.
OCEAN SEASONS
.
now
become abundant.
All these are born in time to
ï
partake of the rich pasturage drifting in the sea.
The
most minute of the animals will feed directly _upon the
diatoms, and in their turn Will fall a ptey to their own
larger enemies.
‘
'
"
,
.
'
By May or june the great crop of drifting plants is
cohsiderably diminished ; much of it has been eatei1, but
a
large quantity also has sunk to the sea oor where it
'
forms food for the large p0pulation of minute animals
living in the mûddy layers just above the bottom.» This
plant community, or phytoplankton as it is called, gives
.
place in the summer months to a community of animals,
the zooplankton, forms which are
growing up and
'
feeding one upon another. 'Throughout the summer the
.
appearance of this population is always changing, new
forms being set free into the water by their parents and
others disappearing to take up their abode on
the sea.
.
bottom.
_
'
‘
_
-
80 the succession of life passes on until
the autumn,
about .October, there is another someWhat
surprising
'
outburst of plant life, yet never so
as,that of the
,
spring.
Soon after this the plankton rapidly dies doWn
until in the winter it is at its poo'rest, only a small number
of animals Surviving to tide over
the lean months and give
rise once more to their numberless progeny in…the folloWing
spring when the sea wakes up from its winter sleep.
One of the most interesting problems in_marine research
has been the " search for the Causes of this succession oi
life in the sea, and it is only in quite recent years that the
.
underlying . principle has been brought to
It
_
is
'
_
evident that on thequatity of plaint-life present depends
the number Of animals that can exist, and that therefore
'
the great changes in» wealth of animal life can be traced to
_
the increase or'decre'ase of plants.
The eountless animals