Polar bear (Ursus maritimus) use of the Cape Bathurst polynya and flaw lead

The Cape Bathurst polynya and flaw lead (CBP) are major, predictable habitat features with ≤15% ice cover in an otherwise ice-covered Beaufort Sea, and thought to provide hunting opportunities for polar bears (Ursus maritimus Phipps, 1774). We assessed 78 adult (female; with and without cubs) and subadult (male and female) polar bears’ use of the CBP from October – June, 2007–2014. The CBP was up to 725 km wide in autumn, ice-covered in winter, and <306 km wide in spring. Seventy-nine percent (n = 62) of the bears used the CBP (≥1 location <2.4 km, or one 4 h step length, from the CBP). Use was higher for solitary adult females and subadult males, which travelled faster with low turning angles along wider sections than females with offspring and subadult females. Bears were closest to the CBP during the spring hyperphagia season. While a wider CBP did not prevent crossing, bears primarily crossed from the coast towards pack ice at locations 53% narrower than areas not crossed. Bears might avoid crossing when it would require a long-distance swim. The CBP affects polar bear ecology by providing hunting habitat and a corridor that could increase prey encounters but may affect movement.

Research on Main Engine Power of Transport Ship with Different Bows in Ice Area According to EEDI Regulation

The Energy Efficiency Design Index (EEDI) has been applied to ship carbon emission standards since 2013, ice ships subject to the Finnish Swedish Ice Class Rules (FSICR) also need to meet the requirements of EEDI. In this study, the engine power requirements by EEDI at different stages for the considered ice class ships with different ice classes (1C, 1B, 1A, 1A Super) are compared with engine power requirements obtained from the resistance calculated by FSICR or Lindqvist method. Three different bow shapes for the considered ice class ships and different pack ice coverage are studied. The results from FSICR or Lindqvist formula show that 1A Super ice classes for all considered bow shapes cannot meet the requirement by EEDI at Phase 2 and 3; For 1B and 1A class, some bow shapes can meet the EEDI requirement for all stages, but some cannot; For 1C class, all bow shapes can meet the EEDI requirements for all stages. The ship main engine power requirements under different pack ice concentration are studied and compared to EEDI requirements.

Antarctic Bacteria, Sea Ice Ecosystem Dynamics, and Global Climate Change

<p>Productivity in the Southern Ocean reflects both the spatial and temporal dynamics of the sea ice ecosystem, as well as the complex cycling of energy through the microbial community. Marine bacteria are thought to be integral to trophodynamics and the functioning of a microbial loop within the ice matrix, but there is no clear understanding of the distribution and diversity of bacteria or the importance of bacterial production. Understanding the bacterial response to environmental change in the sea ice ecosystem may provide an insight into the potential changes to the physical oceanography and ecology of the Southern Ocean. In this study, a multivariate statistical approach was used to compare the distribution and abundance of bacteria occurring in pack ice at the tongue of the Mertz Glacier (George V Coast, Antarctica) with bacteria from fast ice at Cape Hallett (Victoria Land coastline, Antarctica). Estimates of bacterial abundance were derived using both epifluorescence microscopy and flow cytometry and correlated with algal and chlorophyll a data. Significant differences in the vertical distribution of cells within the ice were observed between the Mertz Glacier and Cape Hallett, but no overall difference in cell abundance was found between the two locations with 7.6 ± 1.2 x 109 cells per m2 and 8.7 ± 1.6 x 109 cells per m2 respectively. Bacteria and algae were positively correlated in pack ice of the Mertz Glacier indicating a functional microbial loop, but no discernable relationship was exhibited in multiyear ice at Cape Hallett. These findings support the general consensus that the generation of bacterial biomass from algal-derived dissolved organic matter is highly variable across seasons and habitats. The tetrazolium salt 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) was used to investigate the bacterial response to experimentally induced changes in light and salinity in fast ice at Cape Hallett. Two distinct assemblages were examined; the brine channel assemblage near the surface of the ice and the interstitial or bottom assemblage. This study presents preliminary evidence that the metabolic activity of brine bacteria is influenced by light stimulus, most likely as a response to increased levels of algal-derived dissolved organic matter. No cells were deemed to be metabolically active when incubated in the dark, while on average thirty-eight percent of the cells incubated at 150 =mol photons m-2 s-1 were metabolically active. Additional results indicate that salt concentration is more significant than light irradiance in influencing the metabolic response of cells present in the interstitial region of the sea ice profile. When acclimated over a period of eight hours, cells exhibited a tolerance to changing saline concentrations, but after a further eight hours there is some evidence to suggest activity is reduced at either end of the saline regime. Bacterial metabolic activity in each assemblage is thus thought to reflect the fundamentally different light and saline environments within the sea ice. Metabolic probes such as CTC will prove useful in providing a mechanistic understanding of productivity and trophodynamics in the Antarctic coastal ecosystem, and may contribute to prognostic models for qualifying the resilience of the microbial community to climate change.</p>

Antarctic Bacteria, Sea Ice Ecosystem Dynamics, and Global Climate Change

<p>Productivity in the Southern Ocean reflects both the spatial and temporal dynamics of the sea ice ecosystem, as well as the complex cycling of energy through the microbial community. Marine bacteria are thought to be integral to trophodynamics and the functioning of a microbial loop within the ice matrix, but there is no clear understanding of the distribution and diversity of bacteria or the importance of bacterial production. Understanding the bacterial response to environmental change in the sea ice ecosystem may provide an insight into the potential changes to the physical oceanography and ecology of the Southern Ocean. In this study, a multivariate statistical approach was used to compare the distribution and abundance of bacteria occurring in pack ice at the tongue of the Mertz Glacier (George V Coast, Antarctica) with bacteria from fast ice at Cape Hallett (Victoria Land coastline, Antarctica). Estimates of bacterial abundance were derived using both epifluorescence microscopy and flow cytometry and correlated with algal and chlorophyll a data. Significant differences in the vertical distribution of cells within the ice were observed between the Mertz Glacier and Cape Hallett, but no overall difference in cell abundance was found between the two locations with 7.6 ± 1.2 x 109 cells per m2 and 8.7 ± 1.6 x 109 cells per m2 respectively. Bacteria and algae were positively correlated in pack ice of the Mertz Glacier indicating a functional microbial loop, but no discernable relationship was exhibited in multiyear ice at Cape Hallett. These findings support the general consensus that the generation of bacterial biomass from algal-derived dissolved organic matter is highly variable across seasons and habitats. The tetrazolium salt 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) was used to investigate the bacterial response to experimentally induced changes in light and salinity in fast ice at Cape Hallett. Two distinct assemblages were examined; the brine channel assemblage near the surface of the ice and the interstitial or bottom assemblage. This study presents preliminary evidence that the metabolic activity of brine bacteria is influenced by light stimulus, most likely as a response to increased levels of algal-derived dissolved organic matter. No cells were deemed to be metabolically active when incubated in the dark, while on average thirty-eight percent of the cells incubated at 150 =mol photons m-2 s-1 were metabolically active. Additional results indicate that salt concentration is more significant than light irradiance in influencing the metabolic response of cells present in the interstitial region of the sea ice profile. When acclimated over a period of eight hours, cells exhibited a tolerance to changing saline concentrations, but after a further eight hours there is some evidence to suggest activity is reduced at either end of the saline regime. Bacterial metabolic activity in each assemblage is thus thought to reflect the fundamentally different light and saline environments within the sea ice. Metabolic probes such as CTC will prove useful in providing a mechanistic understanding of productivity and trophodynamics in the Antarctic coastal ecosystem, and may contribute to prognostic models for qualifying the resilience of the microbial community to climate change.</p>

Complementary use of stable isotopes and fatty acids for quantitative diet estimation of sympatric predators, the Antarctic pack-ice seals

The quantitative use of stable isotopes (SIs) for trophic studies has seen a rapid growth whereas fatty acid (FA) studies remain mostly qualitative. We apply the Bayesian tool MixSIAR to both SI and FA data to estimate the diet of three sympatric predators: the crabeater (Lobodon carcinophaga), Weddell (Leptonychotes weddellii) and leopard seal (Hydrurga leptonyx). We used SI data of their vibrissae and FA data of their outer blubber to produce comparable diet estimates for the same individuals. Both SI and FA models predicted the same main diet components, although the predicted proportions differed. For the crabeater seal, both methods identified krill, Euphausia superba, as the main, and almost exclusive, food item, although the FA model estimated a slightly lower proportion, potentially due to the low lipid content of krill compared to the fish species used in the model. For the Weddell seal the FA model identified the fish Pleuragramma antarcticum as the most important prey, whereas the SI model was not able to distinguish among prey species, identifying a ‘fish-squid’ group as the main diet component. For the leopard seal, both models identified krill as the main contributor; however, the predicted proportions for the secondary sources differed. Although vibrissae and outer blubber may not represent the same timeframe, the use of MixSIAR with FA data provides diet estimates comparable to those obtained with SI data, thus, both approaches were complimentary. The use of both biotracers offers a feasible option to study diets of wild animals in a quantitative manner.

Iñupiaq Knowledge of Polar Bears (Ursus maritimus) in the Southern Beaufort Sea, Alaska

Successful wildlife management depends upon coordination and consultation with local communities. However, much of the research used to inform management is often derived solely from data collected directly from wildlife. Indigenous people living in the Arctic have a close connection to their environment, which provides unique opportunities to observe their environment and the ecology of Arctic species. Further, most northern Arctic communities occur within the range of polar bears (nanuq, Ursus maritimus) and have experienced significant climatic changes. Here, we used semi-structured interviews from 2017 to 2019 to document Iñupiaq knowledge of polar bears observed over four decades in four Alaskan communities in the range of the Southern Beaufort Sea polar bear subpopulation: Wainwright, Utqiaġvik, Nuiqsut, and Kaktovik. All but one of 47 participants described directional and notable changes in sea ice, including earlier ice breakup, later ice return, thinner ice, and less multiyear pack ice. These changes corresponded with observations of bears spending more time on land during the late summer and early fall in recent decades—observations consistent with scientific and Indigenous knowledge studies in Alaska, Canada, and Greenland. Participants noted that polar bear and seal body condition and local abundance either varied geographically or exhibited no patterns. However, participants described a recent phenomenon of bears being exhausted and lethargic when arriving on shore in the summer and fall after extensive swims from the pack ice. Further, several participants suggested that maternal denning is occurring more often on land than sea ice. Participants indicated that village and regional governments are increasingly challenged to obtain resources needed to keep their communities safe as polar bears spend more time on land, an issue that is likely to be exacerbated both in this region and elsewhere as sea ice loss continues.

Vertical sonar beam width and scanning behavior of wild belugas (Delphinapterus leucas) in West Greenland

Echolocation signals of wild beluga whales (Delphinapterus leucas) were recorded in 2013 using a vertical, linear 16-hydrophone array at two locations in the pack ice of Baffin Bay, West Greenland. Individual whales were localized for 4:42 minutes of 1:04 hours of recordings. Clicks centered on the recording equipment (i.e. on-axis clicks) were isolated to calculate sonar parameters. We report the first sonar beam estimate of in situ recordings of wild belugas with an average -3 dB asymmetrical vertical beam width of 5.4°, showing a wider ventral beam. This narrow beam width is consistent with estimates from captive belugas; however, our results indicate that beluga sonar beams may not be symmetrical and may differ in wild and captive contexts. The mean apparent source level for on-axis clicks was 212 dB pp re 1 μPa and whales were shown to vertically scan the array from 120 meters distance. Our findings support the hypothesis that highly directional sonar beams and high source levels are an evolutionary adaptation for Arctic odontocetes to reduce unwanted surface echoes from sea ice (i.e., acoustic clutter) and effectively navigate through leads in the pack ice (e.g., find breathing holes). These results provide the first baseline beluga sonar metrics from free-ranging animals using a hydrophone array and are important for acoustic programs throughout the Arctic, particularly for acoustic classification between belugas and narwhals (Monodon monoceros).

Features of the glacial formations structure and bottom relief forms related to them according to seismoacoustic profiling data and their role in the decision of discussion issues of the quarterly cover formation of the Barents Sea

Hot questions in the modern Quaternary geology of the Arctic seas associated with their glaciation are discussed in this article. The questions of the history of the occurrence of the problem of shelf glaciation or “drift” accumulation of boulder-bearing sediments are considered in detail. The results of seismic-acoustic studies and their interpretation with the aim of seismic stratigraphic and genetic partition of the cover of loose sediments of Quaternary age are considered in detail. Arguments are presented in favor of the continental origin of glaciers (Novaya Zemlya, Ostrovnoy and Scandinavian), which in the late Neopleistocene spread to the shelf of the Barents Sea and occupied its surface to depths of 120−150 m. Further development of glaciation was already due to the expansion of the area of shelves glaciers. The facies zoning of glacial-marine deposits is estimated, which is related to the distance from the front of the glaciers. It is concluded that already at the end of the Late Pleistocene, most of the modern Barents Sea was free from glaciers and from the annual cover of pack ice. Data on the absence of the area distribution of frozen sediment strata within the modern Barents Sea shelf are presented.