Ethological analysis of the trace fossil Zoophycos: hints from the Arctic Ocean

Löwemark, L. 2011: Ethological analysis of the trace fossil Zoophycos: Hints from the Arctic Ocean. Lethaia, Vol. 45, pp. 290–298. The distribution of the trace fossil Zoophycos in Quaternary marine sediments from the Arctic Ocean was studied in twelve piston and gravity cores retrieved during the Swedish icebreaker expeditions YMER80, Arctic Ocean‐96 and LOMROG I & II. The sampled cores span an area from the Makarov Basin to the Fram Strait. Zoophycos was only found in two cores taken at more than 2 km water depth on the slope of the Lomonosov Ridge, but was absent in cores obtained at shallower depth, confirming earlier observations of the trace maker’s bathymetric preferences. The two cores containing Zoophycos are characterized by quiet sedimentation and slightly enhanced food flux compared with the general Arctic. The occurrence of Zoophycos in these cores in a setting that is characterized by extreme seasonal variations in food flux due to the total ice coverage during winters and high primary productivity during the long summer days, is interpreted to be a cache‐behaviour response to pulsed flux of food to the benthic realm. □Arctic Ocean, ethology, Quaternary, spreiten, trace fossils, Zoophycos.     

Psychrophilic versus psychrotolerant bacteria--occurrence and significance in polar and temperate marine habitats.

The numerical dominance and ecological role of psychrophilic bacteria in bottom sediments, sea ice, surface water and melt pools of the polar oceans were investigated using isolates, colony forming units (CFU) and metabolic activities. All sediment samples of the Southern Ocean studied showed a clear numerical dominance of cold-loving bacteria. In Arctic sediments underlying the influence of cold polar water bodies psychrophiles prevailed also but they were less dominant in sediments influenced by the warm Atlantic Water. A predominance of psychrophiles was further found in consolidated Antarctic sea ice as well as in multiyear Arctic sea ice and in melt pools on top of Arctic ice floes. A less uniform adaptation response was, however, met in polar surface waters. In the very northern part of the Fram Strait (Arctic Ocean) we found bacterial counts and activities at 1 degree C exceeding those at 22 degrees C. In surface water of the Weddell Sea (Southern Ocean) psychrophiles also dominated numerically in early autumn but the dominance declined obviously with the onset of winter-water and a decrease of chlorphyll a. Otherwise in surface water of the Southern Ocean CFUs were higher at 22 degrees C than at 1 degree C while activities were vice versa indicating at least a functional dominance of psychrophiles. Even in the temperate sediments of the German Bight true psychrophiles were present and a clear shift towards cold adapted communities in winter observed. Among the polar bacteria a more pronounced cold adaptation of Antarctic in comparison with Arctic isolates was obtained. The results and literature data indicate that stenothermic cold adapted bacteria play a significant role in the global marine environment. On the basis of the temperature response of our isolates from different habitats it is suggested to expand the definition of Morita in order to meet the cold adaptation strategies of the bacteria in the various cold habitats.     

Microbial diversity in Cenozoic sediments recovered from the Lomonosov Ridge in the Central Arctic Basin

The current understanding of microbes inhabiting deeply buried marine sediments is based largely on samples collected from continental shelves in tropical and temperate latitudes. The geographical range of marine subsurface coring was expanded during the Integrated Ocean Drilling Program Arctic Coring Expedition (IODP ACEX). This expedition to the ice-covered central Arctic Ocean successfully cored the entire 428 m sediment stack on the Lomonosov Ridge during August and September 2004. The recovered cores vary from siliciclastic sediment low in organic carbon (< 0.2%) to organic rich (∼3%) black sediments that rapidly accumulated in the early middle Eocene. Three geochemical environments were characterized based on chemical analyses of porewater: an upper ammonium oxidation zone, a carbonate dissolution zone and a deep (> 200 m below sea floor) sulfate reduction zone. The diversity of microbes within each zone was assessed using 16S rRNA phylogenetic markers. Bacterial 16S rRNA genes were successfully amplified from each of the biogeochemical zones, while archaea was only amplified from the deep sulfate reduction zone. The microbial communities at each zone are phylogenetically different and are most closely related to those from other deep subsurface environments.     

Ice algal assemblages and vertical export of organic matter from sea ice in the Barents Sea and Nansen Basin (Arctic Ocean)

Algal communities and export of organic matter from sea ice were studied in the offshore marginal ice zone (MIZ) of the northern Barents Sea and Nansen Basin of the Arctic Ocean north of Svalbard by means of ice cores and short-term deployed sediment traps. The observations cover a total of ten stations within the drifting pack ice, visited over a period of 3 years during the period of ice melt in May and July. Maximum flux of particulate organic carbon and chlorophyll a from the ice at 1 m depth (1,537 mg C m⁻² per day and 20 mg Chl a m⁻² per day) exceeded the flux at 30 m by a factor of 2 during spring, a pattern that was reversed later in the season. Although diatoms dominated the ice-associated algal biomass, flagellates at times revealed similarly high biomass and typically dominated the exported algal carbon. Importance of flagellates to the vertical flux increased as melting progressed, whereas diatoms made the highest contribution during the early melting stage. High export of ice-derived organic matter and phytoplankton took place simultaneously in the offshore MIZ, likely as a consequence of ice drift dynamics and the mosaic structure of ice-covered and open water characteristic of this region.     

High intraspecific genetic divergence in the versatile fairy shrimp <Emphasis Type="Italic">Branchinecta lindahli</Emphasis> with a comment on cryptic species in the genus <Emphasis Type="Italic">Branchinecta</Emphasis> (Crustacea: Anostraca)

A new Arctic Ostracode Database-2015 (AOD-2015) provides census data for 96 species of benthic marine Ostracoda from 1340 modern surface sediments from the Arctic Ocean and subarctic seas. Ostracoda is a meiofaunal, Crustacea group that secretes a bivalved calcareous (CaCO₃) shell commonly preserved in sediments. Arctic and subarctic ostracode species have ecological limits controlled by temperature, salinity, oxygen, sea ice, food, and other habitat-related factors. Unique species ecology, shell chemistry (Mg/Ca ratios, stable isotopes), and limited stratigraphic ranges make them a useful tool for paleoceanographic reconstructions and biostratigraphy. The database, described here, will facilitate the investigation of modern ostracode biogeography, regional community structure, and ecology. These data, when compared to downcore faunal data from sediment cores, will provide a better understanding of how the Arctic has been affected by climatic and oceanographic change during the Quaternary. Images of all species and biogeographic distribution maps for selected species are presented, with brief discussion of representative species’ biogeographic and ecological significance. Publication of AOD-2015 is open-sourced and will be available online at several public websites with latitude, longitude, water depth, and bottom water temperature for most samples. It includes material from Arctic abyssal plains and submarine ridges, continental slopes, and shelves of the Kara, Laptev, East Siberian, Chukchi, Beaufort Seas, and several subarctic regions.     

北极浮冰生态学研究进展

近年来随着北极地区的开放和全球变化对北极地区生态环境和海冰现存量的影响日益显现,北极浮冰生态学研究得到了广泛的重视和实质性的进展.最新研究结果显示,浮冰本身包含了一个复杂的生物群落,高纬度浮冰生物群落的初级产量远高于原先的估算,浮冰生物群落在北极海洋生态系统中的作用被进一步确认.但由于对浮冰生物群落的研究受后勤保障条件的制约,目前尚有大量科学问题有待今后进一步深入研究,预期我国科学家将在其中做出贡献.     

Retention of ice-associated amphipods: possible consequences for an ice-free Arctic Ocean

Recent studies predict that the Arctic Ocean will have ice-free summers within the next 30 years. This poses a significant challenge for the marine organisms associated with the Arctic sea ice, such as marine mammals and, not least, the ice-associated crustaceans generally considered to spend their entire life on the underside of the Arctic sea ice. Based upon unique samples collected within the Arctic Ocean during the polar night, we provide a new conceptual understanding of an intimate connection between these under-ice crustaceans and the deep Arctic Ocean currents. We suggest that downwards vertical migrations, followed by polewards transport in deep ocean currents, are an adaptive trait of ice fauna that both increases survival during ice-free periods of the year and enables re-colonization of sea ice when they ascend within the Arctic Ocean. From an evolutionary perspective, this may have been an adaptation allowing success in a seasonally ice-covered Arctic. Our findings may ultimately change the perception of ice fauna as a biota imminently threatened by the predicted disappearance of perennial sea ice.     

Under-ice distribution of polar cod <Emphasis Type="Italic">Boreogadus saida</Emphasis> in the central Arctic Ocean and their association with sea-ice habitat properties

In the Arctic Ocean, sea-ice habitats are undergoing rapid environmental change. Polar cod (Boreogadus saida) is the most abundant fish known to reside under the pack-ice. The under-ice distribution, association with sea-ice habitat properties and origins of polar cod in the central Arctic Ocean, however, are largely unknown. During the RV Polarstern expedition ARK XXVII/3 in the Eurasian Basin in 2012, we used for the first time in Arctic waters a Surface and Under Ice Trawl with an integrated bio-environmental sensor array. Polar cod was ubiquitous throughout the Eurasian Basin with a median abundance of 5000 ind. km^?2. The under-ice population consisted of young specimens with a total length between 52 and 140 mm, dominated by 1-year-old fish. Higher fish abundance was associated with thicker ice, higher ice coverage and lower surface salinity, or with higher densities of the ice-amphipod Apherusa glacialis. The fish were in good condition and well fed according to various indices. Back-tracking of the sea-ice indicated that sea-ice sampled in the Amundsen Basin originated from the Laptev Sea coast, while sea-ice sampled in the Nansen Basin originated from the Kara Sea. Assuming that fish were following the ice drift, this suggests that under-ice polar cod distribution in the Eurasian Basin is dependent on the coastal populations where the sea-ice originates. The omnipresence of polar cod in the Eurasian Basin, in a good body condition, suggests that the central Arctic under-ice habitats may constitute a favourable environment for this species survival, a potential vector of genetic exchange and a recruitment source for coastal populations around the Arctic Ocean.     

Pleistocene agglutinated foraminifera from the Lomonosov Ridge and Amundsen Basin, Arctic Basin. Initial report on piston cores 2177-5 (KAL) and 2176-3 (KAL)

Noncalcareous Pleistocene sediments of the Central Arctic Ocean contain sparse benthic foraminiferal assemblages consisting entirely of agglutinated taxa. Deep water agglutinated foraminifera are studied from two piston cores collected from the Lomonosov Ridge and Amundsen Basin [Cores PS 2177-5 (KAL) and 2176-3 (KAL)]. Core PS 2177-5 (KAL) contains an assemblage of 10 species, dominated by Cyclammina pusilla Brady, and is interpreted to reflect a bathyal environment with variable organic flux and nutrition levels. Core PS 2176-3 (KAL) in the Amundsen Basin yielded a very depauperate benthic foraminiferal assemblage. It is assumed that the environment was inhospitable for agglutinated foraminifera.     

Meiobenthic stocks and benthic activity on the NE-Svalbard shelf and in the Nansen Basin

Summary High Arctic meiofaunal distribution, standing stock, sediment chemistry and benthic respiratory activity (determined by sediment oxygen consumption using a shipboard technique) were studied in summer 1980 on the NE Svalbard shelf (northern Barents Sea) and along a transect into the Nansen Basin, over a depth range of 240–3920 m. Particulate sediment proteins, carbohydrates and adenylates were measured as additional measures of benthic biomass. To estimate the sedimentation potential of primary organic matter, sediment bound chloroplastic pigments (chlorophylls, pheopigments) were assayed. Pigment concentrations were found comparable to values in sediments from the boreal and temperate N-Atlantic. Meiofauna, which was abundant on the shelf, decreased in numbers and biomasses with increasing depth, as did sediment proteins, carbohydrates, adenylates and sediment oxygen consumption. Meiofaunal abundances and biomasses within the Nansen Basin were comparable with those observed in abyssal sediments of the North Atlantic. Nematodes clearly dominated in metazoan meiofauna. Protozoans were abundant in shelf sediments. Probably in response to the sedimentation of the plankton bloom, meiofauna abundance and biomass as well as sediment proteins, carbohydrates and adenylates were significantly correlated to the amount of sediment bound chloroplastic pigments, stressing the importance of food quantity to determine benthic stocks. Ninety-four percent of the variance in sediment oxygen consumption were caused by chloroplastic pigments. Benthic respiration, calculated per unit biomass, was 3–10 times lower than in the East Atlantic, suggesting low turnover rates in combination with a high standing stocks for the high Arctic benthos.     

Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO₂ and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO₂ covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.     

Integrated abundance and biomass of sympagic meiofauna in Arctic and Antarctic pack ice

The abundance and biomass of sympagic meiofauna were studied during three cruises to the Antarctic and one summer expedition to the central Arctic Ocean. Ice samples were collected by ice coring and algal pigment concentrations and meiofauna abundances were determined for entire cores. Median meiofauna abundances for the expeditions ranged from 4.4 to 139.5 × 10³ organisms m⁻² in Antarctic sea ice and accounted for 40.6 × 10³ organisms m⁻² in Arctic multi-year sea ice. While most taxa (ciliates, foraminifers, turbellarians, crustaceans) were common in both Arctic and Antarctic sea ice, nematodes and rotifers occurred only in the Arctic. Based on the calculated biomass, the potential meiofauna ingestion rates were determined by applying an allometric model. For both hemispheres, daily and yearly potential ingestion rates were below the production values of the ice algal communities, pointing towards non-limited feeding conditions for ice meiofauna year-round. Accepted: 29 March 1999     

Limnology of high mountain tropical lake, in Ecuador: characteristics of sediments and rate of sedimentation

Equatorial high mountain lakes are a special type of lake occurring mainly in the South American Andes as well as in Central Africa and Asia. They occur at altitudes of a few thousand meters above sea level and are cold-water lakes (< 20 degrees C). Relatively little is known about them. A long-term limnological study was therefore undertaken at Lake San Pablo, Ecuador, to analyze the basic limnological processes of the lake, which has a tendency for eutrophication. Sediment quality of San Pablo Lake is given under consideration of horizontal and vertical distribution using sediment cores. Significance of sediments for eutrophication process of lakes is demonstrated using phosphorus concentration of sediments as well as the phosphorus retention capacity of the sediments by ratio Fe/P. Dating of the sediments is done using 137Cs and 210Pb, but the activity of 137Cs in the sediment was very low nearly at the detection level. Sedimentation rate is determined to be 3.5 mm/year and the sediment cores represent about 110 years. P concentration of the sediments is high (approximately 5 g/kg dry substance), and P retention capacity by Fe is insufficient (Fe/P = 4). The sediment quality did not change significantly during the past decades, and the trophic state of San Pablo Lake was already less or more eutrophic 110 years ago. The contamination of the lake sediments by heavy metals is insignificant.     

Low organotin contamination of harbour sediment in Svalbard

Arctic sea routes are opening up for maritime transport due to sea ice retreat leading to increasing human activities in the Arctic and concomitant pressures on the environment. Organotin compounds are used in antifouling paints of large seagoing vessels and are known to leach into the marine environment and accumulate in sediments and biota. As organotin levels in Svalbard sediments have not been documented in peer-reviewed literature before, this study describes the levels in sediment of harbours around Svalbard (Ny-Ålesund, Longyearbyen, Svea, Pyramiden and Barentsburg). Organotin levels in sediments of Svalbard harbours were low (below the detection limit up to 14 ng Sn/g dw sum-butyltin) compared to other Arctic regions with a longer history of shipping. Levels were below known no effect levels and in accordance, no imposex was found in marine whelks from Ny-Ålesund harbour. Of all other analysed compounds in sediments of Kongsfjorden (polycyclic aromatic hydrocarbon (PAHs), polychlorinated biphenyls, polybrominated diphenylethers and perfluorinated compounds) PAH levels were highest and in one sample above action levels. It is advised to continue monitoring contaminant levels, for which the current results form a good basis. If contaminant levels rise, mitigation measures can be taken in time.     

Late Quaternary stratigraphy and sedimentology of Orphan Basin: Implications for meltwater dispersal in the southern Labrador Sea

Orphan Basin is a deep-water basin on the continental margin off Newfoundland, which throughout the late Quaternary received proglacial sediment from local ice that crossed the continental shelf. Sediment from more distant sources was transported southward in the Labrador Current as proglacial plumes and in icebergs. Five sedimentary facies related to glacial processes are distinguished in cores recovered from Orphan Basin: hemipelagic sediment, nepheloid-layer deposits (layered mud), beds rich in ice-rafted detritus (IRD), sand and mud turbidites, and glaciogenic debris-flow deposits. IRD-rich beds correspond to periods of intensified iceberg calving, and layered mud, turbidites, and glaciogenic debris-flow deposits with glacial meltwater discharge.

In the Late Wisconsinan, eight periods of meltwater discharge and iceberg calving from the Newfoundland ice sheet are interpreted from the sediment facies in Orphan Basin. These discharges coincide with the terminations of the colder periods of the D–O cycles recorded in Greenland ice cores. The oldest minor meltwater event (27.5–28.5 cal ka) corresponds to the first Late Wisconsinan ice advance across the Grand Banks and NE Newfoundland Shelf. The following three meltwater discharges (23–23.5, 23.8–24.5, and 25–27 cal ka) deposited sand turbidites and glaciogenic debris-flow deposits seaward of Trinity Trough, which was occupied by an ice stream at this time, and mud turbidites in the southern part of the basin derived from a mid-shelf ice margin on the Grand Banks. Four periods of meltwater discharge occurred during the deglaciation and are centered at 15, 18.5, 19.75, and 20.75 cal ka. The youngest is correlated to Heinrich event 1. In the literature, the 18.5 and 20.75 cal ka events have been recorded in multiple glacial settings in the North Atlantic, and therefore, are interpreted as large-scale events of meltwater discharge and iceberg calving, but in Orphan Basin the 19.75 cal ka event is also of similar scale.     

Biogeography and Photosynthetic Biomass of Arctic Marine Pico-Eukaroytes during Summer of the Record Sea Ice Minimum 2012

Information on recent photosynthetic biomass distribution and biogeography of Arctic marine pico-eukaryotes (0.2–3 μm) is needed to better understand consequences of environmental change for Arctic marine ecosystems. We analysed pico-eukaryote biomass and community composition in Fram Strait and large parts of the Central Arctic Ocean (Nansen Basin, Amundsen Basin) using chlorophyll a (Chl a) measurements, automated ribosomal intergenic spacer analysis (ARISA) and 454-pyrosequencing. Samples were collected during summer 2012, the year with the most recent record sea ice minimum. Chl a concentrations were highest in eastern Fram Strait and pico-plankton accounted for 60–90% of Chl a biomass during the observation period. ARISA-patterns and 454-pyrosequencing revealed that pico-eukaryote distribution is closely related to water mass distribution in the euphotic zone of the Arctic Ocean. Phaeocystaceae, Micromonas sp., Dinophyceae and Syndiniales constitute a high proportion of sequence reads, while sequence abundance of autotrophic Phaeocystaceae and mixotrophic Micromonas sp. was inversely correlated. Highest sequence abundances of Phaeocystaceae were observed in the warm Atlantic Waters in Fram Strait, while Micromonas sp. dominated the abundant biosphere in the arctic halocline. Our results are of particular interest considering existing hypotheses that environmental conditions in Nansen Basin might become more similar to the current conditions in Fram Strait. We propose that in response, biodiversity and biomass of pico-eukaryotes in Nansen Basin could resemble those currently observed in Fram Strait in the future. This would significantly alter biogeochemical cycles in a large part of the Central Arctic Ocean.     

Metagenomics of the subsurface Brazos-Trinity Basin (IODP site 1320): comparison with other sediment and pyrosequenced metagenomes

The Brazos-Trinity Basin on the slope of the Gulf of Mexico passive margin was drilled during Integrated Ocean Drilling Progam Expedition 308. The buried anaerobic sediments of this basin are largely organic-poor and have few microbial inhabitants compared with the organic-rich sediments with high cell counts from the Peru Margin that were drilled during Ocean Drilling Program Leg 201. Nucleic acids were extracted from Brazos-Trinity Basin sediments and were subjected to whole-genome amplification and pyrosequencing. A comparison of the Brazos-Trinity Basin metagenome, consisting of 105 Mbp, and the existing Peru Margin metagenome revealed trends linking gene content, phylogenetic content, geological location and geochemical regime. The major microbial groups (Proteobacteria, Firmicutes, Euryarchaeota and Chloroflexi) occur consistently throughout all samples, yet their shifting abundances allow for discrimination between samples. The cluster of orthologous groups category abundances for some classes of genes are correlated with geochemical factors, such as the level of ammonia. Here we describe the sediment metagenome from the oligotrophic Brazos-Trinity Basin (Site 1320) and show similarities and differences with the dataset from the Pacific Peru Margin (Site 1229) and other pyrosequenced datasets. The microbial community found at Integrated Ocean Drilling Program Site 1320 likely represents the subsurface microbial inhabitants of turbiditic slopes that lack substantial upwelling.     

Central Arctic Ocean paleoceanographic interpretations based on Late Cenozoic calcareous dinoflagellates

Four calcareous dinoflagellate morphotypes, interpreted to represent a single species, Thoracosphaera arctica n. sp., occur in upper Miocene to Holocene sediments of the central Arctic Ocean. The calcareous fossils generally are rare except during one interval, that of the latest Pliocene to late Pleistocene. During this interval the fossil dinoflagellates were alternately abundant and rare in approximate coordination with greater and lesser times of foraminifera productivity. Dinoflagellates and foraminifera generally are rare during times of accumulation of abundant coarse textured ice-rafted sediment during this interval.The life cycle of the dinoflagellate that produces the Arctic Ocean calcareous fossil is unknown but the fossils probably are either resting cysts, motile vegetative cells or hypnozygotes. A vegetative cell origin better explains the co-occurrence of foraminifera as well as the negative correlation with ice-rafting. This tentative interpretation leads to the conclusion that during the interval 2.0 to 0.7 m.y. b.p., the Arctic Ocean had relatively productive surface waters with very thin or even periodic absence of pack-ice alternating with conditions more like that of the present. During periods before 2.0 m.y. and since 0.7 m.y., the Arctic Ocean probably was ice-covered, with oceanographic conditions similar to that of the modern ocean. These conclusions differ from previous interpretations that the Arctic was continually ice-covered, had no surface productivity or was covered by a giant, Antarctic-like ice-cap.     

A change in the distribution pattern of diatoms above and below the halocline in bottom sediments of the central Arkona Basin,southern Baltic

Surface sediment samples from the central Arkona Basin, southern Baltic, were investigated by diatom analysis. The samples, taken by a Niemistö sampler, included the sediment-water interface and about 2–3 centimetres of the very water-saturated sediment. The samples represent the sediments deposited in the transition layer of the halocline in the Arkona Basin and immediately above and beneath it. The distribution pattern of diatoms and diatom pieces changed, reflecting the position of the halocline.Diatom analysis is an important tool in identifying Holocene Baltic sediments, and the knowledge of recent hydrological and chemical factors and their impact on the distribution pattern of diatoms is one way to evaluate the usefulness of diatom records in postglacial Baltic marine sediments. The surface-sediment diatom assemblages can be compared with the data from postglacial Baltic offshore cores. They give prelimary indications where diatom records from Littorina or Yoldia stages could be expected.     

United States interests in the Arctic region

Abstract

The Arctic is a vast, forbidding and relatively unknown region. It covers about 14 million square kilometers of which 5.2 square kilometers is ice covered in summer and 11.7 million square kilometers in winter. It is a highly strategic region, and is the shortest distance between the two superpowers. It also contains vast resources, including oil, gas, and coal. Over 830,000 native peoples inhabit the Arctic Rim and have a culture that goes back 4500 years. The United Nations Convention on the Law of the Sea is generally applicable to the Arctic Ocean and has a special provision for ice‐covered areas. However, there are several unresolved jurisdictional and navigational problems between the United States and other Arctic Rim States concerning the Arctic's waters, including the Chukchi Sea, the Beaufort Sea and the Northwest Passage. Although the United States has paid some attention to the Arctic region in recent years, the Arctic still remains a relatively low priority interest for national policy and operational programs.