360
A I A I N ROZTltNIA
times ciin br delimited wound the tinie of the maximum, in order to
lteop the (~rror negligihle. [n t,his way Taylor and Hughes (1967) found
tlmt nieasurenients niade between 08.00 and 16.00 hours vary by only
Any rigid wnipling whcdule muy prove to be impracticable during
occcuiogru~~liie criiises. The possibility thus remains of calculating
correction factors which would cancel out the circadian effect. More
or less sophisticnt1ed at,t,empts were made in this connection by Angot
(1981), I h t y et nl. (l9(13), Ncwhouse (1968), Doty (1969), Quasim el al.
(1969), Margalef (1972) and Small et al. (1972). According to one of
these workera (Newhonse, 1!)68), “ it is unlikely that [the “ periodicitycorrect ion ” iict1ors] cim bc extended beyond the data from which
t h y ww‘c ~)wp:ired ”.
25% 01’ ICSH.
I x . f’HOTOSYNTHESIS lJN1)ER NATURAL (:ONDITIONS
hi the pi~evious section, photosynthesis was measured in an incubator under constant! artificial light. Let U B now see (or imagine. . . )
whiLt haLppcns in sit74 under natural sunlight.
Ono might, reusonably expect a similar afternoon depression to
occiir. Sttrprisingly, this is far from being the rule, as may be seen from
the following records ( 14C mensurements unless otherwise specified) :
--morning production higher than that in lifternoon : Vollenweider
arid NtLuwerck (1961) : Verduin, 1957 (pH-C02 in “free ” fresh water) ;
Ohle, 1958 (oxygen light-und-dark method) ; Capblancq (I 972) ;
---no signitici~nt difference : Forsbergh (1969) ; Occhipinti et aE., 1961
(oxygen light-and-dark method) ;
--ufttornoon product,ion higher t h a n that in morning : Sournia (1968) :
Quttsim rt nl. (1 969) ;
--the iibove tliruc cases ulternatively : Renk and Torbicki (1972).
A compromise is worked out by Panouse (1972) : morning production
would be higher offshore awl lower in coastal waters; as a tentative
expliini~tioii L’unouso aonsidcr,u that, in the second half of the thy,
nutrients become exhuusted in oceanic areas, while temperature increases considerably a t shal low stations. The first point deflerves
considerution but, the second one is nothing less than questionable.
This recalls the inshore/offshore pattern for the rhythm of photosynthetic capncity (see above), ascribed by MaIone (1971) to the
differential rates of nutrient consumption by nano- and microplankton.
‘l’hwi, tor. both photosynthetic capacity ond in situ photosynthesis,
the nhi~pe of‘ the die1 curve may be affected by availability of nutrients
iuld species composition. Further investigations are required, however
A I A I N ROZTltNIA
times ciin br delimited wound the tinie of the maximum, in order to
lteop the (~rror negligihle. [n t,his way Taylor and Hughes (1967) found
tlmt nieasurenients niade between 08.00 and 16.00 hours vary by only
Any rigid wnipling whcdule muy prove to be impracticable during
occcuiogru~~liie criiises. The possibility thus remains of calculating
correction factors which would cancel out the circadian effect. More
or less sophisticnt1ed at,t,empts were made in this connection by Angot
(1981), I h t y et nl. (l9(13), Ncwhouse (1968), Doty (1969), Quasim el al.
(1969), Margalef (1972) and Small et al. (1972). According to one of
these workera (Newhonse, 1!)68), “ it is unlikely that [the “ periodicitycorrect ion ” iict1ors] cim bc extended beyond the data from which
t h y ww‘c ~)wp:ired ”.
25% 01’ ICSH.
I x . f’HOTOSYNTHESIS lJN1)ER NATURAL (:ONDITIONS
hi the pi~evious section, photosynthesis was measured in an incubator under constant! artificial light. Let U B now see (or imagine. . . )
whiLt haLppcns in sit74 under natural sunlight.
Ono might, reusonably expect a similar afternoon depression to
occiir. Sttrprisingly, this is far from being the rule, as may be seen from
the following records ( 14C mensurements unless otherwise specified) :
--morning production higher than that in lifternoon : Vollenweider
arid NtLuwerck (1961) : Verduin, 1957 (pH-C02 in “free ” fresh water) ;
Ohle, 1958 (oxygen light-und-dark method) ; Capblancq (I 972) ;
---no signitici~nt difference : Forsbergh (1969) ; Occhipinti et aE., 1961
(oxygen light-and-dark method) ;
--ufttornoon product,ion higher t h a n that in morning : Sournia (1968) :
Quttsim rt nl. (1 969) ;
--the iibove tliruc cases ulternatively : Renk and Torbicki (1972).
A compromise is worked out by Panouse (1972) : morning production
would be higher offshore awl lower in coastal waters; as a tentative
expliini~tioii L’unouso aonsidcr,u that, in the second half of the thy,
nutrients become exhuusted in oceanic areas, while temperature increases considerably a t shal low stations. The first point deflerves
considerution but, the second one is nothing less than questionable.
This recalls the inshore/offshore pattern for the rhythm of photosynthetic capncity (see above), ascribed by MaIone (1971) to the
differential rates of nutrient consumption by nano- and microplankton.
‘l’hwi, tor. both photosynthetic capacity ond in situ photosynthesis,
the nhi~pe of‘ the die1 curve may be affected by availability of nutrients
iuld species composition. Further investigations are required, however