82
for the water mass from which it was taken. Spectral fingerprinting of phytoplankton
populations by two- dimensional fluorescence and Fourier-transform-based pattern recognition
was attempted by Oldham et al. in 1985. A much simpler method, cluster analysis of
HPLC-derived pigment fingerprints measured in large numbers of samples taken during
surveys in the North Sea and in the Indonesian Banda Sea, revealed that the border front
between water masses can often be better described by differences in phytoplankton species
composition than by hydrographic parameters (salinity, temperature) (see Fig. 13). Of course,
detailed microscopic analysis of populations would have made us conclude the same, but the
disadvantages of microscopy are numerous (see Introduction). Moreover, microscopy is
time-consuming, while a series of chromatograms can be developed rapidly, even on board,
for cluster analysis.
14C Labelling oJpigments: assessment oJphytoplankton-specific biomass and taxon-specific
productivity
In order to estimate the contribution of different algal groups to total phytoplankton
production, we have measured how much 14C was incorporated into different taxon-specific
pigments during incubation of samples of Banda Sea water (eastern Indonesia). Redalje and
Laws (1981) described a method to estimate algal biomass and algal-specific growth rates by
incubating phytoplankton and measuring the amount of 14C that they found in particulate
matter and in chI a, which they separated by TLC. We have expanded this method to
measuring 14C in all major chlorophylls and carotenoids separated by HPLC. By using HPLC,
it is easier to avoid coelution of pigments with other labeled cell compounds than with TLC.
We were able to show (Gieskes and Kraay, 1989) that the specific growth rate of
zeaxanthin-containing groups (in casu Cyanobacteria) was usually highest, except in some
areas where the specific growth rate calculated on the basis of 14C labelling of fucoxanthin was
as high; diatoms were apparently the main producers here. In other areas, the specific growth
rate based on 14C labelling of hexanoyloxyfucoxanthin was highest, suggesting that here the
contribution of Prymnesiophyceae (mainly Coccolithophorids) was highest. An alternative
method for estimating growth rates of individual algal groups in natural populations using flow
cytometry has recently been used by Veldhuis. His (net) growth rates indicate that the high
(gross) rates registered by us are balanced by high rates of consumption.
R. Goericke (1990: Ph.D. thesis; a number of papers will be published in the course of 1991)
has examined the method of 14C_ labelling the various pigments of algal families in great
detail, and he concludes that it should be used with caution. The high, differential turnover
rate of some pigments may be a significant source of error, leading to false estimates of
for the water mass from which it was taken. Spectral fingerprinting of phytoplankton
populations by two- dimensional fluorescence and Fourier-transform-based pattern recognition
was attempted by Oldham et al. in 1985. A much simpler method, cluster analysis of
HPLC-derived pigment fingerprints measured in large numbers of samples taken during
surveys in the North Sea and in the Indonesian Banda Sea, revealed that the border front
between water masses can often be better described by differences in phytoplankton species
composition than by hydrographic parameters (salinity, temperature) (see Fig. 13). Of course,
detailed microscopic analysis of populations would have made us conclude the same, but the
disadvantages of microscopy are numerous (see Introduction). Moreover, microscopy is
time-consuming, while a series of chromatograms can be developed rapidly, even on board,
for cluster analysis.
14C Labelling oJpigments: assessment oJphytoplankton-specific biomass and taxon-specific
productivity
In order to estimate the contribution of different algal groups to total phytoplankton
production, we have measured how much 14C was incorporated into different taxon-specific
pigments during incubation of samples of Banda Sea water (eastern Indonesia). Redalje and
Laws (1981) described a method to estimate algal biomass and algal-specific growth rates by
incubating phytoplankton and measuring the amount of 14C that they found in particulate
matter and in chI a, which they separated by TLC. We have expanded this method to
measuring 14C in all major chlorophylls and carotenoids separated by HPLC. By using HPLC,
it is easier to avoid coelution of pigments with other labeled cell compounds than with TLC.
We were able to show (Gieskes and Kraay, 1989) that the specific growth rate of
zeaxanthin-containing groups (in casu Cyanobacteria) was usually highest, except in some
areas where the specific growth rate calculated on the basis of 14C labelling of fucoxanthin was
as high; diatoms were apparently the main producers here. In other areas, the specific growth
rate based on 14C labelling of hexanoyloxyfucoxanthin was highest, suggesting that here the
contribution of Prymnesiophyceae (mainly Coccolithophorids) was highest. An alternative
method for estimating growth rates of individual algal groups in natural populations using flow
cytometry has recently been used by Veldhuis. His (net) growth rates indicate that the high
(gross) rates registered by us are balanced by high rates of consumption.
R. Goericke (1990: Ph.D. thesis; a number of papers will be published in the course of 1991)
has examined the method of 14C_ labelling the various pigments of algal families in great
detail, and he concludes that it should be used with caution. The high, differential turnover
rate of some pigments may be a significant source of error, leading to false estimates of