97
and (3) transport of particulate matter by advection.
The major cycle in the figure,
organisms,
fish data.
involving the benthic
is well substantiated by the goatfish and surgeonThe goatfish,
typical benthic carnivores,
levels of zinc-65 in their tissues.
have high
The convict surfeonfish,
herbivorous browsers on benthic algae,
have virtually none.
Both species have roughly comparable amounts of stable zinc.
The evidence in support of the pelagic cycles of Figure 8
is not as strong as for the benthic cycle.
There are no true
herbivores among the fish of the pelagic division and it was
not feasible to separate bulk samples of autotrophs and primary
consumers from the rest of the limited plankton collection.
Therefore,
evidence similar to that available from the goatfish-
surgeonfish data was not obtained.
However,
there were high
levels of zinc-65 in the stomachs of the pelagic carnivorous
fish,
indicated in Figure 5,
South
(1957) indicated that it was also concentrated in the
Plankton.
and the data of Lowman,
Negative evidence,
Palumbo and
such as that provided by the sur-
geonfish for the benthic cycle,
would be particularly desirable,
but from the restricted sample of the lagoon biota available for
this study,
it was not possible to obtain it.
A hypothetical model,
showing the uptake,
cycling and loss
of zinc within the organism of a typical carnivorous fish,
is
(oF