Bear Island Research Articles

Prediction of Ionospheric Scintillations Using Machine Learning Techniques during Solar Cycle 24 across the Equatorial Anomaly

Ionospheric scintillation is a pressing issue in space weather studies due to its diverse effects on positioning, navigation, and timing (PNT) systems. Developing an accurate and timely prediction model for this event is crucial. In this work, we developed two machine learning models for the prediction of ionospheric scintillation events at the equatorial anomaly during the maximum and minimum phases of solar cycle 24. The models developed in this study are the Random Forest (RF) algorithm and the eXtreme Gradient Boosting (XGBoost) algorithm. The models take inputs based on the solar wind parameters obtained from the OMNI Web database from the years 2010–2017 and Pc5 wave power obtained from the Bear Island (BJN) magnetometer station. We retrieved data from the Scintillation Network and Decision Aid (SCINDA) receiver in Egypt from which the S4 index was computed to quantify amplitude scintillations that were utilized as the target in the model development. Out-of-sample model testing was performed to evaluate the prediction accuracy of the models on unseen data after training. The similarity between the observed and predicted scintillation events, quantified by the R2 score, was 0.66 and 0.74 for the RF and XGBoost models, respectively. The corresponding Root Mean Square Errors (RMSEs) associated with the models were 0.01 and 0.01 for the RF and XGBoost models, respectively. The similarity in error shows that the XGBoost model is a good and preferred choice for the prediction of ionospheric scintillation events at the equatorial anomaly. With these results, we recommend the use of ensemble learning techniques for the study of the ionospheric scintillation phenomenon.

Major tunnel valleys and sedimentation changes document extensive Early Pleistocene glaciations of the Barents Sea

Sedimentary records of Early Pleistocene (~2.6–0.8 Ma) glaciations are sparse on shelves, yet trough mouth fans on adjacent continental slopes provide a continuous record of ice-sheet and climate development throughout the Quaternary. Here, we interpret high-quality 3D seismic reflection data combined with borehole and chronostratigraphic information from a shelf-slope setting in the southwestern Barents Sea to study meltwater and sediment inputs to the deep ocean, focusing on the onset of Pleistocene glaciations. Sandy deposits were brought to the slopes of the high-latitude Bear Island Fan by a preglacial contourite-turbidite system from ⁓2.6–2.4 Ma. Muddy glacigenic debris flows document the first shelf-edge glaciation at ⁓2.4 Ma. From 1.78–0.78 Ma, muddy turbidity-current- and debris-flow-derived sediments were delivered from shelf to slope via six tunnel valleys measuring up to 12 km in width and 200 m in depth. These tunnel valleys and associated downslope deposits formed during the 41-kyr climate cycles of the Early Pleistocene, and evidence abundant channelized, meltwater discharges from these glaciations. Following the mid-Pleistocene transition to 100-kyr cycles, a change in the style of glaciation is suggested by a change in landform and facies associations consistent with a reduced meltwater contribution. This study shows that the Norwegian-Barents shelf was extensively glaciated in the Early Pleistocene, with a first shelf-edge glaciation from ~2.4 Ma.

Relative contribution of the ocean-air heat exchange and advective heat transport to the increase of the Barents Sea water temperature in the early 21st century

The annual water temperature in the major water masses of the Barents Sea (BS) has significantly increased since the early 2000s. Advective heat transport from the neighboring water areas and heat exchange through the sea surface are the major factors, which shape the hydrological conditions in the BS. The paper estimates the contributions of heat exchange at the sea-atmosphere boundary and advective heat transport to changes in the average water temperature of the BS for the entire sea area. The average annual heat balance of the BS is calculated using atmospheric and oceanic reanalysis data. The change in the average temperature of the BS water is estimated taking into account the heat consumption for ice melting. The average surface heat balance from 1993 to 2018 was negative throughout the entire sea area: –70…–100 W/m2 in the south and –10…–20 W/m2 in the north. The advective heat supply was calculated for 9 straits with neighboring water areas. The determining source of advective heat is the influx of Atlantic waters from the Norwegian Sea between Cape Nordkapp and Bear Island. An average of 40.8 TW of advective heat is supplied through this margin. The calculations showed the predominance of annual heat influx due to advection over heat loss from the sea surface. This excess heat influx resulted in an estimated increase in the water temperature of the BS from 1993 to 2018 at a rate of 0.28 °C per year (taking into account the heat consumption for ice melting). In conclusion, it can be argued that the analysis has validated the hypothesis proposed in the article about compensation of heat losses from the surface of the BS by advective heat flow. The hypothesis is quantitatively confirmed by calculations on a simple box model (with an accuracy of up to an order of magnitude) based on atmospheric and oceanic reanalysis data. The ERA5 and GLORYS12V1 reanalysis data reliably describe the basic patterns of observed variability of ocean, sea ice and atmospheric parameters in the Barents Sea.

Arctic Water Current in the Bear Island Trough

Arctic Water Current in the Bear Island Trough

Depositional environments and source rock potential of some Upper Palaeozoic (Devonian) coals on Bjørnøya, Western Barents shelf

Upper Palaeozoic strata are potential sources for hydrocarbon plays on the Norwegian Barents Shelf. The island of Bjørnøya (Bear Island) is located on the western margin of the Barents Shelf and represents an exposed part of the Stappen High, which makes it an excellent location to investigate the source rock potential of this succession. Here, we investigate the organic geochemical composition and source rock potential of coals and organic-rich mudstones of Late Devonian to middle Permian ages. The thermal maturity of the analysed samples ranges from mature to overmature with some samples being in the late oil generation window, and thus exhibiting higher maturities than age and facies equivalent strata in central Spitsbergen in the NW corner of the Barents Shelf and on the Finnmark Platform to the south. The high maturities and thermal cracking may thus have negatively affected the applied isoprenoid and biomarker-based source facies parameters, which potentially inhibit correct source facies interpretation. However, our results and comparisons with previous studies indicate that the vitrinite- and inertinite-dominated humic coals occurring in the lower part of the succession formed by the accumulation of peat in fluvially-influenced, humid wetlands at paleo-equatorial latitudes during a pronounced episode of rifting in the Late Devonian (Famennian) to earliest Carboniferous (Mississippian). Our source rock evaluation indicates a good potential for liquid hydrocarbon generation for the coals of the Upper Devonian Røedvika Formation prior to maturation. The oil-prone organic matter of these coals is primarily considered as terrestrial and non-aqueous. Because of renewed rifting in the middle Carboniferous combined with a shift to arid climatic conditions, as well as an environmental change from dominantly terrestrial and marginal marine clastic to marine carbonate platform environments, the accumulation of wetland peats effectively came to an end. Thus, the overlying Carboniferous and Permian strata generally seems to yield poor to no hydrocarbon generation potential.

Hydrothermal activity fuels microbial sulfate reduction in deep and distal marine settings along the Arctic Mid Ocean Ridges

Microbial sulfate reduction is generally limited in the deep sea compared to shallower marine environments, but cold seeps and hydrothermal systems are considered an exception. Here, we report sulfate reduction rates and geochemical data from marine sediments and hydrothermal vent fields along the Arctic Mid Ocean Ridges (AMOR), to assess the significance of basalt-hosted hydrothermal activity on sulfate reduction in a distal deep marine setting. We find that cored marine sediments do not display evidence for sulfate reduction, apart from low rates in sediments from the Knipovich Ridge. This likely reflects the overall limited availability of reactive organic matter and low sedimentation rates along the AMOR, except for areas in the vicinity of Svalbard and Bear Island. In contrast, hydrothermal samples from the Seven Sisters, Jan Mayen and Loki’s Castle vent fields all demonstrate active microbial sulfate reduction. Rates increase from a few 10s to 100s of pmol SO42- cm-3 d-1 in active high-temperature hydrothermal chimneys, to 10s of nmol SO42- cm-3 d-1 in low-temperature barite chimneys and up to 110 nmol cm-3 d-1 in diffuse venting hydrothermal sediments in the Barite field at Loki’s Castle. Pore fluid and sediment geochemical data suggest that these high rates are sustained by organic compounds from microbial mats and vent fauna as well as methane supplied by high-temperature hydrothermal fluids. However, significant variation was observed between replicate hydrothermal samples and observation of high rates in seemingly inactive barite chimneys suggests that other electron donors may be important as well. Sediment sulfur isotope signatures concur with measured rates in the Barite field and indicate that microbial sulfate reduction has occurred in the hydrothermal sediments since the recent geological past. Our findings indicate that basalt-hosted vent fields provide sufficient electron donors to support microbial sulfate reduction in high- and low-temperature hydrothermal areas in settings that otherwise show very low sulfate reduction rates.

О согласованности океанического переноса тепла через северные моря: баланс океанического тепла и его межгодовая изменчивость

The Atlantic Water is the main source of heat and salt in the Arctic. Properties of the Atlantic Water inflow regionally affect sea ice extent and deep water formation rate. The Atlantic Water heat transported into the Nordic Seas has a significant impact on the local climate and is investigated here along with its inter-annual variability. We use the ARMOR3D dataset, which is a collection of 3D monthly temperature, salinity and geostrophic velocities fields, derived from in situ and satellite data on a regular grid available since 1993. We compare the heat transport across seven zonal transects in the eastern part of the Nordic seas, from Svinøy section (65°N) to the Fram Strait (78.8°N). 
 The correlations of the interannual variations of the advective heat fluxes rapidly drop from Svinøy to Jan Mayen sections and between Bear Island and Sørkapp sections. This is a result of different tendencies over the latest decades in the southern and the northern parts of the study region, as well as of a differential damping of the observed periodicities along the Atlantic Water path on its way north (the amplitude of 5–6 year oscillations drops significantly faster than that of 2–3 year oscillations). 
 A certain link between the heat fluxes and the North Atlantic Oscillation (NAO), Arctic Oscillation (AO) and East Atlantic (EA) indices is observed only for the southern sections. On the other hand, the heat fluxes at all sections show a consistent increase during the dominance of western weather type W and a decrease – of meridional weather type C. The link is explained by the variations of the wind fields, favourable for the sea-level build-up (Ekman pumping) east of the branching of the Norwegian Current for type W and an opposite tendency for type C.

Occurrence and backtracking of microplastic mass loads including tire wear particles in northern Atlantic air

Few studies report the occurrence of microplastics (MP), including tire wear particles (TWP) in the marine atmosphere, and little data is available regarding their size or sources. Here we present active air sampling devices (low- and high-volume samplers) for the evaluation of composition and MP mass loads in the marine atmosphere. Air was sampled during a research cruise along the Norwegian coast up to Bear Island. Samples were analyzed with pyrolysis-gas chromatography-mass spectrometry, generating a mass-based data set for MP in the marine atmosphere. Here we show the ubiquity of MP, even in remote Arctic areas with concentrations up to 37.5 ng m−3. Cluster of polyethylene terephthalate (max. 1.5 ng m−3) were universally present. TWP (max. 35 ng m−3) and cluster of polystyrene, polypropylene, and polyurethane (max. 1.1 ng m−3) were also detected. Atmospheric transport and dispersion models, suggested the introduction of MP into the marine atmosphere equally from sea- and land-based emissions, transforming the ocean from a sink into a source for MP.

Relative abundance and size composition of prey in the common minke whale diet in selected areas of the northeastern Atlantic during 2000-04

A total of 210 common minke whales (Balaenoptera acutorostrata) were sampled in five different areas in the northeastern Atlantic during May-June 2000-04. Analysis of forestomach contents revealed a relatively mixed diet at the population level, whereas on an individual level, each whale had fed upon mainly one species. There were significant differences in diet composition between areas and some differences between years. The importance of krill in the Barents Sea increased with latitude and krill dominated the Spitsbergen diet. Capelin dominated the diet around Bear Island and contributed considerably to the diet along the coast of northern Norway. In the latter area, herring and haddock were also a great part of the diet. The diet in the Norwegian Sea consisted of mainly mature herring, while the diet in the North Sea was dominated by sand eels and mackerel. The minke whales were found to feed on a wide range of prey sizes, apparently determined by the availability of different size classes.

Cruise CAGE-17-3

The overall goal of cruise CAGE 17-3 is to collect seismic, multibeam and water column data in an area along the northern flank of the Bear island trough and on the W-Svalbard margin. The objectives associated with the overall goal are to better understand the occurrence of gas hydrates and fluid leakage, the source of the gas in these systems, and seafloor expressions of fluid seepage. In order to address these objectives we plan to carry out:
 2D and 3D P-Cable seismic and ocean-bottom seismic acquisition over a complex leakage and source-to-sink plumbing system in the Leirdjupet Fault complex in the SW Barents Sea;Recovery of one of CAGE’s ocean floor observatory from the crater area at the northern flank of the Bear Island Trough;Repeat of P-Cable 3D seismic acquisition on the eastern segment of the Vestnesa Ridge for time-lapse seismic studies of fluid flow and gas hydrates dynamics;2D multi-channel seismic for reconnaissance and stratigraphic correlation in the Molloy Ridge area;Multibeam mapping to fill in gaps and improve resolution of existing data using the upgraded EM302 system on R/V Helmer Hanssen
 The cruise may be known as: CAGE17_3

Oceanic Core Complex or not? When bathymetric structures challenge seafloor spreading models

We use regional magnetic and local multibeam bathymetric data to investigate the geological nature of a prominent high located off-axis near the junction between the Mohns and the Knipovich ridges, in the Norwegian-Greenland Sea. Given the location of this hill, near the bend marking the junction between these two ultraslow spreading centers and the bathymetric asymmetry on both sides of the ridge, an Oceanic Core Complex, corresponding to the outcropping part of an underlying detachment, was proposed as a possible interpretation. Nevertheless, the magnetization distribution over this hill is compatible with a basaltic environment and magnetic gradients are also identical to those existing in basaltic contexts, pointing towards a similar geology. Finally, a combined plate and magnetic reconstruction reveals that this hill has a conjugate structure and that regional magnetic anomalies are symmetric. These observations rule out the Oceanic Core Complex hypothesis, as detachment surfaces are often associated with a marked spreading asymmetry. We therefore propose that this protruding bathymetric feature should rather be seen as a basaltic hill and the depth asymmetry likely results from seafloor subsidence triggered by the massive accumulation of sediments from the Bear Island Fan, on the eastern flank of the ridge axis.

Tidal Motion Enhancement on Spitsbergen Bank, Barents Sea

AbstractThe higher resolution numerical model investigates the semidiurnal and diurnal tides over the shallow Spitsbergen Bank. The tidal wave is trapped around Bear Island, Hopen Island, and Central Hill at the Bank in the semidiurnal range of oscillations. Semidiurnal waves around Bear and Hopen Islands generate a trapped dipole in the sea level distribution revealed by sea level maximum and minimum traveling on the opposite sides of the island. The dipole induces significant sea‐level differences and amplified velocity around the island perimeter. The role of the tidal currents over the Bank is connected through the mixing and transport to the generation of frontal regions. Tidal mixing directly relates to the local ice formation on Spitsbergen Bank as these areas coincide with the regions of strong tidal currents. The trapping of the semidiurnal tides leads to residual (permanent) circulation of up to 15 cm s−1. As this motion interconnects different bathymetric regions of the Bank, it influences the exchange of properties between these regions. The strength of residual currents shows that the large‐scale slow thermohaline motion cannot be complete without residual tidal motion. The diurnal tides show a different distribution since higher spatial resolution reveals sea‐level variability in many locations. These short‐wavelength shelf waves occur at seamounts, submarine peninsulas, and bays. We investigate in detail the wave dynamics in proximity to Central Hill and Hopen Island. We use observations of the buoys deployed on the ice floes to compare the drift velocity to the computed tidal velocity.

Modeling of Thermodynamic Consolidation of Sea Ice Ridges Drifting in the Water with Changing Temperature

Oceanographic and ice conditions in the region of Spitsbergen Bank in the Barents Sea were investigated in research cruises of the “Polarsyssel” in 2017–2019. Trajectories of ice drift were constructed using GPS data of the buoys deployed on the floes in the research cruises. The duration of the ice season in the region was analyzed using ice charts. The air temperature and wind velocities were analyzed using the data of meteorological stations on Bear Island and Hopen Island. Fieldwork on drifting ice showed the existence of thick consolidated floes with drafts up to 8 m, which were identified as completely consolidated sea ice ridges. The presence of such floes is dangerous for winter navigation along Spitsbergen Bank. A model of thermodynamic consolidation of ice ridges was formulated to investigate the thermodynamic evolution of ice ridges. The observed air and sea water temperatures were used in the boundary conditions on top and bottom surfaces of sea ice rubble. It was shown that the regular interaction of sea ice rubble with Atlantic and Arctic waters in the region of Spitsbergen Bank leads to almost complete consolidation of the ice rubble with an initial macro-porosity 0.2 for 150 days.

Simulation of tsunami induced by a submarine landslide in a glaciomarine margin: the case of Storfjorden LS-1 (southwestern Svalbard Islands)

Abstract. A modelling approach to understand the tsunamigenic potentiality of submarine landslides will provide new perspectives on tsunami hazard threat, mostly in polar margins where global climatic change and its related ocean warming may induce future landslides. Here, we use the L-ML-HySEA (Landslide Multilayer Hyperbolic Systems and Efficient Algorithms) numerical model, including wave dispersion, to provide new insights into factors controlling the tsunami characteristics triggered by the Storfjorden LS-1 landslide (southwestern Svalbard). Tsunami waves, determined mainly by the sliding mechanism and the bathymetry, consist of two initial wave dipoles, with troughs to the northeast (Spitsbergen and towards the continent) and crests to the south (seawards) and southwest (Bear Island), reaching more than 3 m of amplitude above the landslide and finally merging into a single wave dipole. The tsunami wave propagation and its coastal impact are governed by the Storfjorden and Kveithola glacial troughs and by the bordering Spitsbergen Bank, which shape the continental shelf. This local bathymetry controls the direction of propagation with a crescent shape front, in plan view, and is responsible for shoaling effects of amplitude values (4.2 m in trough to 4.3 m in crest), amplification (3.7 m in trough to 4 m in crest) and diffraction of the tsunami waves, as well as influencing their coastal impact times.

CHARACTERIZING MODERN AND HOLOCENE BARRIER-ISLAND ENVIRONMENTS WITH FORAMINIFERAL ASSEMBLAGES: AN EXAMPLE FROM A WAVE-DOMINATED, MICROTIDAL BARRIER-ISLAND SYSTEM, NORTH CAROLINA, USA

Abstract Recent research has shown that sedimentological information in barrier-island settings may provide more detailed interpretations of some past coastal environments than interpretations based upon foraminifera. This research investigates whether targeted documentation of modern foraminifera in specific coastal environments can result in higher resolution micropaleontology-based paleoenvironmental reconstructions. Bear Island, North Carolina, characterized by little human disturbance, was chosen for detailed documentation of foraminifera in modern barrier-island-related environments. Modern sediments in all subenvironments were predominantly siliciclastic (< 30 % clastic carbonate debris) in composition: clastic carbonate allochems (e.g., mollusk shell fragments, echinoid spines) were admixed with fine- to medium-grained quartz sand. The hypothesis that modern foraminiferal assemblages of 26 modern coastal subenvironments can be distinguished based upon their foraminiferal assemblages was tested by discriminant analysis and resulted in the recognition of four environmental supergroups: shoreface, ebb-tidal delta, flood-tidal delta/inlet channel, and “barrier-combined” (foreshore, washover, dune, sandflat, spit, longshore bar, and trough). Holocene paleoenvironments represented by foraminiferal assemblages in 16 vibracores collected from the modern inner shelf, shoreface, ebb-tidal delta, and inlet environments of Bogue Banks, immediately adjacent to Bear Island, were interpreted, via discriminant analysis, based upon the modern dataset. Holocene and modern foraminiferal assemblages were similar but variations in species abundance and species diversity allowed for alternative paleoenvironmental classification of core samples at varying levels of probability. The methodology of this research is widely applicable to other coastal environments.

The COMBLE Campaign: A Study of Marine Boundary Layer Clouds in Arctic Cold-Air Outbreaks

Abstract One of the most intense air mass transformations on Earth happens when cold air flows from frozen surfaces to much warmer open water in cold-air outbreaks (CAOs), a process captured beautifully in satellite imagery. Despite the ubiquity of the CAO cloud regime over high-latitude oceans, we have a rather poor understanding of its properties, its role in energy and water cycles, and its treatment in weather and climate models. The Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE) was conducted to better understand this regime and its representation in models. COMBLE aimed to examine the relations between surface fluxes, boundary layer structure, aerosol, cloud, and precipitation properties, and mesoscale circulations in marine CAOs. Processes affecting these properties largely fall in a range of scales where boundary layer processes, convection, and precipitation are tightly coupled, which makes accurate representation of the CAO cloud regime in numerical weather prediction and global climate models most challenging. COMBLE deployed an Atmospheric Radiation Measurement Mobile Facility at a coastal site in northern Scandinavia (69°N), with additional instruments on Bear Island (75°N), from December 2019 to May 2020. CAO conditions were experienced 19% (21%) of the time at the main site (on Bear Island). A comprehensive suite of continuous in situ and remote sensing observations of atmospheric conditions, clouds, precipitation, and aerosol were collected. Because of the clouds’ well-defined origin, their shallow depth, and the broad range of observed temperature and aerosol concentrations, the COMBLE dataset provides a powerful modeling testbed for improving the representation of mixed-phase cloud processes in large-eddy simulations and large-scale models.

A Continuous Seismostratigraphic Framework for the Western Svalbard-Barents Sea Margin Over the Last 2.7 Ma: Implications for the Late Cenozoic Glacial History of the Svalbard-Barents Sea Ice Sheet

Here we present a high-resolution, continuous seismostratigraphic framework that for the first time, connects the over 1,000 km long western Svalbard-Barents Sea margin and covers the last ∼2.7 million years (Ma). By exploiting recent improvements in chronology, we establish a set of reliable age fix-points from available boreholes along the margin. We then use a large 2-D seismic database to extend this consistent chronology from the Yermak Plateau and offshore western Svalbard, southwards to the Bear Island Trough-Mouth Fan. Based on this new stratigraphic framework we divide the seismic stratigraphy along the continental margin into three seismic units, and 12 regionally correlated seismic reflections, each with an estimated age assignment. We demonstrate one potential application of this framework by reconstructing the Svalbard-Barents Sea Ice Sheet evolution from the intensification of the northern hemisphere glaciation at ∼2.7 Ma to the Weichselian glaciations. Through seismic facies distribution and sedimentation rate fluctuations along the margin we distinguish three phases of glacial development. The higher temporal resolution provided by this new framework, allows us to document a clear two-step onset to glacial intensification in the region during phase 1, between ∼2.7 and 1.5 Ma. The initial step, between ∼2.7 and 2.58 Ma shows glacial expansion across Svalbard. The first indication of shelf-edge glaciation is on the Sjubrebanken Trough-Mouth Fan, northwestern Barents Sea after ∼2.58 Ma; whilst the second step, between ∼1.95 and 1.78 Ma shows glacial advances beyond Svalbard to the northwestern Barents Sea. Phase 2 is characterized by variations in sedimentation rates and the seismic facies are indicative for a regional glacial intensification for the whole Barents Sea-Svalbard region with widespread shelf-edge glaciations recorded at around ∼1.5 Ma. During Phase 3, the western Barents Sea margin is characterized by a dramatic increase in sedimentation rates, inferring once again a regional glacial intensification. Our new stratigraphic framework allows for the first time differentiation of the sediments deposited on the slope during Early Saalian (∼0.4 and 0.2 Ma), Late Saalian (∼0.2 and 0.13 Ma), and Weichselian (<∼0.123 Ma) periods, providing new insights into the Barents Sea glaciations over the last ∼0.42 Ma.

Seasonal and interannual variability in abundance and population development of Calanus finmarchicus at the western entrance to the Barents Sea, 1995–2019

Data on copepodid abundance and stage composition of Calanus finmarchicus was collected with seasonal resolution (5–6 times a year) from four stations along an oceanographic transect across the western Barents Sea Opening over 25 years (1995–2019). The stations were located in the Norwegian Coastal Current (NCC), inflowing Atlantic water (two stations), and near the Arctic polar front south of Bear Island. Mean copepodite abundance in the water column for the four stations increased from a level around 1000–10,000 individuals m−2 in winter to 30,000–100,000 individuals m−2 in summer (maximum 670,000 m−2). The overwintering (G0) population was dominated by copepodite stage 5 (CV) (40–70%) but with a relatively high fraction also of stage CIV (25–35%) in January. During winter, there was a progressive development of CVs into adult males and females, with mean abundances from 1500 to 4000 adult females m−2 in April and May for the stations in the NCC and Atlantic water. Young copepodids of the new spring generation (G1) appeared with relatively high abundances in April at the NCC station and in May at the Atlantic water stations. The data showed a gradient of later development from south to north, reflected both in the maturation of the overwintering generation and in the development of the spring generation. Back-calculations based on temperature-dependent development time suggested peak spawning around late April to mid-May for the Atlantic water stations, and a month or so earlier (in March) for the NCC station, during an early phase of the spring phytoplankton growth. The spring generation developed as a distinct cohort but with large interannual variability in numbers. In Atlantic water, the composition of the copepodid developmental stages in August resembled the situation in June, although it was slightly more advanced. This is interpreted to reflect development of a second generation (G2) spawned upstream sometime in June or early July. The June data suggests that only a small fraction of the G1 cohort develops into adults that spawn and form the G2. There was a tendency of increased summer abundance of C. finmarchicus in the inflow region of the southwestern Barents Sea after about 2005. This may be related to the wind regime with more eastward wind-stress at the Barents Sea opening in recent ‘high Calanus’ years compared to ‘low Calanus’ years in the early 2000s.

Feeding Hotspots and Distribution of Fin and Humpback Whales in the Norwegian Sea From 2013 to 2018

Fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) are commonly found in the Norwegian Sea during the summer months. Records from around 1995 to 2004 show that their distribution patterns were mainly associated with those of macro-zooplankton. More recent studies conducted from 2009 to 2012 demonstrate marked shifts, with fin whale distribution related to pelagic fish distribution, decreasing densities of humpbacks, and increased densities of toothed whales. During the same period, historically large abundances of pelagic planktivorous fish in the Norwegian Sea were reported. The goals of this study were to examine the summer distribution of fin and humpback whales from 2013 to 2018 and to assess the potential association between distribution and environmental impact factors. Results suggest a pronounced northerly shift in distribution for both species, a feeding hotspot for fin whales at the shelf area between Svalbard and Norway, and one near Bear Island for humpback whales. Fin whale distribution was associated with that of blue whiting (Micromesistius poutassou) and capelin (Mallotus villosus), whereas humpback whale distribution was associated with that of euphausiids (Meganyctiphanes norvegica, Thysanoessa longicaudata, andThysanoessa inermis), capelin, and herring (Clupea harengus). However, a significant negative spatial correlation was found between whale occurrence and the widely expanding population of northeast Atlantic mackerel (Scomber scombrus). The results of this study suggest that the prey composition of fin and humpback whales in recent years contain a large proportion of fish. The apparent northerly shift in the distribution of these whale species is largely determined by the availability of prey, but it likely is also impacted by direct or indirect interspecific interactions, especially with killer whales (Orcinus orca). Such large-scale pronounced changes in distribution seem to confirm a high degree of plasticity in fin and humpback whale feeding in the Norwegian Sea.

Decabromodiphenylether trends in the European environment: Bird eggs, sewage sludge and surficial sediments

Concern on relatively high levels and the potential bioaccumulation of decabromodiphenylether (BDE209) has led to a European 8-year monitoring program on trends in BDE209 concentrations in birds, sewage sludge and sediments from seven countries. BDE209 was analysed in four environmental matrices: sparrowhawk eggs (UK), glaucous gull eggs (Bear Island, Norway), sewage sludge (UK, Ireland and the Netherlands) and sediment (France, Germany, the Netherlands, UK and Ireland). BDE209 was detected in most of the glaucous gull and sparrow hawk eggs but neither increasing nor decreasing trends in these BDE209 levels were observed. An indication for debromination of BDE209 in sparrowhawk eggs was found. BDE209 concentrations in sediments ranged from very low ng/g (88 ng/g on an organic carbon (OC) basis) concentrations, in the rivers Elbe, Ems, Seine and the Outer Humber, to high μg/g (120 μg/g OC), in the Western Scheldt, Liverpool Bay and River Mersey. Apart from decreasing values in the Western Scheldt sediment no further decreases in BDE209 concentrations were observed over time, neither in sediment nor in sewage sludge showing that the voluntary emissions control program of the bromine industry only had a local effect. In contrast to the sewage sludge samples from the Netherlands (mean 355 ng/g dry weight (dw) or 1026 ng/g OC), the BDE209 concentrations in the UK increased at all sites from 2006 to 2011 (8092 ng/g dw or 22,367 ng/g OC). The BDE209 levels in several UK sediments and sewage sludge were still very high at the end of the program in 2012, most likely caused by frequent use of BDE209 in the textile industry. This may be indicative of the persistence of BDE209 and the limited degradation into lower brominated congeners in sediment, although it cannot be excluded that ongoing BDE209 emissions have played a role as well.