90
to a wider foraging range for the goatfish than for this par~
ticular snapper.
The high level of zinc-65 in the eyes of the surgeonfish
Naso literatus is contrary to the hypothesis that zinc-65 would
not normally be available to a herbivorous fish in a marine
environment contaminated by airborne fallout.
should
However,
it
be noted that this value represents a single specimen
only.
The fish was a large one and therefore it would not be
unusual for it to ingest some inorganic or animal material
associated with the algae upon which it feeds.
observation,
In a single
it would be possible for one radioactive particle
to produce a considerable deviation from the mean radioactivity
of a number of similar fish.
The extremely low values of zine in the eyes of two small
black-tipped sharks suggests the interesting speculation that
the zine in the retina may be more intimately associated with
the cones than with the rods,
since the proportion of cones to
rods has been reported to be low in sharks
Clarke,
6.3
(Gilbert,
1961 and
1961).
General Discyssion
For considering the ecology of the lagoon and its relation to the binding, by the biota, of zinc-65 from airborne
fallout,
it would be perhaps more useful to regard the organizat&