25
plankton was calculated to be in the range of 40 to 50 cal/cm 2 /halflight day.
It should be remembered that during the austral summer
months, total daily flux can exceed that of tropical latitudes (HolmHansen et al., 1977) .
..,9 C/LITER/HOUR
I2f
TEMPERATURE (·C )
Or-1TO--~~r-~~4-~
PS
..,9 C/LITER/HOUR
¥
~4
1' :1 I
l
I()()
FIG. 3 VERTICAl. DISTRII!lITION OF PIIlTOSYIfT1ESIS AND TEI1'ERAlURE AT STATION 14 (lfFT)
AND STATION 16 (RI611T) OF ElTAnIN CRUISE 51 (JAllJARYIFEBRUARY, 19n) IN THE
ROSS SEA. PAR ('011 STATlOII 14): 3'2 CAL CII-~-LIIIIfT-IIA.,..l
PAR (POll STATIOII 16l: n CAL CII-~-LIIIIfT-llAy-l
Holm-Hansen and Sakshaug (personal communication) showed that the
photo-chemical apparatus is "saturated" between 100 and 180 ~ Einstein/
m 2 /sec., depending on the depth from which the sample was obtained. As
the incident light flux (on a sunny day) is about 2,500 ~ Einstein/m 2 /
sec., it is evident that phytoplankton in surface waters will be either
"saturated" by the available flux, or will be photo-inhibited. Other
investigators (Jacques, 1983) found that the metabolism of Antarctic
phytoplankton does not show unusual characteristics.
In his P vs I
experiments, Jacques (ibid.) showed that the photosynthetic parameters
(i.e. initial slope,~,andlight intensity at the onset of light saturation, I k ) gave very low values for both the natural communities and
algal cultures. He contends that during the summer months, "these low
values of Ik express clearly the plankton's inability to use optimally
the available light in the euphotic layer". Further, the very low
assimilation number (AN) for Antarctic phytoplankton compared to phytoplankton from temperate and tropical upwelling regions has been attributed to the low photosynthetic efficiency of Antarctic phytoplankton. Low
plankton was calculated to be in the range of 40 to 50 cal/cm 2 /halflight day.
It should be remembered that during the austral summer
months, total daily flux can exceed that of tropical latitudes (HolmHansen et al., 1977) .
..,9 C/LITER/HOUR
I2f
TEMPERATURE (·C )
Or-1TO--~~r-~~4-~
PS
..,9 C/LITER/HOUR
¥
~4
1' :1 I
l
I()()
FIG. 3 VERTICAl. DISTRII!lITION OF PIIlTOSYIfT1ESIS AND TEI1'ERAlURE AT STATION 14 (lfFT)
AND STATION 16 (RI611T) OF ElTAnIN CRUISE 51 (JAllJARYIFEBRUARY, 19n) IN THE
ROSS SEA. PAR ('011 STATlOII 14): 3'2 CAL CII-~-LIIIIfT-IIA.,..l
PAR (POll STATIOII 16l: n CAL CII-~-LIIIIfT-llAy-l
Holm-Hansen and Sakshaug (personal communication) showed that the
photo-chemical apparatus is "saturated" between 100 and 180 ~ Einstein/
m 2 /sec., depending on the depth from which the sample was obtained. As
the incident light flux (on a sunny day) is about 2,500 ~ Einstein/m 2 /
sec., it is evident that phytoplankton in surface waters will be either
"saturated" by the available flux, or will be photo-inhibited. Other
investigators (Jacques, 1983) found that the metabolism of Antarctic
phytoplankton does not show unusual characteristics.
In his P vs I
experiments, Jacques (ibid.) showed that the photosynthetic parameters
(i.e. initial slope,~,andlight intensity at the onset of light saturation, I k ) gave very low values for both the natural communities and
algal cultures. He contends that during the summer months, "these low
values of Ik express clearly the plankton's inability to use optimally
the available light in the euphotic layer". Further, the very low
assimilation number (AN) for Antarctic phytoplankton compared to phytoplankton from temperate and tropical upwelling regions has been attributed to the low photosynthetic efficiency of Antarctic phytoplankton. Low