Planktic Foraminifera in Holocene Sediments from the Laptev Sea
and the Central Arctic Ocean: Species Distribution and
Paleo biogeographical Implication
H.A. Bauch
GEOMAR ForschungszentrumJur marine GeowissenschaJten, WischhoJstrasse 1-3, D 24148 Kiel, Germany
Received 10 March 1997 and accepted in revised form 24 March 1998
Abstract - Two sediment cores, one from the Siberian Laptev Sea shelf and another from
the central Arctic Ocean were investigated with respect to the temporal distribution of
planktic foraminifera as well as the species composition.
The assemblage in the Laptev Sea, which cover the time back to about 2.3 ka, is mainly
comprised of species that can be related to a subtropical-subpolar biogeography and is
dominated by the minute species Turborotalita clarkei. The origin of the non-polar species
on the Siberian shelf remains unknown. It is suggested that these microfossils were either
reworked from older sediments and/or entrained into sea-ice on other shallow Arctic shelfs,
transporting them eventually to the Laptev Sea.
In contrast to the Laptev Sea the glacial and Holocene sediments from the perennially icecovered central Arctic Ocean reveal a typical monospecific record, which is entirely made up
of the polar species Neoglohoquadrina pachyderma (right and left coiling forms). The
relative variability of the two coiling varieties is of the order of 5%. Although this
variability does not seem to be related to climate-induced environmental changes, total test
concentration shows a clear signal of increasing deposition of foraminiferal tests after 7 ka.
Since sea-ice and surface water conditions seem to be stable in this region, the observed
increase in plankton productivity during the Holocene must be linked to changes in water
mass circulation.
Introduction
The concept that past surface water properties can be deduced from assemblage studies of
planktic foraminifera was established some time ago (Imbrie and Kipp, 1971). This finding is
based on studies of sediments from the surface of the ocean floor which are thought to give a
fairly good reflectance of the species composition in the overlying surface water masses.
Previous faunal studies, in which a detailed mapping of the ocean's floor core-top sediments
was conducted, revealed various foraminiferal assemblages (Kipp, 1976). The faunal
composition could be linked to specific water mass properties such as sea surface water
temperature (SST). In the modern ocean, the SST displays a latitudinal change towards the
northern polar regions that is mirrored by a change in the foraminiferal assemblage from warmwater representing types to a typically subpolar or polar species dominated assemblage
(Bradshaw, 1959; Kipp, 1976).
Studies of plankton tows and sediment samples of Holocene age from the Arctic Ocean
indicate that the faunal assemblage is rather monospecific, consisting mainly of the polar
species Neogloboquadrina pachyderma sinistral (Be, 1960; Steuerwald and Clark, 1972;
Vilks, 1975). In areas of the Arctic Ocean influenced today by inflowing non-Arctic waters,
foraminfera of a subpolar provenance can comprise notable portions of the faunal assemblage
(Carstens and Wefer, 1992). However, these species are not indigenous to the Arctic Ocean but
are rather the result of water-mass advection from the south (Bauch et aI., 1997).
Since planktic foraminifera are deep-ocean surface dwellers, they are commonly not present
on shallow shelf areas unless they are being advected. In this paper the down-core species
In: Kassens, H., H.A. Bauch, I. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhov (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999.601-613.
and the Central Arctic Ocean: Species Distribution and
Paleo biogeographical Implication
H.A. Bauch
GEOMAR ForschungszentrumJur marine GeowissenschaJten, WischhoJstrasse 1-3, D 24148 Kiel, Germany
Received 10 March 1997 and accepted in revised form 24 March 1998
Abstract - Two sediment cores, one from the Siberian Laptev Sea shelf and another from
the central Arctic Ocean were investigated with respect to the temporal distribution of
planktic foraminifera as well as the species composition.
The assemblage in the Laptev Sea, which cover the time back to about 2.3 ka, is mainly
comprised of species that can be related to a subtropical-subpolar biogeography and is
dominated by the minute species Turborotalita clarkei. The origin of the non-polar species
on the Siberian shelf remains unknown. It is suggested that these microfossils were either
reworked from older sediments and/or entrained into sea-ice on other shallow Arctic shelfs,
transporting them eventually to the Laptev Sea.
In contrast to the Laptev Sea the glacial and Holocene sediments from the perennially icecovered central Arctic Ocean reveal a typical monospecific record, which is entirely made up
of the polar species Neoglohoquadrina pachyderma (right and left coiling forms). The
relative variability of the two coiling varieties is of the order of 5%. Although this
variability does not seem to be related to climate-induced environmental changes, total test
concentration shows a clear signal of increasing deposition of foraminiferal tests after 7 ka.
Since sea-ice and surface water conditions seem to be stable in this region, the observed
increase in plankton productivity during the Holocene must be linked to changes in water
mass circulation.
Introduction
The concept that past surface water properties can be deduced from assemblage studies of
planktic foraminifera was established some time ago (Imbrie and Kipp, 1971). This finding is
based on studies of sediments from the surface of the ocean floor which are thought to give a
fairly good reflectance of the species composition in the overlying surface water masses.
Previous faunal studies, in which a detailed mapping of the ocean's floor core-top sediments
was conducted, revealed various foraminiferal assemblages (Kipp, 1976). The faunal
composition could be linked to specific water mass properties such as sea surface water
temperature (SST). In the modern ocean, the SST displays a latitudinal change towards the
northern polar regions that is mirrored by a change in the foraminiferal assemblage from warmwater representing types to a typically subpolar or polar species dominated assemblage
(Bradshaw, 1959; Kipp, 1976).
Studies of plankton tows and sediment samples of Holocene age from the Arctic Ocean
indicate that the faunal assemblage is rather monospecific, consisting mainly of the polar
species Neogloboquadrina pachyderma sinistral (Be, 1960; Steuerwald and Clark, 1972;
Vilks, 1975). In areas of the Arctic Ocean influenced today by inflowing non-Arctic waters,
foraminfera of a subpolar provenance can comprise notable portions of the faunal assemblage
(Carstens and Wefer, 1992). However, these species are not indigenous to the Arctic Ocean but
are rather the result of water-mass advection from the south (Bauch et aI., 1997).
Since planktic foraminifera are deep-ocean surface dwellers, they are commonly not present
on shallow shelf areas unless they are being advected. In this paper the down-core species
In: Kassens, H., H.A. Bauch, I. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhov (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999.601-613.