Polar Research (E-Journal)
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Genetic history and stock identity of beluga whales in Kotzebue Sound
No full textWe investigate the recent history and stock identity of beluga whales (Delphinapterus leucas) in Kotzebue Sound in the Chukchi Sea, a region long frequented by large numbers of belugas in summer until their near disappearance in the 1980s. Wide variation in numbers since then suggests a complex recent history that hinders recovery efforts. Analysis of teeth sampled during the historical (pre-decline) era using ancient DNA (aDNA) methods found that the original Kotzebue Sound whales were differentiated for mitochondrial DNA (mtDNA) from other summering concentrations across the Pacific Arctic revealing a demographically distinct subpopulation where long-established migratory culture likely facilitated population divergence. Analysis of microsatellite (nDNA) and mtDNA markers in belugas from the contemporary (post-decline) era revealed that whales from other stocks likely visited Kotzebue Sound, including during two low ice years when relatively large numbers of whales were present. Some mtDNA lineages were found only in Kotzebue Sound, with one recorded in both the historical and contemporary eras. Exclusion tests found a number of whales in Kotzebue Sound during the contemporary era that had nDNA genotypes unlikely to arise in other contemporary stocks in the Pacific Arctic. Our findings indicate that the Kotzebue Sound belugas comprised a unique stock of which a few remnants likely still co-occur with belugas from other larger stocks. We recommend that the US government work through the co-management process to greatly reduce or eliminate the taking of belugas, especially adult females, likely to belong to the Kotzebue Sound stock, until they recover
Liverworts frequently form mycothalli on Spitsbergen in the High Arctic
No full textMycothalli, symbioses between liverworts and soil fungi, have not previously been recorded in the Arctic. Here, 13 species of leafy liverwort from west Spitsbergen in the High Arctic are examined for the symbiosis using epifluorescence microscopy and sequencing of fungal ribosomal (r)RNA genes amplified from plant tissues. Microscopy showed that intracellular hyphal coils, key indicators of the symbiosis, were frequent (>40% stem length colonized) in nine species of liverwort in the families Anastrophyllaceae, Lophoziaceae, Cephaloziellaceae, Cephaloziaceae and Scapaniaceae, with hyphae occurring frequently (>40% cells occupied) in the rhizoids of 10 species in the same families. Dark septate hyphae, apparently formed by ascomycetes, were frequent on the stems of members of the Anastrophyllaceae, Cephaloziellaceae and Cephaloziaceae, and typically those growing on acidic mine tailings. Sequencing of fungal rRNA genes showed the presence of nine distinct groups (based on a 3% cut-off for ITS sequence divergence) of the basidiomycete Serendipita in the Anastrophyllaceae and Lophoziaceae, with ordinations and correlative analyses showing the presence of the genus to be positively associated with the frequency of hyphal coils, the occurrence of which was positively associated with edaphic factors (soil δ15N value and concentrations of moisture, nitrogen, carbon and organic matter). We propose that the frequency of mycothalli in leafy liverworts on west Spitsbergen, which is an order of magnitude higher than at lower latitudes, may arise from benefits conferred by mycobionts on their hosts in the harsh environment of the High Arctic
Inferring population structure and genetic diversity of the invasive alien Nootka lupin in Iceland
No full textPolar and subpolar regions are known for their particular vulnerability and sensitivity to the detrimental effects of non-indigenous species, which is well exemplified by the Nootka lupin (Lupinus nootkatensis) spread in Iceland. Since understanding the population and ecological genetics of invasive alien species offers hope for counteracting harmful biological invasions, the objective of the present study was to investigate interspecific variation in L. nootkatensis in Iceland in relation to a native population in Alaska. Moreover, we aimed to assess whether internal transcribed spacer 2 (ITS2) has sufficient phylogenetic applicability for a large-scale screening of the genetic diversity of a non-indigenous population of this species. This study, which is the first attempt to investigate the genetic diversity of the Nootka lupin in Iceland, included plant samples from eight locations in Iceland and one in Alaska. The analyses included genotyping by sequencing of the 417-nucleotide fragment of the 5.8S ribosomal RNA, ITS2 and part of the large subunit ribosomal RNA (GenBank MT026578-MT026580, MT077004). The main findings showed the presence of five previously unexplained single-nucleotide polymorphisms (SNPs); however, their discriminatory power for Icelandic populations was relatively low, since polymorphism information content (PIC) values ranged from 0.0182 to 0.0526, with average heterozygosity 0.0296. Concomitantly, analysis of multilocus genotypes (MLG) revealed sufficient differences in MLGs variants and their frequency to form genotypic patterns unique for Alaskan and Icelandic populations, revealing an internal genetic structure of the studied group. The proposed SNP panel needs to be supplemented with other nuclear and organellar markers
Differential acclimation responses to irradiance and temperature in two co-occurring seaweed species in Arctic fjords
No full textArctic fjord systems experience large amplitudes of change in temperature and radiation regime due to climate warming and the related decrease in sea ice. The resultant increase in irradiance entering the water column influences photosynthetic activity of benthic and pelagic primary producers. The subtidal brown alga Desmarestia aculeata and the intertidal red alga Palmaria palmata populate the cold-temperate coasts of the North Atlantic, reaching the polar zone. To evaluate their acclimation potential, we collected both species in Kongsfjorden, Svalbard (78.9°N, 11.9°E), during the Arctic summer and exposed specimens to two different PAR levels (50 and 500 μmol photons m−2 s−1) and temperatures (0, 4 and 8 °C) for 21 days. Photosynthetic parameters and biochemical features (pigment concentration and antioxidants) were assessed. In general, high irradiance was the factor that generated a negative effect for D. aculeata and P. palmata in the photosynthetic parameters of the photosynthesis–irradiance curve and Fv/Fm. The pigment concentration in both species tended to decrease with increasing irradiance. Antioxidant level showed different trends for both species: in D. aculeata, antioxidant potential increased with high irradiance and temperature, while in P. palmata, it only increased with high irradiance. Both species showed responses to the interaction of irradiance and temperature, although D. aculeata was more sensitive to high irradiance than P. palmata. Our study shows how these species, which have similar geographical distribution in the North Atlantic and the Arctic but belong to different taxonomic lineages, have similar strategies of acclimation, although they respond differently to ecophysiological parameters
Stranded beluga (Delphinapterus leucas) calf response and care: reports of two cases with different outcomes
No full textGiven the remote, rugged areas belugas typically inhabit and the low rehabilitation success rate with any cetacean, it is rare to have the opportunity to rescue a live-stranded beluga. The Alaska SeaLife Center cared for two stranded beluga calves with two different outcomes. In 2012, a neonatal male beluga calf (DL1202) stranded following intense storms in Bristol Bay. In 2017, a helicopter pilot discovered a stranded male beluga calf (DL1705) during a flight over Cook Inlet. The Alaska SeaLife Center transported both calves for rehabilitation and utilized supportive care plans based on those for other species of stranded cetaceans and care of neonatal belugas at zoological facilities. Diagnostics included complete blood counts, serum chemistries, microbial cultures, hearing tests, imaging and morphometric measurements to monitor systemic health. Treatments included in-pool flotation support; antimicrobials; gastrointestinal support; and close monitoring of respirations, urination, defecation and behaviour. After three weeks of supportive care, the Bristol Bay calf (DL1202) succumbed to sepsis secondary to a possible prematurity-related lack of passive transfer of antibodies. After seven weeks, the Cook Inlet calf (DL1705) recovered and all medications were discontinued. Unable to survive on his own, he was declared non-releasable and placed in long-term care at a zoological facility, to live with other belugas. Aspects and details from successful cases of cetacean critical care become important references especially vital for the survival of essential animals in small, endangered populations
Subglacial discharge weakens the stability of the Ross Ice Shelf around the grounding line
No full textIn this paper, we examine potential impact of discharge in Subglacial Lake Engelhardt, West Antarctica, on the stability of the Ross Ice Shelf around the grounding line by combining satellite altimetry and remote sensing images. According to satellite altimetry data from the Ice, Cloud and Land Elevation Satellite (ICESat; 2003–06), Subglacial Lake Engelhardt (SLE) discharged ca. 1.91 ± 0.04 km3 of water into the downstream region. The ice-surface record derived from ICESat (2006–09) and CryoSat-2 (2011–17) data shows that the lake gained ca. 2.09 ± 0.05 km3 of water during the refilling event following the drainage event, taking three times as much time to reach the previous water level before the discharge; the calculation demonstrates that water input from an upstream lake is unable to sustain water increase in SLE, indicating that the subglacial, hydrologic system and groundwater flow could have contributed to water increase in SLE via hydrologic networks. Satellite images captured surface depressions and crevasses at the drainage outlet point of hydrologic networks around the grounding line; satellite altimetry data show that the ice surface there is still depressing even though the subglacial discharge has finished, potentially reflecting the long-term impact of subglacial discharge on the stability of the immediate Ross Ice Shelf around the grounding line
Species diversity of macroalgae in Grønfjorden, Spitsbergen, Svalbard
No full textClimate changes in the North Atlantic and Arctic affect the macrophytobenthos along with other components of the ecosystem, resulting in an increase of species diversity and biomass in western Spitsbergen, as has been reported. Grønfjorden is located at the mouth of one of the largest fjords of Spitsbergen, Isfjorden, and is influenced by the recent significant increase in the inflow of Atlantic Water. However, there are nearly no published data on the phytobenthic communities in this area. This research study of the littoral and sublittoral areas of Grønfjorden in 2013–14 documented 68 species, mostly high-boreal and boreal–Arctic species. When compared with species diversity in the other areas of western Spitsbergen, the data show the uniqueness of Grønfjorden’s species composition
Synergy between behavioural research on beluga whales (Delphinapterus leucas) conducted in zoological and wild settings
No full textBehavioural observations of captive beluga whales have complemented and extended much of what has been learnt about this species in the wild. Aquarium-based research has provided finer-scale specificity for many topics, including the seasonal breeding pattern that is characteristic of this species, as well as socio-sexual behaviour that appears to be an important part of the behavioural repertoire of this species. One example is a strong propensity for male–male social interactions that begin to develop at an early age. In addition, detailed behavioural milestones in calves have been documented in ways that extend that which have been collected from wild populations. These include swim positions with mother, separations/reunions with mother, and other social interactions, and play. Characteristics of beluga maternal care have also been studied more often in captive settings than in the wild, particularly with respect to details pertaining to nursing behaviour, individual differences in maternal style and allomaternal care. Other topics that have received scientific scrutiny in zoological settings include individual differences and behavioural laterality. Thus, a greater understanding of beluga behavioural biology has the potential to emerge as a consequence of synergy between research conducted in the two settings
A review of the ecology and status of white whales (Delphinapterus leucas) in Svalbard, Norway
No full textThe Norwegian Polar Institute initiated a research programme on white whales in 1995 to gather biological information relevant for the species’ management; the results of which are reviewed herein. Satellite tracking from two periods (1995–2001 and 2013–16), between which sea ice diminished markedly, showed that the whales in waters off the archipelago of Svalbard spent most of their time foraging close to tidewater glaciers. Transits between glaciers typically followed the coastline, with the whales moving rapidly from one glacier to another. During the later period, the whales spent some time out in the fjords, suggesting that they might be targeting prey in the Atlantic Water masses that now prevail in Svalbard’s west-coast fjords. Most of their dives were extremely shallow (13 ± 26 m; maximum 350 m) and of short duration (97 ± 123 s; maximum 31.4 min). Fatty-acid analyses indicated that polar cod (Boreogadus saida) was the main prey during the first sampling period. An aerial survey in 2018 estimated the population numbered 549 (CI: 436–723) animals. Svalbard white whales are genetically separate from populations off west Greenland and in the White Sea. Predation by killer whales appears to have influenced white whale behaviour in Svalbard; they are often silent, despite having a normal vocal repertoire for the species and their coastal movements take place in very shallow water. This population has extremely high contaminant levels. Climate change poses a threat to this small population of white whales
Minimally invasive physiological correlates of social behaviour in belugas (Delphinapterus leucas) under human care
No full textSimultaneous observations of reproductive physiology and behaviour were conducted on a group of two male and two female belugas under professionally managed care for one year to explore potential mating strategies. Weekly blow sampling for progesterone in females was used to define the breeding season by detecting three oestrous cycles in one female. Twice weekly blow sampling for testosterone and twice monthly testes measurements via ultrasonography were used to detect reproductive seasonality in both males. Female–male association frequency varied longitudinally, with 70% of all interactions occurring during the 16-week breeding season. Male–male associations did not vary seasonally. Male display behaviours towards the female occurred 14.8 times more frequently during the breeding season (0.164 ± 0.188 behaviours/min) than outside of the breeding season (0.011 ± 0.042 behaviours/min). The cycling female responded variably to male display behaviours by altering swim speed or body orientation towards the male. Although this small sample size limits broad conclusions, the frequent display behaviours, low copulation rate and lack of serious male–male aggression are consistent with predictions for pre-copulatory female mate choice developed from the current knowledge of beluga reproductive physiology. These observations, which are not feasible for wild belugas, provide important management considerations because reduced opportunities for mate choice could limit the reproductive rate, especially in small populations