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The history of seabird colonies and the North Water ecosystem: Contributions from palaeoecological and archaeological evidence

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Abstract

The North Water (NOW) polynya is one of the most productive marine areas of the Arctic and an important breeding area for millions of seabirds. There is, however, little information on the dynamics of the polynya or the bird populations over the long term. Here, we used sediment archives from a lake and peat deposits along the Greenland coast of the NOW polynya to track long-term patterns in the dynamics of the seabird populations. Radiocarbon dates show that the thick-billed murre (Uria lomvia) and the common eider (Somateria mollissima) have been present for at least 5500 cal. years. The first recorded arrival of the little auk (Alle alle) was around 4400 cal. years bp at Annikitsoq, with arrival at Qeqertaq (Salve Ø) colony dated to 3600 cal. years bp. Concentrations of cadmium and phosphorus (both abundant in little auk guano) in the lake and peat cores suggest that there was a period of large variation in bird numbers between 2500 and 1500 cal. years bp. The little auk arrival times show a strong accord with past periods of colder climate and with some aspects of human settlement in the area. Electronic supplementary material The online version of this article (10.1007/s13280-018-1031-1) contains supplementary material, which is available to authorized users.
The history of seabird colonies and the North Water ecosystem:
Contributions from palaeoecological and archaeological evidence
Thomas A. Davidson, Sebastian Wetterich, Kasper L. Johansen, Bjarne Grønnow,
Torben Windirsch, Erik Jeppesen, Jari Syva
¨ranta, Jesper Olsen,
Ivan Gonza
´lez-Bergonzoni, Astrid Strunk, Nicolaj K. Larsen, Hanno Meyer,
Jens Søndergaard, Rune Dietz, Igor Eulears, Anders Mosbech
Abstract The North Water (NOW) polynya is one of the
most productive marine areas of the Arctic and an important
breeding area for millions of seabirds. There is, however,
little information on the dynamics of the polynya or the bird
populations over the long term. Here, we used sediment
archives from a lake and peat deposits along the Greenland
coast of the NOW polynya to track long-term patterns in the
dynamics of the seabird populations. Radiocarbon dates
show that the thick-billed murre (Uria lomvia) and the
common eider (Somateria mollissima) have been present for
at least 5500 cal. years. The first recorded arrival of the little
auk (Alle alle) was around 4400 cal. years BP at Annikitsoq,
with arrival at Qeqertaq (Salve Ø) colony dated to 3600 cal.
years BP. Concentrations of cadmium and phosphorus (both
abundant in little auk guano) in the lake and peat cores
suggest that there was a period of large variation in bird
numbers between 2500 and 1500 cal. years BP. The little auk
arrival times show a strong accord with past periods of colder
climate and with some aspects of human settlement in the
area.
Keywords d
15
NGreenland Little auk Palaeoecology
Palaeolmnology
INTRODUCTION
The North Water polynya (NOW) marine ecosystem is host
to the largest seabird populations in Greenland. The com-
munity is diverse with 14 regular breeders and a few more
species occurring as non-breeding summer visitors. The
seabirds are almost exclusively present in the spring and
summer, with the exception of some black guillemots
(Cepphus grylle), which can winter in the NOW. Here, we
focus on the three most abundant seabird species: the little
auk (Alle alle), the thick-billed murre (Uria lomvia), and
the common eider (Somateria mollissima) (Fig. 1). These
species have the largest biomass and the greatest impor-
tance of the locally harvested seabird species. The breeding
population of the little auk in the NOW region is immense,
estimated at 33 million pairs (Boertmann and Mosbech
1998; Egevang et al. 2003) and corresponding to more than
80% of the global breeding population. The thick-billed
murre colonies along the Greenland coast of the NOW
consist of approximately 225 000 breeding pairs (Merkel
et al. 2014) representing two thirds of the breeding popu-
lation in Greenland. Currently, the NOW is the only area in
Greenland where the thick-billed murre population is not in
decline. The common eider breeding population in the
NOW was estimated at 25–30 000 pairs in 2009, and has
had a fivefold increase between 1997 and 2009 (Burnham
et al. 2012). This increase is related to the stricter harvest
regulations which came into force in 2001, especially the
restricting of spring harvest near the colonies, which
sparked a general population increase in all West Green-
land populations following a decline in the 20th century
related to overharvesting (Merkel 2010). Thus, despite the
large uncertainties in the estimates, the NOW is clearly of
great international importance to the species.
Information on the past seabird populations in the High
Arctic is generally scarce, with a few investigations pro-
viding some information on past populations. A study from
the east coast of Greenland (Wagner and Melles 2001) used
lake sediments to track the history of a nearby little auk
colony over much of the Holocene. They found that large
numbers of birds arrived ca. 7500 cal. year BP, but suggest
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s13280-018-1031-1) contains supple-
mentary material, which is available to authorized users.
ÓThe Author(s) 2018. This article is an open access publication
www.kva.se/en 123
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https://doi.org/10.1007/s13280-018-1031-1
Booth Sund (BS1)
2.2 cal. ka BP
Kuukkat (RF1)
2.2 cal. ka BP
Annikitsoq (GL3)
4.4 cal. ka BP
Qoororsuaq (SD1)
2.8 cal. ka BP
Appat (SI1)
5.6 cal. ka BP
Iterlassuup Qeqertaarsui (TSB2)
5.5 cal. ka BP
Qeqertaq (NOW5a)
3.6 cal. ka BP
Pituffik
Qaanaaq Qeqertat
Siorapaluk
Savissivik
02040Km
Coring sites
Thick-billed murre
0 - 10000
10000 - 50000
50000 - 110000
Common eider
1 - 100
100 - 1000
1000 - 2000
2001 - 4500
Little auk
Fig. 1 Overview map of the coring sites and breeding colonies of little auk, Qoororsuaq (Søkongedalen—SD1), Annikitsoq, Great Lake—GL-3
and Kuukkat (Robertson fjord—RF1), Qeqertaq (Salve Ø—NOW5a) thick-billed murre (Saunders Ø—SI-1) and common eider Booth Sund—
BS-1 and Iterlassuup Qeqertaarsui (Three Sister Bess—TSB-2). For the latter two species, colony sizes are given as number of breeding pairs.
Colony data come from Boertmann and Mosbech (1998) and The Greenland Seabird Colony Register, maintained by Danish Center for
Environment and Energy, Aarhus University, and Greenland Institute of Natural Resources. The estimated date of arrival is the median cal.
ka years BP calculated from
14
C dates and age modelling (see ‘Materials and methods’’)
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123 ÓThe Author(s) 2018. This article is an open access publication
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that they have not been continuously present since. The
colony appears to have been present there from 7500 to
1900 cal. BP, from 1000 to 500 cal. BP, and then again over
the last 100 years to the present. The authors suggest that
the absence of birds was related to periods of colder cli-
mate in East Greenland. Expanding to the wider Arctic,
there is evidence of the presence of Arctic tern (Sterna
paradisaea), glaucous gull (Larus hyperboreus), and bar-
nacle goose (Branta leucopsis) in Svalbard as far back as
9400 cal. BP (Yuan et al. 2009). Palaeoecological studies in
the Canadian Arctic found no evidence of variation in the
northern fulmar (Fulmarus glacialis) colonies over the
short time period (maximum 200 years) covered by the
sediment cores (Michelutti et al. 2009; Keatley et al. 2011).
Work on peat deposits in Hudson Bay showed that the
thick-billed murre colonies were at least 1500 and
3800 years old (Gaston and Donaldson 1995). In the NOW
area, there is very little information on the past populations
of seabirds. A study using the sedimentary archive of peat
deposits on the Carey Islands demonstrated the presence of
a seabird colony, probably the Atlantic puffin (Fratercula
arctica), during the period from c. 7100 to 5100 cal. BP
(Bennike et al. 2007). Apart from this study, there is no
information available on the arrival times and change in
abundance of seabirds in the NOW within a long-term
perspective.
Seabirds feed in the marine ecosystem, but use the ter-
restrial environment for breeding. As a result, some species
transport large quantities of nutrients from sea to land,
which transforms the landscape around the colonies,
leaving unequivocal signatures of their presence (Gonza
´-
lez-Bergonzoni et al. 2017; Mosbech et al. 2018). These
signatures in the landscape, both terrestrial and fresh water,
open up the possibility of investigating past dynamics of
seabird populations. The reliance of our three species upon
the marine ecosystem varies and largely depends on their
different feeding strategies and habitats.
All three species require open water in which to feed
upon arrival in spring. Thus, all three species benefit from
the early season open water of the polynya. The little auk is
a zooplanktivore and is highly dependent on the abundant
copepods within their diving range (approx. 50 m) and
foraging range from the colonies (approx. 100 km). They
feed these large, lipid-rich copepods to their chicks
(Frandsen et al. 2014) and also rely on the copepods for
their own foraging, supplemented with larger zooplankton
(Karnovsky et al. 2008). The high density of large Calanus
copepods is a key factor driving the abundance of the little
auk colonies in the NOW area. The diet of the adult thick-
billed murre during summer is dominated by the pelagic
amphipod (Parathemisto libellula) and arctic cod (Bore-
ogadus saida), supplemented with a variety of other
invertebrates and fish (Gaston and Hipfner 2000; Kar-
novsky et al. 2008). It performs pursuit dives down to
150 m of depth within a foraging range of approx. 110 km
around the breeding colonies (Mosbech et al., unpublished
GPS-tracking data). Even though adult murres feed on a
variety of food items, they are strongly dependent on
abundance of forage fish for breeding success. The murre is
a ‘‘single-prey loader’’, capable of bringing home only one
food item at a time to feed its chick, and this renders food
items smaller than fish energetically unsuitable for raising
the chick. (Elliott et al. 2009). The main diet of nestlings in
Canadian Arctic is arctic cod, but also capelin (Mallotus
villosus) and sculpin (Triglops,Gymnocanthus,Myoxo-
cephalus spp.) (Elliott et al. 2009). In contrast to the little
auk and the thick-billed murre, the common eider is
exclusively a benthic feeder, targeting mussels, crus-
taceans, and polychaetes at water depths often below 10 m
(Merkel et al. 2007). In the spring, the eider needs open
water around the small islands and skerries on which they
breed to ensure that foxes are excluded. After laying the
eggs, only the female attends the nest, and neither the
female nor the chicks feed during the brooding period. This
leaves a much smaller nutrient imprint in the colonies, but
as males and non-breeding eiders also spend time in the
colonies, some nutrients are deposited on land.
Analysis of the NOW food web, using stable isotopes,
has further demonstrated that the three seabirds investi-
gated here are linked to the marine ecosystem in different
ways (Hobson et al. 2002). Thus, each species may dis-
play a different degree of dependence on the particular
ecological conditions of the polynya, which is in part
reflected by the distribution around Greenland and the
wider Arctic. Polynyas are characterised by sustained
periods (spring through summer) of open water and rel-
atively high levels of primary production, from which all
seabirds potentially benefit. However, whilst the common
eider and the thick-billed murre are found in many areas
around Greenland, large little auk colonies are found
solely in relation to productive polynyas (NOW and
Scoresbysund).
Here, we set out to elucidate the history of the seabird
populations in the NOW area. Given the dependence of the
little auk on the polynya, it may be possible to use infor-
mation on the past population dynamics to provide insights
into the history of the polynya itself. To do this, we used
palaeoecological methods to investigate the history of
seabird colonies on the east side of the NOW. The key
questions were: (1) How long have the colonies been
present? (2) Is there any evidence of variation over time?
And (3) how do the arrival times and any variation in
abundance over time relate to climatic variation and the
history of human settlement in the region?
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MATERIALS AND METHODS
Field methods
Fieldwork was undertaken in the summers of 2014 and
2015 with sedimentary archives collected from a lake and
peat deposits within seabird colonies.
Core collection
A sediment core was extractedfrom a lake within a large little
auk colony on Qeqertaq (Salve Ø) (Fig. 1). Lake coring was
carried out using a highly portable percussion corer, which
can be operated from a single boat (Chambers and Cameron
2001). Details of core locations, length, and depth of water at
the coring site are given in Table 1. At Qeqertaq, rafting ice
prevented access to the deepest area of the lake (24 m) and so
a relatively deep flat-bottomed area (17 m) was cored. Cores
from peat deposits were extracted at sites within a) little auk
colonies at Qoororsuaq (SD1), Annikitsoq (GL3), and
Kuukkat (RF1); b) from eider duck colonies at Iterlassuup
Qeqertaarsui (TSB2) and Booth Sund (BS1) and c) below a
large thick-billed murre colony on Appat (Saunders Ø)
(Fig. 1). The peat cores were largely permafrost and collected
using an SIPRE corer (Terasmae 1963) driven by an STIHL
BT-121 two-stroke engine (details of the core location and
depth are given in Table 1). At Appat and Annikitsoq, where
there was a significant development of high-centre ice-wedge
polygons, the centre of a polygon was selected for coring. In
all other cases, the flattest area available, furthest away from
the boulder fields and cliffs, was selected for coring to reduce
the likelihood of (a) slumping and (b) large numbers of
stones/rocks in the sample, respectively.
Laboratory methods
Core dating
Samples for radiocarbon dating were selected from the cores
to provide either a reliable chronology of the entire sequence
or, in the case of some of the peat cores, to establish the oldest
age of the peat development. This estimate of the date peat
Table 1 Lake and peat cores locations and detail
Lake cores
Code Location Core length (m) Water depth (m) Point of transition
Salva Ø, 04/08/2014
NOW5a 76.044214 1.46 17 1.20
-65.984154
Peat cores
Code Location Material Total depth below
surface [cm b.s.]
Remarks
Three Sister Bees, 24/07/15
TSB-2 76.76524 Pits and core 0–112 Active layer and
permafrost
(3 subprofiles)
-70.26229
Booth Sund, 25/07/15
BS-1 76.92206 Exposure 0–75 Active layer
-70.080611
Saunders Island, 27/07/2015
SI-1 76.56908 Pit and core 0–197 Active layer and
permafrost
-70.04099
Søkongedalen, 28/07/15
SD-1 76.26716 Pit and core 0–97 Active layer and
permafrost
-68.97227
Annikitsoq 31/07/15
GL-3 76.03288 Pit and core 0–320 Active layer and
permafrost
-67.61811
Robertson Fjord, 07/08/15
RF-1 77.74599 Pit and core 0–99 Active layer and
permafrost
-70.42283
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began to form at the site is assumed to be the date of arrival of
the bird colony. In the lake core, there was a clear transition in
a range of indicators marking the pointof bird arrival (Fig. 2).
Above this change point, there were abundant terrestrial
mosses from the families of the Splachnacea (dung mosses),
Polytrichacaea,Pottiaceae, and from the genus Distichium
(from the family Ditrichacea), which were sampled for
14
C
dating. Below the transition, terrestrial macrofossils were rare
or absent, and thus, bulk sediment samples (humic acid
extraction) were used for radiocarbon dating. Use of bulk
samples can be problematic as it can give anomalously old
ages, if old carbon has been incorporated into the system
(Olsen et al. 2012). For the permafrost peat samples, organic
matter free of shell material, likely of marine origin, was
selected for dating. A full list of samples analysed and used to
derive age models for the lake and peat cores is given in
Table 2. The samples were dated at the Aarhus AMS
14
C
Centre at Aarhus University (AARAMS). The radiocarbon
ages of the samples from the lake and the six peat cores were
converted into calendar years using the IntCal13 calibration
curve (Reimer et al. 2016). Age models for the cores were
calculated using the R routine ‘‘Bacon’’, a Bayesian age-depth
modelling approach (Blaauw and Christen 2011). Ages
reported and used in the figures are median modelled ages in
cal. years BP (before present),
1
with the minimum and the
maximum of the 95% probability intervals are given in the text
and in Table 2.
Peat core sampling
The frozen peat cores were first split at approx. 8 °C and
sectioned into 2–4 cm slices and freeze-dried (Zirbus
Subliminator 3–4–5). The gravimetric ice content was
measured as the weight difference between fresh and
freeze-dried bulk sediment samples, and it is expressed as
ice content in weight percentage (wt%). The samples were
powdered using a Fritsch pulverisette 5-mill equipped with
agate jars. To quantify the total contents of carbon (TC)
and nitrogen (TN), each sample was prepared twice and
measurements were carried out on an elementar vario EL
III elemental analyser. About 5 mg of the sample were put
into tin capsules, combined with a small amount of tung-
sten(VI) oxide to catalyze the full combustion of the
sample in the varioEL. To calibrate the measurement, a set
of calibration standards consisting of acetanilide, sucrose,
and 30% EDTA was used. In addition, every 15 samples, a
control sequence of 30% EDTA, 20% EDTA, 12% calcium
carbonate, IVA33802150 (soil standard, C =6.7%,
N=0.5%, S =1.0%), and soil standard 1 (C =3.5%,
N=0.216%) was measured. The accuracy of the mea-
surement was ±0.1% for nitrogen and ±0.05% for
carbon.
To differentiate the total organic carbon (TOC) content,
the samples were measured using an elementar varioMAX
C elemental analyser. The sample mass to use was calcu-
lated from the total carbon content, giving weights between
15 and 20 mg, which were filled into steel crucibles. 30%
Fig. 2 The NOW5a lake core from Qeqertaq (Salve Ø), selected indicators likely to be influenced by the presence of seabirds
1
Radiocarbon dates use the proportion of C that is
14
C to produce a
radiocarbon age, with associated errors. However the production of
14
C depends on solar activity, which has varied over time. Calibrated
ages use a range of archives to reconstruct variation in
14
C over time
and therefore allow us to calibrate a
14
C date to a calendar date. This
can be expressed as BC\AD or as age expressed as calibrated years
before present or BP.
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Table 2 Description of samples dated,
14
C ages and modelled ages in cal. years BP from lakes and peat cores in the NOW, N.W. Greenland
Core code Type Depth Material Lab No Age Modelled dates
Modelled median
age
95% probability
intervals
(
14
CBP) (cal. yr BP) (cal. yr BP)
Little Auk
Qeqertaq (Salva Ø)
NOW5a Lake 14.5 Terrestrial macrofossil AAR24215 943 ±29 840 744 to 934
NOW 5 Lake 28.5 Terrestrial macrofossil AAR24216 1337 ±31 1281 1178 to 1352
NOW5a Lake 42.5 Terrestrial macrofossil AAR24217 1942 ±54 1782 1599 to 1946
NOW5a Lake 56.5 Terrestrial macrofossil AAR24218 2029 ±28 2025 1929 to 2152
NOW5a Lake 70.5 Terrestrial macrofossil AAR24219 2261 ±31 2282 2159 to 2393
NOW5a Lake 84.5 Terrestrial macrofossil AAR24220 2519 ±31 2635 2455 to 2769
NOW5a Lake 98.5 Terrestrial macrofossil AAR24221 3105 ±31 3256 3050 to 3391
NOW5a Lake 114.5 Terrestrial macrofossil AAR29954 3265 ±41 3575 3425 to 3771
NOW5a Lake 122.5 Bulk AAR24730 3695 ±28 3846 3753 to 4037
NOW5a Lake 133.5 Bulk AAR24731 5184 ±31 5308 4883 to 5799
NOW5a Lake 144.5 Bulk AAR24732 7283 ±30 7819 7054 to 8184
Transition point 3645 3510 to 3812
Annikitsoq
GL3 Permafrost 5–10 Peat AAR24684 652 ±32 703.3 643.5 to 788
GL3 Permafrost 48–52 Peat AAR24685 2474 ±26 2524.2 2439.7 to 2608.3
GL3 Permafrost 87–91 Peat AAR24686 2993 ±33 3145.4 3076.4 to 3213.7
GL3 Permafrost 127–131 Peat AAR24687 3365 ±28 3536.1 3503 to 3587.5
GL3 Permafrost 149–153 Peat AAR24688 3417 ±27 3658 3622.5 to 3695.1
GL3 Permafrost 191–195 Peat AAR24689 3553 ±41 3821.9 3784.3 to 3872.4
GL3 Permafrost 227–231 Peat AAR24709 3605 ±26 3963 3930 to 3994
GL3 Permafrost 248–252 Peat AAR24690 3720 ±31 4046.1 4021.2 to 4083.6
GL3 Permafrost 267–271 Peat AAR24691 3568 ±39 4112.5 4086.3 to 4170.2
GL3 Permafrost 300–305 Peat AAR24692 3802 ±41 4305.1 4254.2 to 4367.7
GL3 Permafrost 316–320 Peat AAR24693 3855 ±30 4409.9 4365.3 to 4444.2
Kuukkat (Robertson’s fjord)
RF1 Permafrost 5–10 Peat AAR24694 Pre 1960 9.8 -32.9 to 77.7
RF1 Permafrost 25–29 Peat AAR24695 250 ±27 344.8 293 to 418.4
RF1 Permafrost 49–54 Peat AAR24696 794 ±25 769.8 738.8 to 816.5
RF1 Permafrost 75–80 Peat AAR24697 1537 ±34 1520.5 1448.1 to 1576.8
RF1 Permafrost 95–99 Peat AAR24698 2223 ±34 2247.3 2176.5 to 2317.8
Qoororsuaq (Søkongdale)
SD1 Permafrost 10–12 Peat AAR24705 225 ±30 229.1 165.9 to 345.2
SD1 Permafrost 48–52 Peat AAR24706 2074 ±26 2027.7 1725 to 2116
SD1 Permafrost 70–74 Peat AAR24707 2553 ±28 2231.2 2043 to 2379.9
SD1 Permafrost 70–74 Peat AAR24707 2280 ±27 2761.2 2706-2815
Thick-billed Murre
Appat (Saunders Island)
SI1 Permafrost 0–10 Peat AAR24699 Pre 1960 51 -19.1 to 167.8
SI1 Permafrost 42–46 Peat AAR24700 1114 ±27 1157.9 1084.5 to 1254.3
SI1 Permafrost 64–68 Peat AAR24701 2912 ±27 3133.6 3061.8 to 3221.2
SI1 Permafrost 103–107 Peat AAR24702 4182 ±26 4702.3 4624.5 to 4767.9
SI1 Permafrost 144–148 Peat AAR24703 4530 ±27 5185.1 5132.8 to 5246.8
SI1 Permafrost 191–195 Peat AAR24704 4851 ±27 5648.1 5613.1 to 5705
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glutamate, pure glutamate, and 2:3 glutamate were used for
calibration. The control sequence consisted of 2:3 gluta-
mate, 10:40 glutamate, 5:45 glutamate, and 1:19 glutamate,
repeated every 15 samples. The accuracy of the measure-
ment was ±0.1%. Subsequently, a ratio was calculated
from TOC and TN, referred to as C/N.
Stable isotopes
Stable isotopes of C and N were analysed as they have been
shown to provide evidence of the influence of marine derived
nutrients from a range of sources in terrestrial and freshwater
ecosystems, using both contemporary (Gonza
´lez-Ber-
gonzoni et al. 2017) and palaeoecological approaches (Fin-
ney et al. 2002; Michelutti et al. 2013). For the analysis of the
stable isotopes of C and N in the peat cores, carbonate was
first removed from the samples. About 2 g of each sample
was transferred into 100 ml Erlenmeyer glass flasks, dosed
with 20 ml 1.3 mol hydrochloric acid, and heated at 97.7 °C
for 3 h. To get rid of the chloride ions as they would interfere
with the isotope analysis, the flasks were repeatedly filled up
with purified water and allowed to settle until the chloride
content was\500 ppm. To regain a dry state, the sample
solution was then filtered under vacuum using GE Health-
care Life Sciences Whatman glass microfiber filters, dried at
50 °C and subsequently ground by hand before being trans-
ferred into plastic jars. Preparation for measurement was
executed by placing the samples in tin capsules, where each
target weight was calculated as 20/TOC. Stable carbon
(d
13
C) and nitrogen (d
15
N) isotope analysis was undertaken
using a Thermo Scientific Delta V Advantage Isotope Ratio
MS supplemented with a Flash 2000 Organic Elemental
Analyser using helium as a carrier gas. The accuracy was
better than ±0.15%for d
13
C and ±0.2%for d
15
N.
In the lake core, samples were taken at 2 cm intervals,
freeze-dried for 48 h, and ground into fine powder. Test
samples were analysed to determine the appropriate mass
of sample for analysis, which was 3 mg post-transition
point and 15 mg pre-transition point. The samples were
packed into tin cups and sent to UC Davies Stable Isotope
Facilities, California, USA, where they were analysed
following the standard procedures (see http://
stableisotopefacility.ucdavis.edu). It was not necessary to
pre-treat the samples to remove carbonates owing to the
very low pH of the lake pH\4.
Metal analysis ICP-MS
Metal concentrations in sediments have been used to track
seabird influence on land and fresh waters in the previous
studies (Outridge et al. 2016). Cadmium (Cd) and phos-
phorus (P) are more abundant in marine waters and become
concentrated up the food web, and these elements have
been used to track seabird populations in the previous
studies (Wagner and Melles 2001; Bennike et al. 2007).
Samples of peat were analysed for trace element com-
position at the accredited trace element laboratory at
Department of Bioscience, Aarhus University, in Roskilde,
Denmark. Peat samples were dried and samples consisting
of c. 0.1 g dry weight were microwave digested in Teflon
bombs in 2 ml/2 ml Merck Suprapure HNO
3
/MilliQ water
using an Anton Paar Multiwave 3000 oven.
Digestion solutions from peat were diluted with MilliQ
water and analysed for 61 elements including phosphorus
(P), titanium (Ti), and cadmium (Cd) (only P, Ti, and Cd
are presented in this study) using an Agilent 7900 ICP-MS.
The analytical quality was checked by analysing blanks,
duplicates, and a selection of Certified Reference Materials
(CRM) along with the samples. For peat samples, the CRM
included MESS-4, PACS-2, and BCR-482 (two marine
sediments and a lichen, respectively). Detection limits for
P, Ti, and Cd (determined as 3 SD on blank values) were
10, 0.06, and 0.0009 mg/kg dry weight, respectively.
Scanning XRF analysis
The scanning X-ray fluorescence is a non-destructive
method of measuring metal concentration of sediment
Table 2 continued
Core code Type Depth Material Lab No Age Modelled dates
Modelled median
age
95% probability
intervals
(
14
CBP) (cal. yr BP) (cal. yr BP)
Common Eider
Iterlassuup Qeqertaarsui (Three Sister Bess)
TSB2 Permafrost 80–84 Peat ARR25292 2891 ±45 2954.3 2833.5 to 3079.8
TSB2 Permafrost 110–112 Peat ARR24682 4804 ±29 5486.6 5391.6 to 5558.7
Booth Sund
BS1 Exposure 45–49 Peat ARR25294 989 ±34 970.4 897.6 to 1035.1
BS1 Exposure 74–75 Peat ARR25293 2337 ±35 2235.3 2115.5 to 2359.7
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cores at potentially very high resolution, down to 0.1 mm
scale. The lake sediment core was split along its length
then placed in an ITRAX core scanner to obtain high-res-
olution pictures and measure micro-XRF. The XRF scans
were made at the Aarhus University core-scanning facility
with a molybdenum tube set at 30 kV and 30 mA with a
dwell time of 4 s. Prior to analysis, the sediment surface
was flattened and covered with a 4 mm ultralene film. A
step size of 0.1 mm was selected to capture possible ele-
mental variations even in small laminations.
RESULTS
Core chronologies and markers of bird arrival
The radiocarbon samples and
14
C dates from the peat
and lake cores collected are given in Table 2, as are the
calibrated modelled ages and the 95% confidence inter-
vals as determined using the bayesian age depth mod-
elling approach (Blaauw and Christen 2011) (Electronic
Supplementary Material, Figs. S1S7). Elemental com-
position, stable isotope ratios of C and N and selected
geochemistry (Fig. 2) combined with
14
C dating and
modelling, estimate the arrival time of the little auk
colonies at Qeqertaq (Salve Ø; NOW5a) to 3650 cal.
years BP, with the 95% probability intervals ranging from
3500 to 3800 cal. years BP. For the peat cores, dating the
base of the core provides the estimate of arrival time,
since the formation of the peat is dependent on the
marine derived nutrients (MDN) supplied by the birds
(Bennike et al. 2007) as there is no peat formation in the
region in the absence of current or past bird influence
(Mosbech et al. 2018). At Annikitsoq (GL3), the median
estimate of little auk arrival was 4400 cal. years BP, with
the 95% probability intervals ranging from 4360 to
4440 cal. years BP. At the little auk colonies at Qooror-
suaq and Kuukkat, the median basal dates of the peat
cores were 2760 cal. years BP (95% probability interval
of 2710–2810) and 2250 cal. years BP (95% probability
interval of 2180–2320), respectively.
Based on the basal dates of the peat cores, and the
age-depth models (albeit based on few samples), we
estimate the arrival of the common eider at Iterlassuup
Qeqertaarsui (Three Sister Bess) to be 5490 (95%
probability interval of 5400–5560) and at Booth Sund
2240 (95% probability interval of 2100–2400) cal. years
BP. The basal date of the peat deposit beneath the thick-
billed murre colony at Appat (Saunders Ø) suggests an
arrival date of 5650 (95% probability interval of
5600–5700) cal. years BP.
Sediment accumulation rates
There was considerable variation in sediment accumulation
rates, both between the localities and within individual
records. At Appat (Saunders Ø), there was a very fast
accumulation rate between 6000 and 4500 cal. years BP
(Fig. 3b), and then a slight slowing down of accumulation
around 4500, which lasted to 2900 cal. years BP. There
followed a further large decrease to a very low accumu-
lation rate of around 90 yrs/cm from 2700 to around
1000 cal. years BP, where there was a very marked increase
in accumulation rates.
At the common eider colonies, the resolution of
14
C
sampling was too low to make the determination of accu-
mulation rates possible. For the little auk colonies, how-
ever, the peat cores provide some information. At
Annikitisoq (Fig. 3a), the record is divided in two around
2400 cal. years BP with high accumulation rates before this
point, and low accumulation rates after. There was also
indication of some change in the period 4400–2400 cal.
years BP, with faster accumulation around 4200 cal. years
BP which was then stable with some slight decreases in rate
before the vary large decrease in accumulation rate at
2400 cal. years BP. At Kuukkat and Qoororsuaq (SD1), the
dating models are based on too few samples to give
meaningful accumulation rates.
The accumulation rates of the NOW5a core (Fig. 2)
show considerable variation with a very large increase at
the arrival of the little auk at 3650 cal. years BP. There is
then a reduction centred around 3000 cal. years BP with
higher accumulation rates at 2700 cal. years BP and then
around again at circa 1900 cal. years BP.
The lake core record of little auk presence
and abundance at Qeqertaq (Salve Ø)
Figure 2illustrates selected parameters from the Qeqertaq
(Salve Ø—NOW5a) lake core likely to reflect the presence
of seabirds, including ratios of XRF generated cadmium
(Cd), phosphorus (P), and titanium (Ti) data, along with
d
15
N, d
13
C, %C, and %N of the sediments. The magnitude
of change reflected by the sedimentary record at the time of
bird arrival was unprecedented and likely changed all
aspects of the ecosystem structure and function as was
observed present day (Gonza
´lez-Bergonzoni et al. 2017)
(Fig. 2). Organic carbon content increased from around 5%
C content to over 40%, demonstrating a large change in the
primary productivity of the lake. The shift in d
15
N values
reflects wholesale alteration of the nutrient sources and
provides an unequivocal marker of the input of MDN
(Gonza
´lez-Bergonzoni et al. 2017) which marks the point
of arrival of the little auk colony. Compared with the
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transition associated with the arrival of the little auk in the
catchment, the variation afterwards is relatively small. The
ratios of both P and Cd to Ti show a peak centred around
3250 cal. years BP covering around 250 years. There fol-
lows a relatively sharp decline in both P/Ti and Cd/Ti to
the year 3000 cal. years BP; this coincides with a fall in the
Fig. 3 a Selected proxies of seabird activity from the Little auk peat core records for GL3 Annikitisoq, SD1 Qoororsuaq (Søkongdale), and RF1
Kuukkat (Robertson’s fjord). bSelected proxies of seabird activity for thick-billed murres from core SI1 Appat (Saunders Ø) and eider duck
records from the peat cores TSB2, Iterlassuup Qeqertaarsui, and BS1 at Booth Sound
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%N composition. From 3000 cal. years BP to 2300 cal.
years BP, there is a period where the loess smoothers of the
Cd/Ti and P/Ti vary little, but end in a peak at circa
2300 cal. years BP. Whilst the loess smoothers do not vary a
great deal over this time period, there is a relatively large
amount of variation around the smoother. Over this time
period of 3000 cal. years BP to 2300 cal. Years, BP d
15
N and
d
13
C were stable and relatively high, whereas % N grad-
ually increases, but all three came to a peak around
2400–2300 cal. years BP. Thereafter, all these indicators
Fig. 3 continued
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show a marked fall ca. 2100 cal. years BP for a relatively
short period, in the case of d
13
C and %N. In general, after
2000 cal. years, BP values of all the little auk indicators
become more stable with fewer high values and a general
decline to consistently low levels post-1900 cal. years BP
until 1500 cal. years when there is a rise in Cd/Ti, P/Ti,
d
13
C, and % N around BP. Thereafter, there is a decline at
around 1200 cal. years BP and then relative stability with a
slight upward trend to the present.
Peat cores
Annikitsoq (GL3), Qoororsuaq (SD1), and Kuukkat (RF1)
and the little auk
Figure 3a shows peat core profiles for the three little auk
colonies sampled. The core from Annikitisoq (GL3) covers
the longest time period with a basal date, reflecting the
little auk colonisation, of 4400 cal. years BP. From the start
of peat formation to ca. 3500 cal. years BP, there was a
period of relatively large variation in d
15
N with a slow
increase to around 4100 then a gradual decline to 3800
where it remained stable and relatively low until a sharp
and brief increase at around 3600 cal. years BP, followed by
a sharp fall to a low at 3400 cal. years BP. This early period
of the core was also characterised by a gradual decline in N
from 4400 cal. years BP to very low levels at around
3500 cal. years BP; during this time, TOC was relatively
stable, and thus, the C:N ratio gradually increased over this
time peaking at exceptionally high values of nearly 100 at
around 3500 cal. years BP when N was at its lowest con-
centration. As stated, the records of P, Cd, and their ratios
with Ti may provide some information on variation in bird
influence at the site (Wagner and Melles 2001). Phosphorus
was initially extremely high and matched the variation in
the d
15
N record until circa 3800 cal. years BP, where there
was a large decline in d
15
N, d
13
C and P but a large increase
in Cd and an increase in Ti, TOC and TN. This large
excursion around 3900 cal. years BP may not be connected
to inputs from the bird community as the MDN would also
cause the P and d
15
N to rise—which did not occur. Apart
from this large excursion, there was good agreement
between P, Cd, and their ratios Ti and d
15
N in the early
record with declines around 3800 cal. years BP. There fol-
lowed a rise in d
15
N at circa 3600 cal. years which was
reflected in Cd and Cd/Ti ratios, and in the P/Ti ratios, the
latter is difficult to see in Fig. 3a as the previous levels
were so high. These previously very high values of P at the
bottom of the record, associated with very high accumu-
lation rates, suggest abundant seabirds for at least
400 years. This early period of large variation was fol-
lowed by a period of stable values from 3500 cal. years BP
to 2500 cal. years BP at which point d
15
N fell to its lowest
value in the record. At this time, P and P/Ti fell to zero
before rising slightly at 2200 cal. years BP, thereafter,
remaining rather low and falling to zero again around
1200 cal. years BP. In contrast at 2500 cal. Years, BP Cd/Ti
rose a little. At Annikitisoq, there was what appears to have
been an input of terrestrial minerogenic material 1500 cal.
years BP as a number of indicators, such as P and Ti, both
rise sharply, whereas Cd did not and there are no dramatic
changes in any of the other indicators (d
15
N, TN, and
d
13
C).
The records from Qoororsuaq (SD1) and Kuukkat (RF1)
both cover a much shorter time period. At Qoororsuaq, the
resolution of sampling of C and N, isotopes, and geo-
chemistry towards the top of the core is lower, and the age-
depth models are based on fewer samples and may thus
lack the temporal resolution to accurately identify points of
variation. However, SD1 shows some agreement with the
longer record from Annikitsoq in that the data suggest the
greatest variability between 2700 and 2000 cal. years BP,
while TN values suggest a decline in bird input from
around 2200 to 2000. The data on Cd and P are not as clear,
suggesting elevated inputs between 2400 and 2200 cal.
years BP. At Kuukkat, the variation in the parameters
measured is rather low, suggesting a rather stable popula-
tion over time, but, in the absence of geochemical data, this
is less certain.
Appat (SI1) and the thick-billed murre
In comparison with the records from the little auk colonies,
the peat core from the thick-billed murre colony at Appat
(Saunders Ø) shows less variability over time. The record
indicates changes in peat productivity/accumulation rates
with high TOC content at the base of the core around
5000 cal. years BP, where the climate was likely warm
(Briner et al. 2016; Lecavalier et al. 2017). Over the initial
period of high accumulation to around 4500 cal. years BP,
d
13
C and d
15
N show a large degree of variation; TOC and
TN also show some variation with rising values, perhaps,
suggesting increased marine inputs. Post 5000 cal. years BP,
TOC and TN start to vary, initiated by a sharp drop in
TOC, which would indicate a decline in productivity fol-
lowed by marked variation in TOC content until around
3400 cal. years BP. In general, however, the record indi-
cates the consistent presence of seabirds with little change.
However, the decline in d
15
N at the top of the core is
notable.
Booth Sund (BS1) Iterlassuup Qeqertaarsui (TSB2)
and the common eider
The two records from common eider colonies cover very
different time spans. At Booth Sund, the record covers
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around 2200 years and shows very little variation, though
there are increases in TN, TOC, and d
15
N over the last
800 years, and, perhaps, more markedly over the last
400 years. The record from Iterlassuup Qeqertaarsui (Three
Sister Bess; TSB2) is much longer, covering around
5500 years. With a couple of exceptions, stable isotope
values and geochemistry also indicate a relatively
stable record in this case. In contrast with the other records,
the accumulation rate was relatively low soon after the start
of the record, with a large reduction around 3000 cal. years
BP. This fall was coincident with a rise in d
15
N and to a
lesser extent a rise in TN and TOC. After this period, post-
2700 cal. years BP, there was an increase in the elements
associated with the transport of MDN (P and Cd and their
ratios with Ti).
Synthesis of data on change in little auk populations
The oldest recorded date of arrival of the little auk found here
was the 4400 cal. years BP at Annikitsoq, and the dates of
arrival at the other sites are 3600 cal. years BP at Qeqertaq
(Salve Ø), 2700 cal. BP at Qoororsuaq, and 2200 cal. years BP
at Kuukkat (Fig. 1). Synthesising the data from the different
indicators of little auk abundance (d
15
N, d
13
C in the lake
core, Cd/Ti and P/Ti) from the peat core at Annikitsoq sug-
gests that, initially, variation in bird numbers was high with a
fall from around 4000 to 3800 cal. years BP and then a rise
again at 3600 cal. years BP. This latter rise corresponds to the
date of colony formation at Qeqertaq. After 3500 cal. years
BP at Annikitsoq, the d
15
N variation does not suggest large
amounts of variation in bird numbers; however, the large
shift in accumulation rate at 2500 cal. years BP could indicate
a large decline in nutrient input, which coincided with P
concentrations falling to zero. The lake core from Qeqertaq
provides much greater temporal resolution than the peat
cores and this record indicates relatively high bird abundance
until around 3000 cal. years BP followed by relatively large
variability in the input of MDN (as indicated d
15
N, d
13
C, Cd/
Ti, and P/Ti) in the period from 3000 to 2000 cal. years BP,
but with a peak centred around 2200 cal. years BP. This latter
date correspond well with the arrival time of little auks at
Kuukkat.
The peat core from Annikitsoq suggests a decline in bird
numbers around 3800 cal. years BP, and the P and P/Ti
record may suggest a complete absence from 2500 to
2200 cal. BP and low numbers from 1700 to 1200 cal. years
BP. The higher resolution record from the lake at Qeqertaq
shows much greater variation than the peat cores. P, Cd,
and their Ti ratios indicate a low input of MDN at Qeqertaq
from around 1700 cal. years BP, which persisted until
1500 cal. years BP. After this point, there were no extended
periods of low P or Cd, suggesting that the little auks were
consistently present.
DISCUSSION
Identification of the point of arrival of seabirds in a par-
ticular catchment is relatively straightforward as the
transport of marine-derived nutrients (MDN) transforms
the landscape (Gonza
´lez-Bergonzoni et al. 2017; Mosbech
et al. 2018). The estimated time of arrival can be deter-
mined by dating basal samples from peat cores, or the point
of marked increases of d
15
N in lake sediments. Values of
d
15
N in organic matter in lake sediments not affected by
seabirds from the High Arctic are generally not higher than
3%and seldom rise higher 4–5%(e.g. Janbu et al. 2011;
Perren et al. 2012). A rise in d
15
N of 2–3%d
15
N has been
used in other studies to track millennial scale change in
sockeye salmon population in Alaska (Finney et al. 2002)
and increases to levels similar to those reported here, up to
and[20%, have been used to track human influence on
fresh waters, via transport of MDN, on the Canadian side
of the NOW (Michelutti et al. 2013). Furthermore, there is
an almost total absence of peat accumulation in the NOW
region outside bird colonies (Mosbech et al. 2018), and in
addition, the d
15
N values of the peat cores, though variable
between sites, are much higher than values reported for
non-bird driven peat accumulation (Skrzypek et al. 2008).
Thus, the combination of data presented here provides an
unequivocal marker of bird arrival. The evidence indicates
that the earliest arrival of the little auk in the NOW region
was around 4400 cal. years BP, whereas the thick-billed
murre and the common eider have been present for at least
1500 years longer. The three species discussed here breed
in completely different habitats and landscape settings, so
there is no possibility of a change in bird community at a
particular site.
A striking feature of the arrival times of the little auk at
the sites across the NOW, compared with the thick-billed
murre and the eider duck, is the correspondence with
periods of cooler climate, as reflected by the oxygen iso-
tope data from the Aggasiz ice core (Fig. 4) (Vinther et al.
2009). Though, it should be noted that not all cool periods
correspond to an arrival event, for example the period of
1900 cal. years BP, but then, only four of more than a
hundred little auk colonies in the region were dated (Bo-
ertmann and Mosbech 1998). In contrast, the earliest record
of the arrival of the thick-billed murre and the common
eider correspond with a period of warmer climate around
5500 cal. years BP (Fig. 4). The common eider is a shallow
water, benthic feeder, which needs ice-free (and thus fox
free) conditions around its breeding series. The thick-billed
murre needs fish to feed its chick—it is only capable of
bringing one food item home at a time, and thus needs
large food items for foraging to be feasible. In particular,
the common eider, but also to some degree the thick-billed
murre, have an extensive breeding distribution around
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Greenland, and seem capable of inhabiting many different
habitats. In contrast, breeding colonies of little auks in
Greenland are almost exclusively found in proximity to
High Arctic polynyas, first and foremost the NOW but also
in connection with the polynya at the mouth of Scoresby
sund. To complete its breeding cycle, the little auk requires
a sustained population of large copepods (C. hyperboreus
and C. glacialis) in the upper 50 m of the water column
during chick rearing in July/August, and presumably also
in May/June during the early stages of the breeding season.
This is provided only by a high Arctic marine ecosystem
with open water and sustained primary production
throughout spring and summer, combined with limited
competition from fish predation on the copepods. In
Greenland today, these conditions are exclusively found
around polynyas, and thus, it is exceedingly unlikely that
little auks would be present in large enough numbers to
transform the landscape in the absence of a polynya. This
means that our oldest date of a little auk colony 4400 cal.
years BP may be seen as a minimum age of the NOW
polynya ecosystem. It may well be possible that the NOW
polynya first formed at this point in time, which corre-
sponds to the end of the mid-Holocene Thermal Maxima
and the onset of the cooling associated with the Neoglacial
period (Vinther et al. 2009; Briner et al. 2016).
The idea that the NOW polynya first developed at a time
of climate cooling is in good accord with the existing
knowledge on the formation of the polynya. The formation
of the NOW polynya primarily rests on the establishment
of an arch or bridge of fast ice across Nares Strait in the
Fig. 4 Ice core d
18
O from Aggasiz which reflects temperature change over the last 8000 years. The vertical lines indicate the arrival points of the
various bird colonies. Red for little auk, blue is the thick-billed murre, and green the eider. The pale blue vertical bands mark periods of colder air
temperature as inferred form the ice core isotope record. Below there is summarised information on the inferred variation in bird numbers at the
sampled colonies and the history of human habitation of the NOW area derived from archaeological records
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southern part of Kane Basin, which blocks the southerly
flow of drift ice from the Polar Sea (Melling et al. 2010).
South of the ice arc in Smith Sound/Northern Baffin Bay,
new ice forms on the sea surface but is continuously blown
southwards by the prevailing northerly winds and currents.
This creates the open water area, and at the same time, this
‘ice factory’ promotes brine formation and downwelling/
upwelling, which seeds the system with nutrients, perhaps,
supplemented by the West Greenland Current. The for-
mation of the ice bridge may be a classic tipping point
(Jeppesen et al. 2018), where a small change in temperature
results in a large alteration of the surrounding ecosystems.
In this case, perhaps, somewhat counter intuitively, the
open water area of the NOW polynya is reliant on colder
temperatures. In addition, colder air temperatures would
result in a larger amount of new ice production in the ‘ice
factory’, more brine formation, and greater circulation of
the system. The fact that the little auk population arrived in
and, perhaps, expanded during colder periods may indicate
a link between the success of the little auk and climate.
Thus, we speculate that a colder climate overall results in a
stronger and more consistent ice bridge, more open water,
more nutrients, increased primary production, and larger
Calanus populations—all beneficial to the little auk. Lower
temperatures may further imply reduced competition from
fish predation on the large Calanus spp., as fish species like
Capelin (Malotus vilosus) may be metabolically limited
and retract their distribution southwards during colder
periods (Rose 2005).
Caution must be exercised in interpreting the sediment
record from the lake at Qeqertaq and also the peat cores,
though their lower temporal resolution is already
acknowledged. Whilst the dating of the arrival of the little
auk is relatively straightforward, inferring changes in
abundance can be more difficult. This is because the
nitrogen in the system stored in the lake itself but also in
the extensive peat developed in the catchment can be
continually recycled, and thus, the ‘memory’ of past bird
populations may be preserved in the d
15
N signal, reducing
its utility as an indicator of bird abundance. This may be
particularly true for the lake at Qeqertaq where there is no
other source of water input to flush the system in the event
that birds were absent. The catchments soils also provide a
large buffer/smoother for the lake as nitrogen enriched in
d
15
N will continue to leach from the soils into the lake for
decades to centuries even in the absence of a bird colony.
However, the combination of a number of indicators of bird
abundance, in this case d
15
N, d
13
C (which in the lake
reflect inputs of marine derived carbon), and Cd and P
appear to provide a relatively robust semi-quantitative
means of tracking relative change in bird abundance.
Cadmium and P data have been used in other studies
(Wagner and Melles 2001) to infer change in little auk
populations as both are abundant in little auk droppings.
Both these elements are more abundant in sea water and are
concentrated by marine zooplankton, an important food
source of the little auk. Here, we also used the ratio of these
elements to Ti. Ti content of seabird guano is low, whereas
Ti is an indicator of input from catchment erosion which,
dependent on geology, may supply both Cd and P. Thus,
the ratios of Cd and P to Ti are more likely to reflect the
input of the little auk, with any catchment input removed.
Cd and P both suffer, to some degree, the same problem as
d
15
N as they can be stored in catchment soils and can also
be mobile in the sediment cores. However, both seem to
provide some evidence for variations in little auk numbers.
It is, however, difficult to discuss absolute numbers with
any certainty, but the records suggest that there has been a
relatively large variation in little auk numbers since their
arrival circa 4400 cal. years BP. The records, the peat core
from Annikitisoq and the lake core from Qeqertaq, do not
entirely agree, but combining the records, taking into
account d
15
N, d
13
C, Cd/Ti, and P/Ti the data from
Annikitisoq suggest that there was a decline in bird num-
bers around 4000 to around 3600–3700 cal. years BP,
whereupon numbers rose again. This latter date is the point
at which the colony was established at Qeqertaq (Fig. 2).
The very high accumulation rates of the peat at Annikitisoq
(GL3) suggest that there were abundant nutrients until at
least 3500 cal. years BP, at which point nitrogen content of
the peat cores was extremely low. It is difficult to interpret
the records for the next 1000 or so years, but the general
indication is a period of relative stability with some
increases in bird influence around 3200 and then a decline
around 3000 cal. years BP. At around 2500 cal. years BP,a
number of the records indicate change, at Annikitisoq
accumulation rate falls, P and P/Ti fall to zero, although Cd
is still present. At Qeqertaq, P, Cd, and their ratios with Ti
fall also fall around 2500 cal. years BP, but the isotope
records and % N do not indicate change. This may be due
to a mismatch in temporal resolution of the observations. P,
Cd, and Ti are XRF data measured at higher temporal
resolution (50 mm), whereas the isotope data are measured
every 2 cm, so large short-term variation may be missed by
the isotope data. The data do, however, agree that there was
a peak at 2200 cal. years BP followed by a fall in indicators
of bird input at Qeqertaq. The peak at 2200 cal. years BP
corresponds with the arrival time of the colony at Kuukkat.
Post-2200 cal. years BP, there follows a period of instability
with sharp increases and falls in these key elements with a
notable low point in P, Cd, and their ratios with Ti post
2000 cal. years BP, which remained low until 1500 cal.
years BP.
The changes in bird numbers suggested by the data must
be treated with some caution, as there is a relatively large
degree of uncertainty associated with inferred changes.
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However, if we try and summarise the change in little auk
numbers and by inference the polynya size and produc-
tivity the data suggest a more productive polynya at 4400,
3600, 2700, 2200, and around 1500 cal. years BP and a less
productive or smaller polynya at 3800, 2500, and
2100–1550 cal. years BP.
Little auks, polynya strength, and human
settlement: Possible correlations
The synthesis of the data presented here has led us to the
reasonable hypothesis that the establishment of little auk
colonies and their fluctuating abundance over time may
reflect the formation and changing conditions of the NOW
polynya. It is interesting to examine how these inferred
fluctuations in the size or ‘strength’ of the polynya are
related to the known history of human presence/absence in
the region.
Evidence from radiocarbon dates of the first Arctic
Small Tool tradition societies in the Eastern Arctic (Saq-
qaq/Independence I) was recently subjected to thorough
analysis (Grønnow 2017). It was concluded that the NOW
(and the rest of Greenland) was settled by pioneer societies
as part of a remarkably fast, initial spread of humans from
the Western/Central Canadian Arctic into Eastern and High
Arctic Canada and Greenland sometime during the period
of 4420–4290 cal. years BP. Thus, there is a remarkable
agreement in the timing of our oldest date of little auk
colonies and the arrival of humans in the area. The fol-
lowing human abandonment of the High Arctic around
3800 cal. years BP (Grønnow and Jensen 2003) takes place
during a period of low or instable occurrence of little auks,
i.e. a ‘weak’ polynya condition. The Early Dorset
(‘Greenlandic Dorset’) expansion into the NOW area
(Grønnow and Sørensen 2004) represents a marked human
re-settling, not only of the High Arctic, but also all of
Greenland. This takes place around 2700 cal. years BP,
which means that there is a correspondence with the timing
of the expansion of the little auk colony and some other
indications of a ‘strong’ NOW polynya. The Dorset groups
abandon the High Arctic sometime before 2300 cal. years
BP, and this event occurs within the period of rather
unstable little auk numbers with likely peaks in numbers
reflected at Qeqertaq, but also low numbers suggested at
Annikitisoq from 2500 cal. years BP.
Following both these periods of abandonment, in 3800
and 2300 cal. years BP, the palaeodata indicate the bird
numbers increased, and by inference, the polynya entered a
period of increased size or greater productivity, in 3600
and 2200 cal. years BP, respectively, although the latter may
have been closely followed by a decline. There was,
however, no return of the human population, indicating the
complexity of the relationship between human habitation
and environmental conditions.
The following millennia, post-2300 cal. BP is charac-
terised by total human abandonment of the NOW area.
According to the little auk data, this period sees low bird
abundance. There is some indication of increased bird
abundance from around 1500 cal. BP which shows some
agreement, at least it precedes the last major demographic
events in the NOW area: the re-occupation of NOW by the
Late Dorset (c. 1300–700 cal. BP), but there does not appear
to any clear correlation with the Thule Culture expansion
(Ruin Island Phase, c. 700–500 cal. BP).
CONCLUSION
This study is the first to investigate the long-term patterns
in the presence, absence, and abundance of seabird colo-
nies in the NOW across multiple locations and to provide
direct evidence of the timing of the onset of colony for-
mation of the three of the key sea bird species the region.
The data, particularly when synthesised together, provide
indirect evidence on the state, or ‘strength’ of the polynya
through time. Some remarkable correlations between cold
periods, bird arrival, and number, inferred polynya condi-
tion, and major human demographic events are evident. We
should caution that these are inferred polynya conditions,
and that there are no simple one-to-one relations between
the polynya and demographic developments. For example,
periods where the polynya is inferred to be large and
productive appear coincide with the absence of humans.
The present study certainly encourages further investiga-
tions along the same lines and in collaboration with other
disciplines exploring polynya formation.
Acknowledgements This study is part of The North Water Project
(NOW.KU.DK) funded by the Velux Foundations, the Villum
Foundation, and the Carlsberg Foundation of Denmark. We are
extremely grateful to Guido Grosse for the loan of the SIPRE per-
mafrost corer. We are also indebted to Tony Rønne Pedersen at Thule
airbase for support, the crew of the Blue Jay for efficient transport,
and Hans of Hot Totty for transport. In 2014, we were privileged to
sail on the Minna Martek and we apologise for skipper’s dismay at its
transformation into a ‘gypsy caravan’. We are also very grateful to the
communities in Qaanaaq, Savissivik, and Siarapoluk for their assis-
tance and hospitality.
Open Access This article is distributed under the terms of the
Creative Commons Attribution 4.0 International License (http://
creativecommons.org/licenses/by/4.0/), which permits unrestricted
use, distribution, and reproduction in any medium, provided you give
appropriate credit to the original author(s) and the source, provide a
link to the Creative Commons license, and indicate if changes were
made.
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ÓThe Author(s) 2018. This article is an open access publication
www.kva.se/en 123
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AUTHOR BIOGRAPHIES
Thomas A. Davidson (&) Ph.D., is a Senior Researcher in the lake
group at Aarhus University, Department of Bioscience, Silkeborg,
Denmark. His diverse research interests centre lake ecology, biodi-
versity, and biogeochemistry past, present, and future from the Arctic
to temperature environments.
Address: Department of Bioscience, Arctic Research Centre, Aarhus
University, Vejlsøvej 25, 8600 Silkeborg, Denmark.
e-mail: thd@bios.au.dk
Sebastian Wetterich Dr. Rer. Nat., is a Researcher at the Alfred
Wegener Institute Helmholtz Centre for Polar and Marine Research in
Potsdam, Germany. His research interests include the development of
permafrost environments in response to Quaternary climate variabil-
ity.
Address: Alfred Wegener Institute, Telegrafenberg A43, 14473
Potsdam, Germany.
e-mail: sebastian.wetterich@awi.de
Kasper L. Johansen M.Sc., is an Academic Associate at Aarhus
University, Department of Bioscience. His research interest include
GIS and spatial modelling of seabird distribution patterns and bio-
diversity hotspots.
Address: Department of Bioscience, Arctic Research Centre, Aarhus
University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
e-mail: kalj@bios.au.dk
Bjarne Grønnow Dr. Phil., is Research Professor at the Department
of Modern History and World Cultures at the National Museum of
Denmark. His main research topics include the earliest societies in the
Arctic as well as Inuit prehistory and ethnohistory.
Address: The National Museum of Denmark, Frederiksholms Kanal
12, 1220 Copenhagen K, Denmark.
e-mail: bjarne.gronnow@natmus.dk
Torben Windirsch B. Sc., is a Master‘s Student at Alfred Wegener
Institute Helmholtz Centre for Polar and Marine Research, Periglacial
Research Unit, Potsdam, Germany. His research has focused on
Arctic sedimentology and permafrost carbon storage.
Address: Alfred Wegener Institute, Telegrafenberg A43, 14473
Potsdam, Germany.
e-mail: torben.windirsch@awi.de
Erik Jeppesen Dr. Scient, is a Professor in the lake group at Aarhus
University, Department of Bioscience, Silkeborg, Denmark. His
interest is nutrient and trophic dynamics in lakes as well as climate
and global change effects on lakes and streams from the Arctic to the
tropics.
Address: Department of Bioscience, Arctic Research Centre, Aarhus
University, Vejlsøvej 25, 8600 Silkeborg, Denmark.
e-mail: ej@bios.au.dk
Jari Syva
¨ranta Ph.D, is an Academy Research Fellow at the
University of Eastern Finland, Department of Environmental and
Biological Sciences, Joensuu, Finland. His research interests include
aquatic food web processes and how these link to greenhouse gas
fluxes from lakes.
Address: Department of Environmental and Biological Sciences,
University of Eastern Finland, PL 111, 80101 Joensuu, Finland.
e-mail: jari.syvaranta@uef.fi
Jesper Olsen Ph.D., is an Associate Professor in the Department of
Physics and Astronomy, Aarhus University, Denmark. He specialises
in radiocarbon dating and age modelling.
Address: Department of Physics and Astronomy, Aarhus University,
Ny Munkegade 120, Building 1522, 8000 Aarhus, Denmark.
e-mail: jesper.olsen@phys.au.dk
Ivan Gonza
´lez-Bergonzoni Ph.D., is a postdoctoral researcher at the
University of the Republic and Clemente Estable Biological Research
Institute in Uruguay. His research area is on freshwater ecosystems
ecology, mainly focused on food web ecology in lotic systems.
Address: Laboratorio de Etologı
´a, Ecologı
´a y Evolucio
´n, Instituto de
Investigaciones Biolo
´gicas Clemente Estable, Av Italia 3318, 11600
Montevideo, Uruguay.
e-mail: ivg@fcien.edu.uy
Astrid Strunk is a Ph.D. Student at Department of Geoscience,
Aarhus University, Denmark. Her research interests include the his-
tory of the Greenland Ice Sheet in northeast Greenland and related sea
level changes in the last 12 000 years.
Address: Institut for Geoscience, Aarhus University, Høegh-Guld-
bergs Gade, 2 bygning 1672, 115, 8000 Aarhus C, Denmark.
e-mail: astrid@geo.au.dk
Nicolaj K. Larsen Ph.D., is an Associate Professor at Aarhus
University, Department of Geoscience, Aarhus, Denmark. His
research interests include paleoclimate in the Arctic and the glacial
history of the Greenland Ice Sheet.
Address: Institut for Geoscience, Aarhus University, Høegh-Guld-
bergs Gade, 2 bygning 1672, 115, 8000 Aarhus C, Denmark.
e-mail: nkl@geo.au.dk
Hanno Meyer Dr. Rer. Nat., is a Senior Scientist and Head of the
Stable Isotope Laboratory at the Alfred Wegener Institute Helmholtz
Centre for Polar and Marine Research in Potsdam, Germany. His
research interests include stable isotopes, climate reconstruction,
permafrost environment, and hydrology.
Address: Alfred Wegener Institute, Telegrafenberg A43, 14473
Potsdam, Germany.
e-mail: hanno.meyer@awi.de
Jens Søndergaard Ph.D., is Senior Advisor at Aarhus University,
Department of Bioscience, Roskilde, Denmark. His research interests
are focused on cycling of contaminants in the environment
Ambio
ÓThe Author(s) 2018. This article is an open access publication
www.kva.se/en 123
particularly in the arctic environment.
Address: Department of Bioscience, Aarhus University, Frederiks-
borgvej 399, 4000 Roskilde, Denmark.
e-mail: js@bios.au.dk
Rune Dietz D.Sc., is a Professor at Aarhus University, Department of
Bioscience. His research interests include impacts of contaminant
studies as well as tracking and population studies of marine mammals
within the Arctic and temperate regions.
Address: Department of Bioscience, Arctic Research Centre, Aarhus
University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
e-mail: rdi@bios.au.dk
Igor Eulears Ph.D., is a Postdoctoral Researcher at Aarhus Univer-
sity, Department of Bioscience. His research interests include inves-
tigating spatiotemporal sources and intensities of environmental
stressors in Arctic and temperate food webs, including humans.
Address: Department of Bioscience, Arctic Research Centre, Aarhus
University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
e-mail: ie@bios.au.dk
Anders Mosbech Ph.D., is a Senior Researcher at the Aarhus
University, Department of Bioscience. His research interests include
impacts of industrial activities on nature and environment in the
Arctic and seabird ecology.
Address: Department of Bioscience, Arctic Research Centre, Aarhus
University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
e-mail: amo@bios.au.dk
Ambio
123 ÓThe Author(s) 2018. This article is an open access publication
www.kva.se/en
... In addition to atmospheric transport, some studies indicate that migratory species may also play a critical role in translocating POPs between ecosystems, increasing productivity in otherwise unproductive systems (Blais et al., 2007;Evenset et al., 2004;Michelutti et al., 2009aMichelutti et al., , 2010. This is especially true for sea birds which feed at sea and come to land to breed, bringing nutrients as well as contaminants into freshwater systems (Blais, 2005;Davidson et al., 2018;Evenset et al., 2007a;González-Bergonzoni et al., 2017;Polis et al., 1997). Many avian species are migratory, travelling thousands of kilometers from breeding sites to wintering grounds, spending majority of their life in both areas (Wang et al., 2019). ...
... The cores were sliced and stored frozen until analysis. Further details of sampling and dating of the sediment cores have been described elsewhere (Davidson et al., 2018). ...
... The waters of NOW5 were highly acidic with a pH of 3.4, whereas the pH values of NOW14 and Q5 were close to 8 (Table 1). This difference can be attributed to the influence of A. ale guano depositions (Davidson et al., 2018). In Spitzbergen, guano depositions of these birds also resulted in acidic lake water (Zwolicki et al., 2013). ...
Article
Full-text available
The role of sea birds as carriers of pollutants over long distances was evaluated by analyzing organochlorine and organobromine compounds in lake sediment cores from three remote sites around the North Water polynya (North West Greenland). One lake, NOW5, was in the vicinity of a little auk (Alle alle L.) bird colony, whereas the other two lakes, NOW14 and Q5, were undisturbed by seabirds. The former was strongly acidic (pH = 3.4) but the latter had a pH close to 8. Due to the guano loading, NOW5 exhibited higher chlorophyll concentrations (74 μg/L) than the other two lakes (1.6–3.4 μg/L), higher content of total phosphorous (0.34 mg/L vs. 0.007–0.01 mg/L) and total nitrogen (3.75 mg/L vs. 0.21–0.75 mg/L). The concentrations of all organohalogen compounds were substantially greater in NOW5 than in the other lakes, indicating the strong influence of these seabirds in the transport and deposition of these compounds to remote sites. However, not all compounds showed the same increases. Hexachlorocyclohexanes and endosulfans were more than 18 times higher in NOW5, the drin pesticides and hexachlorobenzene (HCB), between 9.5 and 18 times and DDTs, polybromodiphenyl ethers (PBDEs), polychlorobiphenyls (PCBs) and chlordanes about 2.7–6 times. These differences demonstrated that the bird-mediated deposition has preservation effects of the less stable and more volatile compounds, e.g. those with log Kaw < −2.4, log Koa < 9 and/or log Kow < 6.8. The sedimentary fluxes of PCBs, HCHs, drins, chlordanes, PBDEs, HCB and endosulfans were highest in the upper sediment layer of the polynya lake (year 2014). In contrast, the highest DDT fluxes were found in 1980. These trends indicate that despite restrictions and regulations, bird transport continues to introduce considerable amounts of organohalogen pollutants to the Arctic regions with the exception of DDTs, which show successful decline, even when mediated by bird metabolism.
... This more productive environment could be linked to occasional openings of a polynya due to an infrequent ice arch in Kane Basin. However, according to Davidson et al. (2018) the inception of the North Water did not occur before ca. 4.5 cal. ...
... The productivity in the polynya is limited by nitrate, meaning that the upwelling of nitrate-rich, Atlantic-sourced water in the eastern North Water dictates the overall biomass produced during spring and summer (J.-É. . Figure 5.1: Study area, location of core AMD16-233 (Georgiadis et al., in prep.; this study), AMD14-Kane2b (Georgiadis et al., 2018;, Agassiz Ice core , Deltadø chironomid record (Axford et al., 2019); Location of modern little auk colonies (red), and common eider and thick billed murre colonies (green; Davidson et al., 2018). POW: Prince of Wales icefield. ...
... Early sea ice melt and minimal sea-ice cover were recorded in Kane Basin between ca 8.1 and 7.5 cal. ka BP and was followed by an increase in seasonal sea-ice cover (Caron et al., 2019;Georgiadis et al., 2020), corresponding to the end of the HTM identified by Lecavalier et al. (2017) (Georgiadis et al., 2020); d) driftwood abundance in northern Ellesmere Island as an indication of landfast ice in northern Nares Strait (England et al., 2008); e) δ18O-derived atmospheric temperature anomaly from Agassiz ice core (black: 200 year running average; Lecavalier et al., 2017); f) WGC current strength and temperature ; g) electric conductivity in Devon Ice Core (Koerner, 1989); h) bowhead whale remains found in east-central CAA (Dyke et al., 1997, compiled by Lecavalier et al., 2017; i) bird abundance in NW Greenland (red: high numbers;yellow: variable number;blue: low numbers;Davidson et al., 2018); j) reconstructed sea surface temperatures (SST) in north-eastern Baffin Bay (Caron et al., 2019). Intervals characterised by predominantly positive (negative) phases of the AO are represented in yellow (green) (Darby et al., 2012;England et al., 2008;Funder et al., 2011), the blue interval represents the 8.2 cold event identified in the Agassiz Ice Core.. ...
Thesis
Nares Strait is one of three channels of the Canadian Arctic Archipelago (CAA) which connect the Arctic Ocean to Baffin Bay. The CAA throughflow is a major component of ocean circulation in western Baffin Bay. Nares Strait borders the CAA to the east, separating Ellesmere Island from Greenland, and is 80% covered in sea ice 11 months of the year. The heavy sea ice cover is constituted of (1) Arctic (multi-year) sea-ice having entered the strait by the north, and (2) locally formed first year sea ice, which consolidates the ice cover. The hydrological history of the area is intimately linked to the formation of land-fast sea ice in the strait, constituting ice arches. The seaice cover in Nares Strait regulates freshwater (liquid and solid) export towards Baffin Bay, and is integral to the formation of an area of open water in northernmost Baffin Bay: The North Water polynya.Nares Strait has been at the heart of major geomorphological changes over the past 10,000 years. Its deglacial and post-glacial history is marked by (1) rapid retreat of the Greenland and Innuitian ice-sheets which coalesced along Nares Strait during the Last Glacial Maximum, (2) post-glacial shoaling associated to isostatic rebound, and (3) variable multi-year and seasonal sea ice conditions. Little is known about the evolution of these three environmental components of the Nares Strait history, and they are poorly constrained in terms of chronology and synchronism with other regional changes. Nares Strait and its eventful Holocene history provide a unique case study of the response of the marine and continental cryosphere to rapid climate change, such as that affecting Arctic regions in modern times.The marine sediment archives that were retrieved during the ANR GreenEdge and ArcticNet (2014 and 2016) cruises of CCGS Amundsen offer a unique opportunity to investigate the Deglacial to Late Holocene history of Nares Strait. Our reconstructions are based on a multi-proxy study of these cores, including sedimentologic (grain size and lithofacies), geochemical (XRF), mineralogical (q-XRD), micropaleontological (planktic and benthic foraminiferal assemblages), and biogeochemical (sea ice biomarkers IP25 and HBI III).Our results include an age for the Deglacial opening of Nares Strait between 9.0 and 8.3 cal. ka BP, with the event likely occurring closer to the later bracket of the timeframe (i.e., ca 8.5-8.3 cal. ka BP). This event established the throughflow from the Arctic Ocean towards northernmost Baffin Bay. Environmental conditions were highly unstable in the Early Holocene, and marine primary productivity was limited. A period of minimum sea-ice cover occurred from ca 8.1 to 7.5 cal. ka BP, during the Holocene Thermal Maximum, when atmospheric temperatures were higher than today in Nares Strait. Sea-ice cover became more stably established as a seasonal feature around 7.5 cal. ka BP and primary productivity related to ice edge blooms increased. Eventually, the duration of the ice arches increased and they were present in spring and into the summer from 5.5 to 3.7 cal. ka BP, which allowed the inception of the North Water polynya. The North Water reached its maximal potential between 4.5 and 3.7 cal. ka BP, when warmer Atlantic-sourced water upwelled in the polynya, providing nutrients for primary productivity. The establishment of a near-perennial ice arch in northern Nares Strait prevented export of multi-year sea ice into Nares Strait and hindered the formation of the southern ice arch, ultimately resulting in a less productive polynya over the past ca 3.0 cal. ka BP.
... Lacustrine environments (i.e., standing water) are preferred, as the sediments tend to accumulate chronologically with minimal mixing, in contrast to those in fluvial environments (i.e., running water) (Smol, 2008). There is also a limited but growing body of literature using similar paleolimnological approaches on peat (Outridge et al., 2016;Davidson et al., 2018;Groff et al., 2020), directly from nests (Burnham et al., 2009), and on guano deposits themselves (Nocera et al., 2012;Gallant et al., 2020Gallant et al., , 2021. Next, the sample is collected using a sediment corer, which, in its simplest form, is a tube inserted into the sediment to retrieve an undisturbed vertical profile of sediment [see Glew et al. (2001) for a detailed overview]. ...
... Changes in sedimentary δ 15 N values have been used to successfully track bird colony sizes in Arctic (Michelutti et al., 2009;Yuan et al., 2010;Keatley et al., 2011;MacDonald et al., 2015;Davidson et al., 2018;Hargan et al., 2019;Ribeiro et al., 2021), Antarctic (Huang et al., , 2016Gao et al., 2018c;Yang et al., 2018), temperate (Stewart et al., 2015(Stewart et al., , 2019Hargan et al., 2018;Duda et al., 2020a,c), and tropical (Conroy et al., 2015;Wu et al., 2017aWu et al., , 2018 systems. Although this method is effective, Nie et al. (2014b) suggested an improvement on δ 15 N as 15 N, which is calculated as the difference between acid-treated and untreated δ 15 N. ...
... Typically, δ 13 C values are positively correlated to colony size (i.e., δ 13 C is enriched as colony size increases). This relationship principally reflects an increase in primary production and organic matter introduction resulting from guano fertilization (Sun et al., 2000;Yuan et al., 2010;Liu et al., 2013;Conroy et al., 2015;Davidson et al., 2018;Gao et al., 2018c;Cheng et al., 2021). However, in some cases, δ 13 C values can also have a negative relationship with colony size (i.e., δ 13 C is depleted as colony size increases). ...
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The lack of long-term monitoring data for many wildlife populations is a limiting factor in establishing meaningful and achievable conservation goals. Even for well-monitored species, time series are often very short relative to the timescales required to understand a population's baseline conditions before the contemporary period of increased human impacts. To fill in this critical information gap, techniques have been developed to use sedimentary archives to provide insights into long-term population dynamics over timescales of decades to millennia. Lake and pond sediments receiving animal inputs (e.g., feces, feathers) typically preserve a record of ecological and environmental information that reflects past changes in population size and dynamics. With a focus on bird-related studies, we review the development and use of several paleolimnological proxies to reconstruct past colony sizes, including trace metals, isotopes, lipid biomolecules, diatoms, pollen and non-pollen palynomorphs, invertebrate sub-fossils, pigments, and others. We summarize how animal-influenced sediments, cored from around the world, have been successfully used in addressing some of the most challenging questions in conservation biology, namely: How dynamic are populations on long-term timescales? How may populations respond to climate change? How have populations responded to human intrusion? Finally, we conclude with an assessment of the current state of the field, challenges to overcome, and future potential for research.
... According to botanical investigations on other North Pacific Islands, even short-term impact of seabird colonies lead to changes in vegetation cover, and in the soil chemistry or bedrock and eventually to the formation of ornithogenic ecosystems and vegetation (Ivanov, 2013). The long-term effects of birds and dynamics of their colonies during the Holocene have been studied in Greenland and Svalbard by the stable isotope analysis of lake sediments and peat cores (Davidson et al., 2018;Gąsiorowski & Sienkiewicz, 2019;Yuan et al., 2010). Seabirds provide large amounts of marine organic matter to nutrient-limited terrestrial ecosystems by guano (Caut et al., 2012;Maron et al., 2006), which is reflected in the sediments by the enrichment of the heavy nitrogen isotope, namely significant increase of δ 15 N value (Croll et al., 2005;Davidson et al., 2018;Gąsiorowski & Sienkiewicz, 2019;Maron et al., 2006;Szpak et al., 2012;Yuan et al., 2010). ...
... The long-term effects of birds and dynamics of their colonies during the Holocene have been studied in Greenland and Svalbard by the stable isotope analysis of lake sediments and peat cores (Davidson et al., 2018;Gąsiorowski & Sienkiewicz, 2019;Yuan et al., 2010). Seabirds provide large amounts of marine organic matter to nutrient-limited terrestrial ecosystems by guano (Caut et al., 2012;Maron et al., 2006), which is reflected in the sediments by the enrichment of the heavy nitrogen isotope, namely significant increase of δ 15 N value (Croll et al., 2005;Davidson et al., 2018;Gąsiorowski & Sienkiewicz, 2019;Maron et al., 2006;Szpak et al., 2012;Yuan et al., 2010). We hypothesized that for Aleutian Islands plant communities depleted by abundant rainfalls and intense leaching, this fertilization has a significant impact. ...
... (Caut et al., 2012;Spazk et al., 2012). Similar increases of several ppm are also shown in Svalbard and Greenland over long periods of time or even the entire Holocene (Davidson et al., 2018;Gąsiorowski & Sienkiewicz, 2019;Yuan et al., 2010). In Alaska, fluctuations in the range of 2-3‰ are estimated for fluctuations in the number of sockeye salmon over the millennia, which also reflect the additional input of nutrients from marine ecosystems to terrestrial (Finney et al., 2002). ...
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In the Aleutian Islands during the Holocene, terrestrial predators were actually absent; as a result, large seabird colonies thrived along the coasts or across entire islands. Bird guano enriches the soil with nitrogen, which can lead to the formation of highly modified ornithogenic (bird-formed) ecosystems. For a more detailed investigation of avian influence, we reconstructed more than 10,000-year-old vegetation dynamics of the coast of Shemya Island (Near Islands) by pollen analysis. At the initial stages of vegetation development (10,000–4,600 cal year BP), sedge–heather tundra grew in the studied area. A seabird colony existed on Shemya from 4,600 to 2,400 cal year BP according to stable isotope analysis. During a period of at least 2,200 years, nitrogen enrichment led to the development of ornithogenic herb meadows with a high presence of Apiaceae. A long-term increase in δ15N above 9–10‰ led to radical shifts in vegetation. Noticeable reduction of seabird colonies due to human hunting led to grass-meadows spreading. After a prolonged decrease δ15N below 9–10‰ (2,400 cal year BP to present), there was a shift toward less productive sedge-tundra communities. However, the significant enrichment of guano affected only the coastal vegetation and did not alter the inland Shemya Island.
... By transporting vast quantities of marine-derived nutrients (MDN) from sea to land in the form of guano, little auks have transformed extensive parts of the NOW coastal landscapes into green oases 13,14 . At little auk colonies, temporal changes in the MDN flux in sediments can be used as a proxy for changes in bird numbers and, by inference, NOW productivity over time 15 . ...
... Significance of the North Water for the human settlement of Greenland. The lake indicators record the arrival of little auks at the colony site between 4400 and 4200 cal yrs b2k (Fig. 4), corresponding to the marked transition in the core, and consistent with data from nearby terrestrial peat deposits 15 . Bird colony influence on the lake appears to be relatively stable from c. 4200 and 2700 cal yrs b2k (Figs. 4 and 5). ...
... The marine coring site lies at the centre of the polynya, whereas the lake site is located close to its present-day southern edge, and therefore any polynya contractions would be recorded somewhat earlier at this location ( Fig. 1). Although dating uncertainties cannot be ruled out as an alternative explanation, this idea is supported by peat core studies from further north, demonstrating that bird colonies spread northwards around 2800 and 2200 cal yrs b2K 15 . ...
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High Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique sea ice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-to-late Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, leading to periods of polynya instability and marine productivity decline, is strikingly coeval with the human abandonment of Greenland from c. 2200–1200 cal yrs b2k. Our long-term perspective highlights the future decline of the North Water ecosystem, due to climate warming and changing sea-ice conditions, as an important climate change risk.
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Chapter
The Cambridge History of the Polar Regions is a landmark collection drawing together the history of the Arctic and Antarctica from the earliest times to the present. Structured as a series of thematic chapters, an international team of scholars offer a range of perspectives from environmental history, the history of science and exploration, cultural history, and the more traditional approaches of political, social, economic, and imperial history. The volume considers the centrality of Indigenous experience and the urgent need to build action in the present on a thorough understanding of the past. Using historical research based on methods ranging from archives and print culture to archaeology and oral histories, these essays provide fresh analyses of the discovery of Antarctica, the disappearance of Sir John Franklin, the fate of the Norse colony in Greenland, the origins of the Antarctic Treaty, and much more. This is an invaluable resource for anyone interested in the history of our planet.
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