Polar Research

Evidence of profuse bark shedding in Dicroidium seed ferns (Umkomasiales) from the Triassic of Antarctica

Philipp Hiller — 2024-09-27

During the 11th German Antarctic North Victoria Land Expedition in 2015/16, exceptionally well-preserved permineralized Kykloxylon stems—the wood of the iconic Dicroidium plants of the Gondwanan Triassic—were collected from the Middle to Upper Triassic Helliwell Formation in north Victoria Land, Transantarctic Mountains, Antarctica. Some of these logs show large borings and cavities that are partly filled with multi-layered periderm. This periderm is identical in cell shape and dimensions to isolated flakes of tissue that are superabundant in bulk macerations of Dicroidium-bearing rock samples from different coeval locations in the Transantarctic Mountains. These flakes are interpreted as shed bark fragments of Dicroidium-bearing umkomasialean trees. Various hypotheses on the adaptive advantages of bark shedding are discussed, including the reduction of epiphyte load. Palynological data document an abundance of potentially epiphytic cryptogams (spikemosses and bryophytes) in the environments in which the Dicroidium trees grew, and modern ecosystems with a climate comparable to that of the Late Triassic in Antarctica are in many cases also characterized by a lush epiphyte vegetation. Another advantage could lie in the reduction of infections by phytopathogenic microorganisms, as abundant fungal remains in both the wound periderm and the dispersed periderm flakes indicate.

Drivers of spatio-temporal variations in summer surface water temperatures of Arctic Fennoscandian lakes (2000–21)

Mingzhen Zhang — 2024-08-08

The Arctic region is covered with numerous small lakes whose ecosystems are vulnerable to current climate warming and resultant changes in water temperature, ice-cover duration and lake levels. Data on thermal features of these lakes are sparse, which hinders our understanding of the possible ecosystem impacts of the warming climate and climate feedbacks at larger spatial scales. We investigated spatial–temporal variations of lake surface water temperatures (LSWT) in 12 Arctic lakes in north-west Finnish Lapland and explored the predominant drivers of LSWTs by continuous year-round observations. The lake surface temperature data were recorded using thermistors at bi-hourly resolution during the years 2000, 2007–08 and 2019–2021. A large regional heterogeneity was observed in the timing of the maximum and minimum LSWTs and the overall patterns of the annual cycle. Our results reveal that July air temperature, maximum lake depth and altitude explained most of the variance in the summer LSWT (> 85%). The remaining variance was related to geographic location (longitude and latitude), lake morphometric features, such as lake area and catchment area, and certain physico-chemical characteristics, such as Secchi depth and dissolved organic carbon content. Our results provide new insights into thermal responses of different types of small Arctic lakes to climate change.

The relationship between Antarctic sea-ice extent change and the main modes of sea-ice variability in austral winter

Lejiang Yu — 2024-07-22

Accompanying global warming, Antarctic sea-ice extent shows a somewhat increasing trend from 1979 to 2014, followed by an abrupt decrease after 2016. Our previous study examined the change of Antarctic sea-ice extent in austral summer, autumn and spring. In this study, we turn our attention to the austral winter, relating the main modes of sea-ice variability to sea-ice extent in the Pacific, Atlantic and Indian sectors of the Southern Ocean. We find that the modes with the strongest correlation with the sea-ice extent are the third, first and first modes in the Pacific, Atlantic and Indian sectors, respectively. Atmospheric circulation anomalies of zonal wavenumber three over the Southern Ocean, related to planetary wave trains induced by the SST anomalies over the south-western Pacific and the southern Indian oceans, can explain sea-ice concentration anomalies of the third mode in the Pacific sector through thermodynamic and dynamic processes. Sea-ice anomalies of the first modes in the Atlantic and Indian sectors result from atmospheric circulation anomalies of a positive and negative phases of the Southern Annular Mode, respectively. The anomalous Southern Annular Mode is also associated with wave trains over the Southern Ocean excited by SST anomalies over the southern Indian Ocean and the south-western Pacific Ocean. The relationship between SST anomalies and Antarctic sea-ice anomalies can provide a reference for the prediction of Antarctic sea-ice anomalies in austral winter on interannual and decadal timescales.

Widespread exposure to Francisella tularensis in Rangifer tarandus in Canada and Alaska

Kayla J. Buhler — 2024-07-18

The range of tularemia, a disease caused by the bacterium Francisella tularensis, may expand alongside climate change in the North. Transmission occurs via biting arthropods, contaminated water sources, infected animal tissues and fluids and even aerosolized bacteria. Little research has been published on F. tularensis in northern Canada. We investigated whether Rangifer (caribou and reindeer) in Canada and Alaska are exposed to F. tularensis, as they provide significant cultural and subsistence value. From 2016 to 2020, 336 serum samples were collected from Rangifer across 17 herds, including captive reindeer in Alaska (n = 30) and wild caribou across Canada (n = 306) during collaring or harvesting efforts. Using a microagglutination test, we detected antibodies against F. tularensis in 7% of captive reindeer (CI₉₅ 2–21), 6% of migratory tundra caribou (CI₉₅ 4–11) and 10% of mountain woodland caribou (CI₉₅ 6–17), with the highest seroprevalence observed in animals from Nunavut (17%) and British Columbia, Canada (18%). Ten of the herds (n = 10/17; 59%) had at least one positive animal. Evidence of exposure to F. tularensis indicates that further studies are needed to characterize sources of transmission for Rangifer species and any potential health effects following infection.

Polar vortex weakening and its impact on surface temperature in recent decades

Seong-Joong Kim — 2024-07-05

The stratospheric polar vortex (SPV) weakening is linked to surface circulation changes. This study employs statistical analysis using reanalysis data to compare the anomalous SPV behaviour in the Northern (NH) and Southern (SH) hemispheres and its downward impacts on surface climate. The onset of annual SPV weakening occurs in mid-January and late September in the NH and SH hemispheres, respectively. Following the onset of SPV weakening, stratospheric polar cap height (PCH) anomalies were strongly correlated with tropospheric PCH anomalies. Significant cold anomalies were observed over Eurasia within 30 days after SPV weakening onset in the NH, whereas warming responses occurred in the SH 30–60 days after onset over Antarctica, except in the Antarctic Peninsula. These contrasting surface temperature responses to SPV weakening events in both hemispheres are the results of changes in the geopotential height in the troposphere, reminiscent of the change in geopotential height in the lower stratosphere, with a trough over Eurasia in the NH, and a higher height anomaly over East Antarctica in the SH. SPV changes have played a role in modulating surface climate via a downward influence on tropospheric circulation in recent decades. Even though they show a weakening trend in both hemispheres, SPV changes cannot fully explain long-term temperature trends. This is partially because SPV trends observed during the analysis period are relatively weak. This study enhances our understanding of the characteristics of the SPV coupled with troposphere circulation and can contribute to improved surface weather forecasting.

Svalbard rock ptarmigan: a first glimpse into parasite infections

Ólafur K. Nielsen — 2024-04-23

Natural ecosystems are under stress due to climate change and impacts are especially prominent at high latitudes. Manifestations of these changes include northward shifts in the distribution of birds, phenological mismatches, improved survival of parasites in the environment and the arrival of new parasite vectors and intermediate hosts. We collected baseline data on parasite infections in the Svalbard rock ptarmigan (Lagopus muta hyperborea), which is endemic to two High Arctic archipelagos, by sampling 10 birds caught in September–October 2015 in Van Mijenfjorden, Spitsbergen. Five species were found, three endo- and two ectoparasites. The endoparasites included a nematode, Heterakis sp. (prevalence 10%), and two species of Eimeria, all with direct life cycles. The Eimeria species are provisionally called Eimeria sp. A and sp. B (prevalence 50% and 20%; mean intensity 1560 and 1850 oocysts per g faeces, respectively). Both show morphological similarities with known rock ptarmigan eimeriids, but further taxonomic research is needed to describe their phylogenetic relationships. The two ectoparasites, the ischnoceran chewing lice Goniodes lagopi and Lagopoecus affinis, both showed 90% prevalence and a mean intensity of 18.3 and 5.6, respectively. The eimeriids are host specific, and the chewing lice are common parasites of closely related grouse species. On the basis of our knowledge of rock ptarmigan parasites, Heterakis sp. is considered a generalist parasite. The parasite fauna of the Svalbard rock ptarmigan is impoverished compared with conspecific populations in other Arctic locations, such as Iceland and Greenland.

Sedimentary facies and mineral provenance of Upper Triassic sandstones offshore Kvitøya, Svalbard: implications for palaeogeographic interpretations in the northern Barents Shelf area

Mai Britt E. Mørk — 2024-04-16

Upper Triassic (Carnian) sandstones of the De Geerdalen Formation cored south of the island of Kvitøya (80°N), north-easternmost Svalbard, are described in terms of sedimentary facies and petrography and compared regionally in the northern Barents Shelf. The succession off Kvitøya is characterized by its great thickness and is dominated by deltaic deposits with high sand content of lithic–feldspathic compositions. Comparison of sediment facies and sandstone compositions with adjacent areas suggest that the succession off Kvitøya is part of a larger delta system with its main sediment source from the east. The delta sedimentation was terminated by marine transgression in the earliest Norian. The sandstone compositions off Kvitøya differ from nearby locations by the higher content of cherty rock fragments and reworked volcanic debris in the Kvitøya sandstone, which is most distinct in the lower part of the succession. Provenance signatures are investigated by mineral–chemical analysis of detrital feldspars, rock fragments, garnet and Cr-spinel, characterizing a wide variety of igneous, metamorphic and sedimentary terranes, including palaeo-Urals and areas farther to east. Additional, more proximal sediment source areas may also have existed that could explain the increased sediment thickness and the mineralogical immature sandstone compositions of the Carnian sediments off Kvitøya.

What does the fox say? Arctic fox vocalization and associated den behaviours

Kayla J. Buhler — 2024-04-04

Foxes (Vulpes spp.) are small, solitary canids with relatively low social complexity compared to more gregarious canids, such as wolves and dogs. They are, therefore, expected to have a relatively simple vocal repertoire, with limited low-intensity sounds for close communication and many high-intensity sounds for long-distance communication. Arctic foxes (Vulpes lagopus), like many other foxes, are largely solitary outside of the breeding season. However, they have the largest litter size in the order Carnivora and may experience enhanced social complexity during the breeding season. In this study, we document the vocal repertoire of the Arctic fox during the breeding season, and how it changes before and after the emergence of pups. We also describe the relationship between vocalizations and other denning behaviours. Camera-traps captured six distinct sounds produced by breeding pairs of Arctic foxes and their young at dens: territorial barks, warning barks, alarm calls, cooing, whines and growling. Our study shows that although high-intensity sounds, such as territorial barks, are an important form of long-distance communication among Arctic foxes, low-intensity sounds and sound mixing are used on their dens following pup emergence. Thus, Arctic fox vocalization may be more complex than previously documented.

Norwegian killer whale movements reflect their different prey types

Emma F. Vogel — 2024-03-21

Norwegian killer whales (Orcinus orca) are thought to be generalists that feed primarily on fish, but some individuals have been observed targeting pinnipeds. In the study reported here, field observations of foraging behaviours formed the basis of a priori classification as either seal-eaters or fish-eaters. Concurrent collection of photographic identification and biopsies for stable isotope analysis were used to validate prey choice classification. We found through satellite tracking that whales classified as seal-eaters took different paths south after leaving the northern fjords seemingly optimized for pinniped predation. Specifically, we found that seal-eaters took paths that tightly followed the coastline, remaining on average 6.9 ± 10.7 km (mean ± SD, n = 315) from the coast, whereas fish-eaters moved offshore along the continental shelf, travelling on average 45.1 ± 30.2 km (n = 1534) from the coast. We also found that, compared to fish-eaters, seal-eaters displayed more movements directed towards harbour seal haul-outs (p = 0.001). As expected, our data suggest that the fish-eaters feed primarily on fish, whilst seal-eaters appear to opportunistically use diverse foraging strategies optimized for either fish or seals based on availability and preference. Our findings demonstrate that tracking data can elucidate Norwegian killer whale movements associated with different prey types and selection.

Some issues related to the Svalbardian tectonic event (Ellesmerian Orogeny) in Svalbard

Winfried Kurt Dallmann — 2024-09-12

Svalbard has long been thought to represent the easternmost realm of the Ellesmerian Orogeny in the late Devonian or early Mississippian (Svalbardian tectonic event). Several authors do not agree and present alternative interpretations of the observed structures in older and more recent articles. This article discusses a number of issues that, in our opinion, are not sufficiently considered in those works, but which are essential for the understanding of the Svalbardian tectonic event: (1) the possibility of re-deposited palynomorphs in the discussion of the deformational ages, (2) the age and structural setting of the crucial Adriabukta Formation in southern Spitsbergen, and (3) the presence and nature of the Svalbardian angular unconformity in central and southern Spitsbergen.

Some considerations regarding corporate social responsibility in the Yamalo-Nenets Autonomous Okrug, Russia

Onur Limon — 2024-05-27

Corporate social responsibility (CSR) practices—by which companies contribute positively to society through their voluntary actions and initiatives—have advanced slowly in Russia. In Russia, the separation between the state and business is not clear, as is the difference between state-owned companies and nominally ‘private’—but still state-controlled—companies, and this has shaped CSR. CSR as practiced in Russia is state-initiated to an extent greater than that in many other countries. The Yamalo-Nenets Autonomous Okrug (YNAO), in the Russian Arctic, has a significant population of indigenous people whose way of life has traditionally been based on reindeer herding, fishing and other subsistence activities that are threatened by the ecological damage caused by the hydrocarbon extraction that is carried out in the region by large state-owned or state-controlled corporations such as the parastatal corporation Gazprom. CSR has the potential to ameliorate some of the problems faced by residents of the YNAO, including difficulties relating to transportation, the supply of goods, health care and environmental protection. To achieve this, the CSR roles of the different parties involved need to be better defined and the CSR actions should shift emphasis from modernizing the larger settlements of the YNAO to improving the lives of people who maintain a more traditional way of life on the tundra. Drawing on interviews, government and company documents, and Russian and non-Russian scholarly papers, this Perspective piece considers some aspects of CSR in the YNAO and points to topics of future research.

The Troll Observing Network (TONe): A contribution to improving observations in the data-sparse region of Dronning Maud Land, Antarctica

Christina A. Pedersen — 2024-05-06

Understanding how Antarctica is changing and how these changes influence the rest of the Earth is fundamental to the future robustness of human society. Strengthening our understanding of these changes and their implications requires dedicated, sustained and coordinated observations of key Antarctic indicators. The Troll Observing Network (TONe), now under development, is Norway’s contribution to the global need for sustained, coordinated, complementary and societally relevant observations from Antarctica. When fully implemented within the coming three years, TONe will be a state-of-the-art, multi-platform, multi-disciplinary observing network in data-sparse Dronning Maud Land. A critical part of the network is a data management system that will ensure broad, free access to all TONe data to the international research community.

Anthropogenic noise in terrestrial Antarctica: a short review of background information, challenges and opportunities

Lucia Ziegler — 2024-04-16

Anthropogenic noise is an inevitable by-product of human activities. However, the potential effects of human noise on terrestrial Antarctica’s ecosystems have been understudied. Documented impacts encompass stress, alterations in behavioural patterns, auditory masking, and, in severe instances, mortality. This Perspective note aims to call attention to human-generated noise as potential sources of impact on Antarctic wildlife and to highlight the potential of soundscape analysis as a flexible, cost-effective tool for environmental monitoring across Antarctica, complementing other non-invasive approaches. Acoustic monitoring in terrestrial environments has been extensively used in different parts of the world to assess biodiversity, monitor populations’ status and trends, and identify and monitor sources of anthropogenic disturbance. Technological advances in passive acoustic monitoring allow for the gathering of detailed information with little need of human attention, and powerful processing tools and algorithms enable researchers to analyse large collections of audio data. Cold climates limit battery-operated instruments, but solar panels in Antarctic summer trials revealed over 100 days of unattended operation, which is promising for the incorporation of acoustic monitoring in Antarctica’s environmental management toolbox.

A bowhead whale vertebra embedded in marine limit beach sediment on Barentsøya, Svalbard

Per Möller — 2024-04-19

A cross-valley beach terrace in Iladalen, in the south-east of the island of Barentsøya, Svalbard, is interpreted as having been built by long-shore sediment transport and deposition, with its maximum height at about 88 m a.s.l., marking the marine limit at deglaciation. A whale vertebra—most probably from a bowhead whale (Balaena mysticetus)—was found embedded in the upper part of the littoral sediments at a height of ca. 80 m a.s.l., that is, about 8 m below the marine limit at deglaciation The bone is dated to 10 762 ± 137 cal yr BP, just a few hundred years after the generally accepted deglaciation of the coastal parts of Barentsøya, about 11 000 years ago. The vertebra’s age and altitudinal position fit well with the relative sea-level curve constructed for the north-eastern tip of the island of Edgeøya, some 29 km east–south-east of Iladalen.

Evidence of a narwhal (Monodon monoceros) summer ground in Nares Strait

Mads Peter Heide-Jørgensen — 2024-03-28

Our limited knowledge of the marine mammal fauna in northernmost Greenland and Canada, specifically north of 80°N, relies largely on opportunistic observations collected during expeditions with different objectives. The narwhal (Monodon monoceros) migrates long distances in response to ice formation and decay and is notoriously skittish, avoiding areas with ice breakers. Scattered observations from the past 20 years, assessed together with historical observations after 1881, suggest that there is a population of narwhals that uses Hall Basin and its adjacent fjord systems—for example, Nares Strait—as a summer ground. Dating the tusks and bones that have been found shows that narwhals were present in this area as far back as nearly 7000 years ago. The wintering locations of these narwhals remain unknown, highlighting the need to investigate whether they are vulnerable to hunting activities in north-west Greenland. By gaining a better understanding of the narwhals’ winter behaviour and potential hunting risks, we can develop more informed conservation and management strategies for this population.

First recorded ice entrapment of a beluga whale (Delphinapterus leucas) in east Greenland

Kristin L. Laidre — 2024-02-28

Beluga whales are rare along the coast of east Greenland and the closest recognized stock occurs around Svalbard. Here we report on an ice entrapment of an adult beluga whale (Delphinapterus leucas) in north-east Greenland. The whale was observed entrapped in the fast ice on 21 April 2023 in Loch Fyne (73°54’N, 21°51’W) during a visual aerial survey for polar bears (Ursus maritimus). The whale was located >100 km from open water (i.e., pack ice) and appeared in poor body condition. A literature review back to the early 1900s failed to produce any other records of beluga whale ice entrapments in east Greenland.

Cretaceous–Palaeogene lobsters, Hoploparia stokesi (Weller, 1903), from Antarctica: historical review, and transfer of specimens from the United States Polar Rock Repository

Loren E. Babcock — 2024-02-16

The nephropid lobster Hoploparia stokesi (Weller 1903a) is widely distributed among the islands of the Antarctic Peninsula, where it occurs in strata of Cretaceous (Campanian–Maastrichtian) to Palaeogene (Paleocene) age. Specimens of H. stokesi collected during expeditions in the 1980s that were in the collection of the United States Polar Rock Repository at The Ohio State University have been transferred to the Orton Geological Museum, joining other geological collections from Antarctica. Some of the transferred specimens are voucher specimens described or illustrated in earlier published work.

Garbage consumption by Arctic terrestrial predators in one of the most pristine land areas on Earth

Araceli Gort-Esteve — 2024-01-05

Garbage may cause substantial environmental perturbations, in part because of its consumption by wildlife. Such consumption may have direct health implications for animals and may also influence trophic relationships. Even in pristine Arctic ecosystems, wildlife feeding in marine environments consume garbage in the form of plastic debris transported by ocean currents. We show that Arctic wildlife in pristine terrestrial environments may also ingest garbage or food items derived from abandoned camp sites. We found the remains of a chocolate wrapper and a milk powder bag in two Arctic fox (Vulpes lagopus) scats and a piece of cloth in an Arctic wolf (Canis lupus arctos) scat collected near Nares Strait, northern Greenland, one of the most pristine terrestrial wilderness regions on Earth. Found on Washington Land and associated with long-abandoned camp sites, these three scats were among 657 Arctic fox scats and 92 wolf scats collected as part of a larger study. Our study demonstrates that these two highly opportunistic predators managed to consume garbage despite the almost complete lack of human activity in this High-Arctic region. Our results highlight that abandoned anthropogenic material in the High Arctic may function as a source of garbage for local terrestrial wildlife over extended time periods, and that garbage consumption may become a potential issue if human activity in remote Arctic regions increases.