Polar Research https://polarresearch.net/index.php/polar <p><em>Polar Research</em>&nbsp;is the international, peer-reviewed journal of the&nbsp;<strong><a href="http://www.npolar.no/en/">Norwegian Polar Institute</a></strong>, Norway's central institution for research, environmental monitoring and mapping of the polar regions. The scope of&nbsp;<em>Polar Research</em>&nbsp;encompasses research in all scientific disciplines relevant to the polar regions. These include, but are not limited to, the subfields of biology, ecology, geology, oceanography, glaciology and atmospheric science. Submissions from the social sciences and those focusing on polar management and policy issues are welcome. Contributions about Antarctica are particularly encouraged.</p> Norwegian Polar Institute en-US Polar Research 1751-8369 <p><span style="color: #4b7d92;">This work is licensed under a <a href="https://creativecommons.org/licenses/by-nc/4.0/" target="_blank" rel="noopener">Creative Commons Attribution-Noncommercial 4.0 Unported License</a>.<br>Authors retain copyright of their work, with first publication rights granted to the Norwegian Polar Institute.</span></p> <p><img src="/public/site/images/ecsemiczky/88x31_CC_BY1.png"></p> <p>&nbsp;</p> The last two millennia: climate, ocean circulation and palaeoproductivity inferred from planktic foraminifera, south-western Svalbard margin https://polarresearch.net/index.php/polar/article/view/3715 <p>We reconstruct climate and changes in water-mass properties in relation to variations in palaeoproductivity at the south-western Svalbard margin throughout the last 2000 years. Environmental conditions in subsurface (ca. 250–75 m) and near-surface to surface water (75–0 m) were studied on the basis of the distribution patterns and fluxes of planktic foraminiferal faunas. Stable isotopes in three different species were measured, and Mg/Ca- and transfer function-based sea-surface temperatures were calculated. The mean shell weights of planktic foraminiferal species were used to assess changes in calcium carbonate preservation. Modern total planktic foraminiferal distribution patterns from plankton tows and the water column carbonate chemistry were investigated for comparison with the palaeo-data. The results show warm sea-surface conditions and moderate to high surface productivity at ca. 21–400 AD, ca. 900–1400 AD and from about 1850 AD until present, which may be local expressions of the European climatic events known as the Roman Warm Period, the Medieval Climate Anomaly and the Recent Warming. In general, cold near-sea-surface conditions and very low to moderate average productivity occurred at about 400–900 AD and ca. 1400–1850 AD, the latter probably the local expression of the Little Ice Age. The highest and most variable planktic productivity occurred at ca. 1300–1500 AD, ca. 1750–1860 AD and during the last 50 years or so. These periods are linked to the general amelioration of conditions from years with a dense sea-ice cover to years with a rapidly fluctuating summer sea-ice margin.</p> Katarzyna Zamelczyk Tine L. Rasmussen Markus Raitzsch Melissa Chierici Copyright (c) 2020-10-20 2020-10-20 10.33265/polar.v39.3715 Unusual drift behaviour of multi-year sea ice in the Beaufort Sea during summer 2018 https://polarresearch.net/index.php/polar/article/view/3617 <p>In summer 2018, thick sea ice blocked the mouth of the Amundsen Gulf (AG), Canada, obstructing shipping through the North-west Passage. This study analysed multi-year ice motion to investigate the source of this thick ice and the reasons for its unusual movement. For this purpose, a daily multi-year ice distribution product was generated by ice tracking using gridded daily sea-ice velocities (2003–2018) derived from the AMSR-E and AMSR-2 data. From autumn 2017 to summer 2018, the area of multi-year ice extended westward to the Beaufort Sea and then migrated towards the AG mouth. The primary cause of the unusual ice cover was anomalous AG-ward wind in September 2018. It is known that multi-year ice has become increasingly moveable over the past decades, as indicated by the increasing wind factor (i.e., ratio of ice-drift speed and wind speed), but the unusual ice motion in the summer of 2018 cannot be explainable by the wind factor alone. Accurately, predicting monthly wind and monitoring old thick ice will reduce the risk posed by thick Arctic sea ice to shipping.</p> Noriaki Kimura Kazutaka Tateyama Kazutoshi Sato Richard A. Krishfield Hajime Yamaguchi Copyright (c) 2020-10-14 2020-10-14 10.33265/polar.v39.3617 Ichnodiversity and bathymetric range of microbioerosion traces in polar barnacles of Svalbard https://polarresearch.net/index.php/polar/article/view/3766 <p>This first comprehensive investigation of microbioerosion traces in polar barnacles addresses two bathymetrical transects from the intertidal down to subtidal water depths in two different carbonate factories in the Svalbard Archipelago: the bay Mosselbukta and the ocean bank Bjørnøy-Banken. Scanning electron microscopy of epoxy resin casts of barnacle shells yielded 20 different microendolithic bioerosion traces, probably produced by cyanobacteria (three), chlorophytes (two), rhodophytes (one), sponges (one), foraminifera (three), fungi (nine) and bacteria (one). The lowest ichnodiversity in both locations was observed in the shallow euphotic zone and is likely a result of strong temperature fluctuations, extreme seasonality of light levels and episodic sea-ice cover. At 25–150 m water depth, the ichnodiversity remains relatively constant (9–13 ichnospecies), albeit with differing ichnospecies composition, generally dominated by borings from chlorophytes and fungi. Ichnotaxa at Mosselbukta and Bjørnøy-Banken were similar in numbers but differed in abundance and slightly also in ichnospecies composition. Statistical tests indicate that water depth (affecting the availability of light) is the most significant driver for the development of different microbioerosion trace assemblages across the bathymetrical transects. In contrast, no significant differences in ichnodisparity were found, indicating a comparable suite of architectural designs of the micro-borings throughout bathymetry and location. The comparison of our results with literature data confirms a decrease in ichnodiversity from lower to higher latitudes, although targeted bioerosion analyses from other polar environments are needed to gain a more complete picture of the role of bioerosion in polar carbonate factories.</p> Neele Meyer Max Wisshak André Freiwald Copyright (c) 2020-09-14 2020-09-14 10.33265/polar.v39.3766 The effect of an experimental decrease in salinity on the viability of the Subarctic planktonic foraminifera <em>Neogloboquadrina incompta</em> https://polarresearch.net/index.php/polar/article/view/3842 <p>Chemical signatures in the calcite of shells of polar and subpolar planktonic foraminifera have been frequently used to trace and quantify past meltwater discharge events. This approach assumes that the foraminifera can tolerate low salinity under extended periods. To obtain a first experimental constraint on salinity tolerance of Subarctic foraminifera, we carried out a culturing experiment with specimens of the subpolar species&nbsp;<em>Neogloboquadrina incompta</em>&nbsp;collected in the northern Norwegian Sea off Tromsø in October 2018. The foraminifera were exposed to a gradient of salinities between 35 and 25 PSU. Survival was monitored over 26 days by measuring the extent of the rhizopodial network. Although chamber growth only occurred in one of the observed specimens, likely due to the largely unknown dietary preference of the species, we observed a strong differential rhizopodial activity pattern along the gradient. The highest rhizopodial activity occurred at salinity between 35 and 31 PSU. The species is clearly able to survive long-term exposure to salinities as low as 28, but no rhizopodial activity and signs of cytoplasm degradation were observed in all specimens exposed to 25 PSU. These preliminary observations provide the first direct evidence for the salinity tolerance of&nbsp;<em>N. incompta</em>, indicating a range of salinity that could be plausibly expected to be recorded in the chemistry of fossil shells of the species.</p> Mattia Greco Ju­lie Meil­land Kasia Zamelczyk Tine L. Rasmussen Michal Kucera Copyright (c) 2020-08-27 2020-08-27 10.33265/polar.v39.3842 New Antarctic clawed lobster species (Crustacea: Decapoda: Nephropidae) from the Upper Cretaceous of James Ross Island https://polarresearch.net/index.php/polar/article/view/3727 <p>A new species of nephropid lobster,&nbsp;<em>Hoploparia echinata</em>&nbsp;sp. nov., from the James Ross Island in the Antarctic Peninsula is here described and illustrated. The material was collected in the Santa Marta Formation (Santonian–-Campanian), the basal unit of the Marambio Group, Larsen Basin, located in the western portion of the Antarctic Peninsula.&nbsp;<em>Hoploparia echinata</em>&nbsp;sp. nov. can easily be differentiated from its congeners by the presence of distinct short spines on dorsal and ventral margins on the third maxillipeds, merus of the chelipeds and pereopods; these are the characters not described in other&nbsp;<em>Hoploparia</em>&nbsp;species so far.</p> Allysson P. Pinheiro Antônio Álamo Feitosa Saraiva William Santana Juliana Manso Sayão Rodrigo Giesta Figueiredo Taissa Rodrigues Luiz Carlos Weinschütz Luiza Corral Martins de Oliveira Ponciano Alexander Wilhelm Armin Kellner Copyright (c) 2020-08-13 2020-08-13 10.33265/polar.v39.3727 Reconstructing the Little Ice Age extent of Langfjordjøkelen, Arctic mainland Norway, as a baseline for assessing centennial-scale icefield recession https://polarresearch.net/index.php/polar/article/view/4304 <p>Current warming in the Arctic is occurring at a rate two to three times higher than that of the rest of the world, leading to rapid glacier wastage. In Arctic mainland Norway, the plateau icefield Langfjordjøkelen has experienced the greatest mass loss of all Norwegian glaciers (excluding Svalbard) in recent decades. In this article, we examine this decline in a centennial-scale context through geomorphological mapping and the analysis of historical aerial photographs and maps. This allows Langfjordjøkelen’s maximum Little Ice Age extent (ca. 1925) to be reconstructed, providing an important baseline for a long-term assessment of icefield change. At the LIA maximum, Langfjordjøkelen covered an area of 14.9 km<sup>2</sup>. A comparison of the LIA dimensions with the icefield extent in 1891/1902, as displayed on a historical map, reveals a substantial overestimation of the map-based glacier outline. The post-LIA evolution of Langfjordjøkelen has been characterized by sustained high rates of glacier recession. By 2018, the icefield had lost 57% (8.5 km<sup>2</sup>) of its original LIA area, at a decadal rate of 9%, and its outlet glaciers had reduced in average length by 42% (1 km), at an annual rate of 11 m. Langfjordjøkelen’s percentage area decline has been greater than that of Norwegian ice masses at lower latitudes where comparable long-term glacier change data are available. This indicates that there is a significant latitudinal variation in Norwegian glacier response to 20th century warming, likely influenced by an enhanced warming signal in Arctic Norway compared to the rest of the Norwegian mainland.</p> Paul Weber Harold Lovell Liss M. Andreassen Clare M. Boston Copyright (c) 2020-08-01 2020-08-01 10.33265/polar.v39.4304 Distribution and source of glycerol dialkyl glycerol tetraethers (GDGTs) and the applicability of GDGT-based temperature proxies in surface sediments of Prydz Bay, East Antarctica https://polarresearch.net/index.php/polar/article/view/3557 <p>Reliable records of Southern Ocean seawater palaeotemperatures are important because this region plays a significant role in regulating global climate change. Biomarkers such as GDGT-based indices have been effectively used to reconstruct seawater temperatures. We analysed the composition and distribution of iGDGTs, OH-GDGTs and brGDGTs and calculated GDGT-based temperature indices in surface sediments from Prydz Bay, East Antarctica. Our results showed that iGDGTs, OH-GDGTs and brGDGTs are all produced in situ, with iGDGTs and OH-GDGTs mostly synthesized by Thaumarchaeota. Concentrations of iGDGTs, OH-GDGTs and brGDGTs showed similar spatial distributions and decreased from the continental shelf towards the deep ocean. The highest concentrations were in the inner bay, which is attributed to a combination of (1) bathymetry that reduces water exchange, (2) the Prydz Bay Gyre stabilizing the upper water column and (3) sea ice that releases archaea and bacteria. Among the temperature indices based on iGDGTs, OH-GDGTs and combinations therein, those based on OH-GDGTs showed the strongest correlation with seawater temperature. Some OH-GDGT-based indices (e.g., OH-0/OHs, OH-1/OHs, OH-2/OHs and RI-OH′) exhibited a stronger correlation with annual subsurface ocean temperature (100–200 m), which may be related to archaeal habitats and production mechanisms. Our study suggests that RI-OH′ and OH-0/OHs could be used as indicators of annual subsurface ocean temperature in Antarctic marginal seas.</p> Ruijuan Liu Zhengbing Han Jun Zhao Haifeng Zhang Dong Li Jianye Ren Jianming Pan Haisheng Zhang Copyright (c) 2020-07-14 2020-07-14 10.33265/polar.v39.3557 Effect of ikaite precipitation on phosphate removal in sea ice https://polarresearch.net/index.php/polar/article/view/3413 <p>Ikaite (CaCO<sub>3</sub>·6H<sub>2</sub>O) precipitation in sea ice has been shown to affect CO<sub>2</sub>&nbsp;exchange between the atmosphere and ocean. A laboratory study indicates that it could also co-precipitate phosphate from sea ice, which has the potential to affect sea-ice biogeochemical processes. However, the relative importance of ikaite precipitation on phosphate removal under sea-ice conditions remains unknown. We investigated ikaite precipitation in both frost flowers and seaice (under two scenarios: flooded by seawater and non-flooded) in an outdoor sea-ice mesocosm experiment, and in sea ice under natural conditions in north-eastern Greenland. The ice mesocosm experiment showed that ikaite was highly enriched in frost flowers with a concentration of up to 350 µmol·kg<sup>–1</sup>. Ikaite was also detected in the surface layer of sea ice, ranging from ca. 13 µmol·kg<sup>–1</sup>&nbsp;in the non-flooded ice to ca. 95 µmol·kg<sup>–1</sup>&nbsp;in the flooded ice. However, under all these conditions, no phosphate co-precipitation with ikaite was observed. The field study in Greenland showed similar results: ikaite was detected in surface ice with an average concentration of 13.8 µmol·kg<sup>–1</sup>, but no phosphate removal due to ikaite precipitation was observed. These results suggest that the impact of ikaite precipitation on phosphate and the sea-ice ecosystem might not be as significant as imagined previously.</p> Yu-Bin Hu Feiyue Wang Copyright (c) 2020-07-08 2020-07-08 10.33265/polar.v39.3413 Revisiting the extended Svalbard Airport monthly temperature series, and the compiled corresponding daily series 1898–2018 https://polarresearch.net/index.php/polar/article/view/3614 <p>The Svalbard Airport composite series spanning the period from 1898 to the present represents one of very few long-term instrumental temperature series from the High Arctic. A homogenized monthly temperature series is available since 2014. Here we increase the resolution from a monthly to daily basis, and further digitization of historical data has reduced the uncertainty of the series. The most pronounced changes in the 120-year record occur during the last three decades. For the 1991–2018 period the number of days warmer than 0 and 5 °C has increased by 25 (21%) and 22 (59%), respectively, per year compared to the 1961–1990 standard normal. Likewise, comparing the same periods, the number of days colder than −10 and −20 °C has decreased by 42 (32%) and 27 (62%), respectively. During the entire time span of the series, the western Spitsbergen climate has gone through stepwise changes, alternating between cold and warm regimes: 1899–1929 was cold, 1930–1961 warm, 1962–1998 cold and 1999–2018 warm. The latest cold regime was 1.0 °C warmer than the first cold one, and the latest warm regime was 1.7 °C warmer than the previous warm one. For the whole series the linear trend for annual means amounts to 0.32°C/decade, which is about 3.5 times the increase of the global mean temperature for the same period. Since 1991, the rate of warming at Svalbard Airport is 1.7 °C/decade, which is more than twice the Arctic average (0.8 °C/decade, north of 66 °N) and about seven times the global average for the same period.</p> Øyvind Nordli Przemysław Wyszyński Herdis M. Gjelten Ketil Isaksen Ewa Łupikasza Tadeusz Niedźwiedź Rajmund Przybylak Copyright (c) 2020-06-27 2020-06-27 10.33265/polar.v39.3614 Ice-out and freshet fluxes of CO<sub>2</sub> and CH<sub>4</sub> across the air–water interface of the channel network of a great Arctic delta, the Mackenzie https://polarresearch.net/index.php/polar/article/view/3528 <p>Carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) were monitored at five sites spanning the upstream–downstream extent of the Mackenzie Delta channel network during May 2010, capturing the historically under-sampled ice-out period that includes the rising freshet, peak water levels and the early falling freshet (flood recession). Unexpectedly, partial pressures of CO<sub>2</sub>&nbsp;in the Mackenzie River were undersaturated during the rising freshet before water levels peaked, indicating net CO<sub>2</sub>&nbsp;invasion at instantaneous CO<sub>2</sub>&nbsp;flux rates (<em>F-</em>CO<sub>2</sub>) ranging from –112 to –258 mg-C m<sup>-2</sup>&nbsp;d<sup>-1</sup>. Net CO<sub>2</sub>&nbsp;invasion was also observed around the time of peak water levels at sites in the middle and outer delta. Following peak water levels, the Mackenzie River switched to saturation and net CO<sub>2</sub>&nbsp;evasion (<em>F-</em>CO<sub>2</sub>&nbsp;from 74 to 177 mg-C m<sup>-2</sup>&nbsp;d<sup>-1</sup>). Although the Peel River (which flows into the west side of the Mackenzie Delta) was a strong emitter of CO<sub>2</sub>&nbsp;(<em>F-</em>CO<sub>2</sub>&nbsp;from 373 to 871 mg-C m<sup>-2</sup>&nbsp;d<sup>-1</sup>), overall, the Mackenzie River and Delta were weak emitters of CO<sub>2</sub>&nbsp;during the 2010 ice-out period. All sites were strong emitters of CH<sub>4</sub>&nbsp;during ice-out, however, with the highest evasive fluxes observed in the outer delta when the extent of flooded delta landscape was greatest. Estimated aerial fluxes from Mackenzie Delta channel surfaces during May 2010 ranged from 2.1 to 4.8 Gg-C as CO<sub>2</sub>, and 186 to 433 Mg-C as CH<sub>4</sub>. These results provide critical information that can be used to refine gas flux estimates in high-latitude circumpolar river deltas during the relatively under-studied ice-out period.</p> Jolie A.L. Gareis Lance F.W. Lesack Copyright (c) 2020-06-26 2020-06-26 10.33265/polar.v39.3528 Does foraminiferal test size reflect changes in palaeoenvironmental conditions?—a case study from the southern Svalbard shelf https://polarresearch.net/index.php/polar/article/view/3624 <p>Although the environmental factors influencing the growth rate and reproduction of benthic foraminifera are known, the relationship between foraminifera test size and environmental variables remains unclear, especially on geological timescales. In this article, we present two records of benthic foraminiferal test size over the last 14 000 years from the southern Svalbard shelf. We use statistical correlation to relate test size changes with environmental conditions recorded by other proxies, including benthic&nbsp;<em>δ</em><sup>18</sup>O and&nbsp;<em>δ</em><sup>13</sup>C, foraminiferal flux and abundance, and relative abundances of different ecologically indicative foraminiferal groups. The general trends in test size were relatively consistent between the two cores. Still, we found that none of the analysed proxies was statistically correlated with the test size in both records. This leads to a conclusion that foraminifera size is primarily impacted by local oceanographic conditions. These local conditions are partly influenced by global oceanographic transitions. Therefore, large-scale changes can have a secondary impact on foraminiferal test size. The analysis of test size correlation between species similarly revealed that not all species react consistently to environmental changes. Our results indicate that foraminiferal test size cannot be used as a universal and straightforward proxy, but in combination with other methods it can yield valuable palaeoenvironmental information.</p> Maciej M. Telesiński Natalia Szymańska Joanna Pawłowska Marek Zajączkowski Copyright (c) 2020-06-19 2020-06-19 10.33265/polar.v39.3624 Marine debris on two Arctic beaches in the Russian Far East https://polarresearch.net/index.php/polar/article/view/3381 <p>In August 2005, marine debris was counted on two Arctic beaches in the Russian Far East. On the north coast of the Chukchi Peninsula east of Kolyuchin Bay, a beach stretch of ca. 2.4 km held a total of 736 items, 0.024 items m<sup>‑2</sup>, while no more than 0.0011 items m<sup>‑2</sup>, 12 items in total, were found on a beach stretch of ca. 1.2 km on southern Wrangel Island. The likely explanation for this difference is that the area around the mainland beach is ice-free for a longer period each year, but a contributing factor may be that late spring ice movement removed plastic from the beach on Wrangel Island. The language on the few items with identifiable labels was for the most part Russian or English, making the Chukchi Sea a possible source region. Beaches at the same latitude in the Atlantic may hold more debris on account of the higher human population density, more shipping and transport of floating debris unhindered by a narrow strait that is ice-covered much of the year. Fishing gear blown across the tundra is suggested as a potential threat to reindeer and other terrestrial wildlife.</p> Henrik Kylin Copyright (c) 2020-06-11 2020-06-11 10.33265/polar.v39.3381 Outline shape analysis of penguin humeri: a robust approach to taxonomic classification https://polarresearch.net/index.php/polar/article/view/4370 <p>Humeri have been useful bones in taxonomic determinations of extinct penguins. In the context of neontological taxonomic studies, however, their potential remains unsatisfactorily explored. Here, the variation of the overall closed-outline shape of 60 humeri, assignable to five genera of extant penguins, was investigated. A set of normalized outlines was quantified via elliptical Fourier analysis and subjected to linear discriminant analysis on principal component scores extracted from harmonic coefficients. These geometric representations proved to be a source of easily extractable genus-level taxonomic information. The constructed model provided meaningful discrimination between taxa: the first two linear discriminants captured almost 90% of between-group variance. A cross-validation method based on jackknifing yielded 93% correct identifications, and statistically significant differences between group centroids were also detected (multivariate analysis of variance,&nbsp;<em>p</em>&nbsp;&lt; 0.05). Predictions of genus membership for the intentionally noisy test data (20 outlines) were accurate in 80% of cases.</p> Piotr Jadwiszczak Copyright (c) 2020-06-11 2020-06-11 10.33265/polar.v39.4370 Smoking guns and volcanic ash: the importance of sparse tephras in Greenland ice cores https://polarresearch.net/index.php/polar/article/view/3511 <p>Volcanic ash (fine-grained tephra) within Greenland ice cores can complement the understanding of past volcanism and its environmental and societal impacts. The presence of ash in sparse concentrations in the ice raises questions about whether such material represents primary ashfall in Greenland or resuspended (remobilized) material from continental areas. In this article, we investigate this issue by examining tephra content in quasi-annual samples from two Greenland ice cores during a period of ca. 20 years and considering their relationships with sulphur and particulate data from the same cores. We focus on the interval 815–835 CE as it encompasses a phase (818–822 CE) of heightened volcanogenic sulphur previously ascribed to an eruption of Katla, Iceland. We find that tephra is a frequent but not continuous feature within the ice, unlike similarly sized particulate matter. A solitary ash shard whose major element geochemistry is consistent with Katla corroborates the attribution of the 822±1 CE sulphur peak to this source, clearly showing that a single shard can signify primary ashfall. Other tephras are present in similarly low abundances, but their geochemistries are less certainly attributable to specific sources. Although these tephra shards tend to coincide with elevated sulphur and fine (&lt;10 µm) particulates, they are not associated with increased coarse (&gt;10 µm) particle concentrations that might be expected if the shards had been transported by dust storms. We conclude that the sparse shards derive from primary ashfall, and we argue that low tephra concentrations should not be dismissed as insignificant.</p> Gill Plunkett Michael Sigl Jonathan R. Pilcher Joseph R. McConnell Nathan Chellman J.P. Steffensen Ulf Büntgen Copyright (c) 2020-06-08 2020-06-08 10.33265/polar.v39.3511 Modelling polar bear maternity den habitat in east Svalbard https://polarresearch.net/index.php/polar/article/view/3447 <p>We evaluated a novel tool that predicts possible maternity den habitat of the polar bear (<em>Ursus maritimus</em>) based on a physical snow transport model, a digital terrain model and weather data. We observed and compared den locations in three important denning areas in east Svalbard (Kongsøya,&nbsp;<em>n</em>&nbsp;= 288; Svenskøya,&nbsp;<em>n</em>&nbsp;= 86; Hopen,&nbsp;<em>n</em>&nbsp;= 115) with modelled snowdrift distributions for 24 years. Accounting for a likely position uncertainty of 100 m, 69% of all dens were located within year-specific modelled snowdrifts. These covered on average 1.8%, 2.1% and 24.7% of the three study islands, respectively. Our snowdrift model accurately predicted maternity den positions (<em>R</em><sup>2</sup>&nbsp;= 0.42, area under the receiving operating characteristic curve [AUC] = 0.85). A model based on slope and altitude, also predicted den positions reasonably well (<em>R</em><sup>2</sup>&nbsp;= 0.35, AUC = 0.88). Habitat maps identifying both current and future areas for maternity denning will become important in managing the Barents Sea population as well as other Arctic populations where changes in sea-ice conditions alter the accessibility to traditional denning areas.</p> Benjamin Merkel Jon Aars Glen E Liston Copyright (c) 2020-03-24 2020-03-24 10.33265/polar.v39.3447 Eurasian winter temperature change in recent decades and its association with Arctic sea ice loss https://polarresearch.net/index.php/polar/article/view/3363 <p>The surface air temperature in the northern mid-latitudes during winter showed a significant cooling trend from the late 1990s to the early 2010s, in spite of increasing greenhouse gas concentrations. This unexpected cooling, which was particularly strong across Eurasia, has been partly attributed to Arctic sea-ice loss. Here, the statistical relationship between Arctic sea-ice loss and surface air-temperature change during winter in Eurasia, which is often referred to as the warm Arctic–cold Eurasia pattern, is re-evaluated by using a break-point trend analysis and maximum covariance analysis. A significant time-lagged covariability is observed between the Arctic sea-ice concentration over the Barents–Kara seas and the Eurasian surface air temperature during winter, with the former leading the latter by approximately two months. More importantly, the timing of an abrupt decline in the autumn Arctic sea ice that occurred in the late 1990s is coincident with the beginning of the Eurasian winter cooling. This concurrent trend change is statistically significant and robustly found in both the break-point analysis and maximum covariance analysis. These results suggest that both the interannual variability and decadal trend change seen for the surface air temperature during Eurasian winters are likely influenced by regional sea-ice changes over the Barents–Kara seas.</p> Hye-Jin Kim Seok-Woo Son Copyright (c) 2020-03-20 2020-03-20 10.33265/polar.v39.3363 Little auks under the midnight sun: diel activity rhythm of a small diving seabird during the Arctic summer https://polarresearch.net/index.php/polar/article/view/3309 <p>Many animal species exhibit a diel, 24-hr pattern of activity, which is steered by timing cues, with the daily light–dark cycle considered the most powerful. This cue, however, is reduced in polar zones under continuous daylight conditions associated with the midnight sun. The rhythm of animal behaviour under such conditions is poorly understood. Here, we examine periodicity and patterns of daily activity (colony attendance and foraging) in a High-Arctic seabird, the little auk (<em>Alle alle</em>). We demonstrated a regular rhythm of colony attendance at the population level, with birds being the most abundant in the colony during hours of relatively low sun elevation. This pattern is likely to be associated with predation pressure that may be perceived by birds as lower during hours with low sun elevation, because of better predator detectability. Regarding rhythms at an individual level, however, we found the most common periodicity to be 23.2 hr (range from 19.9 hr to 30.8 hr) but no clear pattern of daily colony attendance of individuals. Such a flexibility in daily rhythms indicates that individuals may become arrhythmic in regard to the 24-hr environmental cycle, despite regularities observed at the population level. Finally, we compared males and females in terms of daily activity patterns but we did not find significant sex differences.</p> Katarzyna Wojczulanis-Jakubas Piotr Wąż Dariusz Jakubas Copyright (c) 2020-02-27 2020-02-27 10.33265/polar.v39.3309 Growth-related changes in salt gland mass in gentoo and chinstrap penguin chicks https://polarresearch.net/index.php/polar/article/view/3702 <p>The salt gland is a well-developed osmoregulation organ in marine birds, and its relative size often reflects an individual’s feeding environment and osmoregulation capability. The development and functions of salt glands have been described for the Adélie penguin (<em>Pygoscelis adeliae</em>), but this information has been poorly documented in the other two pygoscelid species: gentoo (<em>P. papua</em>) and chinstrap penguins (<em>P. antarcticus</em>). To describe the growth-related changes in salt gland masses in relation to chick growth, we measured the wet mass of the salt glands collected from dead gentoo and chinstrap chicks during the early breeding period. The mass of the salt glands was linearly proportional to their body measurements, especially to body mass, in both species, and no significant difference was detected between the two species. Penguins are obligate marine dwellers throughout their life cycle, and the development of the salt gland in penguin chicks suggests that their ability to regulate dietary osmotic stress begins at an early stage of development after hatching. Furthermore, the linear relationship between the gland mass and body mass also suggests that the osmoregulation capability may continue to develop as penguin chicks grow. This descriptive note provides novel and quantitative information on the early developmental pattern of salt glands in gentoo and chinstrap penguins.</p> Youmin Kim Min-Su Jeong Hae-Min Seo Hankyu Kim Woo-Shin Lee Chang-Yong Choi Copyright (c) 2020-06-29 2020-06-29 10.33265/polar.v39.3702 First record of horned puffin in the North Atlantic and tufted puffin in High Arctic Greenland https://polarresearch.net/index.php/polar/article/view/4458 <p>An accelerating decrease in summer sea-ice extent in the Arctic Ocean and Canadian Arctic Archipelago (North-west Passage) is predicted to increase the movement of species between the North Pacific and North Atlantic oceans. Here we report observations of two Subarctic North Pacific puffin species in the North Atlantic near the coast of north-west Greenland. We observed a horned puffin (<em>Fratercula corniculata</em>) repeatedly during the summer months of 2002–06 and 2013–19 and a single tufted puffin (<em>F. cirrhata</em>) in 2019. While single tufted puffins have been observed a few times in the North Atlantic, this is the first record of a horned puffin in the North Atlantic, and the first record for both horned and tufted puffins in north-west Greenland. In 2019, both puffin species were observed simultaneously at an Atlantic puffin (<em>F. arctica</em>) colony.</p> Kurt K. Burnham Jennifer L. Burnham Jeff A. Johnson Bridger W. Konkel Jack Stephens Hannah Badgett Copyright (c) 2020-06-26 2020-06-26 10.33265/polar.v39.4458 Discovery of a large population of <im>Hygrolembidium isophyllum</im> (Lepidoziaceae, Marchantiophyta) in the South Shetland Islands, Antarctica https://polarresearch.net/index.php/polar/article/view/3663 <p>In February 2019, during fieldwork at Harmony Point, Nelson Island, South Shetland Islands, Antarctica, a large population of the rare liverwort&nbsp;<em>Hygrolembidium isophyllum</em>&nbsp;(Lepidoziaceae) was discovered. The occurrence of this rare species reinforces the need to preserve Antarctic Specially Protected Area 133.</p> Jair Putzke Flávia Ramos Ferrari Carlos E.G.R. Schaefer Copyright (c) 2020-06-08 2020-06-08 10.33265/polar.v39.3663 Hop-on, hop-off: the first record of the alien species crescent-marked lily aphid (Neomyzus circumflexus) (Insecta, Hemiptera, Aphididae) in Greenland https://polarresearch.net/index.php/polar/article/view/3710 <p>We report for the first time the presence of the globally distributed and extremely polyphagous pest species—the crescent-marked lily aphid (or mottled arum aphid) (<em>Neomyzus circumflexus</em>&nbsp;L.) (Insecta, Hemiptera, Aphididae)—in Greenland. This species, of alien origin, was found on the ornamental plant&nbsp;<em>Salix arbuscula</em>&nbsp;L., imported from Denmark and sold in the main supermarket of Nuuk, the capital of Greenland. As this species is not the preferred host plant of&nbsp;<em>N. circumflexus</em>, the possibility must be considered that the aphids were not imported along with&nbsp;<em>S. arbuscula</em>&nbsp;from the mainland but were transferred from other imported ornamental plants sold in the store. Supermarkets selling decorative plants may be becoming reservoirs of alien species, facilitating the movement of aphids and other alien species that “hop on, hop off,” to borrow a phrase from the tourism industry. As unintentional introductions present the greatest threats to the Arctic ecosystems, a stricter approach to regional biosecurity needs to be considered and non-native species control and eradication should be implemented.</p> Karina Wieczorek Dominik Chłond Copyright (c) 2020-05-08 2020-05-08 10.33265/polar.v39.3710