comparatively high levels of sr90 in the carapace probably
represent a condition of equilibrium with the available strontium
rather than an accumulation over a long period of time.
In muscle of land crabs collected at Belle Island in
February and November 1955, and analyzed in January and March -
0
of 1956, cs?37, sp? ayana cetterriHt
accounted for 844,
10%, and 1%,respectively, of the total activity.
In contrast
to the exoskeleton, muscle had a variable, though generally
decreasing level of long lived isotopes throughout the. post
Nectar collecting period at Belle Island.
Whether or not sr?°
levels in the muscle were decreasing during this period is not
known.
Although there was a decrease from 90 d/m/e wet in a
single specimen collected in February 1955 to 60 d/m/g wet
|
in a specimen collected in November 1955, experience has shown
that individual variation may account for such differences.
Values of determinations of Sr?° in muscle of land erabs from
Kabelle Island, Rongelap Atoll, indicate that the sr?° level
is remaining constant.
But here again individual variation is
great; the value for duplicate determinations of muscle from a
single coconut crab collected in January 1955 was 5971.5 a/m/e wet
and the average of three samples of hermit crab muscle taken in
July 1956 was 5937 d,m/g wet.
It should be clearly understood that the above discussion
applies only to the land crabs and not to marine crabs.
Marine
crabs have lower levels of total activity than do the land crabs
0
and contain little, if any, sr? (see for example NRDL-455
Table A.3).
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