benthic foraminiferal assemblages from the southern kara sea, a

Transcription

Journal of Foraminiferal Research, v. 32, no. 3, p. 252–273, July 2002
BENTHIC FORAMINIFERAL ASSEMBLAGES FROM THE SOUTHERN KARA SEA,
A RIVER-INFLUENCED ARCTIC MARINE ENVIRONMENT
LEONID POLYAK1*, SERGEI KORSUN2, LAWRENCE A. FEBO1, VLADIMIR STANOVOY3, TATYANA KHUSID2,
MORTEN HALD4, BJORN EGIL PAULSEN4, AND DAVID J. LUBINSKI5
ABSTRACT
Calcareous foraminifers and hydrographic parameters in 113
bottom samples from the southern Kara Sea were examined to
improve the usage of foraminifers as paleoenvironmental proxies
for river-dominated high-latitude continental shelves. Foraminiferal taxa form a succession from near-estuarine to distal open-sea
locations, characterized by a gradual increase in salinities. Foraminiferal assemblages are discriminated into three groups: riverproximal, -intermediate, and -distal. This succession appears to be
controlled by a combination of feeding conditions and bottom salinities, and are related to riverine fluxes of freshwater, organic
matter, and sediments. Morphological and behavioral adaptations
of foraminifers to specific environments are discussed.
oceanic basins (e.g., Todd and Low, 1966, 1980; Mudie and
others, 1983; Wollenburg and Mackensen, 1998a). However,
patterns of foraminiferal distribution in the Arctic and related
environmental controls are still poorly understood. This paper
analyzes assemblages of benthic calcareous foraminifers in the
southern Kara Sea, an area characterized by a uniquely strong
effect of riverine waters (Figs. 1–2). Our results provide a better understanding of the modern patterns of foraminiferal distribution, which can be applied to the Quaternary subfossil record to help interpret the evolution of Arctic marine environments affected by riverine inputs.
GEOGRAPHIC SETTING
INTRODUCTION
Arctic riverine inputs play a critical role not only in high
latitude hydrographic and biological systems, but also in the
climatic system through controls on sea-ice coverage and interoceanic water mass exchange (e.g., Aagard and Carmack, 1994;
Driscoll and Haug, 1998; Stein, 1998; Forman and others,
2000). Arctic runoff has an especially profound influence on
hydrography, sedimentation, and biology on the continental
shelves adjacent to river mouths. From these areas, riverine
water spreads throughout the Arctic Ocean, where it controls
the vertical structure of the upper water column and sea-ice
formation. River water also supports biological productivity by
delivering nutrients (e.g., Jones and others, 1990; Rudels and
others, 1991). Low-salinity surface waters exported from the
Arctic Ocean affect overturning in the Nordic and Labrador
seas, and thus the formation of North Atlantic Deep Water,
which ventilates the World Ocean (e.g., Aagard and Carmack,
1994). During glacial periods, the Arctic hydrographic environments expanded southwards and dominated even larger areas than at present. Because of the potential increase in highlatitude precipitation with atmospheric warming, the future development of the Arctic hydrology may have significant effects
both on oceanic circulation and climate (Cattle and Crossley,
1995; Delworth and others, 1997). More studies are required
to better predict this future development, including new paleoenvironmental investigations that yield improved insight
into past climate variability and the evolution of the arctic climate system.
Benthic foraminifera are a valuable but poorly understood
paleobiological proxy for the reconstruction of environmental
conditions on continental shelves occupied by Arctic waters.
Benthic foraminifera have a wide environmental distribution
and high preservation potential. They occur in many environments ranging from glaciated fjords and river estuaries to deep
1 Byrd Polar Research Center, Ohio State University, Columbus,
Ohio 43210, USA.
2 P. P. Shirshov Institute of Oceanology, Moscow 117851, Russia.
3 Arctic and Antarctic Research Institute, St. Petersburg 199397,
Russia.
4 Institute of Geology, University of Tromsø, N-9037, Norway.
5 Institute of Arctic and Alpine Research, University of Colorado,
Boulder, CO 80309, USA.
* Corresponding author: Byrd Polar Research Center, 1090 Carmack
Rd., Columbus, OH, 43210; tel. 614-292-2602, fax 614-292-4697,
E-mail: [email protected]
The study area is located north of the western Siberian Lowland and is separated from the Barents Sea to the west by the
Novaya Zemlya islands (Fig. 1). Physiographically, the southern Kara Sea can be divided into two main areas: a shallow
(mostly ,50 m) eastern area adjacent to the estuaries of the
Ob and Yenisey rivers and a western area with water depths
typically exceeding 100 m and reaching .500 m in the narrow
Novaya Zemlya Trough (Fig. 2).
Runoff to the Kara Sea is controlled by the Ob and Yenisey
rivers, which drain a huge catchment area extending to the
northern slopes of the Tibetan Plateau (Fig. 1). The mean annual discharges of the Ob and Yenisey are approximately 400
and 580 km3, respectively; their combined discharge is almost
two times that of the Mississippi River and constitutes more
than ⅓ of the total runoff into the Arctic Ocean (R-ArcticNET,
2001). More than 75% of this discharge occurs between May
and September, the spring-summer flooding period. The offshore spreading of riverine waters, incorporated in the general
Kara Sea water circulation, varies depending on winds and
commonly affects almost half of the total sea area; the multiannual pattern is characterized by net eastward transport into
the Laptev Sea (Figs. 2–3; Burenkov and Vasil’kov, 1995; Pavlov and others, 1996). In the shallow area north of the Ob and
Yenisey estuaries, riverine inputs strongly affect the bottom water (Fig. 4). In the deeper area further west, a pycnocline persists through summer at ca. 20–30 m, separating surface and
more saline bottom waters. The deep Novaya Zemlya Trough
contains dense, fully saline water that is probably produced by
brines during sea-ice formation. The overall modern hydrographic pattern in the southern Kara Sea is characterized by a
steady increase and stabilization of salinities with distance from
the estuaries. Surface water salinities range from ,5 psu (practical salinity units) in the estuaries to 30 psu in distant areas;
corresponding bottom salinities range from ,30 to .34.5 psu
(Figs. 3–4). The strongest salinity gradients (fronts) are located
immediately north of the estuaries; an additional sharp gradient
in bottom salinity occurs at the bathymetrically controlled
boundary between the shallow eastern area and the deeper
western area. The bottom temperature pattern (Fig. 5) has
weaker gradients and is more complex than that of salinity
because of multiple factors such as insolation, the timing of ice
break-up, and the formation and distribution of brines. Generally, bottom temperatures in the Kara Sea do not exceed 08C
except for shallow sites in the proximity of the estuaries and
in Baidarata Bay (Pavlov and others, 1996).
BENTHIC FORAMINIFERAL ASSEMBLAGES FROM THE SOUTHERN KARA SEA
FIGURE 1. Circum-arctic map showing rivers discharging to Arctic
seas (line thickness of rivers represents relative runoff) and the catchment for the Kara Sea (dotted line). Base map courtesy of R. Lammers,
University of New Hampshire.
253
FIGURE 3. Summer surface salinity in the Kara Sea, multi-year
means. Shading highlights salinities .20 psu.
The Ob and Yenisey discharge largely controls not only the
hydrographic structure, but also the sedimentation and biological productivity in the southern Kara Sea. The combined annual runoff delivers .22 3 106 tons of suspended matter and
almost 8 3 106 tons of organic matter, particulate and dissolved
(Gordeev and others, 1996). The bulk of suspended load is
deposited in front of the estuaries, at the mixing zone between
predominantly riverine and marine waters (Lisitzin and others,
1995, 2000). This depositional regime is marked by seafloor
areas of fine-grained sediment off estuary mouths, contrasting
with generally coarse sediment in the shallow part of the sea
(Fig. 6). Beyond the surface isohaline of 20 psu (cf. Fig. 3),
concentrations of suspended load drop to values two orders of
magnitude lower than in the estuaries (Lisitzin and others,
2000). The remaining fines are distributed by currents throughout the shelf and are partly exported into the Arctic Ocean by
surficial waters and/or ice.
Biological productivity in the Kara Sea has not been monitored as extensively as hydrography, but data from several summer seasons provide a general characterization of productivityrelated processes (e.g., Vedernikov and others, 1995; Nöthig
and Kattner, 1999). As runoff contains large amounts of nutri-
FIGURE 2. Map of the Kara Sea showing bathymetry (25, 50 100,
200, 300, and 400 mwd contour lines) and a generalized surface current
system. Shadings highlight depths .50 m and .200 m.
FIGURE 4. Summer bottom salinity in the Kara Sea, multi-year
means. Shading highlights salinities .34 psu.
254
POLYAK, KORSUN, FEBO, STANOVOY, KHUSID, HALD, PAULSEN, AND LUBINSKI
FIGURE 5. Summer bottom temperature in the Kara Sea, multi-year
means (8C). Shading highlights temperatures ,218C.
ents and labile organic matter, productivity is generally high in
and near the estuaries, reaching .300 mg C m22 day21, and
decreases to very low levels of ,50 mg C m22 day21 in the
open sea (Vedernikov and others, 1995). This pattern is enhanced by a relatively early ice break-up in the estuaries and
adjacent areas (Harms, 1997; Borodachev, 1998). The distribution of river-derived nutrients can be illustrated by concentrations of silica in surface waters, which decrease ten-fold
from the estuaries to the northern and western areas of the Kara
Sea (Rusanov and Vasil’ev, 1976; Makkaveev and Stunzhas,
1995). However, excessively high suspended loads in runoff
may decrease biological productivity in the estuaries, causing
maximum production at some distance away (Vedernikov and
others, 1995). Apart from riverine influence, primary production blooms on the Arctic shelves are mostly connected with
the ice-melting zones, which may be the case for river-distal
areas in the Kara Sea. The complex pattern of productivity
blooms is illustrated by different groups of diatoms and dinoflagellates dominating the phytoplankton in various parts of the
Kara Sea in summer (Matishov, 1995; Vavilova and others,
1998). Enhanced productivity has been observed near the
coasts of Novaya Zemlya, which may be related to the summer
melting of glaciers (Matishov and others, 1989; Matishov,
1995).
There are no comprehensive data on the fluxes of organic
carbon to the sea floor, but the total benthic biomass has highest
values of .150 g m22 near the estuaries and decreases north
and westwards, consistent with the general distribution pattern
of the primary productivity (Zenkevich, 1960; Matishov and
others, 1989). Extremely low benthic biomass of ,3 g m22
characterizes the deep Novaya Zemlya Trough, whereas the
shallow area adjacent to Novaya Zemlya has elevated values
of .25 g m22. It must be noted that total organic matter in
bottom sediments may not be representative of food fluxes for
benthic communities because of a large contribution of old,
refractory organics delivered by rivers (Stein, 1996; Boucsein
and others, 1999).
Relatively high rates of production and sedimentation of organic matter are exemplified by seasonally reduced levels of
bottom-water oxygenation off the estuaries (Fig. 7); however,
FIGURE 6. Sand (.63 mm, %) in surficial bottom sediments in the
Kara Sea. Shadings highlight sand contents .25% and .50%. Cross
marks show data points. Russian data were approximately converted
from a metric grain-size scale to .63mm class by interpolating between the .50mm and .100mm values on a logarythmic scale.
anoxic conditions have never been observed in the water column. Because of decreasing biological production and sediment fluxes, the oxidation of bottom sediments in river-distal
areas is generally stronger, as evidenced by a thicker oxidized
surficial layer reaching .20 cm as opposed to ,5 cm at the
estuary mouths (Galimov and others, 1996).
MATERIALS AND METHODS
Our data set of modern benthic foraminifers combines published and new data from a total of 113 surficial sediment sam-
FIGURE 7. Summer bottom oxygen concentration in the Kara Sea,
multi-year means (ml/l). Shading highlights concentrations ,7 ml/l.
255
TABLE 1.
Sources for the foraminiferal data set from surficial sediments of the southern Kara Sea (Fig. 8).
Author
T. Khusid
Ship/Year
L. Polyak
B.-E. Paulsen
S. Korsun
T. Troitskaya
L. Polyak (recount)
Dmitri Mendeleev, 1993;
Professor Shtokman, 1992
Akademik Karpinski, 1991
Ivan Petrov, 1993–1994
Boris Petrov, 1997
Pavel Bashmakov, 1980
Northwind, 1965
V. Slobodin
1953–1958
No. of samples
Collection technique
31 (2 empty)
Grab, boxcore,
gravity core
Grab (stained)
Grab (stained)
Multicorer (stained)
Grab
Grab
25 (1 empty)
23
21
8
4
4
pling sites (Table 1, Fig. 8). These sites provide a generally
dense and even coverage of the southern Kara Sea, bounded
by 778N and 868E towards the open sea; sparse samples beyond
these limits were not included. This large study area contains
a set of river-influenced Arctic shelf environments that grade
from estuaries to normal marine settings. Multi-year hydrographic measurements from the study area allow a thorough
characterization of temperatures, salinities, and oxygen content.
Most sediment samples in this study were collected by grab
samplers, boxcores, or multicorers, which provide a good recovery of surficial sediments representing the most recent time
interval. Over half of all samples have been stained by Rose
Bengal and nearly all of them were found to contain live (or
at least cytoplasm-bearing) foraminifers and other benthic meiofauna. Furthermore, samples in Korsun’s collection were studied wet to ascertain the identification of live specimens (Korsun, 1999).
Present sedimentation in the southern Kara Sea is estimated
to range between approximately 0.2 to 1 mm/yr, with the exception of shallow areas subjected to winnowing (Levitan and
others, 1996; Polyak and others, 2000); these rates indicate that
the samples (uppermost 1–2 cm of sediment) generally span
the last several decades. Historical observations suggest no significant long-term hydrographic changes in the Kara Sea and
adjacent seas other than multi-year to decadal-scale fluctua-
FIGURE 8. Index map of sediment samples used for foraminiferal
studies (see Table 1). Dotted and solid lines show depth contours of
50 and 200 mwd, respectively (same in Figs. 9–29).
Gravity core
Publication
Khusid & Korsun, 1996 1
This study
This study
Paulsen, 1997
Korsun, 1999 1 This study
This study
Todd & Low, 1980 (species
occurrence data only)
Basov & Slobodin, 1965
tions, except perhaps for a still poorly understood anomalous
warming trend in the Eurasian Arctic that started in the 1990’s
(e.g., Shpaikher and Fedorova, 1973; Pavlov and Stanovoy,
1997). Therefore, the investigated foraminiferal assemblages
characterize mean multi-decadal modern environments.
To assess the hydrographic parameters on a time scale corresponding to the foraminiferal samples, we compiled seasonal
data on bottom temperatures, salinities, and oxygen concentrations, as well as summer surface salinities from the southern
Kara Sea for the last 10 (winter) to 20 (summer) years from
the historical database of the AARI (Joint U.S.-Russian Atlas
of the Arctic Ocean, 1997, 1998). Data were included only
when coverage for a particular year and season spanned a majority of the field area. Scattered data from each year were
gridded and then all yearly grids were averaged to form mean
multiyear fields. (Figs. 3–5, 7). These fields provide the first
systematic characterization of multi-annual hydrographic environments in the southern Kara Sea. The mean grid-point values were interpolated to the foraminiferal sampling sites for
direct comparison with foraminiferal distributions. We have
also compiled and plotted the distribution of surficial sediments
using grain-size data associated with the foraminiferal samples
and prior results of Kordikov (1958; Fig. 6).
Foraminifers have been counted in the .0.1 mm size fraction in most samples; .0.125 mm size was used for Korsun’s
samples. Foraminiferal composition does not appear to differ
significantly between these similar sieve sizes, as illustrated by
lack of discrepancies in species distribution patterns. To keep
our results comparable with down-core data, we analyzed the
species composition of only calcareous foraminiferal assemblages. Agglutinated (arenaceous) foraminifers easily disintegrate after death and thus result in variable and typically very
low downcore abundances of tests or test fragments, depending
on diagenetic processes in sediment and sample processing
conditions (e.g., Brodniewicz, 1965; Schröder, 1988). Rare
planktonic foraminifers were counted separately. Benthic species percentages (frequencies) were calculated for samples containing at least 25 calcareous specimens (average sample size
5 128). This, generally low cut-off level was chosen in order
to balance the number of analyzed sites (especially in foraminiferal-poor river-proximal areas) and the accuracy of species
representation. A sample size of 25 provides a 0.95 probability
of recording a species that has a 10% frequency in the population (Dennison and Hay, 1967). We present the distribution
of 17 species, or groups of related species, each having a frequency of 10% in at least one sample and a mean frequency
of 2% minimum; in most samples these taxa account together
for over 90% of the total calcareous assemblages.
FORAMINIFERAL DISTRIBUTION
ENVIRONMENTAL FACTORS
All analyzed mean bottom-water variables, except summer
temperature, have strong linear correlations with each other and
256
TABLE 2. Linear correlation coefficients for environmental variables (multi-annual means for hydrographic parameters). Shown are only the
correlations confident at P . 0.95. Values confident with Bonferroni correction applied are shown in bold.
Ln Water Depth
Summer Surface Salinity (SSS)
Summer Bottom Salinity (SBS)
Winter Bottom Salinity (WBS)
Summer Bottom Temperature (SBT)
Winter Bottom Temperature (WBT)
O2 concentration, ml/l
SSS
SBS
WBS
SBT
WBT
0.66
0.68
0.72
0.64
0.88
0.81
20.44
—
20.62
—
20.54
20.83
20.76
20.92
—
with the surface salinity, which reflects a generalized riverine
signal (Table 2; Figs. 3–5, 7). This pattern highlights that hydrographic processes in the southern Kara Sea are largely controlled by runoff fluxes (cf. e.g., Pavlov and others, 1996). An
additional control on bottom-water properties is provided by
bathymetry. However, because depths also change with distance from the Ob and Yenisey estuaries, there may be a bias
in the correlations. Summer bottom temperatures have a pattern
differing from the other measured parameters due to more complex controls and weaker gradients.
Similar to the hydrographic situation, biological and sedimentation processes in the southern Kara Sea appear to be
strongly affected by riverine fluxes. This trend is exemplified
by inverse relationships between surface salinity and factors
such as primary production, chlorophyll a concentration (Vedernikov and others, 1995; Nöthig and Kattner, 1999) and total
sediment load (Lisitzin and others, 2000). Bottom sediments,
however, show no relationship to hydrographic factors, and
only a weak correlation with water depth, probably due to additional effects of bottom currents and seabed topography on
sediment distribution (Table 2; Fig. 6).
ABUNDANCE PATTERNS
Benthic foraminiferal abundance depends on the interplay
between three main factors: productivity, dilution by clastic
sediments, and taphonomic loss. The distribution of foraminif-
FIGURE 9. Distribution of benthic foraminiferal abundance, combined calcareous and agglutinated (per gram of dry sediment).
O2
0.37
0.79
0.43
0.63
—
20.59
% Sand
20.25
—
—
—
—
—
—
eral abundance in the Kara Sea (Fig. 9) shows consistently low
numbers near the estuaries, which may be mainly controlled
by a high sediment load. Additionally, observations of foraminifers from these sites, including cytoplasm-bearing specimens, indicate a strong dissolution of calcareous tests, possibly
associated with low alkalinity of bottom water, (cf. Makkaveev
and Stunzhas, 1995). Reduced salinity likely sets the barrier for
foraminiferal propagation up the estuaries, with the lowest
mean salinity at which foraminifers have been found in the Ob
and Yenisey near 5 psu. However, these samples contain just a
few non-stained foraminiferal tests, which may have been redeposited from older strata outcropping along the river banks.
If this is the case, then the salinity cut-off rate is closer to 10
psu. Low foraminiferal abundance is also characteristic of the
Novaya Zemlya Trough and adjacent areas to the east, probably
due to a combination of low productivity and dissolution/disaggregation of tests. Strong calcium carbonate dissolution in
this area is corroborated by the generally low percentage of
calcareous foraminifers (Fig. 10), although this index may be
biased by variable rates of disaggregation of arenaceous tests.
Planktonic foraminifers, largely represented by the cold-water
species Neogloboquadrina pachyderma (sinistral), occur mostly near the southern and northern tips of Novaya Zemlya, likely
reflecting inflows from the Barents Sea (Fig. 11).
SPECIES DISTRIBUTION
The mapped distribution of nearly all of the abundant species
shows an orderly succession of maximal frequencies, reflecting
FIGURE 10. Percentage of calcareous foraminifers in total benthic
foraminiferal numbers.
257
FIGURE 11. Distribution of planktonic foraminifers (% in total calcareous counts).
optimal conditions or ecological stress tolerance of species
along a gradient from river-proximal to river-distal locations.
Riverine inputs affect benthic communities through changes in
delivery of freshwater, food, and total sediment, all generally
decreasing on the Siberian shelf with distance from the estuaries (Zenkevich, 1960; Vedernikov and others, 1995; Lisitzin
and others, 2000). As quantitative data on sediment and organic-matter fluxes to the Kara Sea floor are sparse, we approximate the riverine signal by the surface salinity, which is linked
with productivity, nutrients, and sediment fluxes in this region
(Rusanov and Vasil’ev, 1976; Makkaveev and Stunzhas, 1995;
Vedernikov and others, 1995; Nöthig and Kattner, 1999; Lisitzin and others, 2000). To help quantify the distribution of
foraminifera along the river-proximity gradient, mean multiannual summer surface salinity was compared to the mean
maximal percentages of the abundant benthic foraminiferal species. Nearly all species show systematic relationships (Fig. 12).
These relationships, combined with the link between salinity
and distance from rivers, allowed us to differentiate three major
types of assemblages: river-proximal, -intermediate, and -distal,
corresponding to surface salinities of ,15, 15–25, and .25
psu, respectively.
Unaveraged species percentages were compared to mean
multi-annual environmental values of depth, salinity, temperature, oxygen, and sediment grain size using linear and 2nd order polynomial functions. Results for both function types show
the strongest relationships with depth and salinity (see Table 3
for an example of linear-based results). This result probably
reflects the pervasive inter-relationships between river proximity, depth, salinity, productivity, nutrients, and sediment fluxes in the study area. The general lack of strong correlations
with any of the individual environmental variables probably
reflects complex responses of benthic foraminifers to environmental factors, as observed for many biological groups (e.g.,
Jongman and others, 1995).
River-proximal Species
Elphidium incertum (Pl. 1, Figs. 1–7) has maximal frequencies in and near the Yenisey estuary, where they nearly
FIGURE 12. Average frequencies of foraminiferal species vs. mean
summer surface salinities in discrete increments. Plates A, B, and C
illustrate river-proximal, -intermediate, and -distal species, respectively.
constitute the entire assemblage in some samples, and sharply
fall within a distance of ;300 km (Fig. 13). A population at
the Yenisey estuary differs morphologically from a typical E.
incertum, as described from many Arctic/subarctic regions, by
the expansion of tuberculation in the umbilical area (Pl. 1, Figs.
5–7). Although the systematics of E. incertum have not been
fully worked out (see Faunal Reference List, Appendix 1),
available distribution data show its consistent affinity to areas
affected by riverine fluxes in temperate and high latitudes of
Europe, Asia, and North America (Brodniewicz, 1965; Lutze,
1965; Todd and Low, 1966; Fursenko and others, 1979; Culver
and Buzas, 1980; Lukina, 1990).
Haynesina orbiculare (Pl. 2, Figs. 1–3) is easily recognizable and is another major indicator of river-proximal environments. In contrast to E. incertum, H. orbiculare is equally
abundant in front of both the Ob and Yenisey estuaries and its
frequency decreases gradually towards the river-distal areas
(Fig. 14). Overall, H. orbiculare has higher frequencies
throughout the study area than E. incertum and is one of the
most abundant species. The geographic occurrence of H. orbiculare is generally similar to that of E. incertum (Brodniewicz, 1965; Leslie, 1965; Lutze, 1965; Todd and Low, 1966;
Lukina, 1990), but H. orbiculare has a wider distribution and
is not uncommon in cold waters with relatively stable marine
salinities (e.g., Loeblich and Tappan, 1953; Lukina, 1977).
Polymorphinidae. Foraminifers of this family in the Kara
Sea occur most frequently in a narrow zone adjacent to the
estuaries (Fig. 15). Although occurring in modern assemblages
258
TABLE 3. Linear correlation coefficients between foraminiferal species and environmental variables (multi-annual means for hydrographic parameters). Shown are only the correlations confident at P . 0.95. Values confident with Bonferroni correction applied are shown in bold. Abbreviations
as in Table 2.
Ln depth
E. clavatum
C. reniforme
H. orbiculare
E. subarcticum
E. incertum
E. bartletti
Buccella spp.
I. norcrossi
S. loeblichi
N. labradoricum
C. lobatulus
M. barleeanus
A. gallowayi
E. groenlandica
T. fluens
Miliolidae
Polymorphinidae
SSS
SBS
WBS
0.33
20.30
0.30
20.57
20.33
0.33
20.35
0.37
20.27
20.24
0.39
20.47
0.52
20.46
20.34
0.35
20.38
SBT
WBT
0.53
0.25
20.26
0.39
0.32
0.24
0.25
0.27
20.30
0.38
0.38
0.28
0.30
0.24
0.25
20.37
20.33
20.25
20.42
0.37
20.39
20.46
20.50
20.54
0.51
in low numbers, polymorphinids have been reported from a
wide range of environments including shallow-water and lowsalinity settings (e.g., Todd and Low, 1966; Madsen and Knudsen, 1994). Our data suggest that the polymorphinids can be
used as an indicator of the riverine signal on the Arctic shelves.
Elphidiella groenlandica (5E. gorbunovi; Pl. 2, Fig. 8) is
yet another elphidiid that shows a clear river-proximal distribution (Fig. 16). This ecological affinity has been supported by
many observations from Arctic shelves, showing restriction of
this large foraminifer to river-adjacent regions (e.g., Cooper,
1964; Todd and Low, 1966; Tamanova, 1971; Lukina, 1990).
Elphidium bartletti (Pl. 2, Figs. 4–5). This elphidiid joins
E. incertum, H. orbiculare, and E. groenlandica in preferring
river-affected habitats, but its highest occurrences are farther
from the Ob and Yenisey estuaries and form a narrow zone
extending into the southwestern part of the study area (Fig. 17).
This distribution largely co-occurs with sandy, shallow seafloor areas off the estuaries (Fig. 6).
Buccella spp. combines closely related, intergrading species
of B. frigida, B. hannai arctica, and possibly B. tenerrima (Pl.
2, Figs. 14–17). Although widely distributed throughout the
entire southern Kara Sea, Buccella spp. shows a preference
towards river-affected areas and is even recorded from the Ob
estuary (Fig. 18).
River-intermediate Species
Cassidulina reniforme (Pl. 2, Fig. 12) has its maximum
frequencies in the intermediate zone between river-proximal
and river-distal areas and avoids approaching the estuaries (Fig.
19). C. reniforme is one of the most common calcareous foraminifers on the Arctic shelves, occurring from glaciated fjords
to bathyal depths (e.g., Lukina, 1977; Sejrup and Guilbault,
1980; Mudie and others, 1983; Mackensen and others, 1985;
Korsun and others, 1994; Hald and Korsun, 1997). This species
seems to prefer cold-water areas (temperatures below ca. 28C)
with seasonal sea-ice coverage and muddy sediments and is
typically not found in decreased salinities (below ;30 psu).
Trifarina fluens (Pl. 2, Fig. 18) is not abundant in the Kara
Sea, but its occurrences seem to show a preference to areas
intermediately distanced from the estuaries (Fig. 20). In the
Barents Sea and on the Iceland shelf, T. fluens has maximal
abundances at relatively shallow water depths in the vicinity
of the Polar front, an environmental setting characterized by
high seasonal biological productivity and relatively agile bot-
Sand
20.43
20.34
0.29
0.26
0.47
0.25
0.31
0.35
0.27
0.25
20.39
0.60
0.30
0.37
0.24
0.27
O2
0.27
20.32
0.26
20.24
tom waters (Østby and Nagy, 1982; Lukashina, 1987; Korsun
and Polyak, 1989; Steinsund and others, 1994).
Nonion labradoricum (Pl. 2, Fig. 10) occupies a distinct
zone extended across the study area at intermediate distances
from the rivers (Fig. 21). A similar zonal pattern of distribution
occurs in the Barents Sea, where the habitat of N. labradoricum is stretched along the Polar front (Steinsund and others,
1994). This occurrence is consistent with a preference for fresh
phytodetritus as a food source (Cedhagen, 1991). The infaunal
life mode of N. labradoricum (Corliss, 1991; Corliss and Van
Weering, 1993; Hunt and Corliss, 1993) further suggests the
affinity of this species for environments with at least seasonally
elevated concentrations of food in sediment, although N. labradoricum is also capable of surviving prolonged starvation
(Cedhagen, 1991).
Stainforthia loeblichi (Pl. 2, Fig. 19) has a distribution pattern resembling that of N. labradoricum (Fig. 22). Similar distributions of these species have been also observed elsewhere
(Steinsund and others, 1994; Wollenburg and Mackensen,
1998b). Stainforthia species are opportunistic, taking advantage of pulses of high seasonal productivity (Alve, 1995; Gustafsson and Nordberg, 2001). This feeding pattern is corroborated by an observation that a morphologically similar, and taxonomically related, foraminifer Bulimina exilis shows preference to fresh organic detritus (Caralp, 1989).
Miliolidae combine Pyrgo williamsoni, Triloculina trihedra, and several species belonging to the genera Quinqueloculina and Miliolinella. No clear pattern can be recognized in
the distribution of this group, possibly because of a combination of several individual ecological preferences; however, it is
recognizable as intermediate in terms of distance from the rivers (Fig. 23).
Elphidium subarcticum (Pl. 1, Figs. 8–12) is the only elphidiid in our data set that tends to proliferate more in the riverdistal than river-proximal areas (Fig. 24). E. subarcticum has
been reported as widely occurring throughout the high- and
temperate-latitude shelves (e.g., Loeblich and Tappan, 1953;
Todd and Low, 1966; Lukina, 1977, 1990; Culver and Buzas,
1980); the distribution has not shown a clear pattern, possibly
because of varying taxonomic approaches to this species. A
characteristic ecological trait that has been noted for E. subarcticum is an epifaunal, commonly attached habitat (Poag,
1982; Korsun and Polyak, 1989; Korsun and others, 1994).
259
PLATE 1
Scale bars are 100mm unless otherwise indicated. Sampling stations are shown in Fig. 8. 1a–b E. incertum, juvenile, st. 2202. 2 E. incertum, st.
2401. 3a–c Elphidium incertum, st. 4402; b bar 5 50mm; c bar 5 25mm. 4 E. incertum, st. 2701. 5a–b E. incertum, tuberculate morphotype, st.
k32; b detail of an area in front of aperture, bar 5 10mm. 6a–e E. incertum, tuberculate morphotype, st. k32; c area in front of aperture; bar 5
10mm; d umbilical area with numerous diatoms; bar 5 100mm; e diatoms Aulacosira granulata (Ehr.) between the tuberculi; bar 5 10mm. 7 E.
incertum, tuberculate morphotype, st. k32. 8 Elphidium subarcticum, juvenile, st. 2701. 9 E. subarcticum, st. 4398. 10 E. subarcticum, st. 2701.
11a–b E. subarcticum, st. 4398; b bar 5 50mm. 12 E. subarcticum, st. 2703.
260
and coarse sediments, observed on the shelf and upper slope
of the Barents Sea, attests to the attached epifaunal life mode
of this species (Korsun and Polyak, 1989; Korsun and others,
1994; Wollenburg and Mackensen, 1998a).
Other Species
FIGURE 13. Distribution of Elphidium incertum. Area with maximal frequencies is shaded.
River-distal Species
Islandiella norcrossi (Pl. 2, Fig. 13), combining I. norcrossi
sensu stricto and a closely related, intergrading species I. helenae, shows a distinct preference to river-distal areas (Fig. 25).
This distribution pattern is consistent with observations
throughout the Arctic shelves showing that I. norcrossi/helenae
is associated with relatively high and stable bottom salinities
(e.g., Mudie and others, 1983; Korsun and Hald, 1998). Data
from the Barents Sea indicate that this species has maximum
frequencies in the areas with seasonal sea ice and thus may be
related to summer ice-edge productivity (Korsun and Polyak,
1989; Steinsund and others, 1994).
Melonis barleeanus (Pl. 2, Fig. 9) is clearly distanced from
rivers and is mostly localized in the deep Novaya Zemlya
Trough (Fig. 26). Elsewhere, M. barleeanus is typically associated with normal marine salinities, absent or seasonal ice cover, and fine sediments accumulated in shelf depressions and on
the continental slopes (e.g., Mudie and others, 1983; Mackensen and others, 1985; Hald and Steinsund, 1992; Korsun and
Polyak, 1989; Korsun and others, 1994; Wollenburg and Mackensen, 1998a). Species of Melonis have been shown to dwell
mostly infaunally, feeding on buried organic detritus (e.g., Corliss, 1985, 1991; Korsun and others, 1994; Wollenburg and
Mackensen, 1998b; Mackensen and others, 2000). Moreover, it
has been suggested that Melonis can thrive on somewhat altered organic matter (Caralp, 1989).
Cibicides lobatulus also flourishes in river-distal areas, but,
in contrast to M. barleeanus, is associated with coarser sediments at shallower depths with more current activity (Fig. 27).
Cibicides, as well as other plano-convex foraminifers, are
known as clinging epifaunal suspension feeders, populating areas with vigorous bottom waters (e.g., Nyholm, 1961; Lutze
and Thiel, 1987; Korsun and Polyak, 1989; Hald and Steinsund, 1992; Korsun and others, 1994; Wollenburg and Mackensen, 1998a).
Astrononion gallowayi (Pl. 2, Fig. 11) has a distribution
similar to that of C. lobatulus, even more strictly adhering to
the river-distal, shallow area along Novaya Zemlya (Fig. 28).
The association of A. gallowayi with elevated current activity
Elphidium excavatum formaclavata (Pl. 2, Figs. 6, 7) is
the most abundant calcareous benthic foraminifer in the study
area, and the only species that shows no recognizable distribution pattern (Fig. 29). E. e. clavata is known to be widespread on the Arctic shelves, including extreme environments,
such as near tidewater glacier fronts (Leslie, 1965; Lukina,
1977, 1990; Mudie and others, 1983; Polyak and Korsun, 1989;
Hald and others, 1994; Hald and Korsun, 1997; Korsun and
Hald, 1998, 2000). The exceptional ability of this species to
adapt to harsh environments may be related to its high nutritional and habitat versatility, and capability of quickly colonizing seafloor areas temporarily unsuitable for life (Corliss, 1991;
Corliss and Van Weering, 1993; Linke and Lutze, 1993; Wollenburg and Mackensen, 1998b; Alve, 1999). The southward
distribution of E. e. clavatum in the Barents Sea is limited by
water temperatures above ;48C and/or by the winter sea-ice
boundary; this is probably due to competition from species
adapted to more stable feeding conditions. In near-shore waters
affected by riverine fluxes, E. e. clavatum spreads to temperate
latitudes, grading into warmer-water forms of E. excavatum
(Brodniewicz, 1965; Lutze, 1965; Feyling-Hanssen, 1972; Wilkinson, 1979; Miller, 1982).
DISCUSSION
RIVER-PROXIMAL ASSEMBLAGES
The dominant foraminifers in river-proximal assemblages are
the elphidiids, with Elphidium incertum and Haynesina orbiculare being most frequent (Figs. 13–14). Elphidium excavatum f. clavata is also abundant here and even occurs in the
extreme up-river samples; however, its frequencies are evenly
distributed throughout the entire study area, showing only a
slight increase near the estuaries (Fig. 29). The two other elphidiid species characteristic of river-proximal environments
are Elphidiella groenlandica, which occurs exclusively near
estuaries, and Elphidium bartletti (Figs. 16–17). The more offshore optimum of E. bartletti may be related to the presence
of coarser-grained sediment (cf. Fig. 6) or the interplay between
salinity, food availability, and sedimentation rate with distance
from the rivers. Among foraminifers other than elphidiids,
those with strongest affinity to river-proximal environments are
polymorphinids (Fig. 15). Buccella spp. also have elevated frequencies in the vicinity of the estuaries (Fig. 18).
We infer that river-proximal assemblages are adapted to environments with high seasonal, possibly pulsed, fluxes of food
and sediment. Elphidiids and Buccella spp. that constitute the
majority of river-proximal assemblages have supplementary apertures, which allow a quick exertion and withdrawal of large
volumes of cytoplasm for efficient capture and digestion of
various food objects (Brasier, 1982; Alexander and Banner,
1984). In particular, the runoff delivers plentiful terrigenous,
partially labile organic matter and riverine algae, which die out
when entering the marine waters (Lisitzin and others, 1995;
Boucsein and others, 1999). Numerous fresh- or brackish-water
diatoms found on the tests of E. incertum at the Yenisey estuary provide evidence for such a feeding strategy (Pl. 1, Figs.
6d–e). The enhanced tuberculation of these tests may be a morphological adaptation to feed on diatoms by crushing their frustules between the tuberculi (Alexander and Banner, 1984). Interestingly, E. incertum has an asymmetric distribution with
261
PLATE 2
Scale bars are 100mm unless otherwise indicated. Sampling stations are shown in Fig. 8. 1, 2 Haynesina orbiculare, st. 4398. 3 H. orbiculare,
st. k19. 4 Elphidium bartletti, st. 2102. 5 Elphidium bartletti, st. 2102. 6 Elphidium excavatum f. clavata, st. 2704. 7 Elphidium excavatum f.
clavata, st. 2701. 8 Elphidiella groenlandica, st. 2601, bar 5 1mm. 9 Melonis barleeanus, st. 2701. 10 Nonion labrodoricum, st. 2701. 11
Astrononion gallowayi, st. 2701. 12 Cassidulina reniforme, st. 2701. 13 Islandiella norcrossi, st. 2701. 14 Buccella frigida, st. 2701. 15 Buccella
frigida, st. 2701. 16 Buccella hannai arctica, st. 2701. 17 Buccella hannai arctica, st. 2701. 18 Trifarina fluens, st. 2701. 19 Stainforthia loeblichi,
st. 2701.
respect to the two estuaries, being most frequent in the Yenisey
area (Fig. 13). This asymmetry may reflect a higher river-born
productivity in front of the Yenisey estuary (cf. Vedernikov and
others, 1995; Nöthig and Kattner, 1999), which, in turn, is possibly caused by higher fluxes of organic matter from the Yenisey as opposed to higher fluxes of total sediment from the Ob
(Gordeev and others, 1996).
Another factor that most likely affects the adaptations of the
river-proximal assemblages is a high variability of the physical
environment, especially in terms of salinity and sediment fluxes. Although mean bottom salinities near the estuaries are
mostly between 20 and 30 psu, point measurements at the estuary mouths have shown values as low as 5–10 psu. The survival of foraminifers in this environment may be related to their
increased mobility within the sediment that allows them to escape extreme freshening events by burrowing into the substrate,
262
FIGURE 14. Distribution of Haynesina orbiculare. Area with maximal frequencies is shaded.
FIGURE 16. Distribution of Elphidiella groenlandica. Area of occurrence is shaded.
and sediment depositional pulses by moving upwards (cf. Wetmore, 1988; Langer and others, 1989). E. excavatum is known
for its ability to thrive at various depths in and upon sediment
(Corliss, 1991; Corliss and Van Weering, 1993; Linke and Lutze, 1993; Wollenburg and Mackensen, 1998b); high burrowing
skills have been reported for some other shallow-water elphidiids (Banner and Culver, 1978; Langer and others, 1989). Supplementary apertures of elphidiids and Buccella spp. facilitate
their motility in comparison with foraminifera that extend pseudopodia only through the primary aperture (Kitazato, 1988). A
morphological trait that is also most likely related to enhanced
mobility is longitudinal grooves between the tuberculi in the
apertural areas; these grooves are well-developed on the tuberculate E. incertum population from the Yenisey estuary (Pl. 1,
Figs. 5b, 6b–c), and similar grooves are characteristic of related
foraminifers E. albiumbilicatum, H. germanica, and some H.
orbiculare (Knudsen, 1971; Hansen and Lykke-Andsersen,
1976; Banner and Culver, 1978). Such grooves serve as pathways for pseudopodial trunks extended for locomotion and
feeding (Alexander and Banner, 1984; Kitazato, 1992). Another
adaptation of shallow-water and river-proximal foraminifers to
unstable environments is encystment, which has been reported
for E. incertum (Linke and Lutze, 1993).
FIGURE 15. Distribution of Polymorphinidae. Area with maximal
frequencies is shaded.
FIGURE 17. Distribution of Elphidium bartletti. Area with maximal
FIGURE 18.
Distribution of Buccella spp.
RIVER-INTERMEDIATE ASSEMBLAGES
263
FIGURE 20. Distribution of Trifarina fluens. Area with maximal
The most characteristic foraminifers of intermediate assemblages, Nonion labradoricum and Stainforthia loeblichi, avoid
more extreme river-proximal or river-distal environments (Figs.
21–22). Both N. labradoricum and S. loeblichi, or closely related species, have been associated with elevated seasonal productivity (e.g., Cedhagen, 1991; Gustafsson and Nordberg,
2001), which is consistent with their distribution near the Polar
Front in the Barents Sea (Steinsund and others, 1994). The
mostly infaunal habitat of these species supports their preference of at least temporarily high concentrations of food in sediment. Trifarina fluens, generally rare in the study area, has
maximal frequencies adjacent to those of N. labradoricum and
S. loeblichi; this is similar to distributions in the Barents Sea
(cf. Steinsund and others, 1994). Maximal frequencies of T.
fluens consistently occur in the vicinity of the Polar Front, although at somewhat shallower depths than N. labradoricum
and S. loeblichi (Østby and Nagy, 1982; Lukashina, 1987; Korsun and Polyak, 1989). We infer that the distribution of these
three species reflects a relatively high seasonal productivity at
intermediate distances from estuaries, combined with a reduced
sediment flux, which results in a high concentration of food in
bottom sediments. Alternatively, the intermediate zone may reflect a shorter, more pronounced productivity spike than in the
vicinity of the estuaries, controlled by the sea-ice melting. Salinity is also a likely factor preventing the propagation of these
FIGURE 19. Distribution of Cassidulina reniforme. Area with maximal frequencies is shaded.
FIGURE 21. Distribution of Nonion labradoricum. Area with maximal frequencies is shaded.
264
FIGURE 22. Distribution of Stainforthia loeblichi. Area with maximal frequencies is shaded.
species towards the river mouths (cf. Cedhagen, 1991; Alve,
1995; Hald and Korsun, 1997). Other species with elevated
frequencies in the intermediate Kara Sea associations, Cassidulina reniforme, Elphidium subarcticum, and miliolids, have
less accentuated distributions, but mostly avoid river-proximal
areas (Figs. 19, 23–24). This pattern may be caused by their
inability to survive reduced and fluctuating salinities or competition from foraminifers adapted to near-estuarine feeding environments. The epifaunal, commonly attached life mode of E.
subarcticum may explain the avoidance of river-proximal environments because of turbid bottom water and high seasonal
sediment fluxes.
FIGURE 23.
Distribution of Miliolidae.
FIGURE 24. Distribution of Elphidium subarcticum. Area with
maximal frequencies is shaded.
RIVER-DISTAL ASSEMBLAGES
The most river-distal assemblages do not approach the estuaries and are associated with mean bottom salinities mostly
.34.5 psu (Figs. 25–28). These assemblages fall into two
groups readily differentiated by water depths. The deeper-water
group populates the Novaya Zemlya Trough and is characterized by Islandiella norcrossi and especially Melonis barleeanus. The association of M. barleeanus with an area of low biological productivity seems to contradict the commonly-held
view that this species indicates high-productivity environments
(e.g., Wollenburg and Mackensen, 1998a,b). This apparent contradiction is resolved by the inference that M. barleeanus can
FIGURE 25. Distribution of Islandiella norcrossi. Area with maximal frequencies is shaded.
265
FIGURE 26. Distribution of Melonis barleeanus. Area with maximal frequencies is shaded.
FIGURE 28. Distribution of Astrononion gallowayi. Area with
maximal frequencies is shaded.
feed on organic detritus delivered with fine sediments from
shallow areas and deposited in sea-floor depressions, which is
consistent with its infaunal habitat (e.g., Corliss, 1985, 1991;
Mackensen and others, 2000) and its ability to feed on altered
organic matter (Caralp, 1989). In the Barents and Kara seas
this down-slope transportation of fine sediments is common,
being enhanced by fall/winter bottom-water cascading with
brines formed during the ice freezing (cf. Honjo, 1990). I. norcrossi also prefers relatively deep areas on the Arctic shelves,
but not as consistently as M. barleeanus. The distribution of I.
norcrossi appears to be more closely associated with seasonal
ice cover, and thus with ice-margin productivity processes
(Korsun and Polyak, 1989; Steinsund and others, 1994). The
other river-distal foraminiferal group, represented by Cibicides
lobatulus and Astrononion gallowayi, is characteristic of the
shallow zone adjacent to Novaya Zemlya (Figs. 27–28). Both
species, known as epifaunal grazers and filterers, obviously
take advantage of vigorous bottom waters on this narrow strip
of shallow seafloor, which is largely covered by coarse sediment and rock exposures and supports epifaunal communities
with a relatively elevated biomass (Zenkevich, 1960; Matishov
and others, 1989). Patches of C. lobatulus occurrences farther
east may be connected with locally intensified bottom currents.
A strong salinity control is expected for the river-distal assem-
FIGURE 27. Distribution of Cibicides lobatulus. Area with maximal frequencies is shaded.
FIGURE 29. Distribution of Elphidium excavatum f. clavata. Shading highlights the widespread occurrence of this species.
266
blages, possibly associated with epifaunal, attached life mode
of C. lobatulus and A. gallowayi and with a reduced mobility
of infaunal stenohaline foraminifers, as demonstrated for M.
barleeanus (Mackensen and others, 2000).
One other characteristic feature of the river-distal assemblages is the presence of planktonic foraminifers, which rarely
occur closer to the estuaries and appear to be related to the
inflow of Barents Sea waters. However, it is not known whether
this distribution of planktonic foraminifers is controlled primarily by salinity, feeding preferences, or life cycle that may
require a stratified water column (e.g., Volkmann, 2000).
CONCLUSIONS
Hydrographic variables, such as surface and bottom salinities, bottom temperatures, and oxygen content in the southern
Kara Sea reveal a strong interrelationship. This pattern reflects
the overwhelming control of riverine fluxes of freshwater and
associated dissolved and suspended matter on the environments
in the water column and on the sea floor. Accordingly, the
distribution of benthic foraminifers shows an orderly succession along a gradient from the Ob and Yenisey estuaries towards the open sea. The most commonly occurring foraminiferal species, or groups of species, fall into three types of assemblages: river-proximal, intermediate, and river-distal. We
infer that the differences between these assemblages are controlled by their feeding patterns, depending largely on riverine
food and sediment fluxes, and by bottom salinities.
River-proximal assemblages are characterized by various elphidiids (Elphidium incertum, Haynesina orbiculare, Elphidiella groenlandica, and Elphidium bartletti), polymorphinids,
and, less markedly, by Buccella spp. We believe that at least
some of these foraminifers are adapted to specific feeding conditions near estuaries, which have seasonally elevated fluxes of
both organic matter and total sediment, including river-born
labile organics. Enhanced mobility of some foraminifers, such
as elphidiids, in sediment is also inferred to be an adaptation
to the extreme temporal variability of river-proximal environments. The intermediate position between river-proximal and
river-distal environments is most commonly occupied by Nonion labradoricum and Stainforthia loeblichi, with adjacent areal habitats of Trifarina fluens. This position may be connected
with seasonally elevated concentrations of food in sediments
due to a combination of relatively high productivity and lowered sediment load or, alternatively, to a productivity spike at
the ice margin zone. Bottom salinity likely exerts at least partial
control on the distribution of these species and other intermediate foraminifers, such as Cassidulina reniforme, Elphidium
subarcticum, and miliolids. Salinity-controlled distribution is
also implied for the river-distal assemblages, which occupy two
distinct western areas of the southern Kara Sea: the deep Novaya Zemlya Trough and the narrow bank adjacent to Novaya
Zemlya. The trough assemblages are characterized by Islandiella norcrossi and Melonis barleeanus. The latter is believed
to feed on organic matter transported from shallower areas, and
thus indicates the deposition of fine sediment delivered by
downslope water movement. The characteristic foraminifers of
the shallow river-distal area are Cibicides lobatulus and Astrononion gallowayi, both of which are epifaunal species presumably specializing on bottom-water filtration.
The overall results on foraminiferal distribution in the southern Kara Sea enhance our understanding of foraminiferal ecology and provide a framework for paleo-environmental reconstructions in river-influenced Arctic marine settings. Development of more accurate and comprehensive proxy models requires quantitative multi-annual data on seasonal biological
productivity in the Kara Sea, which undoubtedly has a major
control on foraminiferal life patterns. Multi-seasonal sampling
to study the influence of large productivity and hydrographic
changes on distributions of living foraminifers would provide
the most accurate information for understanding proxy relationships (cf. e.g., Korsun and Hald, 2000; Gustafsson and
Nordberg, 2001).
ACKNOWLEDGMENTS
This is Byrd Polar Research Center publication No. 1263 supported
by the US NSF grants OPP-9529133 and 9725418. We are grateful to
O. Kijko and other colleagues from VNII Okeangeologia and P. P.
Shirshov Institute of Oceanology, Russia, who have been involved in
collecting and processing of materials used in the publication. Comments by S. Ishman helped to improve the manuscript.
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Received 15 June 2001
Accepted 12 October 2001
APPENDIX 1
FAUNAL REFERENCE LIST
Most foraminiferal species used in this study are well-defined taxonomically by previous works; we provide a short reference list that
exemplifies our taxonomic views. We mostly refer to recent, readily
available monographic descriptions; see citations therein for extended
synonymy and references to earlier descriptions. Because of varying
systematic approaches to Elphidium incertum and E. subarcticum, we
discuss these species in more detail.
Astrononion gallowayi Loeblich and Tappan, 1953 (Pl. 2, Fig. 11)
Astrononion gallowayi: Loeblich and Tappan, 1953, p. 90, pl. 17,
figs. 4–7; Knudsen, 1971, p. 266, pl. 10, figs. 10–12.
Buccella frigida (Cushman, 1922) (Pl. 2, Figs. 14, 15)
Buccella frigida: Knudsen, 1971, pl. 8, figs. 12–14; pl. 19, fig. 1;
Østby and Nagy, 1982, pl. 2, fig. 2.
Buccella hannai (Phleger et Parker) subsp. arctica Voloshinova, 1960
(Pl. 2, Fig. 16, 17)
Buccella hannai arctica: Voloshinova, 1960, p. 286, pl. 8, figs. 2–4.
Cassidulina reniforme Nørvang, 1945 (Pl. 2, Fig. 12)
Cassidulina reniforme: Sejrup and Guilbault, 1980, p. 79, fig. 2F–K.
Cibicides lobatulus (Walker et Jacob, 1798)
Cibicides lobatulus: Knudsen, 1971, pl. 9, figs. 9–14; Østby and
Nagy, 1982, pl. 3, fig. 11.
Elphidiella groenlandica (Cushman, 1933) (Pl. 2, Fig. 8)
Elphidium groenlandicum: Knudsen, 1971, p. 275, pl. 12, figs. 1–8;
pl. 21, figs. 1–3.
Elphidiella groenlandica: Loeblich and Tappan, 1953, p. 106, pl.
19, figs. 13, 14.
Elphidium gorbunovi: Shchedrina, 1946, p. 144, pl. 4, fig. 21 (name
widely used in Russian literature)
Elphidium bartletti Cushman, 1933 (Pl. 2, Figs. 4, 5)
Elphidium bartletti: Loeblich and Tappan, 1953, p. 96, pl. 18, figs.
10–14; Knudsen, 1971: p. 271, pl. 11, fig. 6–9; pl. 20, figs. 1–4.
Elphidium goesi: Shchedrina, 1946, p. 144, pl. 4, fig. 20 (name
widely used in Russian literature).
Elphidium excavatum (Terquem) forma clavata Cushman, 1944 (Pl.
2, Figs. 6, 7)
Elphidium clavatum Cushman: Loeblich and Tappan, 1953, p. 98,
pl. 19, figs. 8–10; Knudsen, 1971, pl. 11, figs. 10–13; pl. 20, figs.
5–8.
Elphidium excavatum: (Terquem) forma clavata Cushman: FeylingHanssen, 1972, pls. 1, 2.
Elphidium incertum (Williamson, 1858) (Pl. 1, Figs. 1–7)
E. incertum: Buzas, 1966, p. 592, pl. 72, figs. 1–4 (not 5–6); Knudsen, 1971, p. 277, pl. 12, figs. 11–12; pl. 21, fig. 8, 9.
E. asklundi: Knudsen, 1971, p. 270, pl. 10, figs., 20–21, pl. 11, figs.
1–5.
Discussion: E. incertum sensu stricto is characterized by a compressed test, slightly lobate outline, depressed, slightly curved sutures
with irregularly spaced ponticuli, and some degree of tuberculation in
the umbilicus and along the sutures. A population from the Yenisey
estuary mouth, tentatively identified as E. incertum, differs from a
typical E. incertum by the expanded tuberculation forming a starshaped figure in the umbilical area and along the sutures (Pl. 1, Figs.
6–7). The same feature characterizes E. albiumbilicatum (Weiss), a
closely related species morphologically and ecologically (Hansen and
Lykke-Andsersen, 1976; Banner and Culver, 1978). Similar to E. albiumbilicatum, tuberculate E. incertum specimens are relatively small
(maximal diameter ,0.4 mm), a feature possibly resulting from fast
reproductive turnover rates at the sites with pulsed high food fluxes.
Farther off the estuary mouth, E. incertum s.s. (with little tuberculation) may grow to sizes .0.6 mm; similar overgrown forms, which
often acquire double rows of pores, have been identified as E. asklundi.
We admit that the tuberculate morphotype from the Yenisei estuary
may be closer to E. albiumbilicatum than to E. incertum, however we
found it difficult to make a conclusion based on the existing material,
in which most tests have been corroded by dissolution to some degree.
Moreover, the systematic volume of E. albiumbilicatum lacks clarity
with respect to its distinction from E. incertum and/or E. subarcticum.
269
Due to this uncertainty, the tuberculate forms of E. incertum/albiumbilicatum in some samples from the southern Kara Sea have been
previously identified as E. subarcticum (Paulsen, 1997).
Elphidium subarcticum Cushman, 1944 (Pl. 1, Figs. 8–12)
Elphidium subarcticum: Loeblich and Tappan, 1953, p. 105, pl. 19,
figs. 5–7; Buzas, 1966, p. 593, pl. 92, figs. 7–10; Knudsen, 1971,
p. 280, pl. 13, fig. 3–7; pl. 22, fig. 9.
Elphidium frigidum: Loeblich and Tappan, 1953, p. 99, pl. 18, figs.
4–9; Østby and Nagy, 1982, pl. 3, fig. 12.
Elphidium hallandense Brotzen: Hansen and Lykke-Anderson,
1976, p. 14, pl. 11, fig. 1.
E. magellanicum: Knudsen, 1971, p. 279, pl. 12, figs. 15–16.
Discussion: Elphidiids, which we refer to as E. subarcticum, have
been identified under several names. We believe that the morphological
variability of E. subarcticum reflects different age stages and ecological conditions, rather than interspecific differences (cf. Todd and Low,
1967). Juvenile specimens typically have a smooth outline and a starshaped tuberculated area (Pl. 1, Fig. 8), similar to that of E. albiumbilicatum. In adult foraminifers, chambers become more inflated and
the tuberculation forms wide bands along the sutures, extending to the
periphery (Pl. 1, Figs. 9–12). Extreme forms, often identified as E.
frigidum or E. magellanicum, have a distinctly lobate outline and may
have small grooves transverse to the sutures (Pl. 1, Fig. 10); these
forms are typically found at sites with agile bottom water. In our material, E. subarcticum mostly have 5–6 chambers in juvenile specimens
and 7–8 chambers in adults, as opposed to E. incertum/albiumbilicatum, which typically have at least 8 chambers, even in juvenile tests.
The widely used name E. subarcticum should be probably considered
a junior synonym of E. magellanicum or E. frigidum.
Haynesina orbiculare (Brady, 1881) (Pl. 2, Figs. 1–3)
Elphidium orbiculare: Loeblich and Tappan, 1953, p. 102, pl. 19,
figs. 1–4.
Protelphidium orbiculare: Knudsen, 1971, p. 289, pl. 14, figs. 8–11,
pl. 24, figs. 6–8.
Islandiella helenae Feyling-Hanssen and Buzas, 1976
Islandiella helenae: Feyling-Hanssen and Buzas, 1976, text figs.
1–4.
Cassidulina teretis: Loeblich and Tappan, 1953, p. 121, pl. 24, figs.
3–4.
Islandiella norcrossi (Cushman, 1933) (Pl. 2, Fig. 13)
Islandiella norcrossi: Knudsen, 1971, pl. 8, figs. 1, 2.
Cassidulina norcrossi: Loeblich and Tappan, 1953, p. 120, pl. 24,
fig. 2.
Melonis barleeanus (Williamson, 1858) (Pl. 2, Fig. 9)
Nonion barleeanum: Knudsen, 1971, pl. 9, figs. 15–18; Østby and
Nagy, 1982, pl. 3, fig. 15.
Nonion zaandamae (van Voorthuysen): Loeblich and Tappan, 1953,
pl. 15, figs. 11, 12.
Nonion labradoricum (Dawson, 1860) (Pl. 2, Fig. 10)
Nonion labradoricum: Knudsen, 1971, pl. 10, figs. 1, 2; Østby and
Nagy, 1982, pl. 3, fig. 17.
Stainforthia loeblichi (Feyling-Hanssen, 1954) (Pl. 2, Fig. 19)
Stainforthia loeblichi: Østby and Nagy, 1982, pl. 1, fig. 20.
Virgulina loeblichi Feyling-Hanssen: Knudsen, 1971, p. 238, pl. 7,
figs. 1–5.
Bulimina exilis Brady: Loeblich and Tappan, 1953, p. 110, pl. 20,
figs. 4, 5.
Trifarina fluens (Todd, 1947) (Pl. 2, Fig. 18)
Trifarina fluens: Knudsen, 1971, pl. 7, figs. 12–15; Østby and Nagy,
1982, pl. 1, fig. 21.
Angulogerina fluens: Loeblich and Tappan, 1953, p. 112, pl. 20, figs.
10–12.
270
APPENDIX 2. Environmental data and foraminiferal occurrences. Dashes indicate absence of reliable data; crosses (X) indicate foraminiferal
species presence in low-abundance samples.
Station
no. (cf.
Fig. 8)
2102
2104
2202
2204
2207
2209
2305
2314
2401
2501
2504
2507
2601
2603
2701
2703
2704
2706
2708
2709
2712
2715
2717
2719
2721
4377
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4393
4394
4395
4397
4398
4399
4400
4401
4402
4403
4405
4411
4414
4416
4417
1405
1407
t4
t5
t6
t10
t13
t18
t19
t20
b122
b196
Longitude E
Latitude
N
61.68
66.25
66.17
64.81
67.84
72.69
74.10
78.12
79.68
80.81
80.25
81.39
77.22
75.34
69.94
64.87
62.11
59.48
57.53
56.72
59.55
56.84
55.85
59.07
56.62
58.03
59.97
59.93
58.02
64.00
64.33
64.75
64.60
64.57
64.57
64.62
64.50
64.54
64.86
63.15
60.75
72.98
72.97
79.90
79.85
79.89
79.95
79.88
79.93
83.43
82.65
73.52
73.09
73.50
58.28
60.74
66.86
67.12
67.42
66.57
66.13
68.16
67.93
67.63
78.52
80.80
69.80
69.42
70.29
71.57
74.02
73.11
72.52
72.88
75.42
72.90
73.63
74.34
75.15
76.01
76.41
75.28
75.29
74.36
73.44
73.06
72.61
72.35
71.59
71.69
71.14
70.98
72.22
72.62
72.62
74.56
74.37
73.93
73.33
72.69
71.99
71.02
70.54
70.02
69.78
70.34
70.62
74.23
75.99
76.02
74.99
74.25
74.00
73.54
73.00
71.70
71.83
73.65
71.74
70.92
72.71
72.25
74.25
74.26
74.26
74.19
74.13
74.28
74.27
74.27
75.97
75.22
Water
depth, m
27
29
20
120
57
25
16
13
14
15
40
43
44
75
70
330
72
36
60
75
98
332
53
165
85
236
131
106
375
72
100
168
119
70
152
75
99
102
46
216
138
30
150
62
41
29
35
39
26
30
29
25
18
23
380
120
157
70
188
122
79
50
90
105
71
41
Summer
surface
salinity,
psu
Summer
bottom
salinity,
psu
Summer
bottom
temperature, 8C
Winter
bottom
salinity,
psu
Winter
bottom
temperature, 8C
Oxygen
content,
ml/l
29.5
27.4
28.4
28.5
18.6
6.2
4.2
10.0
17.4
8.8
10.2
13.4
16.4
21.6
25.6
22.6
27.3
28.1
28.1
28.5
29.4
28.5
28.4
29.6
28.7
28.6
29.3
28.9
28.6
24.5
24.5
24.7
26.6
27.7
28.1
28.7
28.5
28.3
28.3
28.3
28.2
12.6
20.9
20.1
16.0
14.6
14.0
8.9
10.8
0.6
1.1
9.6
1.2
0.4
28.7
28.9
19.6
19.3
18.8
20.1
20.7
17.5
18.1
18.5
19.8
17.4
34.1
31.4
32.0
34.1
33.7
25.2
21.5
17.8
33.4
30.3
31.3
32.4
33.1
34.0
34.7
34.7
34.9
34.9
34.9
34.7
34.7
34.5
34.2
34.6
34.3
34.2
34.6
34.7
34.7
34.5
34.5
34.4
34.3
34.3
34.4
34.0
33.9
33.5
32.7
34.3
34.6
32.3
34.2
33.8
33.1
32.6
32.5
30.4
28.6
8.1
7.7
29.3
4.9
1.2
34.7
34.6
34.3
34.3
34.1
34.4
34.4
33.4
33.8
34.0
34.0
33.3
0.5
3.0
1.9
20.7
21.1
20.2
0.7
2.4
21.4
20.5
21.1
21.2
21.5
21.5
21.3
21.4
21.5
21.6
21.6
21.5
21.5
21.5
21.2
21.4
21.2
21.1
21.5
21.5
21.6
21.3
21.3
21.3
21.2
21.2
21.1
20.5
0.1
1.3
2.3
20.3
21.3
21.4
21.5
21.4
21.4
21.3
21.2
20.9
20.4
8.3
7.7
20.9
4.0
5.2
21.6
21.5
21.2
21.2
21.2
21.2
21.2
21.1
21.1
21.2
21.5
21.4
34.5
33.6
33.7
34.0
34.0
18.4
15.7
22.4
33.0
29.1
29.1
29.8
31.8
32.9
34.2
34.9
35.1
35.0
34.9
34.8
34.6
34.6
34.5
34.4
34.5
34.5
34.5
34.6
34.7
34.8
34.8
34.7
34.5
34.4
43.0
34.1
34.2
34.2
34.2
34.4
34.4
26.9
32.7
33.8
32.3
30.4
29.9
28.6
29.2
12.8
13.9
22.8
12.7
8.6
34.7
34.5
34.5
34.4
34.3
34.5
34.6
33.9
34.0
34.2
33.7
32.6
21.9
21.8
21.8
21.5
21.5
20.7
20.5
21.1
21.5
21.4
21.5
21.3
21.4
21.4
21.4
21.4
21.4
21.6
21.7
21.7
21.6
21.7
21.7
21.6
21.7
21.8
21.6
21.6
21.7
21.4
21.4
21.4
21.4
21.4
21.4
21.5
21.7
21.8
21.8
21.8
21.7
21.3
21.4
21.4
21.5
21.5
21.5
21.4
21.4
20.1
21.4
21.0
20.4
20.3
21.7
21.5
21.5
21.5
21.5
21.5
21.4
21.5
21.5
21.5
21.4
21.4
7.7
7.5
7.8
7.2
7.1
6.0
6.7
7.2
7.0
6.9
6.1
6.6
7.4
7.4
7.2
7.3
7.1
7.2
7.0
7.1
7.3
7.3
7.4
7.4
7.5
7.5
7.4
7.3
7.2
7.3
7.3
7.3
7.3
7.3
7.1
7.4
7.5
7.6
7.5
7.6
7.6
6.6
7.3
7.1
6.9
6.5
6.3
5.9
6.9
6.0
6.2
6.3
6.9
6.9
7.2
7.4
7.2
7.2
7.1
7.2
7.2
7.0
7.0
7.1
7.2
6.8
Oxygen
content,
%
99
99
100
89
83
70
78
84
80
80
70
77
84
86
85
87
82
84
82
84
86
87
89
89
90
91
88
87
85
85
86
87
87
87
86
93
96
100
101
96
94
75
85
81
80
75
73
69
81
75
77
73
80
81
84
88
86
86
85
86
86
83
83
84
82
79
Sand
content
(.0.063
mm), %
55
13
39
34
52
17
—
74
9
—
28
30
28
21
56
2
15
79
6
36
28
11
33
1
18
6
14
—
7
—
—
—
—
5
2
1
1
4
2
6
33
—
3
25
11
18
2
29
0.4
—
—
5
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Total
benthic
foraminifers no./g
11
30
15
48
16
18
0
1
2
1
12
14
33
54
146
32
212
630
1807
79
107
63
46
24
83
6
9
138
12
18
31
15
6
124
12
7
13
13
43
27
10
2
2
58
9
11
2
4
1
0
0.4
0.4
0.1
0
21
15
10
7
3
23
82
15
12
13
11
2
Calcareous
benthic
foraminifers, %
45
10
18
4
14
22
71
100
36
44
13
19
19
94
31
93
95
93
12
33
4
30
18
18
63
100
Planktonic
foraminifers, %
0.1
0.2
0.4
2
0.4
0.8
0.1
0.1
0.1
2
13
1
2
97
20
89
99
98
43
9
68
70
96
94
90
98
100
100
100
100
100
1
39
92
89
100
98
87
98
91
15
95
4
Calcareous
benthic
foraminifers
counted
199
98
129
28
55
87
0
20
25
8
90
34
151
174
171
160
236
232
238
164
171
27
244
61
184
49
100
0
16
2
2
0
0
120
15
155
144
398
102
15
88
0
70
441
133
82
41
51
25
0
4
12
3
0
0
1
39
92
177
199
195
174
196
181
10
19
271
APPENDIX 2.
Station
no. (cf.
Fig. 8)
2102
2104
2202
2204
2207
2209
2305
2314
2401
2501
2504
2507
2601
2603
2701
2703
2704
2706
2708
2709
2712
2715
2717
2719
2721
4377
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4393
4394
4395
4397
4398
4399
4400
4401
4402
4403
4405
4411
4414
4416
4417
1405
1407
t4
t5
t6
t10
t13
t18
t19
t20
b122
b196
Astrononion gallowayi,
%
1
Buccella
spp.,
%
Cassidulina
reniforme,
%
17
5.9
4.9
5
29
3.8
16
29
13
3.4
34
5.5
1.8
23
1.6
11
11
X
X
X
12
12
11
4
4.1
7.5
5.9
1.7
3.4
1.8
1.2
7.4
2.9
4.9
1.1
4.1
1
40
21
40
45
23
7.5
18
15
22
2.4
4.1
19
4.5
52
14
16
19
Cibicides
lobatulus,
%
Elphidiella
groenlandica,
%
Elphidium
bartletti,
%
8
Elphidium
excavatum
clavata,
%
Elphidium
incertum,
%
Elphidium
subarcticum,
%
2.3
X
X
X
X
X
X
23
15
17
11
7.6
14
36
0.9
11
21
71
19
1.6
6.6
3.3
12
13
1.1
1.2
7.8
9
1.3
9.2
5.5
6
4.6
33
3.8
3
24
26
21
0.6
9
4
1.7
2.5
22
1.6
2.2
4.9
3.3
21
11
10
0.4
0.4
0.4
Islandiella
norcrossi,
%
Melonis
barleeanus,
%
17
2
16
8.1
31
16
2.3
60
11
4.3
15
6.1
7
15
11
0.6
0.4
0.4
1.2
6.6
10
16
3
3
Haynesina
orbicularis,
%
33
24
18
2.7
9.1
19
22
5.5
6.5
8.8
42
2.7
Extended.
2
19
8.2
3
X
Miliolidae,
%
0.5
24
1.6
22
1.8
1.4
Nonion
labradoricum,
%
Polymorphinidae,
%
Stainforthia
loeblichi,
%
Trifarina
fluens,
%
1
2
4.9
14
1.8
3.6
6.8
8.1
3.6
X
X
2
2.9
6.4
2.5
13
4.3
5
1.8
0.6
3.7
10
4.9
31
39
18
X
1.2
1.9
2.1
1.3
2.9
37
0.6
22
15
45
2
4.5
3
5.3
7.5
0.6
0.8
3.9
0.4
2.9
3.7
2
6.6
3.3
6.1
5
3
1.1
1.2
0.6
0.4
0.4
1.2
6
0.7
1.7
0.6
3
0.7
10
0.6
0.6
0.4
0.4
0.4
1.3
0.4
1.3
0.4
0.4
0.4
0.6
0.4
6.6
1.2
7
2.3
0.8
1.6
0.5
4.1
4
1.2
3.3
0.5
2
8
0.5
6.1
X
X
1.5
2.1
X
1.9
1.4
2
2.5
4.5
0.2
11
7
2.1
6.7
X
32
8.4
19
44
29
X
24
29
21
24
30
22
29
X
1.9
0.7
0.5
0.5
2.7
1.1
10
X
X
X
X
1.1
2.6
2.2
5.6
4
0.5
5.7
4.1
3.3
39
X
50
58
31
40
4.5
0.7
31
29
39
34
26
49
27
X
14
4.9
1.5
6.2
4.1
X
6.5
4.9
2
11
16
X
3.2
5.6
13
5.6
5.7
13
2.3
14
1.1
1.4
11
6.7
20
14
X
3.3
2
X
X
X
51
13
16
31
13
30
33
33
2.6
5.4
0.6
0.5
0.5
0.5
0.6
0.5
X
2.3
1
3.1
3.4
3.1
0.6
X
X
13
54
36
51
72
45
48
43
X
5.2
29
6.7
7.3
20
X
27
7
3.2
1.1
1
0.6
X
2.6
3.3
2.6
4.3
3.4
2
2.1
4.6
7.7
X
X
1.1
X
1.3
0.7
0.5
1.6
1.4
3
1.1
4.5
2.5
3.2
1.1
1.1
0.2
1.1
3.3
1.1
1.1
0.5
3.9
3.9
X
X
X
2.2
9
1
1
0.7
1
X
8.4
2.8
1
1.6
X
2.6
2.6
5.1
19
4
1
4.6
3.1
5.5
0.6
4.5
1
X
0.5
2.6
1.1
1.1
0.5
0.5
0.6
1
1.1
X
1
0.5
1.1
3.1
1.1
X
0.5
0.5
0.6
272
APPENDIX 2.
Station
no. (cf.
Fig. 8)
b399
b259
n1
n13
n23
n41
p1
p2
p3
p4a
p5
p7
p9
p10
p11.1
p12
p14
p35
p36
p39
p41
p44
p48
p50
p51
p77
p87
p102
p107
k1
k10
k12
k17
k19
k21
k24
k27
k30
k32
k42
k43
k46
k47
k48
k49
k50
k52
k55
k56
k58
Longitude E
Latitude
N
67.63
63.17
57.17
59.62
62.10
71.60
61.86
65.62
66.24
65.49
65.83
72.98
73.30
73.30
78.58
80.13
81.06
74.66
73.45
72.20
76.60
80.40
85.26
83.50
79.67
80.01
79.10
68.98
65.01
73.18
74.08
74.29
73.73
79.03
81.01
79.92
80.09
80.34
81.48
81.67
82.81
77.20
73.75
73.15
72.89
72.95
72.66
75.62
75.48
74.84
72.73
72.66
72.18
73.75
74.49
75.84
69.96
69.66
69.33
70.65
71.00
73.00
73.98
74.45
74.31
73.61
73.91
76.38
76.50
74.99
76.16
75.77
75.24
75.00
75.00
73.05
72.55
74.00
73.98
73.91
72.50
72.18
72.69
74.00
74.00
73.53
72.89
72.51
72.09
73.90
73.71
74.00
72.58
72.96
73.21
73.61
74.00
73.22
72.89
73.65
Water
depth, m
93
63
499
315
320
223
195
31
24
23
23
27
30
27
31
45
41
101
104
27
64
41
44
48
39
21
9
17
200
29
15
13
21
30
42
41
19
14
10
32
32
27
18
29
30
28
31
14
15
24
Continued.
Summer
surface
salinity,
psu
Summer
bottom
salinity,
psu
Summer
bottom
temperature, 8C
Winter
bottom
salinity,
psu
Winter
bottom
temperature, 8C
Oxygen
content,
ml/l
24.6
28.6
28.5
28.6
28.3
20.4
29.3
28.2
27.3
29.0
29.3
5.6
11.4
13.7
14.2
10.1
11.3
23.3
23.7
16.4
21.4
19.6
19.5
17.8
16.0
10.7
9.4
15.0
24.0
11.0
4.1
3.4
4.8
13.8
11.3
8.9
10.9
7.0
2.3
11.0
9.2
12.7
4.5
5.6
6.9
9.4
11.2
8.4
7.4
9.0
33.8
34.4
34.6
34.8
34.8
34.0
34.2
32.2
31.2
32.9
32.8
26.3
31.4
32.3
31.9
31.3
32.1
34.3
34.5
32.7
34.1
33.7
32.4
32.9
33.1
29.6
16.8
30.7
34.4
31.2
21.2
15.6
25.0
31.7
32.2
30.6
29.1
23.2
12.5
31.8
31.4
31.2
23.2
27.1
27.1
29.7
31.3
27.6
25.6
28.6
20.6
21.3
21.5
21.5
21.5
21.5
0.3
2.6
3.2
1.0
1.0
20.5
21.3
21.4
21.3
21.1
21.2
21.5
21.4
21.5
21.5
21.4
21.1
21.3
21.4
20.7
2.8
20.7
21.3
21.2
0.7
1.9
20.1
21.3
21.2
21.0
20.4
1.7
5.6
21.0
20.8
21.2
0.2
20.7
20.6
21.0
21.4
20.6
20.2
20.7
33.8
34.5
34.6
34.9
34.9
32.7
34.5
34.1
33.6
33.9
33.8
17.6
25.5
28.0
29.6
28.9
29.3
33.4
33.5
30.3
33.5
33.4
30.7
30.6
32.2
29.5
25.3
33.1
34.7
25.0
15.6
14.7
16.4
28.6
29.5
28.6
28.8
26.4
21.0
27.8
25.7
26.8
16.2
17.6
19.5
22.9
25.8
20.2
19.1
20.8
21.6
21.4
21.7
21.6
21.5
21.4
21.9
21.8
21.8
21.7
21.6
20.6
21.2
21.3
21.5
21.5
21.4
21.4
21.4
21.4
21.4
21.4
21.2
21.3
21.5
21.4
21.1
21.5
21.4
21.1
20.5
20.5
20.6
21.4
21.4
21.4
21.4
21.2
20.6
21.2
21.1
21.3
20.5
20.6
20.8
21.0
21.2
20.8
20.7
20.9
7.3
7.3
7.4
7.2
7.1
7.3
7.7
7.6
7.5
7.7
7.7
5.9
6.4
6.7
7.0
6.0
6.5
7.4
7.4
7.3
7.5
7.0
7.0
6.9
6.9
6.8
7.1
7.2
7.3
6.4
6.7
6.8
6.5
6.7
6.5
5.9
6.9
7.0
6.3
6.5
6.7
7.5
6.6
5.9
6.0
6.2
6.7
7.2
7.2
7.0
Oxygen
content,
%
88
87
87
84
83
86
99
102
100
98
98
68
73
77
80
70
76
86
86
84
86
80
82
80
80
79
84
83
87
73
78
79
76
78
76
69
80
81
77
76
77
85
77
68
70
72
76
81
82
79
Sand
content
(.0.063
mm), %
Total
benthic
foraminifers no./g
—
—
—
—
—
—
6
75
—
75
91
15
5
95
84
44
—
50
46
85
34
76
50
16
3
35
32
94
14
—
1
0
5
3
—
—
1
—
2
—
—
—
1
15
6
16
34
—
—
—
3
10
—
—
—
—
17
44
260
22
26
132
5
37
9
15
8
35
38
42
20
23
36
25
11
37
4
33
39
37
0.3
1
2
4
10
4
3
0.5
14
6
3
3
2
8
15
33
97
3
5
9
Calcareous
benthic
foraminifers, %
96
100
—
—
—
—
24
5
1
12
9
2
61
16
7
4
1
2
5
6
9
26
11
24
48
4
83
23
4
23
100
100
50
62
65
61
100
95
100
45
58
48
97
22
28
64
43
98
100
25
Planktonic
foraminifers, %
11
0.7
Calcareous
benthic
foraminifers
counted
192
83
33
64
7
148
129
29
7
59
83
10
197
116
31
29
8
20
31
42
59
137
78
109
165
21
344
94
21
54
13
46
50
111
135
114
115
20
151
119
69
58
78
53
72
177
123
110
104
48
273
APPENDIX 2.
Station
no. (cf.
Fig. 8)
b399
b259
n1
n13
n23
n41
p1
p2
p3
p4a
p5
p7
p9
p10
p11.1
p12
p14
p35
p36
p39
p41
p44
p48
p50
p51
p77
p87
p102
p107
k1
k10
k12
k17
k19
k21
k24
k27
k30
k32
k42
k43
k46
k47
k48
k49
k50
k52
k55
k56
k58
Astrononion gallowayi,
%
1.1
Buccella
spp.,
%
0.5
1.2
24
6.8
X
15
2.3
Cassidulina
reniforme,
%
Cibicides
lobatulus,
%
10
4.6
3
13
0.5
4.1
3.9
Elphidiella
groenlandica,
%
Elphidium
bartletti,
%
Elphidium
excavatum
clavata,
%
19
1.2
18
26
0.7
2.3
7.2
47
8.6
X
12
8.7
29
0.5
X
9.2
2.9
7.8
X
3.2
4.7
3.4
15
1.1
9.4
6.7
X
23
0.8
3.6
X
7.5
X
48
X
1.1
0.8
1.2
X
5.8
1
1.9
1.9
8
2.7
3
3.5
11
X
4
5.4
43
7
3.5
2
3.6
2.2
1.8
9.2
15
14
5.2
2.5
12
17
2.6
1.9
1.4
2.3
5.2
19
13
25
23
47
18
23
22
20
22
3.5
1.9
5.6
1.1
15
0.9
20
8.3
2.3
24
3
2.2
21
43
X
0.3
5.4
X
28
0.7
5.3
2.5
2.9
5.2
0.6
1
19
X
45
29
3.1
X
4.9
X
5.6
19
17
23
12
8.5
1.4
19
10
5.5
X
0.3
24
X
13
X
59
20
9
39
46
74
X
18
29
40
64
54
58
15
68
55
35
Continued, Extended.
Elphidium
incertum,
%
4.2
Elphidium
subarcticum,
%
17
14
6.1
48
2
7.2
6.8
7.1
24
13
11
X
X
1.6
X
0.5
Haynesina
orbicularis,
%
5.2
8
Islandiella
norcrossi,
%
11
20
2.3
X
0.7
1.4
37
24
X
14
23
X
17
65
8
16
2.2
18
0.9
98
31
41
14
1.9
5.6
5.1
7.3
0.9
1.9
10
Polymorphinidae,
%
Stainforthia
loeblichi,
%
1.2
6.3
5.8
0.5
3.5
5.8
Trifarina
fluens,
%
2.3
1.4
3.1
20
10
6.1
0.7
0.8
16
6.9
X
2.9
11
X
X
7
13
7.9
0.8
22
Nonion
labradoricum,
%
X
2.9
31
56
11
61
7.5
X
2
Miliolidae,
%
1.6
6.3
7
1.7
8.1
Melonis
barleeanus,
%
5.5
X
43
3.5
12
2.6
5.4
4.2
17
34
5.6
39
36
30
3
8.8
2.6
X
1.7
16
21
22
7.5
5.6
7.3
8.9
7.3
14
8.3
X
9.4
3.7
3.7
X
16
2.5
13
8.7
13
8.3
0.6
8.5
2.2
3.7
4.6
3.6
X
6.3
4.7
5.1
3.7
3.7
0.6
X
20
3.2
10
14
22
18
1
X
1.9
4
2.7
3
2.6
7.6
2.9
1.3
3.8
1.4
1.6
1.8
1
8.3
X
1.8
0.8
X
3.7
X
2.2
18
1.8
3
1.8
7.8
X
10
7.2
3.4
15
5.7
1.4
2.3
2.4
2.7
6.7
6.3
1.5

benthic foraminiferal assemblages from the southern kara sea, a

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