(!I [WADI AN P ~BIOOZ)l(~ITIEX IN PlIY TOPLAN KTON
343
We rniy coiicludt. that tho chlorophyll content of phytoplankton
in subjected to IL die1 periodicity, intlependently of grazing;, cell division
tmtf vfq*ti(atd mipmtion which art’ actvmicod from time to time iw causes*.
The main infiiicnce is obviously light, but other factors interfere
(nutrients, taxonomic polrition and other8 . . . , to be investigated) so
that n single general scheme could tiardly be conceived in the present
stiite of knowlcclge. For a given set) of conditions, n circutlinn correction
(*an be devtrlopcd for adjusting geographical distributions (Qlooschenko,
1!)67 ; Vorst)wgh, 1969; (iloosc~henlro ct al., 1072), though the error encoimtlcwd nppwred to b(1 negligible in the eutrophic laku studied by
Ichiniura (1960).
It Rhould be iidded liere thnt in vivo fluorescence of chlorophyll a has
recentlg h e n shown to vary reciprocally to solar illumination (D.
Hlasco, personal communication; Kiefer, 1973 and in press); such a
die] component must now be taken into account,, in addition to other
fmtors, when in, vivo fluorescence is measured as an index of pigment
concentrat ion.
VI I. OTHER CELLULAR CHARACTERISTICS
Very little attention has been pibid to the die1 variations of cell
components othcr thnn chlorophyll a, in spite of the fact that every
oellular chirrcwtcristic is expected to show some changes in the course
of 24 hoiirs (synchrony being ausumrd or not), if only because of the
ill t,wnnt,ion of photosynthesizing and non-photosynthesizing phases ;
i t simple look at8 some physiologicul research, for instance that of Cook
( 1 Otil) on EuglPnn or Tumiytt ( 1964) on ChZoreZln should be convincing
ciiouph in this rrqwct. McAllister (1971) has contemplrttc:cl the clifferent ways for cell carbon, cell volume and their ratio to v w y during
11 lightldark cycle.
Eppley and Coittsworth ( I 966) noted that cell volume of Dunaliella
increased throughoub the light period (cell division here being nocturnd). IYitli IlifyZum (Eppley et al., 1967), cell carbon and nitrogen
increased in the light while cell phosphorus increased in the dark, as
did cell silicon in the light and in the early dark phase. ATP content
of diatoms (Coombs et al., 1967 ; Holm-Hansen, 1973) exhibits an abrupt
aiid short decline at the onset of the dark period-and higher plants aa
wc11 (Bomsel nnd Pradet, 1967).
Die1 chunges of pigment ratios have been studied a t sea. Chlor. a/
chlor. c ratio tends to increase during the day in surface layers and to be
higher t i t night in deeper layers, as shown by Koblentz-Mishke (1971),
* To avoitl any roiifuaion, msiiltu should be oxpiwscwd 8~ pigment par 0011, following the
usage of physiologists, in~tead of pigment por unit volume of 8011 water.
343
We rniy coiicludt. that tho chlorophyll content of phytoplankton
in subjected to IL die1 periodicity, intlependently of grazing;, cell division
tmtf vfq*ti(atd mipmtion which art’ actvmicod from time to time iw causes*.
The main infiiicnce is obviously light, but other factors interfere
(nutrients, taxonomic polrition and other8 . . . , to be investigated) so
that n single general scheme could tiardly be conceived in the present
stiite of knowlcclge. For a given set) of conditions, n circutlinn correction
(*an be devtrlopcd for adjusting geographical distributions (Qlooschenko,
1!)67 ; Vorst)wgh, 1969; (iloosc~henlro ct al., 1072), though the error encoimtlcwd nppwred to b(1 negligible in the eutrophic laku studied by
Ichiniura (1960).
It Rhould be iidded liere thnt in vivo fluorescence of chlorophyll a has
recentlg h e n shown to vary reciprocally to solar illumination (D.
Hlasco, personal communication; Kiefer, 1973 and in press); such a
die] component must now be taken into account,, in addition to other
fmtors, when in, vivo fluorescence is measured as an index of pigment
concentrat ion.
VI I. OTHER CELLULAR CHARACTERISTICS
Very little attention has been pibid to the die1 variations of cell
components othcr thnn chlorophyll a, in spite of the fact that every
oellular chirrcwtcristic is expected to show some changes in the course
of 24 hoiirs (synchrony being ausumrd or not), if only because of the
ill t,wnnt,ion of photosynthesizing and non-photosynthesizing phases ;
i t simple look at8 some physiologicul research, for instance that of Cook
( 1 Otil) on EuglPnn or Tumiytt ( 1964) on ChZoreZln should be convincing
ciiouph in this rrqwct. McAllister (1971) has contemplrttc:cl the clifferent ways for cell carbon, cell volume and their ratio to v w y during
11 lightldark cycle.
Eppley and Coittsworth ( I 966) noted that cell volume of Dunaliella
increased throughoub the light period (cell division here being nocturnd). IYitli IlifyZum (Eppley et al., 1967), cell carbon and nitrogen
increased in the light while cell phosphorus increased in the dark, as
did cell silicon in the light and in the early dark phase. ATP content
of diatoms (Coombs et al., 1967 ; Holm-Hansen, 1973) exhibits an abrupt
aiid short decline at the onset of the dark period-and higher plants aa
wc11 (Bomsel nnd Pradet, 1967).
Die1 chunges of pigment ratios have been studied a t sea. Chlor. a/
chlor. c ratio tends to increase during the day in surface layers and to be
higher t i t night in deeper layers, as shown by Koblentz-Mishke (1971),
* To avoitl any roiifuaion, msiiltu should be oxpiwscwd 8~ pigment par 0011, following the
usage of physiologists, in~tead of pigment por unit volume of 8011 water.