-19tsotopes.
Levels of activity were 8,500 d/m/g pre-Nectar, reached
a maximum of 10 d/m/g four days post-Nectar,
and
declined to a
level of 3,000 d/m/g at 305 days and 537 days
(Fig. 1).
Gut with content
The hermit crab gut with its content was generally more variaple than liver in levels of activity, particularly during the
first month post-Nectar.
This difference is to be expected since
digested food would have variable amounts of surface contamination —
and not all crabs would feed on the same thing at any one time.
Initially, following the Nectar test,
the gut had the highest
level of activity of all tissues (5 x 106 a/m/g).
The activity in
the gut also had the shortest ecological half life of all tissues
during the first 100 days post-Nectar.
By 100 days, the levels
of activity in gut and liver approached each other and their eco-
logical half lives were about the same, although the gut remains
so variable from collection to collection that only an approxi-
mation can be made.
The activity in the carapace by 100 days was
higher than that in the gut even though the latter had the highest
initial activity.
This variation is, of course, due
to
the
different rates of decline, which reflect selection of the long-
.
lived isotope Sr?° by the carapace.
No chemical analyses of gut samples were made.
POE ARCHIVES
Gill
The rate of decline of activity of the gill of the crab is
more rapid than the rateof decay of mixed fission produds during
the first 10 to 20 days post-Nectar, but thereafter approximates
es