165
Om
"'m
M+, __ -' __ -',, __ -',, __ -' __ -'
\oblume (ml)
L.f---,~~~.;::::::.4 -/---.~"':::;==r=~
1=
.'~,~~~~~-~~~--~~--~I(OO(~),OO(683l)
Figure 6
System corrected fluorescence
at 485 nm. for D tertiolecta plotted
as a function of volume filtered,
and as a function of the mean light
level and quenching algorithm.
~bm.
..JW
...I a:
>-0
J::;,
1l...J
~~~m.
J:N
U::::i
«
~
a:
2
400
450
500
~
WAVELENGTH
Figure 8.
Depth profile of the chlorophyll normalized
corrected fluorescence, plotted against
excitation wavelength.
Figure 7.
Depth profile of the chlorophyll specific
volume absorption coefficient, plotted
against wavelength.
W
U
Om
~~
~~~~::::;::=;::::::; c::U
ou: :;'"..J W
II..
30m.
OOm
85m.
WAVELENGTH
Figure 9.
......
Depth profile of the fluorescence
efficiency, plotted against
excitation wavelength.
accessory pigment bands between 470 nm. and 520 nm.
Such spectral adaptation is seen to a lesser extent at 30 and 50 m. The high absorption
for surface samples cannot be attributed to photoadaptation, since this
population would be experiencing a much higher mean irradiance than the
deeper samples. It is possible that cells in the mixed layer add protective carotenoid pigmentation (Krinsky,l968) to minimize the detrimental
effects of high light levels including uv radiation (Smith etal., 1980).
Second, the absorption in the blue region of the spectrum for field
samples relative to the red peak (eg. 435:675 nm) is higher in field
samples than is seen for healthy laboratory cultures. This seems to be