.0
.6 -
.4
.2
"
p'
l"
, ,
'0
d ciliates
p
"it
"
~f t,fl. n
Iii flagellates
-,.1
152
.3
.2
.1
o . 0 _ _ L_.....--------.L_~J
o 0
.2
.4
,
,
.6
0.0
~ ~~~~_--L-~L __ t_._~~_~ _i_~ __ L ___ L_~. ___ ~ j_L_L~-L_---,----,I_"---- '---'---o
2
3
4
p
.B
5
Figure 1. The theoretical variations of Q., the efficiency factor for absorption (dashed curves), as a function
of the dimensionless parameter p',. The triangles are experimental determinations of Q. (at 675 nm) for
various algae (Morel and Bricaud, 1986; Ahn, 1990); other symbols are for determinations of 3 algal
species studied by Sosik (1988). The values for heterotrophic organisms, as indicated, come from Morel
and Ahn (1990, 1991). The inset is an enlargment of the initial part of the curve.
As shown in Fig. 1, the Qa values determined for various phytoplankters at 1 := 675 nm nicely
follow the theoretical predictions. This wavelength is chosen because the predominant
absorbing pigment in this part of the spectrum is almost exclusively Chlorophyll a. Thus p'
(Eq. 8') can be computed with the modal diameter of the algal population and with as obtained
through