85
are somewhat different: 0.91 fg divinyl chI a per cell Prochlorophyte near the surface, 5.4
near the bottom of the euphotic zone.
At Station 53, (Banda Sea, Indonesia, March 1985, upper 25 m) (Fig. 13), the zeaxanthin
concentration was 0.0487 p.g/l and the chI a concentration 0.132 p.g/I. Exactly half of this chI
a (0.065 p.g/l) was divinyl-Chl a - the red-shifted chI a (Gieskes and Kraay, 1983b) of
picoplanktonic Prochlorophytes (Chisholm et al., 1988). According to Chisholm et al. (1988),
such Prochlorophytes contain 2.15 fg chI a per cell, so at this station there must have been
30,000 Prochlorophyte cells per mi. These cells contained 0.0207 p.g zeaxanthin per liter
(0.69 fg/cell; Veldhuis and Kraay reported 1.97 fg per cell), so the rest of the zeaxanthin,
0.028 p.g/l, must have been associated with another zeaxanthin-containing group - coccoid
Cyanobacteria (Guillard et al., 1985; Kana et aI., 1988), numbering 15,500 cells per mi. In
Synchococcus, the zeaxanthin:Chl a ratio is 1.2 (Fig. 1D in Kana et al., 1988), so 0.065 -
0.023 = 0.042 p.g chI a/I at this station was associated with other algae. The chromatogram
at this station shows clear peaks of fucoxanthin, hexanoyloxyfucoxanthin and
butanoyloxyfucoxanthin, indicative of the presence of these other algae, in casu diatoms,
Prymnesiophyceae and Chrysophyceae.
The same reasoning can be applied for Station 7 (Fig. 13). In surface samples taken here in
March 1985, 69.3% of the chI a (0.069 p.g/l) was red-shifted divinyl-Chl a (= 0.048 p.g/l).
For Prochlorophytes, 0.048 (red-shifted) chI a corresponds with 0.016 p.g zeaxanthin/I. The
rest of the zeaxanthin, 0.0378 p.g/l, must have been associated with Synchococcus cells,
numbering (0.0378 x 10~: 1.8 = 2.1 x 10 4 cells per ml (each containing, according to Kana
et al., 1988, 1.8 fg zeaxanthin). The number of Prochlorophytes at Station 7 (surface) was
(0.016 x 10 9 ) : 0.69 = 2.3 x 10 4 cells per ml (each containing 0.69 fg zeaxanthin). According
to Kana et al. (1988), each Synchococcus cell may have contained 1.5 fg chI a, so 0.0315 p.g
chI a was associated with this group. Apparently, all normal Chlorophyll a present in the
sample was contained in Synchococcus cells; the contribution of other taxonomic groups was
clearly nil - a conclusion supported by the chromatogram, that did not show any carotenoid
peaks except zeaxanthin.
At Station 25 (Fig. 13) samples taken at the deep chlorophyll maximum (60-80 m) contained
0.263 p.g chI a, 0.118 p.g ChI b, and 0.034 p.g zeaxanthin per liter. The percentage of
divinyl-Chl a was 48.6%, i.e. 0.128 p.g/l - nearly as much as ChI b. Chisholm et al. (1988)
also reported a 1: 1 ratio in Prochlorophytes. Apparently, all ChI b at Station 25 (60-80 m)
was associated with Prochlorophytes. 0.128 p.g chI a corresponds to 0.043 p.g zeaxanthin, so
all zeaxanthin present in the sample was Prochlorophyte zeaxanthin (59,500 cells/ml), leaving
are somewhat different: 0.91 fg divinyl chI a per cell Prochlorophyte near the surface, 5.4
near the bottom of the euphotic zone.
At Station 53, (Banda Sea, Indonesia, March 1985, upper 25 m) (Fig. 13), the zeaxanthin
concentration was 0.0487 p.g/l and the chI a concentration 0.132 p.g/I. Exactly half of this chI
a (0.065 p.g/l) was divinyl-Chl a - the red-shifted chI a (Gieskes and Kraay, 1983b) of
picoplanktonic Prochlorophytes (Chisholm et al., 1988). According to Chisholm et al. (1988),
such Prochlorophytes contain 2.15 fg chI a per cell, so at this station there must have been
30,000 Prochlorophyte cells per mi. These cells contained 0.0207 p.g zeaxanthin per liter
(0.69 fg/cell; Veldhuis and Kraay reported 1.97 fg per cell), so the rest of the zeaxanthin,
0.028 p.g/l, must have been associated with another zeaxanthin-containing group - coccoid
Cyanobacteria (Guillard et al., 1985; Kana et aI., 1988), numbering 15,500 cells per mi. In
Synchococcus, the zeaxanthin:Chl a ratio is 1.2 (Fig. 1D in Kana et al., 1988), so 0.065 -
0.023 = 0.042 p.g chI a/I at this station was associated with other algae. The chromatogram
at this station shows clear peaks of fucoxanthin, hexanoyloxyfucoxanthin and
butanoyloxyfucoxanthin, indicative of the presence of these other algae, in casu diatoms,
Prymnesiophyceae and Chrysophyceae.
The same reasoning can be applied for Station 7 (Fig. 13). In surface samples taken here in
March 1985, 69.3% of the chI a (0.069 p.g/l) was red-shifted divinyl-Chl a (= 0.048 p.g/l).
For Prochlorophytes, 0.048 (red-shifted) chI a corresponds with 0.016 p.g zeaxanthin/I. The
rest of the zeaxanthin, 0.0378 p.g/l, must have been associated with Synchococcus cells,
numbering (0.0378 x 10~: 1.8 = 2.1 x 10 4 cells per ml (each containing, according to Kana
et al., 1988, 1.8 fg zeaxanthin). The number of Prochlorophytes at Station 7 (surface) was
(0.016 x 10 9 ) : 0.69 = 2.3 x 10 4 cells per ml (each containing 0.69 fg zeaxanthin). According
to Kana et al. (1988), each Synchococcus cell may have contained 1.5 fg chI a, so 0.0315 p.g
chI a was associated with this group. Apparently, all normal Chlorophyll a present in the
sample was contained in Synchococcus cells; the contribution of other taxonomic groups was
clearly nil - a conclusion supported by the chromatogram, that did not show any carotenoid
peaks except zeaxanthin.
At Station 25 (Fig. 13) samples taken at the deep chlorophyll maximum (60-80 m) contained
0.263 p.g chI a, 0.118 p.g ChI b, and 0.034 p.g zeaxanthin per liter. The percentage of
divinyl-Chl a was 48.6%, i.e. 0.128 p.g/l - nearly as much as ChI b. Chisholm et al. (1988)
also reported a 1: 1 ratio in Prochlorophytes. Apparently, all ChI b at Station 25 (60-80 m)
was associated with Prochlorophytes. 0.128 p.g chI a corresponds to 0.043 p.g zeaxanthin, so
all zeaxanthin present in the sample was Prochlorophyte zeaxanthin (59,500 cells/ml), leaving