irntl C?~rr~i/o~lirrirrnt n/>lsonii (l'i~Jrt)('~ /J/ nl., 1964) and the diatom Phaeot/~n*t!j/,~ttrt lri(*orn td ~ L ~ I I
( t ' t ~ Init~t* P/ GI., i !%4).
Tho tirning of vcrtici~l ntigriltions in thc dinofl:tgcllates Cmhoninn
rind (hn!/a,~iln,~., grown in the- " tltbep tank " or in the labortltory (Eppley
~t al., IH(iXb), \$,as uot tbxuc.tly ilcljusted to that of the illumination
(but ~.)t~-ee"dctl it slightly) : furthermore, tho vertical pattern inCachonina
rt11nrriric.d uni~fI'i3ctod u ~ ~ t l e r
c~ontinuo~ls light or darkness. The surf
zone cliirtoln (!lrc.e/oc~ros (~rmnlum ~~ises to the surface well before sunrise
(1,cwin iind ti rrtby, 1073).
Eviclonct. for rndogc~nic.it,y in thcb photosynthetic cap:~city cyvcle
hi~s heen rtwit.wc.(l c~bovc~ in the rc*levi~nt section.
A t l r ~ i ~ l
d(.t,c~r~nitiixrn is tilso cI(~~r1.y tle~nonstrated in the case of bio1ttrnitit~~c.enc~c.. 'I'llis rllythm prrsists uncler constilnt conditions
(Swce~lcy and Ilr~stirigs, 1957 i ~ l ~ t l
s~~bse(]uent work), but natural
populiitions rtqspond to it11 c.xtt*;~ol.t3int1r:y ~xtilict~ion of sunlight (an
erlipsc) in thc swtr~c* rliilnt1cr thiit thcy rchact to thta rtsual sunset (Backus
Pt f ~ l . , I!)(%).
1Tnless the t*evic.wc~~- is ~)clrverscly obscssed with or unreasonably
1)jit~cd towitrtls di~ylnigllt ohi~nges, it rnsy be concluded from the above
S I I I + V C ~
t h t ~ t
C~VC'I~J' l)i\riltll('t~'~ or p r u p ~ r t y withi11 the compass of current
pfiiriktology is sttl)ject t o Horn(. circ:i~tlii~n periodicity ; even when observi~tions it1.c Ii~cking or conflicting, i t glance nt algiil physiology suggests
tllitt it shoulcl be so. I t would be more surprising to encounter some
chi~ruoteristic which woul(l remain const,ar~t throughout (lay and night.
As f i ~ r LA t ]I(* ti r n ~ tlimcnsion is conceniecl, oceanographers have
up to now fboussetl ruuch of' their i~ttent~ion on ueasorial changca and
rin~ittttl cycles; let us now recognize thth full importuncc of the 24-hour
time aiai~lr. As IL rnattcr of t'i~(*t, ~)hytoplunkton is not si~tjjectcd to
f(wer c ~ c n t s t~et~~veen two sirccessivt~ duybre;~k~ (the approximate
lifitirllc. Ofi~ phytoplitnkt~r-) t l l i ~ i
it is in the period between two springs ;
('ireadin 11 l~nd i ~ n n ~ w l
hist,ories itre c*y u i ~ lly drumatic. l'hr fbrrner type
C Y L I ~ be in sonle way aonnitlere(l ;is iL " retluctd rlloclel " of the latter;
f'rirt11c~- I P S C ~ ~ ~ C ~ I P S
or1 cire;ldii~n histories will tell us pracisejy how fur
this is trrie.
'fhe i~llll)litlidt'~ of' tnho physici~l it11(1 h i ~ l o g i ~ i ~ l
change^ over 24
Iiours rLn. fixr frorn lwing ncgligiblc. As a whole, milx,'min ratios
rtxs~ilting fr.otn tliel stutlirs do not tliff(:r rnurk(*tlly from thc~ ranges of
~ i ~ r i i i t
ion^ rec.ordctl tl uring miiIv gc.ograpt~ioit l Y U P V ( ~ H 01' ye~r-lorig
cries : ~ L S ( ' X I L I ~ ~ I O ,
the :iniplitrltl~s of hokh die1 an(\ seasonibl ohungen
( t ' t ~ Init~t* P/ GI., i !%4).
Tho tirning of vcrtici~l ntigriltions in thc dinofl:tgcllates Cmhoninn
rind (hn!/a,~iln,~., grown in the- " tltbep tank " or in the labortltory (Eppley
~t al., IH(iXb), \$,as uot tbxuc.tly ilcljusted to that of the illumination
(but ~.)t~-ee"dctl it slightly) : furthermore, tho vertical pattern inCachonina
rt11nrriric.d uni~fI'i3ctod u ~ ~ t l e r
c~ontinuo~ls light or darkness. The surf
zone cliirtoln (!lrc.e/oc~ros (~rmnlum ~~ises to the surface well before sunrise
(1,cwin iind ti rrtby, 1073).
Eviclonct. for rndogc~nic.it,y in thcb photosynthetic cap:~city cyvcle
hi~s heen rtwit.wc.(l c~bovc~ in the rc*levi~nt section.
A t l r ~ i ~ l
d(.t,c~r~nitiixrn is tilso cI(~~r1.y tle~nonstrated in the case of bio1ttrnitit~~c.enc~c.. 'I'llis rllythm prrsists uncler constilnt conditions
(Swce~lcy and Ilr~stirigs, 1957 i ~ l ~ t l
s~~bse(]uent work), but natural
populiitions rtqspond to it11 c.xtt*;~ol.t3int1r:y ~xtilict~ion of sunlight (an
erlipsc) in thc swtr~c* rliilnt1cr thiit thcy rchact to thta rtsual sunset (Backus
Pt f ~ l . , I!)(%).
1Tnless the t*evic.wc~~- is ~)clrverscly obscssed with or unreasonably
1)jit~cd towitrtls di~ylnigllt ohi~nges, it rnsy be concluded from the above
S I I I + V C ~
t h t ~ t
C~VC'I~J' l)i\riltll('t~'~ or p r u p ~ r t y withi11 the compass of current
pfiiriktology is sttl)ject t o Horn(. circ:i~tlii~n periodicity ; even when observi~tions it1.c Ii~cking or conflicting, i t glance nt algiil physiology suggests
tllitt it shoulcl be so. I t would be more surprising to encounter some
chi~ruoteristic which woul(l remain const,ar~t throughout (lay and night.
As f i ~ r LA t ]I(* ti r n ~ tlimcnsion is conceniecl, oceanographers have
up to now fboussetl ruuch of' their i~ttent~ion on ueasorial changca and
rin~ittttl cycles; let us now recognize thth full importuncc of the 24-hour
time aiai~lr. As IL rnattcr of t'i~(*t, ~)hytoplunkton is not si~tjjectcd to
f(wer c ~ c n t s t~et~~veen two sirccessivt~ duybre;~k~ (the approximate
lifitirllc. Ofi~ phytoplitnkt~r-) t l l i ~ i
it is in the period between two springs ;
('ireadin 11 l~nd i ~ n n ~ w l
hist,ories itre c*y u i ~ lly drumatic. l'hr fbrrner type
C Y L I ~ be in sonle way aonnitlere(l ;is iL " retluctd rlloclel " of the latter;
f'rirt11c~- I P S C ~ ~ ~ C ~ I P S
or1 cire;ldii~n histories will tell us pracisejy how fur
this is trrie.
'fhe i~llll)litlidt'~ of' tnho physici~l it11(1 h i ~ l o g i ~ i ~ l
change^ over 24
Iiours rLn. fixr frorn lwing ncgligiblc. As a whole, milx,'min ratios
rtxs~ilting fr.otn tliel stutlirs do not tliff(:r rnurk(*tlly from thc~ ranges of
~ i ~ r i i i t
ion^ rec.ordctl tl uring miiIv gc.ograpt~ioit l Y U P V ( ~ H 01' ye~r-lorig
cries : ~ L S ( ' X I L I ~ ~ I O ,
the :iniplitrltl~s of hokh die1 an(\ seasonibl ohungen