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The impact of climate change on the circumpolar north has raised the profile of the Arctic Ocean to coastal states and presents serious foreign policy challenges. Chief among these is the pending delimitation dispute over the extended continental shelf between Canada, Denmark, the United States, and Russia. While delimitation disputes are not new to Arctic states, extended continental shelf claims are complicated by the existence of multiple claimants and a still developing international legal regime. To inform policymakers about what to expect from overlapping claims to disputed maritime areas, this paper draws comparative lessons for Arctic policymakers based on East Asia's experience responding to overlapping jurisdictional entitlements created by the UN Convention on the Law of the Sea (UNCLOS). East Asian states have been grappling with the challenge presented by overlapping claims to resource-rich seabeds since the region ratified UNCLOS in the mid-late 1990s. In light of similar geographic conditions (a dispute over a semi-enclosed sea), alliance structures and the relative infancy of the claimant states with UNCLOS entitlements-Canada only ratified the treaty in 2003, and the United States has yet to do so-this paper sets out the case that important comparative lessons can be drawn from the East Asian experience with maritime delimitation disputes. [ABSTRACT FROM AUTHOR]

Using cod feeding data, this paper considers the distribution and abundance of macroplankton from different ecological groups (euphausiids and hyperiids) and the variability in their consumption by cod over a period of years during which different water mass temperatures were observed. These years were also characterized by variable abundance of capelin, cod''s main food source. Differences in intensity and duration of cod consumption of euphausiids and hyperiids species are shown, depending on their abundance, temperature conditions, cod distribution, and the supply of capelin for cod. This paper discusses the energetics of consuming different types of prey and the role euphausiids play in the energy balance of cod. The low fat content of cod is sometimes associated with feeding on postspawning euphausiids in summer and autumn. [Copyright &y& Elsevier]

The Arctic Ocean is a substantial energy sink for the northern hemisphere. Fluctuations in its energy budget will have a major influence on the Arctic climate. The paper presents an analysis of the time-series for the polar position, the extent of Arctic ice, sea level at Hammerfest, Kola section sea temperature, Røst winter air temperature, and the NAO winter index as a way to identify a source of dominant cycles. The investigation uses wavelet transformation to identify the period and the phase in these Arctic time-series. System dynamics are identified by studying the phase relationship between the dominant cycles in all time-series. A harmonic spectrum from the 18.6-year lunar nodal cycle in the Arctic time-series has been identified. The cycles in this harmonic spectrum have a stationary period, but not stationary amplitude and phase. A sub-harmonic cycle of about 74 years may introduce a phase reversal of the 18.6-year cycle. The signal-to-noise ratio between the lunar nodal spectrum and other sources changes from 1.6 to 3.2. A lunar nodal cycle in all time-series indicates that there is a forced Arctic oscillating system controlled by the pull of gravity from the moon, a system that influences long-term fluctuations in the extent of Arctic ice. The phase relation between the identified cycles indicates a possible chain of events from lunar nodal gravity cycles, to long-term tides, polar motions, Arctic ice extent, the NAO winter index, weather, and climate. [Copyright &y& Elsevier]

Temperature has been identified in field studies as the physical parameter most influential on growth and recruitment of Arcto-Norwegian cod. However, it has been pointed out by many authors that temperature in this context has not only direct effects on the cod, but also indirect effects through lower trophic levels. Moreover, it has been said that temperature might also be a proxy for other climatic parameters. The present paper analyses the direct quantitative effects of temperature on larval and pelagic juvenile growth from spawning in Lofoten until the 0-group fish settle in the Barents Sea. The approach taken is that of a modelling study, supported by analysis of existing data on fish stocks and climate. It is shown that transport and temperature alone can reproduce key features of the 0-group weight distribution and concentration in the Barents Sea for two consecutive years. The extent of the dispersion of the larvae and pelagic juveniles, as well as the ambient temperature they experience on their route, are shown to depend upon their depth in the water column and, to a lesser degree, the time of spawning. [Copyright &y& Elsevier]

The contribution of brine-enriched bottom water from Arctic shelves to intermediate and deep water masses of the adjacent Arctic Ocean or the Nordic Seas is a widely discussed topic in Arctic Oceanography. This paper presents an overview of process-oriented modelling which was conducted to deepen our understanding of oceanic convection and its role in water mass formation. It arrives at a conceptual picture of the convective formation of bottom water masses in Arctic shelf seas as a consequence of ice–ocean interactions and considers the role of sediments in slope convection. To investigate and discuss the processes which take part in transformation, production and export of dense shelf water masses a hierarchy of numerical models of different type and spatial resolution was applied. The models cover spatial scales from well below the internal Rossby radius of deformation up to the mesoscale. [ABSTRACT FROM PUBLISHER]

Pyroxenites are an essential component in petrological and geochemical models for melt formation at mid-ocean ridges and ocean islands. Despite their rarity, their origin has been widely discussed and various processes have been invoked for their formation. Here, we present a detailed study of the microtextures and major, minor and trace element compositions of relatively fresh pyroxenites and associated harzburgites from the ultraslow-spreading Lena Trough, Arctic Ocean. Microtextural and geochemical characteristics suggest an origin by magmatic assimilation–fractional crystallization with a high ratio of mass crystallized to mass assimilated. The major element compositions of pyroxenes suggest that this process occurred at high pressures (>0·7 GPa), although interstitial plagioclase in two of the pyroxenites indicates that melt–rock reaction continued at lower pressures. The parental melt to the pyroxenites was most probably depleted mid-ocean ridge basalt similar to basalts from the North Lena Trough and westernmost Gakkel Ridge; basalts from the Central Lena Trough cannot have functioned as parental melts. The melt was generated close to the garnet–spinel facies transition by variable degrees of partial melting and reacted with the local refractory harzburgite. Pyroxenites from this study provide further evidence, together with plagioclase-bearing and vein-bearing peridotites, for significant melt stagnation below the Lena Trough that occurred over a range of depths, either continuously or stepwise. Comparison with abyssal pyroxenites reveals common characteristics, suggesting that, consistent with results of high-pressure crystallization experiments, they mark the onset of (reactive) crystallization of melts passing through the deeper parts of the mid-ocean ridge plumbing system. [ABSTRACT FROM PUBLISHER]

Mixotrophy, the combination of phototrophy and heterotrophy within the same individual, is widespread in oceanic systems. Yet, neither the presence nor ecological impact of mixotrophs has been identified in an Arctic marine environment. We quantified nano- and picoplankton during early autumn in the Beaufort Sea and Canada Basin and determined relative rates of bacterivory by heterotrophs and mixotrophs. Results confirmed previous reports of low microbial biomass for Arctic communities in autumn. The impact of bacterivory was relatively low, ranging from 0.6 × 103 to 42.8 × 103 bacteria mL−1 day−1, but it was often dominated by pico- or nanomixotrophs. From 1% to 7% of the photosynthetic picoeukaryotes were bacterivorous, while mixotrophic nanoplankton abundance comprised 1-22% of the heterotrophic and 2-32% of the phototrophic nanoplankton abundance, respectively. The estimated daily grazing impact was usually < 5% of the bacterial standing stock, but impacts as high as 25% occurred. Analysis of denaturing gradient gel electrophoresis ( DGGE) band patterns indicated that communities from different depths at the same site were appreciably different and that there was a shift in community diversity at the midpoint of the cruise. Sequence information from DGGE bands reflected microbes related to those from other Arctic studies, particularly from the Beaufort Sea. [ABSTRACT FROM AUTHOR]

Beszczynska-Möller, A., Fahrbach, E., Schauer, U., and Hansen, E. 2012. Variability in Atlantic water temperature and transport at the entrance to the Arctic Ocean, 1997–2010. – ICES Journal of Marine Science, 69: 852–863.The variability in Atlantic water temperature and volume transport in the West Spitsbergen Current (WSC), based on measurements by an array of moorings in Fram Strait (78°50′N) over the period 1997–2010, is addressed. The long-term mean net volume transport in the current of 6.6 ± 0.4 Sv (directed northwards) delivered 3.0 ± 0.2 Sv of Atlantic water (AW) warmer than 2°C. The mean temperature of the AW inflow was 3.1 ± 0.1°C. On interannual time-scales, a nearly constant volume flux in the WSC core (long-term mean 1.8 ± 0.1 Sv northwards, including 1.3 ± 0.1 Sv of AW warmer than 2°C, and showing no seasonal variability) was accompanied by a highly variable transport of 2–6 Sv in the offshore branch (long-term mean of 5 ± 0.4 Sv, strong seasonal variability, and 1–2 Sv of warm AW). Two warm anomalies were found in the AW passing through Fram Strait in 1999–2000 and 2005–2007. For the period 1997–2010, there was a positive linear trend in the AW mean temperature of 0.06°C year−1, but no statistically significant trend was observed in the AW volume transport. A possible impact of warming on AW propagation in the Arctic Ocean and properties of the outflow to the North Atlantic are also discussed. [ABSTRACT FROM PUBLISHER]

The recent loss of Arctic sea ice provides humans unprecedented access to the region. Marine mammals rely on sound as a primary sensory modality, and the noise associated with increasing human activities offshore can interfere with vital life functions. Many coastal communities rely on marine mammals for food and cultural identity, and subsistence hunters have expressed strong concerns that underwater sound from human activities negatively affects both the animals and hunting success. Federal regulations require scientists and oil and gas operators to acquire incidental harassment authorizations for activities that may disturb marine mammals. Currently, authorization requests are focused on the impacts of sound from activities considered in isolation of one another, and this precludes any possibility of a meaningful analysis of the cumulative impacts from multiple sources. We propose a new assessment framework that is based on the acoustic habitats that constitute the aggregate sound field from multiple sources, compiled at spatial and temporal scales consistent with the ecology of Arctic marine mammals. INSETS: Box 1. Common mitigation and monitoring practices used to...;Box 2. Steps for the creation of acoustic habitats as a.... [ABSTRACT FROM AUTHOR]

SUMMARY In 1999, an unusual earthquake swarm at the 85°E/85°N volcanic centre on the ultraslow spreading Gakkel Ridge, Arctic Ocean, was detected teleseismically. The swarm lasted over 9 months and counted 252 events with mb≥ 3.1. It represents the strongest and largest ever recorded mid-ocean ridge earthquake swarm, and it occurred at a site where spreading rates are only about 10 mm yr-1. We relocated the earthquake swarm comparing the performance of three different localization algorithms: (1) the absolute least-squares routine HYPOSAT, (2) the absolute probabilistic routine NonLinLoc and (3) the relative least-squares routine Mlocate. The epicentres as calculated by each algorithm mostly did not agree within their error ellipses. Thus, the choice of location algorithm proved more critical than, for example, the choice of a local velocity model. We compiled a set of well-localized events which closely agree in at least two routines, mostly Mlocate and NonLinLoc. We conclude that the earthquake swarm of 1999 was related to a spreading episode and shows a complex interplay of tectonic and magmatic events. Our geological interpretation revealed three phases in swarm activity: In the first phase from January 17 up to February 1 fracturing of the crust took place, either as a result of or enabling magmatic intrusion. Seismicity in the second phase from February 2 to April 6 expanded along- and across axis. It showed signs of magmatic interaction, but a clear dyke migration pattern is absent. At the beginning of the third phase, a distinct break in the event rate suggested a change in the physical process, either an adjustment of the stress field to the new regime or a transition to an effusive stage. [ABSTRACT FROM AUTHOR]

Mid-ocean ridge basalts (MORB) from the Arctic Ocean have been significantly less studied than those from other oceans. The Arctic ridges (Gakkel Ridge and Lena Trough) are ultraslow-spreading ridges with low melt productivity and are thus the best locations to investigate mantle heterogeneity. We report the major and trace element and Sr–Nd–Pb–Hf isotope compositions of basalts generated along the Lena Trough and the westernmost part of the Gakkel Ridge in the Arctic Ocean. Basalts from the northern Lena Trough and westernmost Gakkel Ridge (NLT–WGR) have compositions close to normal MORB. The geochemical composition of the NLT–WGR lavas confirms a binary mixing model involving melts from a depleted MORB mantle source and a Spitsbergen amphibole-bearing subcontinental lithospheric mantle (SCLM) source. In contrast, in the central part of the Lena Trough (CLT), the basalts are alkalic with relatively high Mg-number (60–65), high SiO2 (51·0–51·6 wt %), Al2O3 (18·1–18·4 wt %), Na2O (4·0–4·2 wt %), K2O (1·0–1·6 wt %), K2O/TiO2 (0·6–0·9) and (La/Sm)PM (1·4–1·8), and low FeO (6·5–6·8 wt %) contents. These basalts display isotope variations with 87Sr/86Sr ranging from 0·70361 to 0·70390, 143Nd/144Nd from 0·51283 to 0·51290 (&varepsilon;Nd + 3·7 to +5·2), 176Hf/177Hf from 0·28313 to 0·28322 (&varepsilon;Hf + 11·6 to +14·9) and 206Pb/204Pb from 17·752 to 17·884, 207Pb/204Pb from 15·410 to 15·423 and 208Pb/204Pb from 37·544 to 37·670. These isotope compositions clearly distinguish the CLT lavas from those generated along the Gakkel Ridge. For the CLT lavas, involvement of a phlogopite- or amphibole- and (possibly garnet)-bearing SCLM source component is proposed. Owing to SCLM contamination along the entire length of the Lena Trough, we classify the Lena Trough as an ocean–continent transition boundary. Magmatism similar to that observed in the Lena Trough would be expected to occur wherever ocean spreading initiates. [ABSTRACT FROM AUTHOR]

Calanoid copepods dominate mesozooplankton biomass in the Arctic Ocean. Variations in C content, C:N ratio and stable isotope composition (δ13C, δ15N) of Calanus hyperboreus, Calanus glacialis and Metridia longa collected from January to August 2008 in the southeast Beaufort Sea provided insights into their metabolism, feeding and reproduction. Seasonal differences in the C–prosome length relationships and C:N ratios were driven by distinct spawning strategies and changes in lipid content. Relatively high copepod biomass over the study period (2.6–9.7 g C m−2) corresponded to favorable growth conditions in 2007–2008. The mean 15N enrichment of copepods (+2.8–4.7‰) relative to particulate organic nitrogen values recorded at the ice bottom and at the chlorophyll maximum indicated a primarily herbivorous diet. In all species, δ13C and δ15N decreased markedly in April, reflecting the feeding onset on ice algae, but a rapid transition to feeding on phytoplankton occurred as a pelagic bloom was triggered by the early ice melt in May. A second decline in the δ13C and δ15N of copepods was recorded in June–July, coincident with a second increase in phytoplankton production. The two isotope depletion events in copepods were both followed by a return to high values and an increase in their C:N as a consequence of previous C fixation and nitrate limitation in phytoplankton and the likely formation of body reserves/tissue. Our results illustrate that Arctic calanoids respond quickly to any increase in primary production and can cope with changes in its nature and timing. [ABSTRACT FROM AUTHOR]

On the northern passive margin of Ellesmere Island and Greenland, two long wide-angle seismic reflection/refraction (WAR) profiles and a short vertical incident reflection profile were acquired. The WAR seismic source was explosives and the receivers were vertical geophones placed on the sea ice. A 440 km long North-South profile that crossed the shelf, a bathymetric trough and onto the Lomonosov Ridge was completed. In addition, a 110 km long profile along the trough was completed. P-wave velocity models were created by forward and inverse modelling. On the shelf modelling indicates a 12 km deep sedimentary basin consisting of three layers with velocities of 2.1–2.2, 3.1–3.2 and 4.3–5.2 km s−1. Between the 3.1–3.2 km s−1 and 4.3–5.2 km s−1 layers there is a velocity discontinuity that dips seaward, consistent with a regional unconformity. The 4.3–5.2 km s−1 layer is interpreted to be Palaeozoic to Mesozoic age strata, based on local and regional geological constraints. Beneath these layers, velocities of 5.4–5.9 km s−1 are correlated with metasedimentary rocks that outcrop along the coast. These four layers continue from the shelf onto the Lomonosov Ridge. On the Ridge, the bathymetric contours define a plateau 220 km across. The plateau is a basement high, confirmed by short reflection profiles and the velocities of 5.9–6.5 km s−1. Radial magnetic anomalies emanate from the plateau indicating the volcanic nature of this feature. A lower crustal velocity of 6.2–6.7 km s−1, within the range identified on the Lomonosov Ridge near the Pole and typical of rifted continental crust, is interpreted along the entire line. The Moho, based on the WAR data, has significant relief from 17 to 27 km that is confirmed by gravity modelling and consistent with the regional tectonics. In the trough, Moho shallows eastward from a maximum depth of 19–16 km. No indication of oceanic crust was found in the bathymetric trough. [ABSTRACT FROM AUTHOR]

The active mid-ocean ridge of the Arctic Ocean, named Gakkel ridge, is the slowest spreading ridge of the global system of mid-oceanic ridges with full spreading rates declining from about 12.5 to 6 mm yr−1 from west to east. Geological models of seafloor spreading predict a decreasing intensity of magmatic processes with decreasing spreading rate. In summer 2001, the multidisciplinary Arctic Mid-Ocean Ridge Expedition (AMORE2001) discovered robust magmatism at western Gakkel ridge, an amagmatic section further east and pronounced volcanic centres at eastern Gakkel ridge. During AMORE2001, an attempt was made at recording the microearthquake activity of the ridge which allows important insights into the character and dynamics of active crustal accretion at the ridge axis. Due to the permanent ice cover of the Arctic Ocean, the use of ocean-bottom seismometers bears the risk of instrument and data loss. In this pilot study, we used for the first time drifting ice floes as platforms for small seismological arrays. The arrays consisted of four three-component seismometers equipped with GPS devices and arranged as a triangle with a central seismometer and a side length of about 1 km. Three such arrays were deployed in different rift segments and recorded the seismic activity continuously for 5–11 days at a sampling rate of 100 Hz. The array technique allowed to distinguish clearly between icequakes and earthquakes and to localize the earthquake source to within few kilometres or less depending on epicentral distance. We intensively discuss the detection capabilities and the location accuracy of this single array on a drifting ice floe. Earthquake magnitudes could not be calculated in our pilot study but are estimated to be significantly smaller than magnitude 2 by comparison with a regional earthquake of known magnitude. Furthermore, we analyse the characteristics of the recorded seismic events ranging from long waveforms of regional events to short local events with reverberations in the water column. All of the arrays recorded numerous microearthquakes in the central rift valley and on its flanks which we interpret as tectonic earthquakes. A swarm of microearthquakes was localized with high accuracy underneath the crest of a volcanic ridge in the rift valley and is proposed to have magmatic origin. The pilot study was thus successful in detecting, localizing and interpreting microearthquakes below magnitude 2 at Gakkel ridge. However, we suggest improvements of the method for a comprehensive microearthquake survey of Gakkel ridge which should aim at an understanding of active magmatism and faulting at ultraslow-spreading ridges. [ABSTRACT FROM AUTHOR]

The genetic structure of shrimp (Pandalus borealis) in the Northeast Atlantic was examined by RAPD analysis on specimens caught at eight stations in the Barents Sea, three off Svalbard, two off Jan Mayen, and in two northern Norwegian fjords (19< n >31 per station). A total of 34 polymorphic markers generated by seven 10-mer arbitrary primers was used to assess the genetic population structure using analysis of molecular variance (AMOVA). There was considerable RAPD diversity (>90%) among shrimp at all stations. The two Norwegian fjords and the Jan Mayen stations were different from all the others, and the Jan Mayen stations also differed from each other. More than 98% of the genetic variation between Barents Sea and Svalbard was ascribed to individual diversity, and there was no significant difference between the two areas, although there seemed to be a subpopulation structure in the Barents Sea. Principal component analysis on the frequency of each RAPD marker on each sampled station confirmed the presence of three populations: Barents Sea and Svalbard, northern Norwegian fjords, and Jan Mayen. We postulate that the large genetic variability found at an individual level may provide the total population with a diverse genetic pool from which traits can be selected to respond to variations in local environmental conditions, and that this local selection may be the cause of the subpopulation structure observed. [Copyright &y& Elsevier]

The unresolved interrelationships of North Atlantic redfish stocks have prevented adaptive fisheries assessment and management in the past. Otolith shapes of golden redfish (S. marinus) and deep-sea redfish (S. mentella) were analysed for geographic variation within the entire distribution range in the North Atlantic, in order to evaluate this technique for stock separation. Multivariate analysis of elliptical Fourier shape descriptors revealed high similarity of S. marinus within the central North Atlantic areas (West and East Greenland, Iceland) that were relatively well separated from the Flemish Cap and Barents Sea samples. A similar separation of the Barents Sea area was also observed for S. mentella, whereas the western (Flemish Cap, Davis Strait) and central areas were overlapping to a greater extent. The overall classification rate given by discriminant analysis was poor for both species (<50%) but increased to 72–74% by combining sampling areas to regions (west, central, east). Geographic variation in otolith shapes of both redfish species suggests a separation of the Northeast Arctic stocks (Barents Sea) of both species from the other redfish stocks assessed within ICES and NAFO, whereas similarities observed for the highly migratory S. mentella give reason for integrated management of demersal and pelagic occurrences of this important fisheries resource that straddles the ICES/NAFO boundaries. [Copyright &y& Elsevier]

While the origin of the 1800-km-long Lomonosov Ridge (LR) in the Central Arctic Ocean is believed to be well understood, details on the bathymetry and especially on the sediment and crustal structure of this unique feature are sparse. During two expeditions in 1991 and 1998 into the Central Arctic Ocean several high quality seismic lines were collected along the margin of the ridge and in the adjacent Makarov Basin (MB). The lines collected between 87°36′N and 80°N perpendicular to and along the LR show a sediment starved continental margin with a variety of geological structures. The different features may reflect the different geological histories of certain ridge segments and/or their different subsidence histories. The sediments in the deep MB have thicknesses up to 2.2 km (3 s TWT) close to the foot of the ridge. At least in part basement reflections characteristics suggest oceanic crust. The acoustically stratified layers are flat lying, except in areas close to the ridge. Seismic units on the LR can be divided into two units based on refraction velocity data and the internal geometry of the reflections. Velocities <3.0 km s−1 are considered to represent Cenozoic sediments deposited after the ridge subsided below sea level. Velocities >4.0 km s−1 are associated with faulted sediments at deeper levels and may represent acoustic basement, which was affected by the Late Cretaceous/Early Cenozoic rift events. Along large parts of the ridge the transition of the two units is associated with an erosional unconformity. Close to the Laptev Sea such an erosional surface may not be present, because of the initial great depths of the rocks. Here, the deeper strata are affected by tectonism, which suggests some relative motion between the LR and the Laptev Shelf. Stratigraphic correlation with the Laptev Sea Shelf suggests that the ridge has not moved as a separate plate over the past 10 Myr. The seismic and regional gravity data indicate that the ridge broadens towards the Laptev Shelf. Although the deeper structure may be heavily intruded and altered, the LR appears to extend eastwards as far as 155°E, a consequence of a long-lived Late Cretaceous rift event. The seismic data across LR support the existence of iceberg scours in the central region of the ridge as far south as 81°N. However, no evidence for a large erosional events due to a more than 1000-m-thick sea ice cover is visible from the data. South of 85°N the seismic data indicate the presence of a bottom simulating reflector along all lines. [ABSTRACT FROM AUTHOR]

We analysed catch records of Atlantic salmon (Salmo salar), cod (Gadus morhua), and halibut (Hippoglossus hippoglossus and Reinhardtius hippoglossoides) from the 17th and 18th centuries from several locations of the Barents and White Seas areas. Historical records, found in Russian archives, allow analysis of long-term series of catches, and sometimes of the average weight of the fish. In total, we obtained data on catches of salmon for 51 years (for the period from 1615 to 1772) and of cod and halibut for 33 years (for the period from 1710 to 1793). These data are comparable with respect to fishing effort within the series. The data on Atlantic salmon are also comparable with statistical data for the period 1875–1915. We found notable fluctuations in catches and sometimes in the average weight of salmon. There was also fluctuation in catches of cod and halibut. Both observational comparison of catch series and temperature data and formal statistical analysis showed that catches tended to decrease during relatively colder periods. [Copyright &y& Elsevier]

Future CO2-induced climate change scenarios from Global Circulation Models (GCMs) indicate increasing air temperatures, with the greatest warming in the Arctic and Subarctic. Changes to the wind fields and precipitation patterns are also suggested. These will lead to changes in the hydrographic properties of the ocean, as well as the vertical stratification and circulation patterns. Of particular note is the expected increase in ocean temperature. Based upon the observed responses of cod to temperature variability, the expected responses of cod stocks throughout the North Atlantic to the future temperature scenarios are reviewed and discussed here. Stocks in the Celtic and Irish Seas are expected to disappear under predicted temperature changes by the year 2100, while those in the southern North Sea and Georges Bank will decline. Cod will likely spread northwards along the coasts of Greenland and Labrador, occupy larger areas of the Barents Sea, and may even extend onto some of the continental shelves of the Arctic Ocean. In addition, spawning sites will be established further north than currently. It is likely that spring migrations will occur earlier, and fall returns will be later. There is the distinct possibility that, where seasonal sea ice disappears altogether, cod will cease their migration. Individual growth rates for many of the cod stocks will increase, leading to an overall increase in the total production of Atlantic cod in the North Atlantic. These responses of cod to future climate changes are highly uncertain, however, as they will also depend on the changes to climate and oceanographic variables besides temperature, such as plankton production, the prey and predator fields, and industrial fishing. [Copyright &y& Elsevier]

On the basis of data from cold (1982 and 1987) and warm summers (1983, 1984, 1990, and 1992), we explore the relationship between the phytoplankton bloom and the timing and intensity of the zooplankton bloom. In warm years, there is more overlap in the time between the zooplankton and the phytoplankton bloom. In northern areas (76–78°N) with seasonal ice, the phytoplankton bloom and reproductive processes in Calanus finmarchicus and Calanus glacialis continue well into August, evidenced by the presence of an abundance of nauplii and younger copepodites. We analyse feeding intensity of capelin and its distribution relative to food availability and capelin abundance. The extent to which feeding areas of cod and capelin, its major prey, overlap is subject to the abundance of these species, distribution of zooplankton, and sea temperature in a given year. [Copyright &y& Elsevier]

The eastern Bering Sea and the Barents Sea share a number of common biophysical characteristics. For example, both are seasonally ice-covered, high-latitude, shelf seas, dependent on advection for heat and for replenishment of nutrients on their shelves, and with ecosystems dominated by a single species of gadoid fish. At the same time, they differ in important respects. In the Barents Sea, advection of Atlantic Water is important for zooplankton vital to the Barents Sea productivity. Advection of zooplankton is not as important for the ecosystems of the southeastern Bering Sea, where high levels of diatom production can support production of small, neritic zooplankton. In the Barents Sea, cod are the dominant gadoid, and juvenile and older fish depend on capelin and other forage fish to repackage the energy available in copepods. In contrast, the dominant fish in the eastern Bering Sea is the walleye pollock, juveniles and adults of which consume zooplankton directly. The southeastern Bering Sea supports considerably larger fish stocks than the Barents. In part, this may reflect the greater depth of much of the Barents Sea compared with the shallow shelf of the southeastern Bering. However, walleye pollock is estimated to occupy a trophic level of 3.3 as compared to 4.3 for Barents Sea cod. This difference alone could have a major impact on the abilities of these seas to support a large biomass of gadoids. In both seas, climate-forced variability in advection and sea-ice cover can potentially have major effects on the productivity of these Subarctic seas. In the Bering Sea, the size and location of pools of cold bottom waters on the shelf may influence the likelihood of predation of juvenile pollock. [Copyright &y& Elsevier]

Reaction norms for age and size at maturation describe the probability of immature fish maturing at a certain age and size. Knowledge of such reaction norms is increasingly important, both for observing and understanding changes in maturation and for calibrating size- and age-structured population models. Estimating the reaction norms for age and size at maturation by logistic regression requires data on the size and age distribution of immature and maturing fish. To permit such estimation when measurements of the size and age distribution of immature fish are not available, the information can be reconstructed by means of a back-projection procedure. For the reconstruction, only the size and age distribution of maturing fish, or first-time spawners, together with the age-dependent proportion of mature fish, given in the form of maturity ogives, have to be known. The method of Gulland (1964) is used to generate maturity ogives in the absence of data on immature fish. The robustness of the estimation method is demonstrated by analysing artificial data generated with a known reaction norm. Application of the reconstruction method to a set of measurements on Northeast Arctic cod (Gadus morhua) collected between 1933 and 1944 illustrates how the approach allows new information to be extracted from real data. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

Examines the high-resolution magnetostratigraphic record from the eastern Arctic Ocean. Existence of the Laschamp and the Mono Lake excursion; Utilization of the accelerator mass spectrometry; Estimation of relative paleointensity variations.

The physical oceanographic conditions in the Barents Sea depend mainly on the variability in the Atlantic inflow from the Norwegian Sea and the inflow of Arctic water from the Kara Sea and the Arctic Ocean. The transport out of the Barents Sea consists of transformed Atlantic water to the Arctic Ocean and also partly to the Norwegian Sea. [ABSTRACT FROM PUBLISHER]

We assess evidence for significant adverse effects on the arctic marine environment associated with global and regional releases of chemical and radioactive contaminants from human activities. The sources, mode of transport, and biological effects of persistent organic compounds, lead, cadmium, mercury, artificial radionuclides, and oil are reviewed. An outline of the physical and biogeochemical processes occurring within the Arctic Ocean is used as a basis for identifying contaminant transport, accumulation, and exposure pathways. Where significant anthropogenic impacts can be inferred or suspected, we evaluate opportunities for human intervention through the introduction of new source controls, or other restrictions, to reduce impacts. We conclude that additional controls are justified only in the cases of persistent artificial organic compounds and petroleum exploitation and transport. Artificial radionuclides pose threats that are largely nominal. Protection of the arctic environment and human health can be achieved through universal compliance with existing international standards. Threats posed by cadmium and lead from anthropogenic sources are relatively minor. Trends in the anthropogenic mobilization of mercury are not currently defined with sufficient confidence to assess the associated dangers posed to animal and human health in the Arctic. Nevertheless, the properties of mercury and its current environmental levels suggest that the Arctic is sensitive to increased anthropogenic mobilization of this metal. There is also evidence that mercury levels in the Arctic are increasing due to anthropogenic activities. Accordingly, priority should be given to determining temporal trends of mercury within the Arctic. [ABSTRACT FROM PUBLISHER]