93
In the benthic division,
autotrophs are present,
consumers.
on the other hand,
sessile
providing a food source for primary
Very little particulate radiomaterial would be
associated with these benthic algae because:
nutrition is autotrophic,
(1) their mode of
(2) suspended particles are subject
to adsorption and ingestion by the pelagic biota prior to
reaching the benthos, and (3) the larger sizes of the benthic
algae and the settling particles reaching the benthos reduce
the likelihood of adsorption due to surface forces.
The avail-
ability of particulate radiomaterials to fish feeding on benthic algae would be,
‘
therefore, very limited.
The almost complete lack of radiozinc in the convict
surgeonfish, coupled with what appear to be usual amounts of
stable zinc, supports the hypothesis that the radiozinc was
bound to a particulate phase in the lagoon and was thus una-~
vailable to primary consumers, but available to carnivores.
Stable zinc,
since it is dissolved in sea water is available
to fish regardless of feeding habit.
A model illustrating
this hypothesis has been constructed and presented in Figure 8.
It is based on available physico-chemical and ecological information and the data presented in this thesis.
In Figure 8,
inorganic fallout particles, comprised
largely of Ca(OH)z to which zinc-65
(among other radiomaterials)
{OF