134
'
ËTHE SEAS
.
”forms atousiderablé part of modern investigations into the
.
“resourCes of the
'
This Chapter has been
.
mainly to describing what the planktOn is and where and
how it” lives,— but in a future chapter‘will be given further
information of the part played by these small orgaisms
in the Watery world, in the light of recent research.
f
.
We cannot conclude, however, without Some mention of
recent application of plankt‘on research to shery investigations.
It has been found that in some régions, such as the
.
southern North Sea the diatoms may develOp into
of sufcient concentration to be avoided by certain pelagic .
shes such as the herring.
Under these circumstances
the heiring may be diverted from their normal course of
_
migration, and this has important effects on the sheries.
It is now a part of shery research to watch the develop- . '
ment and movement of these diatom patches in an attempt
to show the sherman where he is likely to obtainthe best
.
_’
catchès. '
'
'
The study of plankton organismS is also proving of
use‘ in helping to show the movements of Water' masses.
Some species of plankton animals
restricted to waters ot
'
Certain types.
_The presence of océanic water can, for
instance, be detected in coastal areas by the presence of
certain ocèanic plankton organisms; which 'theref0re give
an‘additional indication of the origin of the water to those
,
chemical and physical characteristics usually made use of
..
by” hyd$graphers. 'The Study of this interesting drifting
_
community thus now. assumes practical
f