Chukchi Sea Research Articles

Satellite Multi-Sensor Data Analysis of Unusually Strong Polar Lows over the Chukchi and Beaufort Seas in October 2017

Polar lows (PLs) are intense mesoscale weather systems that often cause severe storm winds in the Nordic Seas but were considered as being exceedingly rare in the Pacific Arctic region before sea ice decline. Here, we explore four PLs observed on 18–22 October 2017 in the Chukchi and Beaufort Seas—an area with an exceptionally sparse observation network. The study is based on the combined use of the satellite microwave measurements, as well as infrared imagery, the ERA5, MERRA-2 and NCEP-CFSv2 reanalysis data sets. An unusually strong PLs pair developed near the marginal ice zone during a marine-cold air outbreak in anomalously low sea ice extent conditions. PLs pair moved southward as a mesocyclonic system called the “merry-go-round”, under the upper-level tropospheric vortex with a cold core. Multi-sensor satellite measurements show that, in the mature stage, a PL pair had near-surface wind speeds (W) close to hurricane force—over 30 m/s. Comparison analysis of W distributions within the strongest PL showed that all reanalysis data sets reasonably reproduce the PL median wind speed but underestimate its extreme values by 15–23%. The reanalysis data sets detected only two PLs with horizontal scales of over 220 km. Tracks of identified PLs for all data sets are in good agreement with the ones obtained from satellite images capturing the main features of the mesoscale weather system propagation. For the track of the strongest PL event, ERA5 exhibited the most accordance with satellite observations with a tracking error of 50–60 km.

Trait-based assessment of polychaete assemblages distinguishes macrofaunal community structure among four distinct benthic eco-regions on a shallow arctic shelf

In a rapidly changing Arctic, effects of taxonomic and functional composition of infaunal benthic communities on ecosystem function are poorly characterized for many areas of the continental shelf environment. Infaunal macrobenthos perform essential ecosystem services in soft-sediment habitats, including sediment oxygenation, organic-matter burial, and nutrient regeneration. Changes in the distribution and composition of infauna are likely to impact these important processes. We investigated spatial patterns in macrofauna on the northern Bering and southern Chukchi Sea continental shelves in conjunction with a suite of environmental variables as part of the Arctic Shelf Growth, Advection, Respiration, and Deposition (ASGARD) project. Depth-stratified macrofauna samples (>500 μm) were collected from multi-cores in June 2017 and 2018. Abundance and biomass were recorded for broad taxonomic categories (phylum or class). Polychaetes were identified to family to capture well-described functional-trait information. Functional guilds were assigned to polychaete families, reflecting feeding mode, motility, and feeding structures. Macrofauna exhibited no significant spatial patterns when examined at higher taxonomic levels; however, analysis of polychaete families yielded three distinct station groups, and polychaete functional guilds yielded four distinct groups. These groups were aligned with variations in key habitat characteristics and suggest variation in ecosystem function across the study area. At sandy stations, tube-dwelling, particle-selective suspension and surface deposit feeders were relatively abundant, reflecting an advective system with moderate current speeds and low deposition. Sites with gravelly substrate and moderate levels of organic matter in deeper sediment layers likely experience sporadic organic-matter deposition and disturbance from scouring and were inhabited by larger-bodied species, including bivalves and subsurface deposit-feeding or carnivorous polychaetes. Muddy, offshore stations in the southern Chukchi Sea also contained large bivalves and large carnivorous polychaetes, with evidence of high bioturbation. At more coastal Chukchi Sea stations, macrofauna were dominated by small, motile polychaetes concentrated in the 1-cm surface layer, with indications of anaerobic conditions below. Overall, polychaete functional traits and vertical distribution reflected the quality and quantity of organic matter input and the depositional environment inferred from grain size and current speed, with implications for biogeochemical cycling in sediments.

Sr, Nd, and Pb isotope provenance of surface sediments on the East Siberian Arctic Shelf and implications for transport pathways

The East Siberian Arctic Shelf (ESAS) is a crucial area for sea ice formation and exportation in the Arctic Ocean. Precise sedimentary identification in the ESAS is vital to trace sea ice transport. However, tracking sea ice transport is challenging due to the complexity of the sediment sources and transport processes in the ESAS. In this study, we investigated Sr, Nd, and Pb isotopes in residual fractions of recent surface sediments in the ESAS to explore the distribution, sources, and transport pathways of terrigenous materials and track regional sea ice transport. Our results show that approximately 20–30% of the Western Laptev Sea (WLS) sediments were derived from Siberian flood basalt, characterized by a high εNd (ca. -9.0) and a high 87Sr/86Sr ratio (ca. 0.715). Furthermore, most sediments of the Eastern Laptev Sea–Western East Siberian Sea (ELS–WESS) were derived from ancient clastic and metamorphic rocks, with the lowest εNd values (ca. -12.3), highest 87Sr/86Sr ratios (ca. 0.717), and highest 207Pb/206Pb ratios (ca. 0.836). Additionally, sediments in the Eastern East Siberian Sea–Western Chukchi Sea (EESS–WCS) had the highest εNd values (ca. -7.6), lowest 87Sr/86Sr ratios (ca. 0.712), and relatively high 207Pb/206Pb ratios (ca. 0.830) due to the influence of Okhotsk–Chukotka volcanic belt (OCVB) weathering products, which contributed approximately 10–20% of the local sediments. Eastern Chukchi Sea (ECS) sediments showed relatively low εNd values (ca. -9.2), low 87Sr/86Sr ratios (ca. 0.712), and the lowest 207Pb/206Pb ratios (ca. 0.810), which probably influenced by coast erosion inputs from Alaska and Yukon River material transported via Pacific Sea Water. Based on the sediment provenance with Nd isotope, sea ice formed in the WLS and ELS–WESS is predominantly transported by the Trans-Polar Drift (TPD) to the Eurasian Basin and Fram Strait. This study provides insights for further understanding and tracking sea ice transport processes from the ESAS to the Arctic Ocean.

Phytoplankton and seston fatty acid dynamics in the northern Bering-Chukchi Sea region

Arctic and subarctic ecosystems are transitioning due to ocean warming, resulting in conditions that will lead to shifts in phytoplankton communities, their nutritional compositions, and production of fatty acids (FAs). FA biomarkers are useful indicators of changing phytoplankton community composition and provide insight into basal resource quality for higher trophic level consumers such as zooplankton, fish, birds and marine mammals, yet phytoplankton FA information is largely lacking from the Bering and Chukchi Sea regions. Therefore, we analyzed suspended particulate matter (seston) FAs, chlorophyll-a (Chl-a) and environmental data collected from four surveys in the northern Bering and Chukchi Seas, two during June of 2017 and 2018 and two during August and September 2017 and 2019. Our objectives were to determine 1) whether seston FA composition was correlated with phytoplankton taxonomic composition analyzed using imaging microscope (FlowCAM) techniques, 2) if there were seasonal differences in seston FA concentrations, and 3) how FA concentrations varied with environmental variables. We found significant seasonal differences in seston FA compositions, with diatom biomarkers more prevalent in spring, followed by a community shift to dinoflagellate and small flagellate FA biomarkers in late summer. These results were confirmed by FlowCAM analyses. FA biomarkers were correlated with total and large size-fractioned Chl-a concentrations, nitrogen concentration and temperature. Lastly, we used a model framework to predict availability of the diatom-associated essential FA, eicosapentaenoic acid (EPA, 20:5n-3). Our analysis provides new information on phytoplankton FA dynamics and the important nutritional role of phytoplankton for higher trophic level consumers in the northern Bering and Chukchi Sea regions.

SEISMICITY of the NORTH-EAST of RUSSIA in 2016–2017

The results of seismic monitoring of the region of Magadan, Chukotka Autonomous Area and the shelf of adjacent seas (the Okhotsk, Chukchi, Bering and East Siberian seas) are considered. There were 14 seismic stations working in the region in 2016–2017. The new station “Talon” was opened on the Okhotsk sea coast. The catalog includes information about 577 earthquakes with energy classes KR=4.6–12.7. As usual, most of them (88 %) are located in the Kolyma region (area № 2). The additional catalog contains information about 12 earthquakes in the Chukchi. The total seismic energy released within the region’s borders was equal to ΣЕ=1.861013 J. The energy representativeness map of earthquakes with Kmin=5–10 was built. It shows that the described network of stations records earthquakes with Kmin=7 at the Magadan region, with Kmin=8 in the Okhotsk sea without omissions. In 2016–2017 the strongest earthquake with KR=12.7 (mbMOS=4.8) occurred on November 5 in Chukchi Peninsula. Five earthquakes with the intensity I=2–4 (according to the Russian Seismic Intensity scale introduced in 2017) were felt in the North East settlements. The maximum shaking intensity of I=4 was observed in the Beringovskiy settlement (∆=22 km). Joint map of epicenters of the Magadan region earthquakes and tectonic zoning scheme shows that most earthquakes are confined to the largest deep faults in the northwestern and sublatitudinal directions. All hypocenters are located within the Earth's crust. The seismicity level of the North-East of Russia in 2016–2017 according to the “SOUS-09” scale was assessed as "background average" for the observation period from 1968 to 2017. Spatially, all earthquakes are traditionally concentrated in large seismogenic belts: Chersky, North-Okhotsk and Trans-Beringian.

Re-examining flow pathways over the Chukchi Sea continental shelf

Velocity records from 8 mooring sites (2010–2019) and trajectories of drogued drifters (2012–2020) are used to evaluate patterns of flow on the Chukchi Sea continental shelf, with an emphasis on the latter three years (2016–2019). Together, these data provided insight into the temporal and spatial variability of the currents over this shelf. These data extend previous observations by five years and include three previously unoccupied sites, two of which span the Central Channel. Bathymetry directs a significant portion of the northward flow in Central Channel eastward across the Chukchi shelf where it joins the coastal flow prior to exiting Barrow Canyon and entering the Beaufort Sea. In addition, shelf-wide volume transport estimated from three mooring sites located off Icy Cape is modified from earlier analysis and extended in time. The resulting transport is highly correlated with that flowing through Central Channel, with similar magnitude. Icy Cape transport varies seasonally with variations in atmospheric forcing, as well as inter-annually, with an annual low of 0.24 Sv (September 2011–August 2012) to a annual high of 0.64 Sv (September 2017–August 2018), and a 9-year average of 0.43 Sv, or approximately 40% of the flow through Bering Strait. This nearly decade-long Icy Cape volume transport record also exhibits an increasing, although not significant, trend of ∼0.03 Sv/year.

Distribution of diatoms in seafloor surface sediments of the Laptev, East Siberian, and Chukchi seas: implication for environmental reconstructions

Distribution of diatoms in seafloor surface sediments of the Laptev, East Siberian, and Chukchi seas: implication for environmental reconstructions

Modeling vital rates and age‐sex structure of Pacific Arctic phocids: influence on aerial survey correction factors

AbstractTo estimate abundance, surveys of marine mammals often rely on samples of satellite‐tagged individuals to correct counts for the proportion of animals that are unavailable to be detected. However, naïve application of this correction relies on the key assumption that availability of the tagged sample resembles that of the population. Here, we show how matrix population models can be used to estimate stable age‐ and stage‐proportions, and how these can be used to adjust aerial survey correction factors so that they represent population‐level availability. We illustrate this procedure using data from ice‐associated seals in the Bering, Chukchi, and Beaufort Seas. After compiling life history data for bearded (Erignathus barbatus), ribbon (Histriophoca fasciata), ringed (Pusa hispida), and spotted seals (Phoca largha), we find that correction factors ignoring age‐sex composition can positively bias spotted seal abundance by an average of 13% and negatively bias ribbon seal abundance by an average of 5%. Note that we did not examine potential bias for bearded or ringed seals due to low sample sizes; as such, we urge caution in interpretation of abundance estimates for these species.

Observations of Ringed Seal (Phoca hispida) in the Nearshore Waters of the Chukotka Peninsula

Despite the importance of ringed seals in the regional economy of the Chukotka Autonomous District, with the end of the commercial fishery, research on the ringed seal in Russia has almost completely ceased. The coastal zone of the Chukotka Peninsula, where the Native people hunt for seals, has seen very little research. This paper is devoted to the study of the modern distribution and habitat of the ringed seal (Phoca hispida) in the coastal waters of Chukotka. Observations of ringed seals were carried out simultaneously with observations of other species of marine mammals from posts located on the coast of the Chukotka Peninsula in 1993 – 96, 1998 – 2000, 2002 – 05, and 2010 – 11. Field studies provided information on the spatial and seasonal distribution, movements, and relative abundance of the ringed seal in the coastal zone. In winter, seals were found on the drifting ice in the southern coastal area of the northern part of the Gulf of Anadyr, and on fast ice and its edge in the bays of the eastern part of the Chukotka Peninsula. In spring, the main aggregations of ringed seals were observed on fast ice in Senyavin Strait, Lavrentiya Bay, and Tkachen Bay. The migration of immature seals to the Chukchi Sea was noted. In summer, animals were distributed in the coastal zone of the entire Chukotka Peninsula, but their relative number decreased by 85%. In late autumn, the main aggregations of seals were observed on the young ice of Lavrentiya Bay, in Senyavin Strait, and in Tkachen Bay. The landfast ice of the eastern coastal zone of Chukotka Peninsula is one of the main areas for the reproduction of ringed seals in the Bering Sea.

Chukchi Sea — new walleye pollock fishing area

The purpose: to identification of the features of the distribution and biology of walleye pollock Gadus chalcogrammus, as well as the presentation of information on the stocks of the species and the initial stage of development of its resources in the western part of the Chukchi Sea.Methods used: to achieve this goal, we used materials from nine integrated trawl surveys carried out in 1995– 2020 on research vessels, as well as coastal studies on the Arctic coast of the Chukotka Autonomous Okrug, which analyzed data on the distribution, biology, biomass and fishery of walleye pollock.Novelty: elements of novelty are generalized modern materials on the distribution, biology and for the first time organized pollock fishery.Practical significance: the Chukchi Sea can be attributed to the most favorable areas for studying the variability of the organization of Arctic ecosystems, due to the instability of climatic conditions on Earth during the period of warming. The obtained results of studies on the distribution, biology, stocks and fishery of such a mass indicator species as walleye pollock will increase the efficiency of using the raw material base of marine fish in this reservoir.

Unusually high production of C37:4 alkenone by an Arctic Gephyrocapsa huxleyi strain grown under nutrient-replete conditions

The percentage of C37:4 alkenone relative to total C37 alkenones (C37:4%) in northern high-latitude ocean waters and surface sediments, which can be up to 77%, has been recently found to correlate strongly with annual mean sea ice coverage. Genomic data and culture experiments suggest these high percentage of C37:4 alkenones may be mainly attributed to the production by Group 2i Isochrysidales, because the cosmopolitan Isochrysidales, Emiliania huxleyi (recently renamed to Gephyrocapsa huxleyi) typically does not produce significant amount of C37:4 alkenone in laboratory cultures. However, the presence of significant amounts of C38 methyl alkenones in high-latitude ocean sediments and suspended particulate samples suggests possible contributions from G. huxleyi as well. Here we performed the first culture experiments on G. huxleyi strain NIES3366 from the Chukchi Sea. This strain was isolated from the coldest and highest latitude ocean waters known for G. huxleyi strains so far. NIES1312 from the Bering Sea was also cultured under identical conditions for comparison. We show that, in f/2 growth media, NIES3366 was capable of producing unusually large amounts of C37:4 alkenone reaching 12.8% at 12 °C and up to 20% between 6 °C and 9 °C. In comparison, NIES1312 only produced 3.6% C37:4 at 12 °C. Our results suggest that Arctic strains of G. huxleyi may have also contribute to the inventory of the high-C37:4 alkenone profile in northern high-latitude oceans. Importantly, however, when NIES3366 was grown in 10 times lower nutrient (f/20) at 12 °C, the C37:4% decreased by ∼ 50% (to 6%), indicating a strong impact of nutrients on the production of C37:4 alkenone. In contrast, salinity levels had a negligible impact on the percentage of C37:4 for both strains, indicating an absence of a physiological effect of salinity. We also demonstrate that at low temperatures, tetra-unsaturated alkenones must be included for calculating unsaturation indices to achieve strong linear correlation with temperatures for NIES3366, a feature contrary to other G. huxleyi strains isolated from mid- and low- latitude oceans. Our findings provide a refined mechanistic explanation for the application of alkenone C37:4% as a quantitative sea ice proxy in high-latitude oceans.

Population structure of walleye pollock within the Asian part of the range based on the analysis of various genetic markers

The aim: The aim of this work is focused on a phylogeographic analysis of the relationship between the population groups of walleye pollock Gadus chalcogrammus of the Asian part of the range.The methods: The analysis of phylogeographic analysis is based on the data of polymorphism of microsatellite markers, a fragment of the mtDNA control region (D-loop) and a fragment of the mtDNA cytochrome b gene. The newness: A comprehensive phylogeographic analysis using samples of spawning walleye pollock individuals from most of the Asian part of the range from the Sea of Japan to the northwestern Bering Sea using various genetic markers was carried out for the first time.The results: The results of the analysis of the variability of walleye pollock samples by mitochondrial markers (fragments of the cytochrome b and D-loop genes) allow us to distinguish two large population groupings within the Asian part of its range: the first one in the Sea of Okhotsk, the Sea of Japan, the waters of the Kuril Islands and southeastern Kamchatka and the second one in the Bering and Chukchi seas. Analysis of the variability of walleye pollock samples by microsatellite markers allows us to judge the absence of population groupings in the waters of the Sea of Okhotsk, the Sea of Japan, off the Kuril Islands and southeastern Kamchatka.The practical significance: When regulating pollock fishing in the Russian waters, it is necessary to establish a single total allowable catch (TAC) for each of the two superpopulations: the Sea of Okhotsk — Sea of Japan (1) and the Bering Sea (2) combining the sizes of proposed catch for walleye pollock groups belonging to each of these superpopulations.

Oceanographic conditions within the main area of walleye pollock

Purpose: to characterize oceanographic conditions and their variability at various time scales within the walleye pollock area, including all Far Eastern seas of Russia, the Chukchi Sea, and the South Kuril and East Kamchatka regions.Methods: analysis of literary sources and data of expedition studies conducted by the Far Eastern branches of «VNIRO».Novelty: for the first time, a generalization of current information on the oceanological conditions of walleye pollock habitat in the main areas of its reproduction, feeding and fishing was given.Results: In the Bering Sea, three periods were identified during 1950–2020: cold period (1950–1976), moderate period (1977–2013) and warm period (2014–2020). Strong year-classes of walleye pollock were formed only over the moderate period. During the modern warming of the Bering Sea migrations of walleye pollock from the US EEZ into Russian waters occurs by one month earlier that favors the pollock fishery in the Navarin area and Gulf of Anadyr. The warming of Okhotsk Sea waters, combined with the tendency to reduction of its ice cover, favor expansion of the walleye pollock feeding area northward and westward. The warming of the Sea of Japan results in a depressive trend for all Japan Sea walleye pollock populations. At the same time, against the background of depression in modern (abnormally warm) conditions, the formation of single strong year-classes of any Japan Sea walleye pollock population is still possible.Practical significance: the results of this work can be used to improve the methods of the medium-r ange and long-range forecasts of walleye pollock catch.

Evidence of large-scale absence of frozen ground and gas hydrates in the northern part of the East Siberian Arctic shelf (Laptev and East Siberian seas)

This study investigated the zones associated with the potential distribution and absence of frozen ground and gas hydrates on the East Siberian Arctic Shelf in the Laptev and East Siberian seas. The investigation was based on an analysis of velocities of refracted waves registered as first breaks from common-shot gathers along 71 common depth point seismic lines with a total length of 15 630 km acquired by JSC MAGE in 2007–2016. Consequently, essentially new data that illustrate the state of the cryolithozone on the East Siberian Arctic Shelf were obtained. In particular, this study confirmed a significant decrease in the area of possible existence of frozen ground and methane hydrates in the postglacial period. Based on an extensive analysis of subsea frozen ground degradation zones on the shelves of the Laptev, East Siberian, Chukchi, and Beaufort seas (∼57% of the total area), it can be concluded that there is a low probability of considerable contribution of methane, being released from the dissociating gas hydrates, to climate change.

Arctic cod (Boreogadus saida) hatching season and growth rates in the Bering, Chukchi and Beaufort seas

Arctic cod is an important prey species in Arctic marine ecosystems that provides efficient energy transfer from producers to consumers in the food web. Arctic cod are locally abundant throughout the Arctic, though little is known about their early life stages in the Pacific Arctic, especially when and where they spawn and hatch. This study estimated hatch dates and growth rates of first year Arctic cod through analysis of otolith growth increments. First-year Arctic cod were captured in the northern Bering, Chukchi, and Beaufort seas during the spring or summer between 2012 and 2017. Estimated hatch dates ranged widely from November to June with peak hatching occurring from February through May, depending on the region of capture. Combined with large individual and regional variability in growth rates, this suggests a bet-hedging strategy to ensure some larvae encounter favorable growth conditions. In addition to regional differences, we identified a clear separation of hatch dates between spring- and summer-caught Arctic cod in the Chukchi Sea, suggesting different origins or strong size-dependent mortality. Finally, differences in hatch dates between pelagic and demersal juveniles indicate that older, larger juveniles begin to settle to the seafloor on deeper portions of the shelf in late summer. The results of this study set a benchmark for Arctic cod early life history in these regions and provide context for monitoring early life stages in a changing environment.

Benthic bacteria and archaea in the North American Arctic reflect food supply regimes and impacts of coastal and riverine inputs

Benthic bacteria and archaea can be considered biogeochemical engineers as they play a major role in organic matter (OM) degradation and nutrient cycling. As such, prokaryotic community structure, yielded from 16S rRNA amplicon sequencing, can reflect environmental conditions such as OM composition and quantity, nutrient availability, redox conditions, and natural/anthropogenic contaminants (e.g. petroleum hydrocarbons). To assess prokaryotic community structure, we sequenced marine sediments in the upper 10-cm layer on the northern Bering and southern Chukchi Sea shelves, a high-latitude region undergoing rapid environmental change. We then explored broader spatial patterns in community structure for surface sediments (upper 1 cm), incorporating samples from the Northeast Chukchi and Beaufort Seas in relation to environmental variables. Three assemblages were characterized at distinct depth horizons in the upper 10-cm sediment layer from the Northern Bering and Southern Chukchi benthos. One assemblage was exclusively found in sediments at greater than 1 cm sediment depth and contained a relatively higher proportion of anaerobic taxa (e.g. Anaerolineaceae, Desulfobulbaceae, and Desulfosarcinaceae). Overall, community distribution in the upper 10-cm reflected sediment grain size, OM quantity and composition, and possibly the influence of bioturbation. Two assemblages were characterized in surface sediments (upper 1 cm) across the broader Northern Bering and Chukchi Sea study area. A relatively high abundance of anaerobic taxa (e.g. SEEP-SRB4, Subgroup 23, and R76-B128) in one assemblage suggested comparatively suboxic sediments, and the other suggested allochthonous input of phytodetritus based on high abundance of diatom/particle associated microbes (e.g. Polaribacter, Dokdonia, and Ulvibacter), combined with high sediment Chl-a concentration. This latter assemblage may reflect depositional areas influenced by hydrographic patterns. Prokaryotic community structure across the North American Arctic highlights regional differences in environmental controls, with food-supply regimes influencing structure on the Bering-Chukchi inflow shelves, in contrast to the Beaufort interior shelves where nearshore heterogeneity (riverine input and terrigenous material) are major drivers of sediment prokaryote communities.

Accuracy and precision when deriving sea-ice thickness from thermistor strings: a comparison of methods

A precise knowledge of landfast sea-ice (fast-ice) thickness is relevant to many different disciplines. Sea Ice Monitoring Stations (SIMS) are used to measure time series of fast-ice thickness at a location. SIMS measure ice and ocean temperature via thermistor strings with many different methods for extracting sea-ice thickness from temperature existing. This study investigates: if thickness results from temperature recorded by SIMS of different designs, and analysed with different methods are comparable; which methods are recommended for their robustness, precision and accuracy and how they compare to independent thickness measurements; how otherwise unuseable data can be salvaged through specific SIMS designs. We present an analysis of fast-ice thickness calculated from SIMS deployed in McMurdo Sound, Antarctica and in the Chukchi Sea near Utqiaġvik, Alaska, over two decades. We find that median thicknesses derived by different methods agree within 1 ± 1.5 cm for McMurdo Sound and 2 ± 3 cm for Utqiaġvik. Thus, it is possible to confidently compare data collected from different stations and analysed with different methods. The vertical gradient of sea-ice temperature gives the best results for fast-ice thickness during the growth season and including standard resistors in a thermistor string can reduce potential data loss due to noise.

Growth, maturity, reproduction, and life expectancy in ex-situ pacific walruses (Odobenus rosmarus divergens)

BackgroundPacific walruses are found in Arctic regions of the Chukchi and Bering Sea where rapid changes in environmental conditions resulting in loss of sea ice are occurring. Therefore, accurate life history data are crucial for species management plans and longitudinal data collected over the lives of individual walruses housed in zoos and aquaria provide otherwise difficult to obtain biological information.ResultsWhile similar at birth, Gompertz regression curves indicated that males grew faster than females (p < 0.0001) in weight (99 kg vs 57.6 kg/y) and length (26.9 cm vs 26.3 cm/y) with physical differences being detected by age 3 for weight and age 7 for length. Males reached adult weight at 13.5 ± 3.3 y and females by age 12.3 ± 2.3 y. The mean age at first ovulation and at first conception occurred at 8.8 y and 9.6 y. Greater than 75% of all conceptions and calving occurred between February and March and from May to June, respectively. Mean gestation lasted 423 d and false pregnancies lasted at least 169 d with a decrease (p < 0.05) in serum progesterone concentration between false pregnancy and pregnancy occurring within 6 months after ovulation. Based on these results, we estimated embryonic diapause to last from 120 to 139 days, and fetal growth last ~ 284 days. All males older than 8 y had an increase in serum testosterone and body weight that was highest in February and lowest in July. Overall, no differences were observed between male and female survival, with a mean (± SEM) life expectancy of 19.5 ± 1.5 y, respectively. Currently, the oldest male and female captive walruses are 40 and 43 y, respectively.ConclusionsData provided herein include details of life history characteristics of zoo and aquaria housed walruses that are useful for wild population recovery models. In particular, results on survivorship and the identification of the most vulnerable period for calf survival can help with model development and suggests that for recovery to occur birthing locations for this species must be protected.

Distribution of Gutless Siboglinid Worms (Annelida, Siboglinidae) in Russian Arctic Seas in Relation to Gas Potential

In the Russian Arctic seas and adjacent areas of the Arctic basin, 120 sites of siboglinid records are currently known. Individuals belonging to 15 species have been collected. The largest number (49.2%) of records were made in the Barents Sea, followed by the Laptev Sea (37.5%) and the Arctic basin (10 records; 8.3%). No siboglinids have been reported from the Chukchi Sea. The largest number of species has been identified in both the Laptev Sea and Arctic basin (seven species each). Seventy-eight percent of the records were discovered at water depths down to 400 m. Many of the siboglinid records in the Arctic seas of Russia are associated with areas of high hydrocarbon concentrations. In the Barents Sea, Nereilinum murmanicum has been collected near the largest gas fields. The records of Oligobrachia haakonmosbiensis, N. murmanicum, Siboglinum ekmani, Siboglinum hyperboreum, Siboglinum norvegicum, as well as two undetermined species of siboglinids are associated with the marginal areas of bottom gas hydrates where methane emissions can occur. The Arctic seas of Russia feature vast areas of permafrost rocks containing gas hydrates flooded by the sea. Under the influence of river runoff, gas hydrates dissociate, and methane emissions occur. Crispabrachia yenisey and Galathealinum karaense were found in the Yenisei estuary, and O. haakonmosbiensis was found in the Lena estuary.

Thermodynamical and Dynamical Impacts of an Intense Cyclone on Arctic Sea Ice

AbstractThis study investigates the thermodynamical and dynamical influences of the intense cyclone in the Arctic Ocean in August 2012 on the synoptic‐scale sea ice evolution, using the Arctic Ice Ocean Prediction System (ArcIOPS). As it is hard to fully isolate sea ice loss owing to extreme cyclone from that owing to background atmospheric state in most previous studies on this topic, this study introduces a newly developed algorithm to remove the cyclone component in atmospheric forcing, and conducts sea ice and heat budget analyses in two simulations driven by atmospheric forcing with and without the cyclone. Strong impact of the intense cyclone on sea ice locates on the east side of the cyclone's path, that is, Pacific Arctic for this case. The cyclone affects sea ice in two ways. First, cyclone‐induced enhancement in ice‐ocean interaction leads to increased sea ice basal melt in the Pacific Arctic and part of the Atlantic Arctic, which induces strong sea ice area and volume loss when the cyclone's intensity peaks. Second, as the cyclone strengthens, the increases in air temperature, humidity and wind speed accelerate turbulent heat exchange at the air‐ocean and air‐ice interfaces, leading to enhanced local sea ice surface melt in the Chukchi Sea and northern Beaufort Sea. The cyclone‐induced strong winds stir sea ice leading to enhanced gradients in sea ice velocity field and thus increased sea ice deformation, which further induces strong sea ice area loss. This study also demonstrates a precise atmospheric forcing field is essential for sea ice modeling.