause of this belief, the experimental work 

 was concerned first with individual fission 

 products, and later with fission-product mix- 

 tures. Because scintillation counting tech- 

 niques had not then been developed, identifica- 

 tion of beta-emitting radionuclides accumulated 

 by marine organisms from fission-product 

 mixtures was laboriously determined by the 

 use of aluminum -absorption data. 



With the discovery of the importance of the 

 accumulation of zinc 65 in tuna and cobalt 60 in 

 mollusks collected from the Pacific, emphasis 



was shifted somewhat to include accumulation 

 and retention of neutron-induced radionuclides 

 by invertebrate species under study. Along 

 with this research there was a shift in counting 

 techniques to make use of the more efficient 

 gamma detectors (scintillation) being de- 

 veloped. Because of the great interest in con- 

 tamination of tuna that was being reported, a 

 supplemental project requested by the AEC 

 was initiated to emphasize accumulation by 

 fishes. The large fish-holding tanks at the 

 laboratory were rebuilt, the laboratory boat 

 was fitted for collecting and transporting fish, 

 and a boat crew was employed. 



