124
Baumann et al.
Total coccolithophores
[103Ind!l]
E.huxleyi
G.oceanica
U. irregularis
U.lel1uis
o 100 200 300
20% 50% 80%
20% 50% 80%
20% 50% 0%
0% 20% 40%
. , I , ! I , ! I , t
,
t
I . , I . , I , ,
• I "
I
" 1 •
Fig.4. Coccolithophore standing stocks and frequency distributions in surface-water samples collected across the
equator during Meteor cruise M 29/3 in August'September 1994. Area of equatorial upwelling is marked with bar.
in isotope stages 6 and 7, together making up >5060% of the assemblage. A first increase in E.
huxleyi occurs in late stage 6 whereas abundances
increase after the stage 5/4 transitIOn.
Gephyrocapsa ericsonii and Florisphaera
profunda dominate the assemblage in isotope stage
5. In addition, relative abundances ofF. profunda
show a cyclic variation troughout the record with
values ranging from 7 to 48%. A conspicuous increase in C. leptoporus can be seen in stage 3,
whereas the assemblage is dominated by F. profunda and E. huxleyi in stages 1-2.
Eastern South Atlantic
Plankton
Considerable variation in both cell numbers and
species composition are observed. Total cell densities range from less than 10 x 103coccospheresi
I to maximum values of more than 400 x 10 3
coccospheres/l. Emiliania huxleyi is the dominant
species, although G. ericsonii, Umbellosphaera irregularis, U. tenuis, 0. fragilis,
Syracosphaera spp., and holococcolithophores are
occasionally prevalent. The lateral and vertical distribution pattern ofthe geologically important species are shown in Fig. 6.
The highest cell numbers of E. huxleyi are
observed in the Benguela Current above the
thermocline at a water depth of 40m (199 x 10 3
coccospheres/l) and in the subtropical gyre (SG)
below the thermocline at 80m (129 x 10 3
coccospheres/l). Concentrations of G. oceanica
are generally lower, but its distribution pattern resembles that of E. huxleyi. The other species show
slightly different distribution and reach highest numbers in the SG below the thermocline (Fig. 6).
Sediments
The highest coccolith numbers in surface sediments
of this area were determined in samples derived
from the Walvis Ridge (> 10 x 10 9 coccoliths/g sediment), whereas on the upper continental margin off
SW-Africa concentrations <5 x 10 9 coccoliths/g
sediment are observed (Fig. 7) . The assemblages
are dominated by E. huxleyi, which usually com-
Baumann et al.
Total coccolithophores
[103Ind!l]
E.huxleyi
G.oceanica
U. irregularis
U.lel1uis
o 100 200 300
20% 50% 80%
20% 50% 80%
20% 50% 0%
0% 20% 40%
. , I , ! I , ! I , t
,
t
I . , I . , I , ,
• I "
I
" 1 •
Fig.4. Coccolithophore standing stocks and frequency distributions in surface-water samples collected across the
equator during Meteor cruise M 29/3 in August'September 1994. Area of equatorial upwelling is marked with bar.
in isotope stages 6 and 7, together making up >5060% of the assemblage. A first increase in E.
huxleyi occurs in late stage 6 whereas abundances
increase after the stage 5/4 transitIOn.
Gephyrocapsa ericsonii and Florisphaera
profunda dominate the assemblage in isotope stage
5. In addition, relative abundances ofF. profunda
show a cyclic variation troughout the record with
values ranging from 7 to 48%. A conspicuous increase in C. leptoporus can be seen in stage 3,
whereas the assemblage is dominated by F. profunda and E. huxleyi in stages 1-2.
Eastern South Atlantic
Plankton
Considerable variation in both cell numbers and
species composition are observed. Total cell densities range from less than 10 x 103coccospheresi
I to maximum values of more than 400 x 10 3
coccospheres/l. Emiliania huxleyi is the dominant
species, although G. ericsonii, Umbellosphaera irregularis, U. tenuis, 0. fragilis,
Syracosphaera spp., and holococcolithophores are
occasionally prevalent. The lateral and vertical distribution pattern ofthe geologically important species are shown in Fig. 6.
The highest cell numbers of E. huxleyi are
observed in the Benguela Current above the
thermocline at a water depth of 40m (199 x 10 3
coccospheres/l) and in the subtropical gyre (SG)
below the thermocline at 80m (129 x 10 3
coccospheres/l). Concentrations of G. oceanica
are generally lower, but its distribution pattern resembles that of E. huxleyi. The other species show
slightly different distribution and reach highest numbers in the SG below the thermocline (Fig. 6).
Sediments
The highest coccolith numbers in surface sediments
of this area were determined in samples derived
from the Walvis Ridge (> 10 x 10 9 coccoliths/g sediment), whereas on the upper continental margin off
SW-Africa concentrations <5 x 10 9 coccoliths/g
sediment are observed (Fig. 7) . The assemblages
are dominated by E. huxleyi, which usually com-