(‘1 RCADIAN P &It10 1) ICII’I 103 IN PHYTOPLANKTON
363
rdgwc! wnsitnilrithig iii the light i l n d dividing in the dark while the
miniall; fed tit night, mti bred tluriiig the day. In spite of this scheme
I~ning prob:tbl,v oversimplified, motrher oue will add to our perplexity
(anti ariiiise childreii AH well), nuniely the general tendency of zoopltinktcrs to migrate up a t night! while phytoplankters climb up in the
morning. . .
b ‘ . 1 &rftwm:P.y with rion-circadian, periods
Clirc.idinri rliythins oitn bc obslarir*c*d or confused by periodic varitLtions othor t h ~ i
circiidittn, wlicther riltradian (periods from 30 minutes
to 20 hours) or infradian (from 28 hours to 5 days) according to the
nomenclatmre of chronobiologists.
Such ptirasit~e-effects often arise from tidal influence ; examples for
the various physico-chemical rind biological parameters will be found
in Allen (1923), Teixeira and Kutner (1963), Sournia (1965b, 1968),
Angot and G4rard (1967), Shah (1967, 1968, 1969), Welch and Isaac
(1967), Qasim and Gopinathan (1969), Platt and Conover (1971) and
others. In a productivity study of an Alaska lake, MacIseac (1965)
observed a combination of 12- and 24-hour cycles. Internal waves
also rnny interfere (Armstrong and LaFond, 1966 ; Koblentz-Mishke et
al., 1071 : Colton, 1972; see also Alexander and Corcoran, 1963).
As :I t,oiicli of poetry, let UH evoke the enigmatical lunar periodkitieH (Wootl, 1954 ; Tsiidn, 2969 ; Greuet, 1973).
(1. Itxo!pous verttm ijnckyenou6 factors
It is iiot t,he purposc? of this revicw to enter into the long-standing
tii~put~e tibout caxtcrntil and internal control of cii*c:adisn rhythms*. Both
views icr(? c:lcarly set forth hy Brown ( I t al. (1 970). Probably itny rhythm,
11s our knowledge of it develops, c m clispluy fciitures supporting either
theory, nud t h task of the inyestiptor is to explore both pwsibilities
in grcuter dcpth. In practical terms, endogenous timing is tested by
studying t h e phenomenon under constant-or supposedly constantenvironrnentd conditions (usuaIIy light and temperature only arc
ronsidercrl) : if i t persists, an endogenous clock is assumed. Again,
t hi8 postdatt* will not be discussed here, but relevant observations on
inarine phytoplunkton will be listed below.
The rhythm of cell division hits been shown to proceed under
continuous light, in laboratory cultures. Organisms tested were the
dirioflngel Iiiti’s (Jonyynulnx pol!jrdra, Gymnodinium aplenrhne, Promcuntr.lcm rniccrns (Sweeney and Hastings, 19.58, 1962 ; Sweeney, 1959)
. l a wfatotl a t thtt hrgmmng (we footnoto 1). 328).
p p w 111 i t s broder .miiwo.
oirrntlitln ” IS umtl throughout this
363
rdgwc! wnsitnilrithig iii the light i l n d dividing in the dark while the
miniall; fed tit night, mti bred tluriiig the day. In spite of this scheme
I~ning prob:tbl,v oversimplified, motrher oue will add to our perplexity
(anti ariiiise childreii AH well), nuniely the general tendency of zoopltinktcrs to migrate up a t night! while phytoplankters climb up in the
morning. . .
b ‘ . 1 &rftwm:P.y with rion-circadian, periods
Clirc.idinri rliythins oitn bc obslarir*c*d or confused by periodic varitLtions othor t h ~ i
circiidittn, wlicther riltradian (periods from 30 minutes
to 20 hours) or infradian (from 28 hours to 5 days) according to the
nomenclatmre of chronobiologists.
Such ptirasit~e-effects often arise from tidal influence ; examples for
the various physico-chemical rind biological parameters will be found
in Allen (1923), Teixeira and Kutner (1963), Sournia (1965b, 1968),
Angot and G4rard (1967), Shah (1967, 1968, 1969), Welch and Isaac
(1967), Qasim and Gopinathan (1969), Platt and Conover (1971) and
others. In a productivity study of an Alaska lake, MacIseac (1965)
observed a combination of 12- and 24-hour cycles. Internal waves
also rnny interfere (Armstrong and LaFond, 1966 ; Koblentz-Mishke et
al., 1071 : Colton, 1972; see also Alexander and Corcoran, 1963).
As :I t,oiicli of poetry, let UH evoke the enigmatical lunar periodkitieH (Wootl, 1954 ; Tsiidn, 2969 ; Greuet, 1973).
(1. Itxo!pous verttm ijnckyenou6 factors
It is iiot t,he purposc? of this revicw to enter into the long-standing
tii~put~e tibout caxtcrntil and internal control of cii*c:adisn rhythms*. Both
views icr(? c:lcarly set forth hy Brown ( I t al. (1 970). Probably itny rhythm,
11s our knowledge of it develops, c m clispluy fciitures supporting either
theory, nud t h task of the inyestiptor is to explore both pwsibilities
in grcuter dcpth. In practical terms, endogenous timing is tested by
studying t h e phenomenon under constant-or supposedly constantenvironrnentd conditions (usuaIIy light and temperature only arc
ronsidercrl) : if i t persists, an endogenous clock is assumed. Again,
t hi8 postdatt* will not be discussed here, but relevant observations on
inarine phytoplunkton will be listed below.
The rhythm of cell division hits been shown to proceed under
continuous light, in laboratory cultures. Organisms tested were the
dirioflngel Iiiti’s (Jonyynulnx pol!jrdra, Gymnodinium aplenrhne, Promcuntr.lcm rniccrns (Sweeney and Hastings, 19.58, 1962 ; Sweeney, 1959)
. l a wfatotl a t thtt hrgmmng (we footnoto 1). 328).
p p w 111 i t s broder .miiwo.
oirrntlitln ” IS umtl throughout this