Linking the Modern Distribution of Biogenic Proxies in High
Arctic Greenland Shelf Sediments to Sea Ice, Primary
Production, and Arctic-Atlantic Inflow
Audrey Limoges1,2 , Sofia Ribeiro1 , Kaarina Weckström1,3, Maija Heikkilä1,3,
Katarzyna Zamelczyk4, Thorbjørn J. Andersen5, Petra Tallberg3, Guillaume Massé6,
Søren Rysgaard7,8 , Niels Nørgaard-Pedersen9, and Marit-Solveig Seidenkrantz7,10
1Department of Glaciology and Climate, Geological Survey of Denmark and Greenland, Copenhagen, Denmark, 2Now at
Department of Earth Sciences, University of New Brunswick, Fredericton, New Brunswick, Canada, 3Department of
Environmental Sciences, Environmental Change Research Unit, University of Helsinki, Helsinki, Finland, 4Centre for Arctic Gas
Hydrate, Environment and Climate, Department of Geosciences, Arctic University of Norway, Tromsø, Norway, 5CENPERM,
Department of Geosciences and Natural Resource Management, Copenhagen University, Copenhagen, Denmark, 6UMI3376
TAKUVIK, Department of Biology, CNRS and Université Laval, Quebec City, Quebec, Canada, 7Arctic Research Centre, Aarhus
University, Aarhus, Denmark, 8Centre for Earth Observation Science, Department of Environment and Geography, University
of Manitoba, Winnipeg, Manitoba, Canada, 9Department of Marine Geology, Geological Survey of Denmark and Greenland,
Copenhagen, Denmark, 10Centre for Past Climate Studies, Department of Geoscience, Aarhus University, Aarhus, Denmark
Abstract The eastern north coast of Greenland is considered to be highly sensitive to the ongoing Arctic
warming, but there is a general lack of data on modern conditions and in particular on the modern
distribution of climate and environmental proxies to provide a baseline and context for studies on past
variability. Here we present a detailed investigation of 11 biogenic proxies preserved in surface sediments
from the remote High Arctic Wandel Sea shelf, the entrance to the Independence, Hagen, and Danmark
fjords. The composition of organic matter (organic carbon, C:N ratios, δ13C, δ15N, biogenic silica, and IP25) and
microfossil assemblages revealed an overall low primary production dominated by benthic diatoms,
especially at the shallow sites. While the benthic and planktic foraminiferal assemblages underline the
intrusion of chilled Atlantic waters into the deeper parts of the study area, the distribution of organic-walled
dinoflagellate cysts is controlled by the local bathymetry and sea ice conditions. The distribution of the
dinoflagellate cyst Polarella glacialis matches that of seasonal sea ice and the specific biomarker IP25,
highlighting the potential of this species for paleo sea ice studies. The information inferred from our
multiproxy study has important implications for the interpretation of the biogenic-proxy signal preserved in
sediments from circum-Arctic fjords and shelf regions and can serve as a baseline for future studies. This is the
first study of its kind in this area.
1. Introduction
As the Arctic warms, the thickness, duration, and extent of the sea ice cover are declining, with significant
impacts on both small- and large-scale primary production patterns (Arrigo & van Dijken, 2015; Arrigo et al.,
2008; Bélanger et al., 2013; Gradinger, 1995; Kahru et al., 2011; Pabi et al., 2008; Tremblay et al., 2015). Sea
ice and snow restrict light transmittance essential for photosynthesis, influence the onset of phytoplankton
blooms, and ultimately shape phytoplankton communities. A reduction in the sea ice extent creates more
openwater habitats for phytoplankton, thus enhancing the length of their growing season. However, regional
sea ice loss may alter the convectivemixing processes that recycle nutrients into the surface waters during ice
formation and naturally trigger algal blooms in spring when the ice breaks up (Niebauer et al., 1990; Stabeno
et al., 2010). It is therefore expected that the ongoing warming and associated changes in the sea ice regime
will have profound effects on both the abundance and species composition of Arctic algal communities
(Arrigo, 2013; Boetius et al., 2013; Loeng et al., 2005; Nöthig et al., 2015; Smetacek & Nicol, 2005; Tremblay
et al., 2009), with implications for Arctic ecosystem functioning and biogeochemical cycles.
Another important aspect related to Arctic sea ice melt is the inherent alterations in the freshwater budget at
high latitudes (Curry & Mauritzen, 2005; Dickson et al., 2007). Increased export of freshwater and drift ice from
the Arctic to the North Atlantic Ocean will impact global ocean circulation and climate through various feed-
back mechanisms (Aargaard & Carmack, 1989; Clark et al., 2002; Curry et al., 2003; Holland et al., 2007; Jones
LIMOGES ET AL. 760
PUBLICATIONS
Journal of Geophysical Research: Biogeosciences
RESEARCH ARTICLE
10.1002/2017JG003840
Key Points:
 A new multiproxy reference baseline
is provided for assessing past changes
in High Arctic fjord and shelf
environments
 Cysts of the ice-dwelling
dinoflagellate Polarella glacialis are
tightly connected with seasonal sea
ice and show promise as new paleo
sea-ice proxy
 Benthic diatoms and ice algae are the
main primary producers in the
shallower sites, whereas heterotrophic
dinoflagellates and benthic
foraminifera are indicative of Atlantic
water intrusion and dominate at the
deeper sites
Supporting Information:
 Supporting Information S1
 Table S1
 Table S2
 Table S3
 Table S4
Correspondence to:
A. Limoges,
audrey.limoges@unb.ca
Citation:
Limoges, A., Ribeiro, S., Weckström, K.,
Heikkilä, M., Zamelczyk, K., Andersen, T. J.,
… Seidenkrantz, M-S. (2018). Linking
the modern distribution of biogenic
proxies in High Arctic Greenland shelf
sediments to sea ice, primary produc-
tion, and Arctic-Atlantic inflow. Journal
of Geophysical Research: Biogeosciences,
123, 760–786. https://doi.org/10.1002/
2017JG003840
Received 15 MAR 2017
Accepted 4 JAN 2018
Accepted article online 9 JAN 2018
Published online 2 MAR 2018
©2018. The Authors.
This is an open access article under the
terms of the Creative Commons
Attribution-NonCommercial-NoDerivs
License, which permits use and distri-
bution in any medium, provided the
original work is properly cited, the use is
non-commercial and no modifications
or adaptations are made.
et al., 2008; Mauritzen & Hakkinen, 1997; Peterson et al., 2006). Off eastern Greenland, this could translate into
strengthened advection of the low salinity Polar surface water carried by the East Greenland Current (EGC)
through Fram Strait (Figure 1a) (Dmitrenko et al., 2017; Sejr et al., 2017; Sutherland & Pickart, 2008), the main
gateway for Arctic water into the Atlantic Ocean. The sea ice dynamics and local hydrology of Greenlandic
fjords and shelf areas further play a critical role for the stability of tidewater outlet glaciers (see Andresen
et al., 2012; Bendtsen et al., 2017; Kirillov et al., 2017) and the mass balance of the Greenland ice sheet.
Fjord systems located on the eastern North Greenland shelf therefore are key areas for investigating the
effects of changing freshwater budgets on the coastal ecosystems.
One way to obtain a retrospective view on the state and change of biological and hydrological parameters in
marine settings is to look at the sedimentary remains of various groups of protists (e.g., dinoflagellates, dia-
toms, and foraminifera). Once settled on the seafloor, the fossil or geochemical remains of the marine protists
are incorporated into the sediment, carrying with them the environmental signature of the overlying water
masses they inhabited. Diatoms and dinoflagellates constitute two major groups of marine primary produ-
cers that thrive in the upper layers of the oceans. Their immediate grazers comprise heterotrophic or mixo-
trophic dinoflagellates and foraminifera that live at different water-depth intervals within the water
column. Accordingly, the fossil remains of diatoms, dinoflagellates, and planktic foraminifera are widely used
for investigating past sea surface hydrography, whereas benthic foraminifera are useful proxies for recon-
structing subsurface and deep-water mass properties (see Polyak et al., 2010, and references therein).
Since they are at the basis of the marine food chain, their assemblage composition and abundances also
provide key information on regional paleo-productivity. Unlike the organic-walled cysts of dinoflagellates,
which are generally well preserved in the sediment (see, however, Zonneveld et al., 2008), the calcareous
(e.g., foraminifera and ostracods) and siliceous (e.g., diatoms and chrysophyte cysts) microfossils can be
susceptible to dissolution at high latitudes (e.g., Koç et al., 1993; Matthiessen et al., 2001; Schroeder-Adams
& van Rooyen, 2011; Seidenkrantz et al., 2007; Zamelczyk et al., 2012). The absence of siliceous and calcareous
fossils from the sediment can therefore be interpreted either as a result of dissolution or low pelagic produc-
tivity. A multiproxy approach is thus preferable for making robust inferences of past primary production and
hydrographic parameters from high latitudes.
The composition of organicmatter in the sediment also provides information on past primary production and
specific environmental parameters. The sea ice proxy IP25, a monounsaturated highly branched isoprenoid
(HBI) lipid specifically produced by certain sympagic (i.e., ice dwelling) diatom species (Brown et al., 2014),
is notably used for reconstructing past trends in Arctic sea ice (Belt et al., 2007; Fahl & Stein, 2012; Hörner
et al., 2016; Müller et al., 2009; Stein et al., 2012; Vare et al., 2009, 2010; Xiao et al., 2013). It was recently sug-
gested that studying IP25 with its close relative HBI III (triene), likely produced by diatoms blooming in the
marginal sea ice zone (Belt et al., 2000), allows for more precise information on past sea ice dynamics (Belt
et al., 2015; Smik et al., 2016). However, so far relatively few studies have investigated the use of these proxies
in fjord and coastal environments (Brown et al., 2015; Ribeiro et al., 2017).
In this study, we have analyzed a broad suite of biogenic proxies (dinoflagellate cysts, benthic and planktic
foraminifera, diatoms, IP25, HBI III, biogenic silica, and elemental and isotopic composition of organic matter)
from 16 surface sediment samples collected on the Wandel Sea shelf, the entrance to the Independence
fjord, Hagen fjord, and Danmark fjord system (hereafter referred to as Independence fjord system), eastern
North Greenland (Figure 1), in relation to present-day sea ice and hydrographic data. Our aim was to establish
a reference multiproxy data set that can help in assessing past changes in High Arctic coastal environments,
with focus on sea ice conditions and primary production. We also intend to refine the interpretation of the
studied proxies through an improved understanding of their distribution in relation to modern conditions.
Furthermore, we investigate, for the first time, modern primary producers from the Independence fjord sys-
tem, one of the most poorly studied fjord systems in Greenland.
2. Materials and Methods
2.1. Regional Settings
The Independence fjord system lies between Peary Land and Kronprins Christian Land in eastern North
Greenland (between ~ 80°410 and 82°270N; 16°360 and 32°400W) (Figure 1b). The fjord system is approxi-
mately 150 km long and drains into the Wandel Sea. Two large glaciers, Academy and Hagen, discharge
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 761
into the head of the Independence and Hagen fjord branches, respectively. The region also supports the
largest peripheral ice cap of Greenland, the Flade Isblink ice cap, which covers an area of ~ 7,500 km2
(Kelly & Lowell, 2009) and drains through two outlets (see Figure 1c) at velocities of a few hundred
Figure 1. (a) Location of the study area (black rectangle) and schematic illustration of the major circulation patterns in the Arctic Ocean (based on Loeng et al., 2005).
The yellow and red arrows indicate the penetration of the North Pacific and Atlantic Waters into the Arctic Ocean. Abbreviations are as follows: PcW, Pacific
Waters; AW, Atlantic Waters; TPD, Transpolar Drift; BG, Beaufort Gyre; and EGC, East Greenland Current. The eastern North Greenland region is located directly at
the outflow of the Transpolar Drift from the Arctic Ocean, and a major part of the outflows of Arctic Waters occur through Fram Strait, via the East Greenland
Current. The dark and light grey dotted lines correspond to the median (1981–2010) extent of the sea ice cover in summer (September) and winter (March),
respectively (National Snow and Ice Data Center, nsidc.org/data/seaice_index). (b) Satellite image of the fjord system (image from 13 August 2015; credit: NASA
Worldview: https://worldview.earthdata.nasa.gov) and location of the study area (black square). The main regional flows are also illustrated: the Arctic-derived
Atlantic water (ArAW) and the Pacific water (PcW) (modified from Kirillov et al., 2017). Abbreviation: GIS, Greenland ice sheet. (c) Bathymetry (m) of the study area
(modified from Nørgaard-Pedersen et al., 2016) and location of the surface sediment samples. The region characterized by multiyear sea ice cover is white,
whereas the region where sea ice melts seasonally is colored in dark grey (see Figure 2 for annual variability in open water extent for the six years preceding
sampling). The striped area corresponds to the region characterized by a mélange of sea ice and icebergs. The position of the Villum Research Station (small black
square) and Princess Dagmar Island (PDI) is also illustrated. The black arrows represent the Flade Isblink ice cap drainage outlets.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 762
ma1 (Higgins, 1991). Limited information is available for the region, but data from the Danish
Meteorological Institute indicate that the fjord system was covered by permanent ice from 1950 to
1964 (Rysgaard et al., 2003). It is only in 1978 that open water leads were first reported in the region
through aerial photography (Higgins, 1991).
The geological setting is fairly complex, with Archaic to Paleoproterozoic crystalline basement found closest
to the present Greenland ice sheet, unconformably overlain by the proterozoic Independence Fjord Group of
alluvial clastic deposits that is cut by dolerites and overridden by proterozoic basalts (Jepsen & Kalsbeek,
1998). Younger siliciclastic and calcareous sedimentary deposits from the late Paleozoic, Mesozoic, and early
Cenozoic are found at various, but geographically restricted, locations (Henriksen et al., 2000, 2009). The
region was repeatedly glaciated during the Quaternary (Funder, 1989). Following the last deglaciation
(Funder, 1989; Nørgaard-Pedersen et al., 2008), the fjord system was inundated by marine waters, and during
the Holocene Thermal Maximum (circa 8,000–5,000 years ago) warmer than present summer temperatures
may have resulted in open, sea ice-free waters in the summer (Funder et al., 2011).
2.1.1. Present-Day Sea Ice and Hydrographic Conditions
Most of the Independence fjord system is covered by semipermanent sea ice. Only the southern branches of
the fjord system and the area adjacent to the Villum Research Station (Station Nord), where the surface sedi-
ment samples were collected, are consistently partially ice free during late summer. Satellite images (MODIS)
from the area adjacent to the Villum Research Station are available for 6 years preceding sampling (2009 to
2014) (Figure 2). They show that during this time window, sea ice typically started to retreat from the coast at
the end of July and formed again in early September—leaving only a little more than a month for open water
phytoplankton growth. While there was some variability in the maximum open water extent, the general
pattern and timing of sea ice melt and freezeup was relatively consistent over this period.
Figure 2. Maximum annual open water extent in the study area based on MODIS imagery (credit: NASA Worldview; https://worldview.earthdata.nasa.gov) for the
six years preceding sampling (2009 to 2014). The general outline of the Flade Isblink ice cap front shown in these images is not exactly the same as reported in
Figure 1c. Note that we consider the outline presented in Figure 1c to be the most accurate. The sampling sites are illustrated by the yellow circles.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 763
The first oceanographic data from the study area are presented in Bendtsen et al. (2017), Dmitrenko et al.
(2017), and Kirillov et al. (2017). Conductivity-temperature-depth (CTD) profiles obtained during spring
2015 revealed the origin of the water masses and the interactions with ambient water in the regions deeper
than 10 m of our study area. On the Wandel Sea shelf (Figure 1b), the water column can generally be divided
into six layers of distinct water masses: a low-salinity surface layer (~1.5–5 m depth) formed by the summer
melt of the glaciers and sea ice, a subsurface halocline with a strong vertical salinity gradient down to a depth
of 15 m, a Halostad layer of Pacific origin with near freezing temperatures (15–65 m), an Atlantic-modified
halocline (65–100 m), Atlantic-modified Polar Water (100–140 m), and relatively warmer and more saline
Atlantic bottom waters (>140 m) (Dmitrenko et al., 2017). Accordingly, the deepest sites located North of
Princess Dagmar Island (Sites k9–k6; Figure 1c) are the most affected by halocline disturbance caused by
Atlantic water intrusions, whereas the hydrological conditions south of Princess Dagmar Island (Sites k22,
k21, and k15) seem to be mainly governed by the fjord’s ambient waters, and no intrusion of outer-shelf
waters was observed in this region. The local influence of cold and turbid subglacial meltwaters originating
from the Flade Isblink ice cap was also observed directly at the outlet of the glacier. It has been suggested
that subglacial meltwater discharges from marine-terminating glaciers could help promote primary produc-
tivity through increased nutrient supplies (e.g., Meire et al., 2017). According to the data from Dmitrenko et al.
(2017), the influence of the meltwater originating from this glacier only reaches a few kilometers away from
the glacial tongue, only directly affecting Site k8 of this study. No CTD data are available for the southern gla-
cier outlet, near our sampling station k14.
2.2. Methods
Surface sediment samples were collected from the area adjacent to the Villum Research Station (~ 20–30 km
from the station) in spring 2015 (Nørgaard-Pedersen et al., 2016). Sampling was conducted while the study
area was covered by ice and could be used as a platform for coring. Sediment samples from a total of 16 loca-
tions were retrieved using a Van Veen Grab sampler and a Kajak Corer, along transects of varying depths and
sea ice thicknesses, starting near the front of the Flade Isblink glacier outlets and the Villum Research station
(Figure 1c and Table 1). The sampling sites were targeted based on georeferenced high-resolution radar
satellite images, which were used to distinguish between areas of first and multiyear sea ice cover (see
Nørgaard-Pedersen et al., 2016). The sediment sampling and coring devices were deployed through holes
made in the sea ice with an ice auger, after snow removal. The topmost sediments (0–1 cm) were directly
subsampled from the grabs and Kajak cores, subsequently stored at 2–4°C at the Villum Research Station,
and transported cooled to Copenhagen. Samples were frozen at 20°C and freeze dried before all analyses
were conducted. While sediment mass accumulation rates are not known for all sites, 210Pb and 137Cs ana-
lyses were carried out for selected cores (k6, k9, k22, see supporting information). The results show a rapid
downcore decline in the activity of unsupported 210Pb, which was generally absent below a depth of
4–6 cm. This suggest sedimentation rates of the order of 4–6 cm/100 years, which must be regarded as
Table 1
Sampling Site Locations, Water Depth (m), and Sea Ice Thickness as Measured During Fieldwork (Late April 2015)
Sites Core numbers Latitude Longitude Water depth (m) Sea ice thickness (m)
1G k9 81.77878 16.59632 154.5 1.15
1Fb k6 81.76615 16.82502 128 1.25
1O k32 81.71694 16.33982 154 3.10
1M k8 81.67112 16.02637 111 2.50
1E k29 81.72030 17.12090 87 1.30
1D k28 81.69560 17.04250 75 1.33
1C k4 81.67298 16.96524 73 1.01
1B k3 81.65198 16.89640 57 0.99
1K k11 81.67753 16.64113 20.8 0.99
1A k33 81.62295 16.80726 19.6 0.95
3E k22 81.53870 18.05310 115 1.27
3D k21 81.50400 17.83700 135 0.99
3F k25 81.51110 17.48025 61 1.22
3B k17 81.51717 17.21174 54.5 1.22
3C k15 81.46380 17.63130 113 1.00
3G k14 81.39508 17.21150 55 1.20
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 764
maximum sedimentation rates since a tendency for covariation of the content of unsupported 210Pb and
137Cs indicates that some sediment mixing takes place at the sites.
2.2.1. Grain Size Analysis
The surface sediment was ultrasonically dispersed (2 min on a Bandelin UW 2200) in a sodium pyrophosphate
solution and subsequently wet sieved at 1 mm. Particle size analysis was conducted using a Malvern
Mastersizer E/2000. The grain size distribution of the samples is reported as percentages of clay, silt, and sand.
2.2.2. Carbon and Nitrogen Elemental and Isotopic Analyses
The freeze-dried surface sediment samples for total organic carbon (TOC) and total nitrogen (TN) analyses
were rinsed with distilled water in order to remove the salt residue. For the TOC analysis, samples were trea-
ted with hydrochloric acid (HCl, 10%) for 24 h in order to eliminate the inorganic carbon fraction. These sam-
ples were then washed with deionized water until the pH of the supernatant equaled that of the deionized
water. The sediment for the TOC analyses was freeze dried again. Samples for TOC and nitrogen concentra-
tion analyses were weighed (9–150 mg) in tin cups. Elemental analysis was carried out using a MICRO CUBE
Elemental Vario elemental analyzer (Laboratory of Geochemistry, University of Helsinki). Lake sediment mate-
rial (LKSD-4) was used as a reference material. An uncertainty of ±0.1% on the measurements is estimated
from replicate analyses of the samples.
Samples for the isotopic composition of bulk organic carbon (δ13C) and nitrogen (δ15N) were rinsed with
deionized water. Prior to δ13C analyses, sediment samples were treated with HCl (10%) to eliminate the
carbonate fraction. Samples were weighed into tin cups and analyzed with a ThermoQuest Finnigan
DeltaPlus XL Isotope Ratio Mass Spectrometer. Replicate measurements of both the samples and a sediment
standard “High Organic Content Standard” indicate reproducibility of ±0.5‰ and ±0.2‰ for the sediment
material, for δ13C and δ15N respectively. The isotopic ratios are expressed in the δ notation as deviations
per mil (‰), so that δsample = 1000 × [Rsample/Rstandard  1], where R is the ratio of heavy to light isotope
(13C/12C or 15N/14N). δ13C values were calibrated to the Vienna Peedee belemnite scale by using the interna-
tional reference standards USGS41, IAEA-CH3, and IAEA-CH7. δ15N values are expressed relative to atmo-
spheric nitrogen gas, using the international reference standards USGS01, IAEA-N1, and IAEA-N2.
2.2.3. Biogenic Silica
Biogenic silica measurements were conducted at the University of Helsinki following the wet alkaline extrac-
tion technique (e.g., DeMaster, 1981). Known weights of sediment samples (30 ± 2 mg) were added to poly-
ethylene bottles and leached for 5 h in a 85°C water bath using 40mL 1% sodium carbonate (Na2CO3). After 3,
4, and 5 h, an aliquot of 1 mL was taken from each sample and analyzed for dissolved silica through spectro-
photometry (Perkin Elmer Lambda 25 UV/VIS spectrometer) according to the blue ammonium-molybdate
method (Mullin & Riley, 1955). Biogenic silica concentrations were calculated using a linear regression.
While mineral-derived silica dissolves at a constant rate throughout the extraction, all biogenic silica is
assumed to have dissolved after the first 3 h of the extraction (see, e.g., Barão et al., 2015 for further details).
2.2.4. Biomarkers (Highly Branched Isoprenoids)
Samples for highly branched isoprenoid (HBI) analyses were prepared at Laval University, Quebec, following
the procedure described by Belt et al. (2007). An internal standard (7-hexylnonadecane) was added to ~ 0.5 g
of freeze dried and homogenized sediment before analytical treatment. Total lipids were ultrasonically
extracted (times 3) using a mixture of dichloromethane (DCM: CH2Cl2) and methanol (MeOH) (2:1, v/v).
Extracts were pooled together, and the solvent was removed by evaporation under a slow stream of nitrogen.
The total extract was subsequently resuspended in hexane and purified through an open column chromato-
graph (SiO2). Hydrocarbons (including IP25 and triene (HBI III)) were eluted using hexane (8 mL). Procedural
blanks and standard sediments were analyzed every 15 samples.
Hydrocarbon fractions were analyzed using an Agilent 7890 gas chromatograph (GC) fitted with 30 m fused
silica Agilent J&C GC columns (0.25 mm i.d. and 0.25 μm phase thickness) and coupled to an Agilent 5975C
Series mass selective detector. Oven temperatures were programmed as follows: 40–300°C at 10°C/min,
followed by an isothermal interval at 300°C for 10 min. The data were collected using ChemStation and
analyzed using MassHunter quantification software. IP25 was identified on the basis of retention time and
comparison of mass spectra with authenticated standards. Abundances were obtained by comparison of
individual GC-mass spectrometry responses against those of the internal standard. For both IP25 and HBI
III, data are reported in ng g1 sediment.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 765
2.2.5. Diatoms
Diatom analyses were conducted on ~ 0.2 g of freeze-dried sediment that was prepared following standard
methodologies (Battarbee et al., 2001). Sediment was oxidized at 90°C for 6 h using hydrogen peroxide (H2O2,
30%) in order to remove organic material. Carbonates were then dissolved by addition of a few drops of HCl
(35%). The test tubes in which samples were treated were subsequently filled with distilled water and left to
settle for 12 h. Residues were then washed several times using demineralized water. A known number of
microscopic markers (microspheres) were added to each sample for concentration determinations. A few
drops of the final suspension were then dried on a coverslip and subsequently mounted in Naphrax® for light
microscopy observation. Identification and quantification were performed using an optical microscope (Leica
DMLB), equipped with phase contrast, at a magnification of 1000X. Owing to the generally very low diatom
concentrations, the relative abundances of individual taxa are based on counts completed over 10 transects
per slide (amounting to ~ 580 microspheres on average).
2.2.6. Dinoflagellate Cysts (Dinocysts) and Other Organic-Walled Microfossils
Samples for palynological analyses were prepared at Ghent University, Belgium, following the standard
preparation method described in Quaijtaal et al. (2014). A known weight of freeze-dried sediment (~2–5 g)
was rehydrated with demineralized water. A calibrated tablet of Lycopodium clavatum spores was added to
each sample before treatment in order to estimate the absolute dinocyst concentrations (Stockmarr, 1971).
The sediment was repeatedly treated with room-temperature hydrochloric acid (HCl, 2 N) and room-
temperature hydrofluoric acid (HF, 40%) to remove calcium carbonate and silicate, respectively. Samples
were rinsed stepwise with deionized water. The residues were sonicated for 30 s to break up clusters of amor-
phous organic matter and sieved through a 10 μm nylon mesh to remove the finer particles. The final resi-
dues were mixed with glycerin jelly and mounted on microscope slides. The identification of dinocysts and
other organic-walled microfossils was carried out using a light microscope at magnifications of 400X and
1000X. In general, a minimum of two slides was counted per sample, but because of very low cyst concentra-
tions, the total number of counted specimens remains below 300 in every sample. Cysts with visible cell
contents were noted.
2.2.7. Foraminifera and Ostracods
For quantitative assemblage analyses, known weights (~1–2 g) of untreated (wet) surface sediment were
soaked in tap water, gently sieved through a 63 μm mesh, and subsequently dried. Calcareous benthic
and planktic foraminifera from the>63 μm fraction were counted dry on a square-picking tray and identified
to the species level. Agglutinated species were not distinguished, but their counts are included in the sums.
With the exception of five sites, at least 300 specimens were counted per sample. Ostracod valves were also
counted from the same samples, although these were not identified to species level.
3. Results
3.1. Particle Size Analysis
The surface sediment samples were mainly composed of silt (46–81%), with lower proportions of sand
(1–38%) and clay (12–35%). Overall, the samples were relatively similar in terms of their grain size distribution.
However, the surface sediments from Sites k11, k21, k25, and k28 had sand contents above 25% (Table 2;
supporting information).
3.2. Carbon and Nitrogen Elemental and Isotopic Analyses
The total organic carbon (TOC) contents ranged between 0.40 and 2.37 wt % (Figure 3a and Table 2), and total
nitrogen (TN) ranged between 0.09 and 0.18 wt % (Table 2). The C:N ratios, which correspond to the ratio
between TOC (wt %) and TN (wt %), varied between 3.33 and 15.86 (Figure 3c and Table 2). The highest values
were found at Sites k33, k25, k14, and k8 (≥10). The δ13C values ranged from 26.0 to 23.5‰ ± 0.5‰
(average = 24.9‰) (Figure 3c and Table 2). The sedimentary organic matter from sites north of Princess
Dagmar Island was more enriched in 13C compared to the region south of Princess Dagmar Island. The
δ
15N values ranged from 2.6 to 5.8‰ ± 0.2‰ (average = 4.8‰) (Figure 3b and Table 2).
3.3. Biogenic Silica
Biogenic silica in sediments is a widely used indicator of paleoproductivity (primarily of diatoms and also radi-
olarians, silicoflagellates, plant phytoliths, and sponge spicules). Biogenic Silica (BSi) concentrations varied
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 766
between 0.45 and 4.96 mg g1 dry mass Si (average 1.89 mg g1) (Figure 4a and Table 3), corresponding to
0.17 to 1.06 wt % SiO2 (average 0.40 wt % SiO2). These values are low in comparison with measurements from
other high-Arctic fjord regions such as the Young Sound-Tyrolerfjord, where the average value is almost 3
times higher (Ribeiro et al., 2017). This can likely be explained by a longer lasting sea ice cover in the study
area, with less biogenic silica accumulating on the seafloor as the result of reduced marine productivity.
3.4. Biomarkers (Highly Branched Isoprenoids)
The biomarker IP25 was identified from all sites at low concentrations (from 3.47 to 69.93 ng g
1 dry sedi-
ment) and is also shown normalized to TOC (μg IP25/g TOC) (Figures 4b and 4c and Table 3). The highest
TOC-normalized IP25 concentrations were found at the shallow sites with seasonal sea ice cover located in
the vicinity of the Villum Research Station (k33 and k11). The lowest concentrations occurred at Sites k9,
k6, and sites located south of Princess Dagmar Island (k14, k15, k21, k22, and k25). Triene (HBI III) concentra-
tions were extremely low and ranged from 0 to 0.74 ng g1 dry sediment (Table 3).
3.5. Diatoms
A total of 39 diatom taxa were identified from the sediment samples. The majority of these were benthic spe-
cies, most of them belonging to the genera Diploneis, Navicula, and Nitzschia (Plate 1). Resting spores of
Chaetoceros (and one Thalassiosira antarctica var. borealis spore) were the only planktic taxa found in the sam-
ples. Overall abundances were very low, and for Sites k4, k9, k14, k15, and k29 no diatoms were encountered
along the analyzed transects (Figure 4d, Table 3, and supporting information). Consistent with high biogenic
silica content for the shallow area next to the Villum Research Station, considerably higher diatom concentra-
tions were found at Sites k33 and k11, yielding total counts of ~ 100 valves, whereas only a few valves were
found at all other sites. These were also the sites where the majority of species were encountered.
Assemblages were dominated by the cosmopolitan marine species Diploneis nitescens. Other taxa included
the brackish-marine Diploneis smithii and Navicula cf. perminuta; the marine widespread Fallacia litoricola,
Nitzschia cf. distans, Nitzschia cf. marginulata, and Nitzschia cf. rorida; and the marine (sub)arctic Pinnularia
quadratarea var. maxima. Worth noting is the presence of only two sympagic taxa throughout the study
area—Diploneis litoralis var. clathrata and Stauroneis cf. radissonii—at very low abundances (<1%). Resting
spores of Chaetoceros were included in the sums. The good preservation of the diatom valves indicates the
absence of significant diatom dissolution, implying that the low diatom abundance at most sites is not a
dissolution artifact.
3.6. Dinocysts and Other Organic-Walled Microfossils
Dinocyst concentrations were relatively low with values ranging from 52 to 717 cysts g1 dry sediment
(Figure 4e and Table 4). While the highest concentrations were found north of Princess Dagmar Island,
Table 2
Grain Size Distribution of the Surface Sediment Samples and Contributions to the Sediment of Total Carbon (TC), Nitrogen (TN), and Organic Carbon (TOC) (wt %), Organic
Carbon Over Nitrogen Ratios and Carbon and Nitrogen Isotopic Signatures (δ13C, δ 15N) of the Sediment (‰)
Core numbers Clay (%) Silt (%) Sand (%) TC (wt %) TN (wt %) TOC (wt %) C:N δ13C (‰) δ15N (‰)
k9 15.1 63.9 21.0 1.43 0.14 0.83 5.93 23.9 5.5
k6 23.4 70.4 6.2 1.31 0.14 0.74 5.29 26.0 5.8
k32 21.5 72.5 6.0 1.27 0.12 0.67 5.58 23.7 5.6
k8 34.7 61.7 3.6 2.14 0.17 1.70 10.00 26.0 4.4
k29 21.4 66.1 12.5 1.20 0.13 0.75 5.77 23.8 5.6
k28 18.2 56.2 25.6 1.35 0.14 0.69 4.93 24.4 5.4
k4 24.1 66.4 9.5 1.13 0.12 0.71 5.92 23.8 5.1
k3 15.7 69.7 14.5 1.33 0.13 0.79 6.08 24.7 5.3
k11 12.3 59.7 28.0 2.08 0.18 0.92 5.11 23.7 5.3
k33 15.0 69.7 15.3 1.90 0.18 2.37 13.17 23.5 5.0
k22 28.6 65.1 6.3 1.26 <Dl 0.59 <Dl 25.7 <Dl
k21 16.9 45.5 37.6 1.25 0.12 0.40 3.33 25.8 4.9
k25 14.0 49.1 37.0 2.83 0.14 2.22 15.86 25.6 2.6
k17 13.5 71.2 15.3 2.00 0.14 1.11 7.93 25.6 4.1
k15 24.6 71.0 4.4 1.18 0.12 0.69 5.75 26.0 4.0
k14 17.6 81.0 1.4 2.21 0.09 1.20 13.33 25.4 2.8
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 767
sites located south of the island and close to the glacier outlets contained only a few cysts, providing very low
counts. Nine dinocyst taxa were identified from the surface samples, with seven of them significantly
contributing to the assemblages: Brigantedinium spp. (mainly B. simplex) (6–54%), Islandinium minutum
(2–47%), Echinidinium karaense (0–14%), unspecified “spiny brown cysts” (0–10%), Polarella glacialis
(0–82%), cf. Biecheleria sp. (2–47%), and a cyst here referred to as “round brown type A” (0–4%) (Figure 5a,
Plate 2, and supporting information). The spiny brown cyst category encompasses all specimens that could
either belong to the genus Islandinium or Echinidinium, but for which preservation, folding, or orientation
did not allow for unequivocal identification. Indeterminate cyst types of probable dinoflagellate affinity
were also observed. Although they were not included in the total cyst counts, these taxa are shown in
Plate 2.
 e dal F
l bsI
in
k
PDI
A
PDI
B
C
N
22
21
15
25
14
17
33
3
428
29 11
8
32
9
6
N
13
C 
(‰
 )
25
14
33
3
28
11
9
32
21
6 15
17
8
29
4
2 6 10 14 18
-24
-25
-26
-27
-22
Ice OM
Te
rr
e
st
ria
l O
M
TOC:TN
Marine OM
Villum R.S.
TOC (wt %)
1.0-1.5
0.5-1.0
1.5-2.0
<dl
>2
Villum R.S.
3.5-4.5
2.5-3.5
4.5-5.5
<dl
5.5-6.5
15N (‰ )
Figure 3. Results from carbon and nitrogen elemental and isotopic analyses. (a) Distribution of total organic carbon (wt %), (b) δ15N signature of surface sediment
(‰), (c) δ13C values versus TOC:TN ratios of bulk organic matter. The circles indicate the sampling sites. The color code for the sampling sites refers to the
subdomains described in section 4.2 (I = blue, II = green, III = red, and IV = yellow). The white boxes represent end-members for ice particulate OM and land-derived
OM. The arrows indicate that ice particulate OM is more enriched in 13C compared to pelagic particulate OM values, and land-derived OM yields higher C:N ratio
(20 to 100; Meyers, 1994) than aquatic OM. The grey box shows the potential range of values associated to pelagic particulate OM on account of high pCO2 in cold
surface water. Our data indicate varying mixing ratios of pelagic, sympagic, and terrestrial organic carbon in the surface sediment from the fjord system. Higher
C:N ratios suggest larger terrestrial input at Sites k25, k14, k33, and k8, whereas enriched δ13C values may be indicative of higher ice algal input to the sediment.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 768
Figure 4. Distribution and concentrations of the main biogenic proxies studied from the surface sediment: (a) biogenic silica (mg g1); (b) IP25 (ng g
1); (c) TOC-
normalized IP25 (μg g
1); (d) concentrations of diatoms (valves g1), and proportion of benthic (dark blue) and planktic species, including resting spores of
Chaetoceros (green); (e) concentrations of dinocysts (cysts g1) and proportions of phototrophic (light blue) over heterotrophic species (dark blue); (f) concentrations
of foraminifera (tests g1) and proportions of planktic (green), calcareous benthic (dark blue), and agglutinated benthic (light blue) species; (g) concentrations of the
heterotroph dinocyst species Islandinium minutum (cysts g1); (h) concentrations of the dinocyst cf. Biecheleria sp. (cysts g1); and (i) concentrations of the
phototrophic sea ice dweller dinocyst Polarella glacialis (cysts g1).
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 769
Foraminiferal linings were very abundant at the deepest Sites (k9
and k6) and at Sites k4 and k3, where they reached concentrations
of ~ 20,000 linings g1 (Table 4). The samples also showed a signif-
icant presence of the acritarch Radiosperma corbiferum and several
types of ciliate cysts (Plate 3). While a few reworked cysts were
found on most slides, they were particularly abundant at Site k14,
which is located directly next to an outlet of the Flade Isblink ice
cap (Table 4). Most of these reworked cysts were identified to origi-
nate from the Ordovician period, consistent with the bedrock in the
fjord catchment, which would indicate input from land rather than
in situ reworking of the fjord sediments. Otherwise, a high proportion
of the analyzed dinocysts featured visible cellular material, suggesting
generally good preservation and/or recent cyst production (see
Plate 2).
Important heterogeneities in the spatial distribution and the relative
abundances of the dominant species of palynomorphs were
recorded. Generally, a fivefold decrease in cyst abundances was
observed from the outer to the innermost part of the study area,
south of Princess Dagmar Island. This is concomitant with an increase
in the proportions of R. corbiferum and in the ciliate cysts in the latter
region (Figure 5b). With the exception of Site k22, samples from the
inner part of the study area yielded very low cyst counts and species’ relative abundances were therefore
not used for further interpretations.
Classical cluster analysis using a paired-group clustering algorithm and a Euclidean similarity index was car-
ried on the assemblage data for samples with total cyst counts higher than 60. The resulting dendrogram
clearly highlights the important compositional shift in the assemblages for the region north of Princess
Dagmar Island (Figure 5a). Sites located at shallow depths (k11 and k33), close to the Villum Research Station,
are the most dissimilar of all sites. These sites are characterized by a striking dominance of the phototrophic
species P. glacialis. It is also at these sites that the highest total cyst concentrations were recorded. On the
contrary, heterotrophic species belonging to Brigantedinium spp. and spiny brown sensu lato (e.g., I. minutum,
Islandinium? cezare, E. karaense, and other unspecified spiny brown) were prevalent at the deepest sites
(k6, k9, and k32), where the sea ice cover is semipermanent. Intermediate cyst abundances and diversity were
found to characterize sites located between these two compositional poles (k29, k28, k3, and k4), where
assemblages are still mainly composed of heterotrophic species. Finally, although Site k22 features a bathy-
metry and general sea ice conditions close to that of the deepest sites located north of Princess Dagmar
Island, this sample forms its own group possibly owing to the significant proportion of phototrophic species
(mainly cf. Biecheleria sp.).
3.7. Foraminifera and Ostracods
Concentrations of total foraminifera varied from 0 to 2,714 tests g1 (Table 4). Whereas calcareous and agglu-
tinated benthic foraminifera were present at most studied sites, planktic species were only present in signifi-
cant abundances (>800 tests g1) at the deepest sites (k6 and k9) (see Figure 4). In total, 37 species of
calcareous benthic and 3 species of planktic foraminifera were identified (Table 5). The main benthic species
included Cassidulina neoteretis (7 to 53%), Cassidulina reniforme (0 to 32%), Elphidium hallandense (0–63%),
Elphidium clavatum (often described as E. excavatum f. clavata) (0–46%), Epistominella arctica (0–30%),
Stetsonia horvathi (0–22%), Cibicides lobatulus (0–18%), Buccella frigida (0–12%), Elphidium albiumbilicatum
(0–9%), Triloculina trihedra (0–11%), Quinqueloculina sp. (0–10%), Stainforthia loeblichi (0–7%), and
Islandiella helenae (0–6%) (Figure 6, Plate 4, and supporting information). The planktic foraminiferal assem-
blages are dominated by Neogloboquadrina pachyderma sinistral (0–97%) and Turborotalita quinqueloba
(0–26%), accompanied by lower abundances of Neogloboquadrina incompta (0–14%) (Figure 6). Note that
all right coiling N. pachyderma in all samples with more than 3% of right coiling N. pachyderma are identified
as N. incompta (Sites k1, k3, k21, and k32), and in all samples with less than 3% they are called N. pachyderma
(the rest of the samples) (cf. Darling et al., 2006).
Table 3
Biogenic Silica (BSi) (mg g1), IP25 (ng g
1), HBI III (ng g1), and Total Diatom
Concentrations (valves g1)
Core
numbers
Bsi IP25 HBI III
Total diatom
concentrations
(mg g1) (ng g1) (ng g1) (valves g1)
k9 0.79 7.64 0.04 < 3.91E + 04
k6 1.51 5.79 0.00 2.96E + 05
k32 1.21 7.02 0.11 2.52E + 04
k8 1.15 20.21 0.74 3.89E + 05
k29 1.29 11.38 0.06 < 5.89E + 04
k28 1.17 7.27 0.06 1.04E + 05
k4 2.57 10.79 0.07 < 2.64E + 04
k3 1.71 7.61 0.05 9.70E + 04
k11 4.96 38.49 0.17 1.41E + 06
k33 4.92 69.93 0.23 2.85E + 06
k22 1.73 4.26 0.03 5.09E + 04
k21 1.23 3.47 0.01 6.06E + 04
k25 1.15 3.84 0.15 8.70E + 04
k17 2.87 11.03 0.20 8.85E + 04
k15 1.64 5.03 0.04 < 9.70E + 04
k14 0.45 3.73 0.11 < 7.99E + 04
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 770
In the study area, a calcareous fauna prevails at the deepest sites, where total abundances also are at their
highest (Figure 4). In contrast, assemblages from the shallowest sites are mostly composed of agglutinated
species and yielded very low total concentrations. Owing to the relatively shallow environmental setting
Plate 1. Differential interference contrast photomicrographs of the diatom taxa recovered from the surface samples. 1–2: Diploneis nitescens, 3: Diploneis smithii var.,
4: Navicula sp.1, 5: Fallacia litoricola, 6: Navicula sp.2, 7: Trachyneis aspera, 8: Navicula cf. wunsamiae, 9–10: Nitzschia cf. rorida, 11: Nitzschia cf. marginulata var. Scale
bars represent 10 μm.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 771
(20 to 160 m), the low abundance and diversity of planktic foramini-
fera at most sites is not surprising. Their marked presence (719 indivi-
dual g1) at the deepest sites is however noteworthy.
Ostracods were common in four samples (k6, k9, k29, and k33) and
absent to rare in the other samples. Abundances ranged from 0
to 45 individuals g1.
4. Discussion
4.1. Source of Organic Matter
The organic matter C:N ratios and δ13C can be used to discriminate
between terrestrial versus marine sources of organic matter (OM)
deposited in the sediments. Phytoplankton and zooplankton have
atomic C:N ratios ranging between 4 and 10, whereas these are gen-
erally above 20 for terrestrial vascular plants (Meyers, 1994). The δ13C
signature indicates both the dynamics of carbon assimilation during
photosynthesis and isotopic composition of the carbon source
(Hayes, 1993; Meyers, 1997). In general, aquatic OM (between 22
and 20‰) is more enriched in 13C than terrestrial OM (~ 27‰)
(Belicka & Harvey, 2009; Meyers, 1994; Naidu et al., 2000). The carbon
isotopic signature is, however, more complicated in Arctic environ-
ments where high pCO2 and slow algal growth in cold surface water
can lead to depleted δ13C values approaching those of terrestrial OM (Pineault et al., 2013; Rau et al.,
1989), while enriched ice algal OM (2–10‰ more enriched than pelagic OM; Hobson & Welch, 1992;
Søreide et al., 2006) has an opposite influence on the values. Enriched δ13C values associated to ice algal
OM are due to limited atmospheric CO2-exchange under sea ice, which eventually results in reduced
13C dis-
crimination during photosynthesis as biomass increases and the pool of dissolved inorganic carbon declines
(Fischer, 1991; Kerby & Raven, 1985; Rau et al., 1992). Thus, the range of marine δ13C values in the Arctic is
broad (34.7 to 18‰) (Goericke & Fry, 1994; Pineault et al., 2013). For example, particulate OM in
Northeast Water Polynya, off northeastern Greenland, has δ13C values between 28 and 27‰ (Hobson
et al., 1995) and ice algae around 18.5‰. These δ13C values are comparable to those reported from the
Arctic Ocean (Schubert & Calvert, 2001), where pelagic and ice particulate OM δ13C values range between
24.2 to 27.6‰ and 18.3 to 20.6‰, respectively.
Carbon isotope values at our stations indicate a mixed input of marine and terrestrial sources. More enriched
values (higher than 24‰ δ13C) are recorded in the relatively higher productivity region north of the Villum
Research Station, while more depleted values are recorded south of Princess Dagmar Island (around 26‰).
The OM from terrestrial sources is more clearly distinguished by higher C:N values at stations k25, k14, k33,
and k8 (Figure 3). The more enriched δ13C at k33 compared to other stations with high C:N values could
be due to high ice algal input as indicated by high concentrations of P. glacialis and IP25 (Figure 4). It is also
important to note that our C:N ratios were not corrected to remove potential land-derived inorganic nitrogen
(ammonium attached to clay minerals), which can lead to underestimated C:N values in Arctic clay-rich sedi-
ments (see Kumar et al., 2016). This could affect Site k8 in particular, where the clay content is 34.7%, although
this clay content is low in comparison to other Arctic sediments (Stein et al., 1994).
4.2. Environmental Interpretation
The reliability of environmental reconstructions from biogenic proxies strongly relies on existing information
about the different species-specific ecological requirements (temperature, salinity, sea ice cover, nutrient and
food availability, sediment substrate, etc.), and the chemical properties of their fossil remain. In the study area,
we found no evidence for poor preservation of the fossil assemblages. Because the foraminiferal linings
counted from palynological slides are likely the remnants of benthic calcareous species (Jennings et al.,
2014), a comparison between these and the tests found in the sediment can indicate the degree of carbonate
dissolution (De Vernal et al., 1992). At most stations, the relatively similar trends in both records indicate good
preservation of calcareous material (R2 = 0.75; see supporting information). The differences in their
Table 4
Total Concentrations of Modern Dinocysts (cysts g1), Reworked Dinocysts
(cysts g1), Organic Linings of Foraminifera (linings g1), and Foraminifera,
Including Benthic and Planktic Species (tests g1)
Core numbers
Modern
dinocysts
Reworked
dinocysts
Organic linings
of foraminifera Foraminifera
(cysts g1) (cysts g1) (linings g1) (tests g1)
k9 717 9 16136 2714
k6 705 34 17580 1871
k32 492 82 7539 1063
k8 85 43 503 <Dl
k29 363 77 4727 1570
k28 359 17 8943 838
k4 231 61 20890 n/a
k3 709 233 13666 1011
k11 783 42 629 164
k33 659 62 923 75
k22 129 0 3867 887
k21 85 13 3226 388
k25 52 26 619 23
k17 76 0 991 129
k15 93 5 2351 <dl
k14 58 498 16 <dl
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 772
abundances are likely the result of the different sizes of the analyzed fractions; linings were studied from the
palynological residues in the fraction between 10 and 106 μm, while tests were counted in the hand-sieved
bulk sediment, from the fraction larger than 63 μm.
Similarly, the generally good state of preservation of the diatom valves does not suggest that the assem-
blages were affected by dissolution. Consequently, it is assumed that changes in the composition of the fossil
assemblages reflect the ecological conditions influencing the living assemblages. Accordingly, the spatial
structure in the proxy data fairly closely follows the interplay between the bathymetry, water masses, and
sea ice conditions, and four assemblage subdomains were defined:
1. Subdomain I: Region south of Princess Dagmar Island (Sites k14, k15, k17, k21, k22, and k25). Surface sedi-
ments from this region contained low concentrations of marine microfossils and biomarkers.
Furthermore, depleted δ15N values can be indicative of low nitrate utilization, assuming that the nitrate
pool is not limited (Altabet & Francois, 1994). Within the main groups of organic-walled microfossils,
R. corbiferum dominates over dinocysts, which are almost absent. The biological affinity of R. corbiferum
is currently unknown, but this acritarch is commonly reported from brackish environments or inner-
shelf settings with low surface salinities (Kunz-Pirrung, 1999; Matthiessen et al., 2000; Milzer et al., 2013;
Sorrel et al., 2006). The assemblages likely indicate lower salinities in this area. Although hydrographical
measurements are very scarce for this subdomain, the area does not appear to be influenced by
offshore-advected water masses (Dmitrenko et al., 2017). Similar to what has been observed in other
Polarella glacialis
cf. Biecheleria sp.
Round Brown type A.
Echinidinium karaense
Brigantedinium spp.
Islandinium minutum
Islandinium cezare
Spiny brown
Protoperidinium spp.
Very low cyst counts 
Dinocyst taxa:
50
100%
Pa
ly
no
m
or
ph
s 
g-
1
k3 k11 k33k9 k6 k32 k8 k29 k28 k4 k22 k21 k25 k17 k15 k14
1200
Dinocysts
R. corbiferum
Ciliate cysts
800
400
0
Groups of palynomorphs
R
el
at
iv
e 
ab
un
da
nc
es
 (%
)
A
B
Site numbers
10
50
90D
is
ta
nc
e
Heterotrophic:
Phototrophic:
Figure 5. (a) Dinocyst assemblage composition diagram and dendrogram resulting from the cluster analysis. The dots indicate sites with very low cyst counts (<30
cysts), which were not included in the cluster analysis. (b) Total abundance of three groups of palynomorphs (g1 of dry sediment). Dinocysts are shown in black, the
acritarch Radiosperma corbiferum in dark grey, and the ciliate cysts in light grey. Note the low contribution of dinocysts to the total palynomorph abundances
from station k21 onward in parallel with a slight increase in the contribution of R. corbiferum.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 773
High Arctic settings (cf. Mueller et al., 2003), the bathymetry and sea ice dynamics south of Princess
Dagmar Island possibly create a physically constrained basin that allows pooling of freshwater derived
from the southern branch of the fjord drainage basin (Kirillov et al., 2017). This seems consistent with
the very low salinity (16–21) recorded from the water layer directly below the ice during the
oceanographic campaign of 2015 (Dmitrenko et al., 2017).
2. Subdomain II: Outermost and deeper sites (Sites k9, k6, and k32). This subdomain comprises sites from the
deepest part of our study area, under the influence of a semipermanent sea ice cover. The nitrogen
isotopic signature is the most enriched (δ15N between 5.5 and 5.8‰), which could reflect high nitrate
utilization in sea ice relative to the water column (Fripiat et al., 2014). However, in oligotrophic Arctic
Plate 2. Bright-field photomicrographs of themain dinocyst taxa recovered from the surface samples. 1–2: high and low focal views of the same specimen of B. simplex,
3–6: midfocal views of different specimens of the round brown type A., 7–8: midfocal views of two different specimens of I. minutum, 9: midfocal view of
E. karaense, 10–11: midfocal and high focal views of the same specimen of E. karaense, 12: midfocal view of E. karaense, 13–14: midfocal and low focal views of
B. tepikiense, 15–16: midfocal and high focal views of cf. Biecheleria sp., 17: midfocal view of P. glacialis, 18: high view of the indeterminate cyst type, 19–20: high
focal and midfocal views of the same specimen of the indeterminate cyst type. Scale bars represent 10 μm.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 774
systems nitrate is typically also limited in the water column, leading to overlapping δ15N ranges in
sympagic and pelagic OM (Kohlbach et al., 2016; Pineault et al., 2013). Phototrophic organisms (diatoms
and autotrophic dinoflagellates) are nearly absent; this is consistent with limited light penetration.
Surprisingly, however, their potential grazers (heterotrophic dinoflagellates, ciliates, and foraminifera)
are present in relatively high abundances. Dinocyst assemblages are dominated by species belonging
to the Protoperidinium/Archaeperidinium and Diplopsalid groups, notably Brigantedinium simplex,
Islandinium minutum, and Echinidinium karaense. These cysts are typically found in sediments from
marine settings characterized by prolonged seasonal sea ice cover (de Vernal et al., 2001; Rochon et al.,
1999). Their cyst production, however, appears to take place during the open water period (Heikkilä
et al., 2016). Similarly, foraminiferal assemblages are diverse and composed of benthic and planktic
species, the latter mainly consisting of N. pachyderma (sinistral) and T. quinqueloba. Although some
polar species possibly feed on phytodetritus (Cornelius & Gooday, 2004), N. pachyderma is known to
feed primarily on diatoms (Hemer et al., 2007; Salvi et al., 2006; Volkmann, 2000) and T. quinqueloba is
especially abundant in frontal zones and other high-productivity regions (Johannessen et al., 1994;
Nørgaard-Pedersen et al., 2007). Considering the sea ice thickness of the order of 1.15–1.25 m for Sites
k9 and k6 compared to 3.10 m for Site k32 measured during the field campaign (late April 2015), our
data can be interpreted in different ways: (1) The semipermanent sea ice cover restrains in situ primary
production, but tests of planktic foraminifera and dinocysts are advected from the productive offshore
open waters via subsurface currents. This would explain why the grazers are found in the sediment,
while the primary producers are extremely scarce. Following this line of reasoning, however, one might
expect more planktic diatom valves since their size and weight make them more prone to lateral
transport than the heavy tests of foraminifera (de Vernal et al., 2006). (2) The semipermanent sea ice
cover restrains in situ primary production, but food supply is advected from the productive offshore
open waters via nutrient-rich subsurface currents. (3) Flaw leads sometimes open in the sea ice,
allowing for short-term algal blooms that sustain a relatively broad autochthonous foraminiferal and
dinoflagellate community. However, due to efficient grazing, the remains of diatoms and phototrophic
Plate 3. Bright-field micrographs of organic-walled microfossils recovered from the surface samples. 1: acritarch type A, 2: acritarch type B, 3: Turbellaria oocyte?,
4: Radiosperma corbiferum, 5: ciliate cyst type B, 6: ciliate cyst type C, 7: ciliate cyst sp., 8: ciliate cyst sp., 9: ciliate cyst sp., 10: ciliate cyst type A, 11: unidentified
medium-sized cell with cell content, and 12: reworked Ordovician acritarch sp.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 775
Ta
bl
e
5
Li
st
of
D
in
oc
ys
t,
Fo
ra
m
in
ife
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la
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xa
En
co
un
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re
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in
th
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rf
ac
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in
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ys
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ta
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re
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(M
on
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or
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.,
19
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ig
an
te
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ni
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si
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ex
(W
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l,
19
67
;e
x
Le
nt
in
&
W
illi
am
s,
19
93
)
Bu
cc
el
la
fr
ig
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(C
us
hm
an
,
19
21
)
N
eo
gl
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a
(E
hr
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,1
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1)
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ph
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a
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is
(G
re
go
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,1
85
7)
Th
al
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va
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bo
re
al
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(F
ry
xe
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et
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.,
19
81
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ni
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nt
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&
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.
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ss
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a
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ot
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is
(S
ei
de
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ra
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19
95
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dr
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ife
lli
,1
96
1)
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hr
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ar
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ar
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et
al
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98
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H
ea
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ss
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ør
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at
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93
8)
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or
a
sp
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O
pe
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od
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um
A
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or
ph
ot
yp
e
se
ns
u
(d
e
Ve
rn
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et
al
.,
20
01
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Is
la
nd
in
iu
m
?
ce
za
re
(d
e
Ve
rn
al
et
al
.,
19
89
ex
de
Ve
rn
al
in
Ro
ch
on
et
al
.1
99
9;
Ra
di
et
al
.,
20
13
)
Ca
ss
id
ul
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la
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ig
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a
(d
’
O
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,1
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6)
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ci
lla
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xi
lli
fe
r
(M
ül
le
r,
17
86
;M
ar
ss
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,1
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1)
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hi
ni
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ni
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se
(H
ea
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et
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.,
20
01
;R
ad
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20
13
)
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bi
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(W
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ke
r
&
Ja
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17
98
)
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,1
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8)
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to
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(S
ch
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,1
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6)
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Co
rn
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ra
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vo
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s
(R
eu
ss
,1
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or
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(Ø
st
ru
p,
18
95
;C
le
ve
,1
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6)
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ph
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lic
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(W
ei
ss
,1
95
4)
D
ip
lo
ne
is
ni
te
sc
en
s
(G
re
go
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18
57
;C
le
ve
18
94
)
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ph
id
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m
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rt
le
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i
(C
us
hm
an
,1
93
3)
D
ip
lo
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sm
ith
ii
va
r.
El
ph
id
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m
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av
at
um
(C
us
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,1
93
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ip
lo
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su
bc
in
ct
a
(S
ch
m
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18
74
;C
le
ve
,1
89
4)
El
ph
id
iu
m
ha
lla
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se
(B
ro
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,1
94
3)
D
ip
lo
ne
is
sp
p.
El
ph
id
iu
m
sp
.
Fa
lla
ci
a
lit
or
ic
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a
(H
us
te
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,1
95
5;
M
an
n,
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)
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is
to
m
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el
la
ar
ct
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a
(G
re
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,1
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yr
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m
a
cf
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i
(S
m
ith
,1
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,1
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6)
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is
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.
G
yr
os
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Fi
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Ka
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(G
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,1
88
0;
Ro
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d
&
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kh
tiy
ar
ov
a,
19
99
)
G
ut
tu
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a
da
w
so
ni
(C
us
hm
an
&
O
za
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a,
19
30
)
N
av
ic
ul
a
di
re
ct
a
(S
m
ith
18
53
;R
al
fs
,1
86
1)
G
ut
tu
lin
a
sp
.
N
av
ic
ul
a
ka
ria
na
va
r.
fr
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a
(G
ru
no
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18
80
;C
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,1
89
5)
Is
la
nd
ie
lla
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e
(F
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H
an
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&
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19
76
)
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av
ic
ul
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cf
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a
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la
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(C
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,1
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av
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a
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(H
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2)
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ge
na
el
on
ga
ta
(D
un
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18
79
)
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av
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a
(E
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en
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18
43
;K
üt
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,1
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4)
La
ge
na
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ria
ta
(d
’
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,1
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9)
N
av
ic
ul
a
cf
.p
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(G
ru
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,1
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0)
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 776
Ta
bl
e
5
(c
on
tin
ue
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D
in
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H
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lc
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eo
us
be
nt
hi
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Pl
an
kt
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Be
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Pl
an
kt
ic
M
el
on
is
ba
rle
ea
nu
s
(W
ill
ia
m
so
n,
19
58
)
N
av
ic
ul
a
ph
yl
le
pt
a
(K
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84
4)
M
ill
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.
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av
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a
cf
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un
sa
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(W
itk
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00
)
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on
io
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lli
na
la
br
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or
ic
a
(D
aw
so
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60
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a
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.
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itz
sc
hi
a
cf
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(G
re
go
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,1
85
7)
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te
lli
na
co
rr
ug
at
a
(W
ill
ia
m
so
n,
19
58
)
N
itz
sc
hi
a
m
ar
gi
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ta
(G
ru
no
w
,1
88
0)
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rg
o
w
ill
ia
m
so
ni
(S
ilv
es
tr
i,
19
23
)
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itz
sc
hi
a
cf
.m
ar
gi
nu
la
ta
va
r.
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rg
oe
lla
irr
eg
ul
ar
ris
(d
’
O
rb
ig
ny
,1
83
9)
N
itz
sc
hi
a
cf
.r
or
id
a
(G
iff
en
,1
97
5)
Q
ui
nq
ue
lo
cu
lin
a
ar
ct
ic
a
(C
us
hm
an
,1
93
3)
N
itz
sc
hi
a
cf
.s
ig
m
a
(K
üt
zi
ng
,1
84
4;
Sm
ith
,1
85
3)
Q
ui
nq
ue
lo
cu
lin
a
sp
.
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itz
sc
hi
a
sp
p.
Ro
be
rt
in
oi
de
s
sp
.
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nn
ul
ar
ia
qu
ad
ra
ta
re
a
va
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m
ax
im
a
St
ai
nf
or
th
ia
lo
eb
lic
hi
(F
ey
lin
g-
H
an
ss
en
,1
95
4)
Pi
nn
ul
ar
ia
qu
ad
ra
ta
re
a
va
r.
m
in
or
St
ai
nf
or
th
ia
co
nc
av
a
(H
ög
lu
nd
,1
94
7)
Pl
an
ot
hi
di
um
de
lic
at
ul
um
(K
üt
zi
ng
)(
Ro
un
d
&
Bu
kh
tiy
ar
ov
a,
19
96
)
St
et
so
ni
a
ho
rv
at
hi
(G
re
en
,1
95
9)
Pl
eu
ro
si
gm
a
sp
p.
Tr
ilo
cu
lin
a
tr
ih
ed
ra
(L
oe
bl
ic
h
&
Ta
pp
an
,1
95
3)
St
au
ro
ne
is
cf
.r
ad
is
so
ni
i
(P
ou
lin
&
Ca
rd
in
al
,1
98
2)
Tr
ilo
cu
lin
a
sp
.
Sy
ne
dr
a
ta
bu
la
ta
(A
ga
rd
h)
(K
üt
zi
ng
,1
84
4)
Tr
ac
hy
ne
is
as
pe
ra
(E
hr
en
be
rg
)
(C
le
ve
,1
89
4)
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 777
dinocysts do not settle in the sediment. In all cases, the marine signature of the sedimentary assemblages
strongly suggests this area is under marine influence.
3. Subdomain III. Transect of decreasing depths (Sites k29, k28, k4, and k3). Although dinocyst abundances are
conspicuously lower in this subdomain than in subdomains II and IV, gradual changes in the total abun-
dances of foraminifera as well as in the ratio of heterotrophic/phototrophic dinocysts are observed with
decreasing distance to the coast. This transient proxy signature appears to be primarily linked to (1)
varying bathymetry that impacts the structure of the water column, and (2) the dynamics of sea ice
retreat, which likely affects the timing of light availability for phytoplankton growth.
4. Subdomain IV. Shallower sites (Sites k11 and k33). This shallow area (below 40 m depth) is located in the
region of early seasonal sea ice retreat (July ice edge) and corresponds to the local productivity “hot spot”.
With the exception of the foraminifera, all biogenic proxies display their peak abundances here, clearly
illustrating that conditions are most favorable for photosynthetic activity. Furthermore, enriched δ15N
values relative to the region south of Princess Dagmar Island reflect higher nitrate utilization. This is how-
ever only under the assumption that diagenetic enrichment (Robinson et al., 2012) of δ15N affects all the
study sites similarly. The bathymetry conditions and dynamics of sea ice retreat further suggest that IP25 is
locally produced. Together with cf. Biecheleria sp., the sea ice dwelling P. glacialis dominates the dinocyst
assemblages. The latter species is known to produce cysts in sea ice brine in the spring (Stoecker et al.,
1997) and has been recorded in sediment traps directly after the ice breakup (Heikkilä et al., 2016).
Benthic calcareous foraminifera are only present at low concentrations, and their assemblages are domi-
nated by E. clavatum and E. arctica. The opportunistic species E. clavatum is widespread on the Arctic
600 0 50 0 25 0 15250500 50 0 50
.
0 10 100 015
k9
k6
k32
k29
k28
k3
k11
k33
k22
k21
k25
k17
Benthic foraminifera Planktic foraminifera
Very low 
counts
N. pachyderma (sin)
T. quinqueloba
N. incompta
0 100
Co
re
 
n
u
m
be
rs
0 0 10
k8
k22
k21
k9
k6
k32
k29
k28
k3
k11
k33
k22
k21
k25
k17
k8
k22
k21<dl
<dl
<dl <dl
<dl
<dl
Figure 6. Benthic and planktic foraminiferal percentages in the>63 μm fraction. The dots indicate sites with very low planktic foraminiferal counts (<35 tests). Sites
k8, k22, and k21 were virtually barren of foraminifera.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 778
shelves, including extreme environments such as near tidewater glacier fronts (Hald et al., 1994; Hald &
Korsun, 1997; Korsun & Hald, 1998, 2000; Leslie, 1965; Mudie et al., 1983). The exceptional ability of this
species to adapt to harsh environments may be related to its high nutritional and habitat versatility,
and its capability to quickly colonize seafloor areas that are temporarily suitable for growth (Alve, 1999;
Corliss, 1991; Corliss & Van Weering, 1993; Linke & Lutze, 1993; Wollenburg & Mackensen, 1998).
Furthermore, E. arctica shows an affinity to areas with both low productivity and high seasonal
production (Cornelius & Gooday, 2004; Pawlowski, 1991; Wollenburg & Mackensen, 1998); this suggests
that this species is capable of adapting to contrasting conditions (Wollenburg & Kuhnt, 2000). All
proxies are indicative of typical glacio-marine conditions that are seasonally favorable for algal blooms
in this area.
4.3. Primary Production
Photosynthetic organisms at the base of the food webmodulate the amount of fresh organic matter available
for the upper trophic levels; this plays a key role in ecosystem functioning. In our study area, notable spatial
heterogeneity in primary production can be inferred from the various biogenic tracers.
Although the low diatom, dinocyst, TOC, and biogenic silica contents that prevail at most sites suggest overall
low primary production—coherent with short periods of photosynthetically favorable light conditions—
enhanced production is nonetheless recorded in the subdomain IV (Sites k11 and k33). Despite a clear
sedimentary signal from ice-derived algae (e.g., the dinocyst P. glacialis), the markedly higher diatom concen-
trations at these sites dominated by benthic diatoms suggests that the microphytobenthos contributes to a
significant fraction of the local primary production. A dominance of benthic over pelagic productivity has
been documented from other Arctic fjord regions (Glud et al., 2002, 2009) and was further suggested to
predominate in oligotrophic areas (Glud et al., 2009). Sediment-dwelling diatoms have the ability to rapidly
adjust to fluctuating light conditions (Kühl et al., 2001, Wulff et al., 2008, 2009; Karsten et al., 2011) and
Plate 4. SEM micrographs of the main species of foraminifera recovered from the surface samples. 1–2: Buccella frigida, 3: Islandiella helenae, 4–5: Cibicides lobatulus,
6: Cassidulina reniforme, 7: Cassidulina neoteretis, 8: Elphidium clavatum, 9: Elphidium albiumbilicatum, 10: Stainforthia loeblichi, 11: Neogloboquadrina pachyderma
sinistral, and 12: Turborotalita quinqueloba. Scale bars: 100 μm.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 779
efficiently use the nutrients released by mineralization processes in the sediment underneath (Glud et al.,
2009; Karsten et al., 2011). A number of species have proven to be able to withstand several months of
complete darkness (Wulff et al., 2008). In addition to benefiting from extended growth season, benthic
diatoms possess a clear advantage over pelagic organisms when nutrients are limited.
Although our multiproxy approach only allows for investigating the response of a selection of primary
producers to their environment, diatoms are often considered the most important functional group within
the microphytobenthos in marine coastal regions (MacIntyre et al., 1996; Karsten et al., 2011). Whether
dynamic interactions take place between the benthic and sea ice habitats for optimal food acquisition cannot
be unraveled from our data, but the fact that the concentrations of benthic diatoms exceed those of planktic
and sympagic diatoms in subdomain IV clearly indicates that the benthic community fulfills a significant
ecological role in this system, as in other High Arctic fjords.
4.4. Sea Ice Conditions
The only known producers of IP25 are marine benthic diatoms belonging to Haslea (H. spicula andH. kjellmanii)
and Pleurosigma (P. stuxbergii var. rhomboides) (Brown et al., 2014; G. Massé and M. Poulin, personal commu-
nication, 2017). These species typically flourish on the underside of sea ice, near the ice-water interface
(Brown et al., 2011). In addition to other constraining environmental factors (e.g., salinity and nutrients), their
growth strongly depends upon a complex interplay between sea ice occurrence and sufficient light availabil-
ity. The presence of IP25 at all sites suggests the presence of IP25-producing taxa in the ice from the fjord sys-
tem—although none of the above species were observed from the fossil assemblages (IP25-producing
species typically represent ~ 1–5% of Arctic sea ice assemblages (Belt et al., 2013) and their frustules do
not preserve in the sediments)—and reflects the regional thinning andmelting of the ice cover over the sum-
mer months. However, with the exception of Sites k11 and k33, the generally low contents of the biomarker
in the sediment suggest that the conditions are probably not optimal for IP25-producing taxa to grow. This is
particularly apparent in the region south of Princess Dagmar Island, where sea ice conditions similar to those
in the northern region do not lead to comparable sediment IP25 concentrations. A change in the dominant
groups of palynomorphs in this region as well as the δ13C, δ15N, and C:N signature of the organic matter also
points to a lower salinity. This is consistent with observations from Ribeiro et al. (2017), Xiao et al. (2013), and
Hörner et al. (2016), where low sedimentary IP25 concentrations were linked to reduced salinities. IP25 is pro-
duced in the ice and released when the sea ice melts, in contrast to HBI III, which is thought to be produced in
open waters by diatoms possibly blooming near the marginal ice zone (Belt et al., 2000), although not exclu-
sively (Belt et al., 2017). In our study area, HBI III concentrations are extremely low, supporting a very short
period of open water.
Interestingly, the regional patterns of IP25 and cysts belonging to the dinoflagellate P. glacialis are very similar
(R2 = 0.80; see supporting information), and for both proxies, peak abundances are found at Sites k11 and
k33. P. glacialis is a very halotolerant sea ice-dwelling dinoflagellate (Montresor et al., 1999; Zheng et al.,
2012). This species was first recorded from land-fast sea ice in McMurdo Sound (Antarctica; Stoecker et al.,
1997), and it has since been found to have a circumpolar distribution (Montresor et al., 2003). The tiny cysts
(<20 μm) produced by this photosynthetic dinoflagellate have, however, rarely been reported from marine
sediment samples. Only Heikkilä et al. (2014, 2016) and Kunz-Pirrung (1998) have reported P. glacialis from
sediment samples, from the Hudson Bay and Laptev Sea, respectively. Note that Kunz-Pirrung (1998) identi-
fied and illustrated P. glacialis cysts as “Acritarch type A”. It is difficult to disentangle the possible effects of the
poor resistance to degradation in the sediment and/or water column and loss during palynological prepara-
tions from its near absence from paleoenvironmental study records (Heikkilä et al., 2016). In the study area
P. glacialis occurs in all samples, except Sites k25 and k8, where overall cyst abundances are extremely low
(<90 cysts g1). Furthermore, the absolute abundance of P. glacialis reaches values in the order of
500 cysts g1 at the shallow Sites k11 (20.8 m) and k33 (19.6 m), which represent a critical area in terms of
local sea ice retreat. P. glacialis is the only dinoflagellate species known today to be able to complete its
biological cycle in the sea ice and produces potentially fossilizable resting cysts. Cysts of P. glacialis further
appear to be well preserved in the Independence Fjord system. We therefore recommend a careful
consideration of their presence in sedimentary archives as they have the potential to represent an extremely
valuable proxy for tracing past sea ice conditions.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 780
The presence of cf. Biecheleria sp. at all studied sites is also noteworthy. These cysts appear to be an important
component of the assemblages from High Arctic fjord regions and Hudson Bay (Heikkilä et al., 2016). At pre-
sent, the ecological preferences of this species and its relation to sea ice cover are poorly known, but its pre-
sence is important in the study area, contributing to the diversity of the assemblages.
4.5. Tracing Arctic-Atlantic Inflow
The overall faunal composition and prevalence of benthic foraminifera is typical for East Greenland fjords and
shelf margins (Andresen et al., 2013; Jennings & Helgadottir, 1994; Perner et al., 2015). The distribution of the
main foraminiferal species further seems to be strongly modulated by the structure of the water column,
which is, in turn, partly shaped by the bathymetry of the study area. The highest concentrations of both cal-
careous benthic and planktic species were found at the deepest sites (k9, k6, k32, and k29), and concentra-
tions dropped considerably with decreasing depth. C. neoteretis and C. reniforme dominate the
assemblages from all sites, except for the shallow Sites k11 and k33. Both species are infaunal and generally
inhabit shallow shelf to deep-sea environments (150–3000 m) (Hald & Korsun, 1997; Seidenkrantz, 1995). In
modern Greenland and Svalbard shelf and fjord environments, C. neoteretis thrives in relatively cool (1 to
2°C), saline (34.9 practical salinity unit, psu) bottom water conditions, and C. reniforme prefers colder water
(<2°C) and also relatively high salinity (>30 psu) environments (Hald & Korsun, 1997; Jennings et al., 2004;
Polyak, Korsun, et al., 2002; Polyak, Levitan, et al., 2002; Steinsund et al., 1994). Thus, in Arctic shelf regions,
both species are commonly associated with the advection of chilled subsurface Atlantic waters (Bartels
et al., 2017; Hald & Korsun, 1997; Jennings et al., 2004; Lubinski et al., 2001; Mackensen & Hald, 1988;
Polyak & Mikhailov, 1996; Polyak, Levitan, et al., 2002; Seidenkrantz et al., 2013). The relatively high abun-
dance of N. pachyderma and the presence of heterotrophic dinocyst species in an area characterized by semi-
perennial sea ice cover (subdomain II) would further support the advection of Atlantic waters through
subsurface currents, as planktic foraminifera likely do not live here and the specimens would all have been
carried to the site from the open shelf.
CTD measurements from the outer fjord region (Dmitrenko et al., 2017) show the presence of subsurface
freshened waters of Pacific origin (Halostad), which overlie a deeper layer of Atlantic-modified Polar Water.
Here an intrusion of relatively saline bottomwaters can clearly be inferred from the microfaunal assemblages.
Also, since the bottom water masses appear to be associated with relatively high abundances of foraminifera
and heterotrophic dinocysts, it is likely that surface conditions supported significant primary productivity.
Finally, in line with the observations of Dmitrenko et al. (2017), the area surrounding Site k32 appears to
be less influenced by this intrusion. This is underlined by lower foraminiferal and dinocyst total abundances
but similar assemblage compositions.
5. Conclusions
Our multiproxy investigation provides a robust foundation for investigating past environmental changes,
particularly regarding the interplay of sea ice, primary production, and hydrography along eastern North
Greenland, one of the most sensitive regions to the ongoing Arctic warming. Furthermore, this study
provides new insights into the distribution of the sea ice species Polarella glacialis and its cysts, which
have the potential to become a useful proxy for reconstructing past seasonal sea ice. Further work on
their preservation potential in sediment archives and during palynological preparation treatments
is needed.
A number of important points can also be made.
1. Microfossil preservation is generally good, providing a strong modern baseline for future studies.
2. Overall modern primary production is low, consistent with limited light availability, and is largely gov-
erned by the sea ice conditions and bathymetry.
3. The microphytobenthos contributes to a significant fraction of the local primary production, especially in
the shallow parts of the fjord.
4. Based on the microfossil and geochemical signal, the study area could be divided into four ecological sub-
domains linked to bathymetry, water mass distribution, sea ice cover, and primary production.
5. The distribution of benthic foraminifera generally reflects the major bottom water masses and can be
used to trace changes in the Arctic inflow in relation with changes in the Arctic sea ice cover.
Journal of Geophysical Research: Biogeosciences 10.1002/2017JG003840
LIMOGES ET AL. 781
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Acknowledgments
The raw data obtained in this study are
available in the supporting information.
This study received financial support
from the Villum Foundation, Denmark
(grant VKR023454 to SRi.). Field work
was funded by the Arctic Research
Centre, Aarhus University, and the
Villum Foundation. The Department of
Environmental Science, Aarhus
University is acknowledged for provid-
ing logistics at Villum Research Station
in North Greenland. A. L. was also
funded by the Fonds de Recherche du
Québec - Nature et technologies
(FRQNT grant 188947). M. H. was also
funded by the Academy of Finland
(grant 296895). SRy was funded by the
Canada Excellence Research Chair pro-
gram (CERC grant 214902). M. S. S. was
funded through the Danish Council for
Independent Research (DFF-FNU grants
0602-02361B, OceanHeat) and the
Independent Research Fund Denmark
(grant 7014-00113B, G-Ice). We thank
Kunuk Lennert, Jesper Hofmann, and
Egon R. Frandsen for technical and
logistical assistance in the field. We also
appreciate outstanding logistical sup-
port from the Station Nord Danish mili-
tary personnel. We further thank Leonid
Polyak and Steffen Aagaard Sørensen
for useful advice on benthic foraminif-
eral identification, Andrzej Witkowski
for help with diatom taxonomy, and
Laurence Dyke for commenting on the
manuscript. This work is a contribution
to the Arctic Science Partnership (ASP)
and the ArcticNet Networks of Centres
of Excellence programs.
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