Polar Research (E-Journal)
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Foraging behaviour of sympatrically breeding macaroni (Eudyptes chrysolophus) and chinstrap (Pygoscelis antarcticus) penguins at Bouvetøya, Southern Ocean
No full textSpecies with similar ecological requirements that overlap in range tend to segregate their niches to minimize competition for resources. However, the niche segregation possibilities for centrally foraging predators that breed on isolated Subantarctic islands may be reduced by spatial constraints and limitations in the availability of alternative prey. In this study we examined spatial and trophic aspects of the foraging niches of two sympatrically breeding penguin species, macaroni (Eudyptes chrysolophus; MAC) and chinstrap (Pygoscelis antarcticus; CHIN) penguins, at Bouvetøya over two breeding seasons. To measure at-sea movements and diving behaviour, 90 MACs and 49 CHINs were equipped with GPS loggers and dive recorders during two austral summer breeding seasons (2014/15 and 2017/18). In addition, blood samples from tracked birds were analysed for stable isotopes to obtain dietary information. CHINs displayed marked interannual variation in foraging behaviour, diving deeper, utilizing a larger foraging area and displaying enriched values of δ15N in 2014/15 compared to the 2017/18 breeding season. In contrast, MACs dove to similar depths and showed similar δ15N values, while consistently utilizing larger foraging areas compared to CHINs. We suggest that low krill abundances in the waters around Bouvetøya during the 2014/15 season resulted in CHINs shifting toward a diet that increased their niche overlap with MACs. Our findings may partly explain the decreasing number of breeding CHINs at the world’s most remote island, Bouvetøya, while also highlighting the importance of characterizing niche overlap of species using multi-season data sets
Modelled realistic daily variation in low winter sea-ice concentration over the Barents Sea amplifies Asian cold events
No full textThe boreal wintertime atmospheric responses, especially cold events over central Asia, to low sea-ice concentration (SIC) with and without realistic daily variation over the Barents Sea are explored with the Community Atmosphere Model version 4.0 (CAM4.0). The results show that the general atmospheric responses to approximately equal winter-mean Arctic sea-ice loss with a similar pattern but with climatological versus realistic daily variation are different. With the forcing of low SIC with climatological daily variation, Asian cold events become a little longer and stronger than in the control experiment; this mainly results from the enhancement of a 500-hPa Ural anticyclonic anomaly. However, the low SIC forcing that includes realistic daily variability greatly intensifies central Asian cold events and the cyclonic anomaly downstream of the Ural anticyclone. Further analysis reveals that Asian cold events are closely associated with Arctic deep warming at an intraseasonal time scale, which is also the strongest in the perturbed experiment forced by low SIC with realistic daily variation. This work provides a better understanding of the linkage between sea-ice variation over the Barents Sea and central Asian cold events, which may improve extreme weather prediction. It also implies that it is necessary to force air–sea coupling models and atmospheric models with realistic daily SIC in the study of the relationship between Arctic sea ice and mid-latitude cold events
Five decades of terrestrial and freshwater research at Ny-Ålesund, Svalbard
No full textFor more than five decades, research has been conducted at Ny-Ålesund, in Svalbard, Norway, to understand the structure and functioning of High-Arctic ecosystems and the profound impacts on them of environmental change. Terrestrial, freshwater, glacial and marine ecosystems are accessible year-round from Ny-Ålesund, providing unique opportunities for interdisciplinary observational and experimental studies along physical, chemical, hydrological and climatic gradients. Here, we synthesize terrestrial and freshwater research at Ny-Ålesund and review current knowledge of biodiversity patterns, species population dynamics and interactions, ecosystem processes, biogeochemical cycles and anthropogenic impacts. There is now strong evidence of past and ongoing biotic changes caused by climate change, including negative effects on populations of many taxa and impacts of rain-on-snow events across multiple trophic levels. While species-level characteristics and responses are well understood for macro-organisms, major knowledge gaps exist for microbes, invertebrates and ecosystem-level processes. In order to fill current knowledge gaps, we recommend (1) maintaining monitoring efforts, while establishing a long-term ecosystem-based monitoring programme; (2) gaining a mechanistic understanding of environmental change impacts on processes and linkages in food webs; (3) identifying trophic interactions and cascades across ecosystems; and (4) integrating long-term data on microbial, invertebrate and freshwater communities, along with measurements of carbon and nutrient fluxes among soils, atmosphere, freshwaters and the marine environment. The synthesis here shows that the Ny-Ålesund study system has the characteristics needed to fill these gaps in knowledge, thereby enhancing our understanding of High-Arctic ecosystems and their responses to environmental variability and change
Value of the Copernicus Arctic Regional Reanalysis (CARRA) in representing near-surface temperature and wind speed in the north-east European Arctic
No full textThe representation of 2-m air temperature and 10-m wind speed in the high-resolution (with a 2.5-km grid spacing) Copernicus Arctic Regional Reanalysis (CARRA) and the coarser resolution (ca. 31-km grid spacing) global European Center for Medium-range Weather Forecasts fifth-generation reanalysis (ERA5) for Svalbard, northern Norway, Sweden and Finland is evaluated against observations. The largest differences between the two reanalyses are found in regions with complex terrain and coastlines, and over the sea ice for temperature in winter. In most aspects, CARRA outperforms ERA5 in its agreement with the observations, but the value added by CARRA varies with region and season. Furthermore, the added value by CARRA is seen for both parameters but is more pronounced for temperature than wind speed. CARRA is in better agreement with observations in terms of general evaluation metrics like bias and standard deviation of the errors, is more similar to the observed spatial and temporal variability and better captures local extremes. A better representation of high-impact weather like polar lows, vessel icing and warm spells during winter is also demonstrated. Finally, it is shown that a substantial part of the difference between reanalyses and observations is due to representativeness issues, that is, sub-grid variability, which cannot be represented in gridded data. This representativeness error is larger in ERA5 than in CARRA, but the fraction of the total error is estimated to be similar in the two analyses for temperature but larger in ERA5 for wind speed
Why are Svalbard Arctic foxes Brucella spp. seronegative?
No full textArctic foxes (Vulpes lagopus) are susceptible to smooth Brucella (s-Brucella) infection and may be exposed to such bacteria through the consumption of infected marine mammals, as implied by the finding of s-Brucella antibodies in polar bears (Ursus maritimus). Arctic foxes in Svalbard have not previously been investigated for s-Brucella antibodies, but such antibodies have been detected in Arctic foxes in Iceland, Alaska (USA) and Russia. We investigated blood from Svalbard Arctic foxes for s-Brucella antibodies using an indirect enzyme-linked immunosorbent assay (iELISA). The animals (0–13 years old) were either caught by fur trappers (1995–2003, n = 403) or found dead (1995 and 2003, n = 3). No seropositive animals were detected. Morbidity and mortality due to the infection cannot be ruled out. However, no known, large disease outbreaks of unknown aetiology have been reported. Furthermore, it is unlikely that the Svalbard Arctic fox is resistant to infection as Arctic foxes from other populations are susceptible, and there is circumpolar connectivity between populations. The discrepancy between the findings in Iceland and Svalbard is surprising as both populations are on islands with no known local sources of exposure to s-Brucella other than marine mammals. However, our negative findings suggest that marine mammals may not be a major source of infection for this species. Comparative investigations are needed in order to draw conclusions regarding the epizootiology of s-Brucella in Arctic foxes in Svalbard and Iceland
Tusk anomalies in narwhals (Monodon monoceros) from Greenland
No full textThe elongated, spiraled tusk of male narwhals (Monodon monoceros) grows continuously throughout the life of the whale and is most likely a secondary sexual trait used in male–male hierarchical competition and possibly in female mate choice. Sex determination in narwhals is typically based on the presence (male) or absence (female) of an erupted tusk, but anomalies such as females with tusks, tuskless males or double-tusked whales occur, although infrequently. In this study, we collected reproductive data and recorded the presence or absence of a tusk in narwhals from the Inuit hunt in Greenland (1993 and 2010–19) with the purpose of estimating the frequency of tusk anomalies. We found that of the 173 whales, 2.9% displayed tusk anomalies. Tusked females constituted 1.5% of sampled females, tuskless males 2.8% of sampled males and double-tusked males 0.9% of sampled males. Biological information on a tusked female, a tuskless male and a double-tusked male was collected and is presented here. The tusked female was sexually mature, and 18 ovarian scars (indicating pregnancies) documented a long reproductive lifespan. The complete female tusk was estimated to be between 146 and 151 cm in length. The tuskless male was sexually maturing, as indicated by body dimensions, and the double-tusked male was sexually immature, with the two tusks measuring <90 cm in length. Although narwhals exhibit extremely low levels of genetic diversity, tusk anomalies persist in the populations, perhaps facilitated by the reproductive ability of whales with tusk anomalies
Aggregations of foraging black guillemots (Cepphus grylle) at a sea-ice edge in front of a tidewater glacier
No full textSeabirds in cold biomes sometimes aggregate near glacier fronts and at sea-ice edges to forage. In this note, we report on large aggregations of black guillemots (Cepphus grylle) at the edge of sea ice in front of the tidewater glacier Kongsbreen (Kongsfjorden, Svalbard). During several days in the second half of June 2011, we observed 49–155 individuals of black guillemots at this ice edge. They foraged actively, and many of the dives were directed underneath the sea ice. The outflow of glacial meltwater and resulting upwelling generated opportunities for the black guillemots to feed, likely on zooplankton or fish. The black guillemots used the sea ice as a resting platform between dives or diving sessions, and whilst on the ice, they interacted socially. On our last visit, the sea ice was gone, and the black guillemots had left the bay. At the neighbouring tidewater glacier Kronebreen, there was no sea ice connected to the glacier. Surface-feeding seabirds, particularly black-legged kittiwakes (Rissa tridactyla), were numerous at the plumes generated by meltwater from Kronebreen. Black guillemots were not seen at these plumes, but some individuals were seen scattered in the fjord system. Our observations add to the natural history of black guillemots and enhance our knowledge of ecological interactions and seabird habitat use shaped by tidewater glaciers
The polar sciences journal: the past and future of a crucial research instrument
No full textJournals dedicated to the polar sciences have been outliers. Within both the history of science and the history of media, they stand out in several ways, including their comparatively late establishment of peer-review. It was not until the second half of the 20th century, that polar sciences journals began to carry predominantly peer-reviewed original research rather than synopses of research published elsewhere. This Perspective piece uses the 40th anniversary of Polar Research as an opportunity to look at the past of polar sciences periodicals—and invites reflection on their future
Historic temperature observations on Nordaustlandet, north-east Svalbard
No full textLong-term meteorological data for the Arctic are sparse. One of the longest quasi-continuous temperature time series in the High Arctic is the extended Svalbard Airport series, providing daily temperature data from 1898 until the present. Here, I derive an adjustment to historic temperature observations on the island of Nordaustlandet, north-east Svalbard, in order to link these to the extended Svalbard Airport series. This includes the Haudegen observations at Rijpfjorden during 1944/45 and a previously unrecognized data set obtained by the Norwegian hunters and trappers Gunnar Knoph and Henry Rudi during their wintering at Rijpfjorden in 1934/35. The adjustment is based on data from an automatic weather station at Rijpfjorden during 2014–16 and verified with other independent historic temperature observations on Nordaustlandet. An analysis of the Haudegen radiosonde data indicates that the surface temperature observations at Rijpfjorden are generally well correlated with the free tropospheric temperatures at 850 hPa, but occasionally show the occurrence of boundary-layer inversions during winter, where local temperatures fall substantially below what is expected from the regression. The adjusted historic observations from Nordaustlandet can, therefore, be used to fill remaining gaps in the extended Svalbard Airport series
