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hy ertebrates
:
Rongelap invertebrates showed levels of activity of from
0 to 104 uc/kg on March 26, 1954. By late January 1955 the
evels had dropped about two orders of magnitude.
The almost
Abiquitous black sea cucumber, Holothuria atra, serves best to
exemplify the trend (Figure 6).
Next best as indicators were
riant clams, Hippopus and Tridacna; land hermit crab, Coenobita;
boconut crab, Birgus; corals; and spider snail, Pterocera.
Rad loactivity was highest in the digestive and excretory organs,
intermediate in the integumentary organs, and lowest in the
muscle.
Jappendix.
Actual values for the samples are tabulated in the
The kidney of the giant clam (Figure 7) is of special
Jinterest because of its high level of activity and slow rate of
decline.
A graph of activity of the tissues of land hermit
jorabs collected at the more radioactive northern islands in
fMarch and July 1954, and from a less radioactive southern island
} in January 1955, shows the effect of geographical differences in
radioactivity upon the trend of decline, accentuating the slope
}in the later period (Figure 8). The spider snail was similar
}to the hermit crab in the level of activity of its tissues,
|while the corals were about an order of magnitude lower.
|Land Plants and Algse
Land plant and algae collections were made at Labar
ed j,
| Kabelle, Lomuilal, Gejen, and Rongelap Islands.
Most of the
, edible plants were collected in December 1954
and January 1955
F at Rongelap Island.
These were coconut, squash, papaya, arrawr ©)