Polar Research (E-Journal)
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Discovery of a large population of Hygrolembidium isophyllum (Lepidoziaceae, Marchantiophyta) in the South Shetland Islands, Antarctica
No full textIn February 2019, during fieldwork at Harmony Point, Nelson Island, South Shetland Islands, Antarctica, a large population of the rare liverwort Hygrolembidium isophyllum (Lepidoziaceae) was discovered. The occurrence of this rare species reinforces the need to preserve Antarctic Specially Protected Area 133
Occurrence of sperm whale (Physeter macrocephalus) in the Russian Arctic
No full textWe report two sperm whale (Physeter macrocephalus) strandings observed in the south-east corner of the Barents Sea (i.e., Pechora Sea) in 2018, unusually far from the species’ hitherto known distribution. While compiling a comprehensive overview of the occurrence of sperm whale sightings and strandings in the Russian Arctic, we learnt about one further stranding in the Pechora Sea, observed in 2017. All other records were from sites considerably closer to the species’ usual distribution. Reports from the eastern Russian Arctic suggest that sperm whales rarely, if ever, entered the Arctic from the Pacific Ocean. Although observed occurrences in the Russian Barents Sea have been few and sporadic, the occurrence of sperm whales in its south-eastern section appears to be a recent phenomenon, which is possibly related to declining sea-ice cover
Variable predator–prey relations in zooplankton overwintering in Subarctic fjords
No full textZooplankton predator–prey relations in northern Norwegian fjords are highly variable in time and space, and the mechanisms driving this variability are still poorly understood. Replicate Juday net sampling in October and February from 1983 to 2005, which included five repeated tows from bottom to surface, was conducted in Saltfjord and Mistfjord, northern Norway. The time-series provided evidence of in situ variability in species abundance, as well as seasonal and interannual changes in standing stock abundance. The shallow sill of one fjord caused accumulation of coastal water in the fjord’s basin, while the other fjord’s deeper sill selected denser water of Atlantic origin from the same open shelf habitat. The selective advection caused differences in the immigration of species recruiting to the fjords’ specific overwintering communities of zooplankton. Statistical analyses of the cumulated replicate data indicated significant in situ variability in the spatial density of species. Cases with an abundance of carnivores relating positively to other species probably resulted from the carnivores’ attraction to patches with concentrations of prey. Interspecific negative density relations likely indicated either predator avoidance or substantial trophic activity during the sampling. During years of high abundance, some wintering stocks of carnivores evidently reduced the local stocks of overwintering prey. We conclude that predator–prey interactions and stock variability in Subarctic fjords result from complex bio-geophysical interactions that occur on the scales of local habitats and basin-scale population systems
Smoking guns and volcanic ash: the importance of sparse tephras in Greenland ice cores
No full textVolcanic 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 (<10 µm) particulates, they are not associated with increased coarse (>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
The last two millennia: climate, ocean circulation and palaeoproductivity inferred from planktic foraminifera, south-western Svalbard margin
No full textWe 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
First record of horned puffin in the North Atlantic and tufted puffin in High Arctic Greenland
No full textAn 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 (Fratercula corniculata) repeatedly during the summer months of 2002–06 and 2013–19 and a single tufted puffin (F. cirrhata) 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 (F. arctica) colony
Ice-out and freshet fluxes of CO2 and CH4 across the air–water interface of the channel network of a great Arctic delta, the Mackenzie
No full textCarbon dioxide (CO2) and methane (CH4) 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 CO2 in the Mackenzie River were undersaturated during the rising freshet before water levels peaked, indicating net CO2 invasion at instantaneous CO2 flux rates (F-CO2) ranging from –112 to –258 mg-C m-2 d-1. Net CO2 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 CO2 evasion (F-CO2 from 74 to 177 mg-C m-2 d-1). Although the Peel River (which flows into the west side of the Mackenzie Delta) was a strong emitter of CO2 (F-CO2 from 373 to 871 mg-C m-2 d-1), overall, the Mackenzie River and Delta were weak emitters of CO2 during the 2010 ice-out period. All sites were strong emitters of CH4 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 CO2, and 186 to 433 Mg-C as CH4. 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
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
No full textReliable 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
Little auks under the midnight sun: diel activity rhythm of a small diving seabird during the Arctic summer
No full textMany 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 (Alle alle). 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
Morphological measurements of Atlantic puffin (Fratercula arctica naumanni) in High-Arctic Greenland
No full textMorphological measurements of 45 adult Atlantic puffins Fratercula arctica were collected in High-Arctic Greenland between 2010 and 2016. Measurements support that the population belongs to the F. a. naumanni subspecies and were significantly larger than those from populations found at lower latitudes, including F. a. grabae and F. a. arctica populations. Male puffins from High-Arctic Greenland had greater mass, bill length and tarsus length than females, but no difference was found in wing length. In comparison to other naumanii populations, body size was most similar to puffins in Svalbard. Overall, the measured Atlantic puffins from High-Arctic Greenland had some of the largest and most variable morphological measurements reported for any studied Atlantic puffin population. While morphological measurements and the relative geographic isolation of the puffin population in High-Arctic Greenland support the naumanni subspecies designation, additional research should use genetic methods to determine if this population and other populations in the North Atlantic are isolated. This is the only collection of naumanni morphometric measurements from geographical North America and enhances our collective knowledge of the species