13
water, or radionuclides may be adsorbed on the surface of the
animal.
Although adsorption is an important means of contami-
nation of organisms by fresh fallout,
it is probably no longer
important at Bikini, where the last significant fallout occurred
in 1958.
The astronomically large surface area presented by the
masses of branching corals and their associated flora and fauna
must have removed,
from the water,
all adsorbable radionuclides
not already removed by the plankton soon after fallout.
The land organisms contain primarily the long-lived fission
products 1374, and 90... and,
as expected,
these radionuclides
are found associated with those tissues or organs which contain
potassium and calcium,
respectively,
since cesium and potassium
behave similarly in metabolism, as do strontium and calcium.
There are quantitative and qualitative differences in
radionuclide content of organisms associated with feeding habit.
The goatfish,
a bottom-feeding carnivore,
contains more 6000
and 20754 than the convict surgeonfish, a grazing herbivore,
or the mullet, a plankton feeder
(Tables 2 and 3).
Higher order
carnivores, the grouper and ulua, also contain more ©0%6 and
20735
(Table 4) than the convict surgeonfish; however, the
differences may be associated with age as well as with feeding
habit.
The smaller,
and presumably younger, reef fish of a species
contain less 90 Sr than the larger fish of the same species