Oxygen Isotope Values of Planktic Foraminifera
lSI
et al. (1989): < 50 m, Deuser and Ross (1989):
25 - 50 m, and Ottens (1992): 0 - 50 m. In the subtropical South Atlantic Ocean a near-surface depth
habitat (0 - 100 m) is described by Kemle v. Mlicke
and Oberhansli (this volume) on the basis of nettow investigations. For the subtropical and transitional parts of the oceans, Be (1977) as well as
Hemleben and Spindler (1983) describe a depth
preference for G. bulloides within the upper 100
m. Due to its shallow apparent calcification depth
and wide geographic distribution, G. bulloides is
highly qualified to function as a recorder of surface
water conditions. This feature makes G. bulloides
useful in reconstructions of the stratification in the
upper water column, especially in the transitional
and subpolar zones of the oceans. The temperature-related 8 18 0"icite range of 3.07 %0 (fraction
size 230 - 250 Ilm) on the north-south transect between 34 and 51 ° S (0 - 20° E) corresponds to a
temperature difference of 14.5 °C in 30 m water
depth (Fig. 9).
A small species, confined between the Antarctic Zone and the Subtropical Gyre is Turborotalita
quinqueloba, but significant amounts were only
obtained in the Antarctic Circumpolar Current
(Niebler and Gersonde 1998). An "oxygen isotope
disequilibrium" for this species has not been described and assuming equilibrium fractionation, the
8 18 0,aicite values of T. quinqueloba reflect a mean
calcification depth within the first 100 m of the
water-column (Figs. 6, 8). This agrees well with
the data published by Be (1977) and Ottens (1992),
who describe a depth preference in the first 50 m.
Net-tow investigations in the tropical and subtropical South Atlantic Ocean indicate a wide range
in depth distrubution (0 - 1000 m) of living
T. quinqueloba (Kemle v. Milcke and Oberhansli
this volume). In the ice-free region of the northern
North Atlantic Ocean, Carstens et al. (1997) found
a depth preference of T. quinqueloba between 50
and 100 m. However, it can be assumed, that
T. quinqueloba has its maximum occurrence
within the first 100 m ofthe water column.
Neogloboquadrina pachyderma (dextral and
sinistral), which is widely used for paleoceanographic reconstructions stretching from the transition zone to polar regions, tolerates a broad range
of temperatures and occurs in the water masses
extending from Antarctica to the Subtropics (Figs.
3-8). In the Southern Ocean the sinistral form prevails, whereas at temperatures above 12°C the
dextral form does becomes dominant. It is still a
matter of debate whether the coiling direction is
temperature-dependent or has a genetic basis
(Brummer and Kroon 1988). Darling et al. (1996)
proposed that the different coiling directions ofN
pachyderma is not environmentally (in particular
temperature) controlled, but resulted from restricted genetic exchange across major water mass
boundaries. On the other hand Bijma et al. (1990)
demonstrated in laboratory tests that the measured
in vitro temperature ranges of planktic
foraminifera compare well with the global temperature distribution patterns, suggesting that temperature plays one major role in their biogeographical
distribution. However, irrespective of what the
background of morpho type evolution is, our data
show, ifthe corresponding "oxygen isotope disequilibrium" is used (Table 2), thatN pachyderma
(dextral and sinistral) usually calcifies at a water
depth between 100 and 200 m. This is in contrast
to investigations carried out by Berger (1969): 50 -
100 m; Be (1977): 50 -100 m; Fairbanks and Wiebe
(1980): 20 - 80 m; Hemleben and Spindler (1983):
50 - 100 m; Deuser and Ross (1989): 0 - 75 m; and
Ottens (1992): 0 - 50 m, respectively. In the cold
water region ofthe northern North Atlantic Ocean,
Carstens and Wefer (1992) and Carstens et al.
(1997) showed a depth habitat for N pachyderma
(sinistral) of 0 - 150 m. New tow investigations in
the cold water realms of the North and South Atlantic Ocean prove that N. pachyderma is not
necessarily a surface-dwelling species and
cannot be assumed for shallow paleoreconstructions (Kohfeld et al. 1996). For this reason, N. pachyderma is not used on further statistical treatment within this study.
It can be summarized that, according to their
oxygen isotope values, 23 ofthe studied species and
morphotypes (all, exceptG. glutinata) can be subdivided into four depth groups (Table 3). In the subtropical and transitional region of the South
Atlantic Ocean, the shallow-calcifying species
S. dehiscens, P. obliquiloculata, 0. bilobata,
G. sacculifer, G, aequilateralis and G. ruber as
well as the deep-calcifying species G. hirsuta,
lSI
et al. (1989): < 50 m, Deuser and Ross (1989):
25 - 50 m, and Ottens (1992): 0 - 50 m. In the subtropical South Atlantic Ocean a near-surface depth
habitat (0 - 100 m) is described by Kemle v. Mlicke
and Oberhansli (this volume) on the basis of nettow investigations. For the subtropical and transitional parts of the oceans, Be (1977) as well as
Hemleben and Spindler (1983) describe a depth
preference for G. bulloides within the upper 100
m. Due to its shallow apparent calcification depth
and wide geographic distribution, G. bulloides is
highly qualified to function as a recorder of surface
water conditions. This feature makes G. bulloides
useful in reconstructions of the stratification in the
upper water column, especially in the transitional
and subpolar zones of the oceans. The temperature-related 8 18 0"icite range of 3.07 %0 (fraction
size 230 - 250 Ilm) on the north-south transect between 34 and 51 ° S (0 - 20° E) corresponds to a
temperature difference of 14.5 °C in 30 m water
depth (Fig. 9).
A small species, confined between the Antarctic Zone and the Subtropical Gyre is Turborotalita
quinqueloba, but significant amounts were only
obtained in the Antarctic Circumpolar Current
(Niebler and Gersonde 1998). An "oxygen isotope
disequilibrium" for this species has not been described and assuming equilibrium fractionation, the
8 18 0,aicite values of T. quinqueloba reflect a mean
calcification depth within the first 100 m of the
water-column (Figs. 6, 8). This agrees well with
the data published by Be (1977) and Ottens (1992),
who describe a depth preference in the first 50 m.
Net-tow investigations in the tropical and subtropical South Atlantic Ocean indicate a wide range
in depth distrubution (0 - 1000 m) of living
T. quinqueloba (Kemle v. Milcke and Oberhansli
this volume). In the ice-free region of the northern
North Atlantic Ocean, Carstens et al. (1997) found
a depth preference of T. quinqueloba between 50
and 100 m. However, it can be assumed, that
T. quinqueloba has its maximum occurrence
within the first 100 m ofthe water column.
Neogloboquadrina pachyderma (dextral and
sinistral), which is widely used for paleoceanographic reconstructions stretching from the transition zone to polar regions, tolerates a broad range
of temperatures and occurs in the water masses
extending from Antarctica to the Subtropics (Figs.
3-8). In the Southern Ocean the sinistral form prevails, whereas at temperatures above 12°C the
dextral form does becomes dominant. It is still a
matter of debate whether the coiling direction is
temperature-dependent or has a genetic basis
(Brummer and Kroon 1988). Darling et al. (1996)
proposed that the different coiling directions ofN
pachyderma is not environmentally (in particular
temperature) controlled, but resulted from restricted genetic exchange across major water mass
boundaries. On the other hand Bijma et al. (1990)
demonstrated in laboratory tests that the measured
in vitro temperature ranges of planktic
foraminifera compare well with the global temperature distribution patterns, suggesting that temperature plays one major role in their biogeographical
distribution. However, irrespective of what the
background of morpho type evolution is, our data
show, ifthe corresponding "oxygen isotope disequilibrium" is used (Table 2), thatN pachyderma
(dextral and sinistral) usually calcifies at a water
depth between 100 and 200 m. This is in contrast
to investigations carried out by Berger (1969): 50 -
100 m; Be (1977): 50 -100 m; Fairbanks and Wiebe
(1980): 20 - 80 m; Hemleben and Spindler (1983):
50 - 100 m; Deuser and Ross (1989): 0 - 75 m; and
Ottens (1992): 0 - 50 m, respectively. In the cold
water region ofthe northern North Atlantic Ocean,
Carstens and Wefer (1992) and Carstens et al.
(1997) showed a depth habitat for N pachyderma
(sinistral) of 0 - 150 m. New tow investigations in
the cold water realms of the North and South Atlantic Ocean prove that N. pachyderma is not
necessarily a surface-dwelling species and
cannot be assumed for shallow paleoreconstructions (Kohfeld et al. 1996). For this reason, N. pachyderma is not used on further statistical treatment within this study.
It can be summarized that, according to their
oxygen isotope values, 23 ofthe studied species and
morphotypes (all, exceptG. glutinata) can be subdivided into four depth groups (Table 3). In the subtropical and transitional region of the South
Atlantic Ocean, the shallow-calcifying species
S. dehiscens, P. obliquiloculata, 0. bilobata,
G. sacculifer, G, aequilateralis and G. ruber as
well as the deep-calcifying species G. hirsuta,