176
Niebler et al.
- Temper.,u,. rC)
o 6 12 1824
o ~...,.,~
100
200
[300
( PS2076-1)
1
400
I:
700
lIOO
900
size fraction
1 : > 400 ~m
~
2 : 3 1
5·400 ~m
,ooo ~~..j,..,j
3 : 250·315,.m
- s:.ni1y(~!o;···· · ···· · ··········4· 3 2· ··· ···················· ............................... .1... ~ : ~g~: ~~ ~~
3' 2
h i I
- - - 1-;3 2 1
- n =======11= 10 m
o
hi
~ - 543 21 - ~ -'-'-' -- n - 4 3
50 m
...... . 54 32 1.. ............ , .................. ............... .................... 43 .. .......... .... 54 3 2 ...... ..
7
w....L-L.J
5 4 3
Ll-W 2 1
~
- 250m
~: · · · · · · · · · · · · · · · · · · · : s!~t~:
4
-..... ........ ............................ .............. ..... ................... ,., ............................... 4
CI)
CI)
II>
~
~
.l'.l
~
:!
12
~
§
<:>
<:>
:c ...
~
~
~
~
Q
I
.'!!
~
'II
II>
.!.
' *
.2
~
'II
'II
~
~
'0
{g ~
~
.' !!
~ . ~
it= ... :, ~ \lI = rl =
Q
Q)
8 ~
O
"" ~
. .~
'II
Q)
o
II>
rl
~
""
\liZ
\lI 0
:,iil ~~
\lI
.c
0>
.:::
.f<
E
Q.X
e CI) CI) ~ '2
Qi
Qi Qi
<: Qi Qi
Qi
Qi ci <::8- Qi Qi Qi Qi :§' Fig. 5. Site PS2076 (41.135 °S, 13.481 °E), north of the Agulhas Ridge (south of the Subtropical Front): O I8 O,rudto
composition of examined foraminifera as a function of their shell-size. Profile of summer season temperature and
salinity from World Ocean Atlas (Levitus and Boyer 1994). The gray shaded lines indicate the isotope equilibrium
to the sea-water, respectively to the dissolved CO" at the water depths of 10, 50 and 250 m.
with Berger (1969): 0 - 50 m, Be (1977): 0 - 50 m,
Deuser and Ross (1989): 0 - 25 m, Hem leben and
Spindler (1983): 0 -30 m and Ottens (1992): upper
50 m. When we assume a higher "oxygen isotope
disequilibrium" the calcification depth ofG. ruber
(white) would lie between 50 and 100 m. Similar
to G. sacculifer, the shells ofG. ruber(white) also
become enriched in 18 0 below the euphotic zone
due to gametogenic calcification (Duplessy et al.
1981).
Globorotalia hirsuta lives in the Subtropical
Gyre as well as in the northern part of the
Subantarctic Zone. This species usually calcifies at
a water depth between 250 and 400 m (Figs. 3-5),
considering its range of "oxygen isotope disequilibrium" (Table 2), but it seems that individuals in
neanic stage calcify for a short period at a water
depth of approximately 100 m, before they descend
in the water column . The depth preference of
G. hirsuta below 250 m confirms observations
made by Be (1977) and Deuser and Ross (1989),
who described a depth habitat below 100 m, down
to 600 m.
It was a point of discussion in the literature
whether Orbulina universa and Orbulina
bilobata are two different subspecies, or
Niebler et al.
- Temper.,u,. rC)
o 6 12 1824
o ~...,.,~
100
200
[300
( PS2076-1)
1
400
I:
700
lIOO
900
size fraction
1 : > 400 ~m
~
2 : 3 1
5·400 ~m
,ooo ~~..j,..,j
3 : 250·315,.m
- s:.ni1y(~!o;···· · ···· · ··········4· 3 2· ··· ···················· ............................... .1... ~ : ~g~: ~~ ~~
3' 2
h i I
- - - 1-;3 2 1
- n =======11= 10 m
o
hi
~ - 543 21 - ~ -'-'-' -- n - 4 3
50 m
...... . 54 32 1.. ............ , .................. ............... .................... 43 .. .......... .... 54 3 2 ...... ..
7
w....L-L.J
5 4 3
Ll-W 2 1
~
- 250m
~: · · · · · · · · · · · · · · · · · · · : s!~t~:
4
-..... ........ ............................ .............. ..... ................... ,., ............................... 4
CI)
CI)
II>
~
~
.l'.l
~
:!
12
~
§
<:>
<:>
:c ...
~
~
~
~
Q
I
.'!!
~
'II
II>
.!.
' *
.2
~
'II
'II
~
~
'0
{g ~
~
.' !!
~ . ~
it= ... :, ~ \lI = rl =
Q
Q)
8 ~
O
"" ~
. .~
'II
Q)
o
II>
rl
~
""
\liZ
\lI 0
:,iil ~~
\lI
.c
0>
.:::
.f<
E
Q.X
e CI) CI) ~ '2
Qi
Qi Qi
<: Qi Qi
Qi
Qi ci <::8- Qi Qi Qi Qi :§' Fig. 5. Site PS2076 (41.135 °S, 13.481 °E), north of the Agulhas Ridge (south of the Subtropical Front): O I8 O,rudto
composition of examined foraminifera as a function of their shell-size. Profile of summer season temperature and
salinity from World Ocean Atlas (Levitus and Boyer 1994). The gray shaded lines indicate the isotope equilibrium
to the sea-water, respectively to the dissolved CO" at the water depths of 10, 50 and 250 m.
with Berger (1969): 0 - 50 m, Be (1977): 0 - 50 m,
Deuser and Ross (1989): 0 - 25 m, Hem leben and
Spindler (1983): 0 -30 m and Ottens (1992): upper
50 m. When we assume a higher "oxygen isotope
disequilibrium" the calcification depth ofG. ruber
(white) would lie between 50 and 100 m. Similar
to G. sacculifer, the shells ofG. ruber(white) also
become enriched in 18 0 below the euphotic zone
due to gametogenic calcification (Duplessy et al.
1981).
Globorotalia hirsuta lives in the Subtropical
Gyre as well as in the northern part of the
Subantarctic Zone. This species usually calcifies at
a water depth between 250 and 400 m (Figs. 3-5),
considering its range of "oxygen isotope disequilibrium" (Table 2), but it seems that individuals in
neanic stage calcify for a short period at a water
depth of approximately 100 m, before they descend
in the water column . The depth preference of
G. hirsuta below 250 m confirms observations
made by Be (1977) and Deuser and Ross (1989),
who described a depth habitat below 100 m, down
to 600 m.
It was a point of discussion in the literature
whether Orbulina universa and Orbulina
bilobata are two different subspecies, or