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primary production rates of some classes. High rates of pigment production can, for example,
be due to rapid interconversions related to photo-adaptation of algal cells, e.g. those in the
diadinoxanthin / diatoxanthin system. Measurement of such rates may be useful as an indicator
of the rate of vertical water movements through a light gradient (Welsch meyer and Hoepffner,
1986).
Prof. E. Laws (University of Hawaii at Manoa, U.S.A.), one of the originators of the
Redalje-Laws Method, also recently pointed out some (minor) flaws in the calculations of
Gieskes and Kraay (1989). He objected to their statement that Since chI a is the pigment
common to all three classes, its specific activity should be ... equal to the mean of the specific
activities of the class-specific carotenoids.; G. and K. then went ahead and averaged the
growth rates calculated from the carotenoids and compared that average with the chlorophyll
a - specific growth rate (Gieskes and Kraay, 1989). Laws argues as follows: first, the chI a
specific activity is a weighted average of the specific activity of the chI a in the components
of the phytoplankton community. The weighting factor is the fraction of chI a contributed by
each component. For example, in a two- component system
total chI a = (chI a)A + (chI a)B
activity chI a = (activity chI a)A + (activity chI ah
where A and B are the two components. The specific activity of the chI a is then (activity chI
a)/(total chI a). It is easy to show that the specific activity of the chI a is therefore equal to
fA (specific activity chI a)A + fB (specific activity chI ah where fA = (chI a) A/total chI a and
fB = (chI a)B/total chI a. This conclusion is easily generalized to show that
specific activity chI a = EfK (specific activity chI a)K
where the summation is performed over all components in the population. Given information
on the carotenoids in the population, one would need to know the ratio of carotenoid to chI
a for each component in order to calculate the weighted average of the component specific
activities. What one can rigorously say is that the specific activity of the total chI a will lie
somewhere between the extreme specific activities of the components. The total chI a specific
activity will lie close to the minimum component specific activity if most of the total chI a is
associated with the slowest-growing component and close to the maximum component specific
activity if most of the total chI a is associated with the fastest-growing component.
primary production rates of some classes. High rates of pigment production can, for example,
be due to rapid interconversions related to photo-adaptation of algal cells, e.g. those in the
diadinoxanthin / diatoxanthin system. Measurement of such rates may be useful as an indicator
of the rate of vertical water movements through a light gradient (Welsch meyer and Hoepffner,
1986).
Prof. E. Laws (University of Hawaii at Manoa, U.S.A.), one of the originators of the
Redalje-Laws Method, also recently pointed out some (minor) flaws in the calculations of
Gieskes and Kraay (1989). He objected to their statement that Since chI a is the pigment
common to all three classes, its specific activity should be ... equal to the mean of the specific
activities of the class-specific carotenoids.; G. and K. then went ahead and averaged the
growth rates calculated from the carotenoids and compared that average with the chlorophyll
a - specific growth rate (Gieskes and Kraay, 1989). Laws argues as follows: first, the chI a
specific activity is a weighted average of the specific activity of the chI a in the components
of the phytoplankton community. The weighting factor is the fraction of chI a contributed by
each component. For example, in a two- component system
total chI a = (chI a)A + (chI a)B
activity chI a = (activity chI a)A + (activity chI ah
where A and B are the two components. The specific activity of the chI a is then (activity chI
a)/(total chI a). It is easy to show that the specific activity of the chI a is therefore equal to
fA (specific activity chI a)A + fB (specific activity chI ah where fA = (chI a) A/total chI a and
fB = (chI a)B/total chI a. This conclusion is easily generalized to show that
specific activity chI a = EfK (specific activity chI a)K
where the summation is performed over all components in the population. Given information
on the carotenoids in the population, one would need to know the ratio of carotenoid to chI
a for each component in order to calculate the weighted average of the component specific
activities. What one can rigorously say is that the specific activity of the total chI a will lie
somewhere between the extreme specific activities of the components. The total chI a specific
activity will lie close to the minimum component specific activity if most of the total chI a is
associated with the slowest-growing component and close to the maximum component specific
activity if most of the total chI a is associated with the fastest-growing component.