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The southern North Sea is a particularly important area for understanding the behaviour of the British-Irish Ice Sheet (BIIS) during the last glacial cycle. It preserves a record of the maximum extent of the eastern sector of the BIIS as well as evidence for multiple different ice flow phases and the dynamic re-organisation of the BIIS. However, to date, the known ice sheet history and geochronology of this region is predominantly derived from onshore geological evidence, and the offshore imprint and dynamic history of the last ice sheet remain largely unknown. Using new data collected by the BRITICE-CHRONO project this paper explores the origin and age of the Dogger Bank; re-assesses the extent and age of the glaciogenic deposits across the shallow areas of the North Sea between the Dogger Bank and the north Norfolk coast and; re-examines the dynamic behaviour of the BIIS in the southern North Sea between 31.6 and 21.5 ka. This paper shows the core of the Dogger Bank to be composed glaciolacustrine sediment deposited between 31.6 and 25.8 ka. Following its formation the western end of the Dogger lake was overridden with ice reaching ∼54°N where the ice margin is co-incident with the southerly extent of subglacial tills previously mapped as Bolders Bank Fm. This initial ice override and retreat northwards back across the Dogger lake was complete by 23.1 ka, but resulted in widespread compressive glaciotectonism of the lake sediments and the formation of thrust moraine complexes. Along the northern edge of the bank moraines are on-lapped by later phase glaciolacustrine and marine sediments but do not show evidence of subsequent ice override. The shallow seafloor to the west and southwest of the Dogger Bank records several later phases of ice advance and retreat as the North Sea Lobe flowed between the Dogger Bank and the Yorkshire/Lincolnshire coasts and reached North Norfolk. New optically stimulated luminescence (OSL) ages from Garrett Hill on outwash limit the arrival of the BIIS on the Norfolk coast to 22.8–21.5 ka. Multiple till sheets and chains of moraines on the seafloor north of Norfolk mark dynamic oscillation of the North Sea Lobe margin as it retreated northwards. This pattern of behaviour is broadly synchronous with the terrestrial record of deposition of subglacial, glaciofluvial and glaciolacustrine sediments along the Yorkshire coast which relate to post Dimlington Stadial ice marginal oscillations after 21.5 ka. With respect to forcing mechanisms it is likely that during the early phases of the last glacial maximum (∼30-23ka) the interaction between the southern margin of the BIIS and the Dogger Lake was critical in influencing flow instability and rapid ice advance and retreat. However, during the latter part of the last glacial maximum (22–21 ka) late-phase ice advance in the southern North Sea became restricted to the western side of the Dogger Bank which was a substantial topographic feature by this time. This topographic confinement, in addition to decoupling of the BIIS and the Fennoscandian Ice Sheet (FIS) further north, enabled ice to reach the north Norfolk coast, overprinting the seabed with late-phase tills of the Bolders Bank Fm. Highlights • New acoustic and chronological data from the southern North Sea casts fresh light on British-Irish Ice Sheet history. • The Dogger Bank is composed of glaciolacustrine sediment heavily glaciotectonised between 31.6 and 23.1 ka. • A key trigger for the re-advance of the British-Irish Ice Sheet at 21.5 ka was the catastrophic drainage of Dogger Lake. [ABSTRACT FROM AUTHOR]

This paper presents a new approach for the optimization of neighbouring offshore wind farms. Offshore wind energy is one of the most promising and developed low-carbon generation technologies. However, the high capital costs, which are strongly dependent on seabed depth, currently limit the geographical expansion of this technology to areas with relatively shallow waters and appropriate wind resource. This, along with the advantages of sharing a submarine transmission system among several projects, leads to a high concentration of offshore wind farms in certain zones, as happens, for example, in the North Sea. The presence of other neighbouring offshore wind farms has to be taken into account when a developer plans a new project, since the wake effect of wind turbines belonging to other neighbouring wind farms will affect the annual energy production and, consequently, the profitability of the project under study. However, not only already operating or installed neighbouring projects have to be borne in mind, but also the possible design of future neighbouring wind farms yet to be developed. In order to tackle this issue, an innovative co-evolutionary algorithm is proposed in this paper with the objective of determining a Nash equilibrium solution that would provide the best possible configuration of the wind farm under study by taking into account and limiting the disturbance introduced by other neighbouring projects. The performance of the proposed methodology has been successfully tested through the analysis of a realistic case and compared with other collaborative approaches and the classic single-project optimization methods already existing in the literature. [ABSTRACT FROM AUTHOR]

The European Blue Growth strategy aims to expand the new maritime sectors of aquaculture, energy, biotechnology, coastal tourism and mineral mining. Growth of these sectors will increases pressure on the seas, particularly on those areas that are densely used by traditional sectors such as fisheries and transport. This has triggered interest in developing multiuse of space and multiuse platforms at sea. This paper assesses the feasibility of offshore mussel production project in wind farms by design and ex-ante evaluation of a mussel aquaculture system in the North Sea. A system for mussel cultivation in the Dutch Borssele offshore wind farm was designed, producing both mussel seed and consumption-sized mussels with semi-submerged longlines. Based on the economic model and the risk assessment, this paper concludes that mussel aquaculture is an appealing commercial model for increased returns in offshore wind farms. The economic models shows that the internal rate of return and net present value are positive and based on the sensitivity analysis, it can be concluded that these results are robust. [ABSTRACT FROM AUTHOR]

Microbiologically influenced corrosion (MIC) is the terminology applied where the actions of microorganisms influence the corrosion process. In literature, terms such as microbial corrosion, biocorrosion, microbially influenced/induced corrosion, and biodegradation are often applied. MIC research in the oil and gas industry has seen a revolution over the past decade, with the introduction of molecular microbiological methods: (MMM) as well as new industry standards and procedures of sampling biofilm and corrosion products from the process system. This review aims to capture the most important trends the oil and gas industry has seen regarding MIC research over the past decade. The paper starts out with an overview of where in the process stream MIC occurs − from the oil reservoir to the consumer. Both biotic and abiotic corrosion mechanisms are explained in the context of managing MIC using a structured corrosion management (CM) approach. The corrosion management approach employs the elements of a management system to ensure that essential corrosion control activities are carried out in an effective, sustainable, well-planned and properly executed manner. The 3-phase corrosion management approach covering of both biotic and abiotic internal corrosion mechanisms consists of 1) corrosion assessment, 2) corrosion mitigation and 3) corrosion monitoring. Each of the three phases are described in detail with links to recent field cases, methods, industry standards and sampling protocols. In order to manage the corrosion threat, operators commonly use models to support decision making. The models use qualitative, semi-quantitative or quantitative measures to help assess the rate of degradation caused by MIC. The paper reviews four existing models for MIC Threat Assessment and describe a new model that links the threat of MIC in the oil processing system located on an offshore platform with a Risk Based Inspection (RBI) approach. A recent field case highlights and explains the conflicting historic results obtained through serial dilution of culture media using the most probable number (MPN) method as compared to data obtained from corrosion monitoring and the quantitative polymerase chain reaction (qPCR) method. Results from qPCR application in the field case have changed the way MIC is monitored on the oil production facility in the North Sea. A number of high quality resources have been published as technical conference papers, books, educational videos and peer-reviewed scientific papers, and thus we end the review with an updated list of state-of-the-art resources for anyone desiring to become more familiar with the topic of MIC in the upstream oil and gas sector. [ABSTRACT FROM AUTHOR]

Marine activities have been increasingly competing for space and reducing areas for fishing. The use of spatially explicit tools can assist the decision making process on defining the optimal location of closures for fishing due to these emerging activities. This paper presents the Spatial Integrated bio-economic Model for FISHeries (SIMFISH). In this model fishers behaviour is simulated based on optimal effort allocation. The added value of this model compared to other existing spatial management tools lies in the presence of (i) short and long term fishers behaviour (ii) spatial explicit stock and fleet dynamics and (iii) relatively low data requirements. As an illustration, SIMFISH is applied in this paper to estimate the impact of area closures in the North Sea. Overall area closures have a negative impact on the profitability of the fleets. This would be worsened with higher fuel prices and decreased stock productivity. [ABSTRACT FROM AUTHOR]

Abstract: This paper concerns the calculation of the wave statistics in nonlinear mixed sea states (i.e. sea states of combined wind waves and swell). The calculations have been carried out by incorporating a 2nd order nonlinear wave model into a random phase deterministic spectral amplitude (DSA) simulation method. To demonstrate the effectiveness of this approach, the calculation results from a linear simulation method and a random phase non-deterministic spectral amplitude (NSA) simulation method and from using some empirical formulas have also been presented for comparison purpose. In order to validate the approach proposed in this article, the wave characteristics directly calculated from the wave data measured at an oil field in the North Sea were utilized. It has been shown, contrary to the usual belief, that the nonlinear DSA simulation method used in this study can predict slightly more accurate wave characteristics than the nonlinear NSA simulation method does. The calculation results in this paper are analyzed, and some findings valuable for marine structural design have been pointed out. [Copyright &y& Elsevier]

Abstract: When building offshore wind turbines, a static scour protection is typically designed, allowing no movement of top layer stones under design conditions, leading to an often conservative design. Furthermore, little design guidelines exist for a scour protection around a monopile foundation under combined wave and current loading. In part 1 (De Vos et al., 2011), preceding this paper, a static design guideline for a scour protection around a monopile is suggested, based on a combined wave and current flow field. By allowing some movement of the top layer stones of the scour protection, a more economical design is obtained. This paper describes the derivation of a dynamic design formula to calculate the required stone size for a scour protection around a monopile foundation in a combined wave and current climate. The formula is based on the results of an experimental model study, described in this paper. The formula gives an expected damage level to the scour protection, based on the wave orbital velocity, wave period, steady current velocity, water depth, relative stone density and stone size. When applying the formula for a typical situation in the North Sea, a reduction of 20% to 80% of the required stone size is obtained, compared to the static design approach, described in part 1. [Copyright &y& Elsevier]

• It is quick and easy for Stakeholders and Managers to use. • It integrates most of the important tradeoffs involved in EBFM. • The paper discusses how this model could be developed further as needs for other features arise. The trade-offs North Sea (T-ONS) model is presented. This is centred upon a simple multispecies Schaefer model where the long term steady state yield of each species is approximated by quadratic functions of fishing mortality rate of all species. To this are added the main mixed fishery constraints and the available economic, social and ecosystem consequences of concern to Ecosystem Based Fisheries Management (EBFM). For ease of transportability this model is written in EXCEL. It can swiftly emulate the long term behaviour of more complex age based North Sea multi-species models and is broadly similar to, but has a wider range of outputs than similar models presented in earlier years and differs from them in how it treats mixed fisheries. The essence of how it fits the ICES age based SMS multi-species fisheries model and uses the STECF fishing effort data series to mimic multi-fleet constraints is explained. In addition to the fishery outputs, the model provides economic and social outputs both overall and on a fleet by fleet or country by country basis. It also provides an as yet restricted set of good environmental status (GES) indicators. It is designed to be user friendly and so to empower managers and stakeholders to personally explore how different management approaches would affect the trade-offs that are of most concern to them. It also allows managers to see how acceptable their solutions would be to the different interest groups of stakeholders. The T-ONS model is also the basic tool of the Mareframe decision support framework for the North Sea. It may be used either as a decision support tool by itself or used to provide inputs to formal decision support tools such as multi-criteria analysis (MCA). [ABSTRACT FROM AUTHOR]

Abstract Offshore pile driving is a high-risk activity as delays can be financially punitive. Experience of pile driving for offshore jacket structures where pile diameters are typically < 2 m has led to the development of empirical pile driveability models with proven predictive capability. The application of these methods to larger diameter piles is uncertain. A major component of driveability models involves estimating the static resistance to driving, SRD, a parameter analogous to pile axial capacity. Recent research on axial capacity design has led to improved models that use Cone Penetration Test, CPT data to estimate pile capacity and include for the effects of friction fatigue and soil plugging. The applicability of these methods to estimating pile driveability for larger diameter piles is of interest. In this paper, recent CPT based axial capacity approaches, modified for mobilised base resistance and ageing, are applied to estimating driveability of 4.2 m diameter piles. A database of pile installation records from North sea installations are used to benchmark the methods. Accounting for factors such as pile ageing and the relatively low displacement mobilised during individual hammer blows improves the quality of prediction of pile driveability for the conditions evaluated in this study. Highlights • Traditional pile driveability methods mainly underestimate predicted blow counts. • Stevens Plugged Approaches should not be used for large diameter piles. • Applying unmodified IC-05 and UWA-05 is mostly unsuitable for monopile driveability. • Adopting base-settlement model with UWA-05 improves the prediction. • The inclusion of residual base stresses leads to a further improvement with UWA-05. [ABSTRACT FROM AUTHOR]

Abstract: The Siri Canyon has proved to be a perfect area for investigating various morphologies of diagenetic silica in sandstones. The development in silica morphologies can be observed from very shallow (∼1700m) to increased burial depth (∼3000m) and increased proximity to the Central Graben (distance from 0 to 65km). Hydrocarbons and pore fluids, now found in the Siri Fairway, have (at least partly) originated from the Central Graben. The Siri Canyon is a submarine canyon system eroded into the uppermost chalk deposits and filled with Palaeogene hemipelagic and turbiditic marls and mudstones interbedded with sandstone units deposited from sandy mass-flows and sandy turbidites, which originated on the Stavanger Platform. Several hydrocarbon exploration and production wells have been drilled in the Siri Canyon, seven of which are included in this study (Nini-3, Nini-1, NA-2P, Sofie-1, Siri-4, Celilie-1A and Augusta-1). The reservoir sandstones in these wells all contain authigenic silica of various morphologies identified with a combination of traditional optical microscopy and scanning electron microscopy. The silica morphologies in some places are classic and well-documented in the literature, whereas others, at least to our knowledge, have never previously been described. Some of the silica morphologies presented here show gradual transition from one to another, and others are stand-alone forms without clear relationships to other forms. The silica morphologies can be expressed in the following way: [1.] Opal rims; characteristic of the initial phase of the silica diagenesis in most sandstone units in the Siri Canyon. Thick opal rims characterise the sandstone parts adjacent to the mudstone units in the Stine segment of the Siri Field. [2.] Microquartz (quartz crystals with a size of 1–5µm); seen as coatings on the opal rims, both ordered and random. [3.] Cavity overgrowth; found as quartz outgrowths in circular and angular cavities formed by dissolution of early authigenic phases. Angular cavities in the microquartz coatings origin from dissolution of clinoptilolite, possibly with a source in volcanic ash, whereas dissolution of lepispheres probably resulted in circular cavities. [4.] Quartz ridges (syntaxial quartz overgrowths, a few micro millimetre in width, in parallel lines — defined in this paper). [5.] Quartz mountains (syntaxial, irregular 5–10µm large quartz crystals — defined in this paper); developed in the water-filled sandstone intervals where fluids from the Central Graben were introduced, possibly together with the hydrocarbon, and where the continued growth was not retarded by the presence of hydrocarbons in the pore fluids. [6.] Macroquartz (syntaxial quartz overgrowths >20µm); seen as continued growths from quartz mountains. This takes place in the deeper reservoir sandstones, promoted by fluids originating from the Central Graben and increased burial depth. [7.] Quartz with sutured grain contacts; occurring only in the deepest well (3000m). [Copyright &y& Elsevier]

Abstract: An ecosystem approach to the management of the marine environment has received considerable attention over recent years. However, there are few examples which demonstrate its practical implementation. Much of this relates to the history of existing marine monitoring and assessment programmes which (for many countries) are sectoral, making it difficult to integrate monitoring data and knowledge across programmes at the operational level. To address this, a scientific expert group, under the auspices of the International Council for the Exploration of the Sea (ICES), prepared a plan for how ICES could contribute to the development of an Integrated Ecosystem Assessment (IEA) for the North Sea by undertaking a pilot study utilising marine monitoring data. This paper presents the main findings arising from the expert group and in particular it sets out one possible integrated approach for assessing the relative significance of environmental forcing and fishing pressure on the ecological status of the North Sea, it then compares the findings with assessments made of other Large Marine Ecosystems (LMEs). We define the North Sea ecosystem on the basis of 114 state and pressure variables resolved as annual averages between 1983 and 2003 and at the spatial scale of ICES rectangles. The paper presents results of integrated time-series and spatial analysis which identifies and explains significant spatial and temporal gradients in the data. For example, a significant shift in the status of the North Sea ecosystem (based upon 114 state-pressure variables) is identified to have occurred around 1993. This corresponds to previously documented shifts in the environmental conditions (particularly sea surface temperature) and changes in the distribution of key species of plankton (Calanus sp.), both reported to have occurred in 1989. The difference in specific timing between reported regime shifts for the North Sea may be explained, in part, by time-lag dependencies in the trophic structure of the ecosystem with shifts in higher trophic levels occurring later than 1989. By examining the connection (or relatedness) between ecosystem components (e.g. environment, plankton, fish, fishery and seabirds) for the identified regime states (1983–1993; 1993–2003) we conclude that both the North Sea pelagic and benthic parts of the ecosystem were predominantly top-down (fishery) controlled between 1983 and 1993, whereas between 1993 and 2003 the pelagic stocks shifted to a state responding mainly to bottom-up (environment) influences. However, for the demersal fish stocks between 1993 and 2003 top-down (fishery) pressure dominated even though over this period significant reductions in fishing pressure occurred. The present analysis, therefore, provides further evidence in support of the need for precautionary management measures taken in relation to setting fishery quotas. [Copyright &y& Elsevier]

The Models-3 Community Multiscale Air Quality (CMAQ) model is setup on a 54×54km2 grid for Europe and on a nested smaller domain with a 18×18km2 grid for the North Sea region. This paper concentrates on the models ability to represent the transport and deposition of atmospheric pollution in North Sea coastal areas. Comparisons to NO2 and PM10 measurements at selected sites of the Co-operative Program for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP) are used for quality control for atmospheric concentrations. We use modeled nitrogen deposition fields and EMEP wet deposition measurements during January and July 2001 as a measure to evaluate the deposition schemes. Close agreement between the model and the measurements was found for the oxidised nitrogen compounds in January, when on average NO2 was overestimated by 18% (measured: 3.52μgN/m3, modeled: 4.16μgN/m3) and nitrate deposition was only slightly underestimated by 2%. However, ammonia was underestimated by 44%. In July, NO2 levels are much lower than in January and the model underestimates the mean concentration by 35% (measured 1.49μgN/m3, modeled 0.97μgN/m3). Wet deposition is also underestimated, but again the results for nitrate (−38%) were in better agreement with the measurements than for ammonium (−57%). PM10 concentrations are largely underestimated in January and July (by about 65% on average), but this result was expected, because only anthropogenic emissions were considered. Nevertheless, especially in January high daily correlations (0.69–0.84) between the modeled dry PM10 and the measurements in Germany were found. This indicates that the aerosol transport pathways are captured quite well by the model. CMAQ has been expanded to represent also persistent organic pollutants (POPs). In this paper first results of deposition fields of the carcinogenic benzo(a)pyrene (B(a)P) are shown. Preliminary comparisons to air concentration and deposition measurements show that the model results are in the right order of magnitude. In particular the observed strong seasonal cycle of B(a)P in air was also present in the model. [Copyright &y& Elsevier]

Abstract: This paper examines the use of aerial surveillance activities conducted in the North Sea region of Europe since 1986 to assess trends in levels of oil inputs into the marine environment, both across the whole region and within the waters of the different coastal states. It makes use of data collected under the aegis of the 1969 Bonn Agreement through its Annual Reports on Aerial Surveillance and examines developments in surveillance methods and technology which have led to improvements in the detection of oil spills, even during the hours of darkness. The paper then examines country specific data for the eight North Sea contracting parties to the Agreement to assess trends in oil spills in the region. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to evaluate the results of a survey of the availability and uptake of port reception facilities within the North Sea area. The evaluation is based primarily on original survey data from the autumn of 2002 which followed on from a similar survey conducted in the summer of 2000. The EU Directive on port reception facilities for ship-generated waste etc. (Directive 2000/59/EC) was due to enter into force in December 2002, and required all EU ports to provide reception facilities to meet the needs of the vessels normally calling in at them. This paper examines the readiness of North Sea ports to meet that requirement and also considers the actual uptake levels of facilities, where ports were able to provide such information. [Copyright &y& Elsevier]

Detailed interpretation of 2D and 3D seismic data from the Sable Subbasin (continental margin of eastern Canada) has revealed an extensive polygonal fault system affecting Upper Cretaceous chalk of the Wyandot Formation (the Wyandot Chalk) and Cenozoic mudrocks of the Banquereau Formation. This paper offers the first detailed study of a basin-scale polygonal fault system affecting a chalk-dominated unit. The Wyandot Chalk is up to 300m thick and pervasively deformed by small-scale faults that are morphologically and quantitatively similar to those previously described from polygonal fault systems observed in mudrocks of the North Sea, and elsewhere. This suggests that they may have formed due to a common mechanism. The data presented in this paper point towards a lithological control upon the development of the polygonal fault system and argue that the syneresis hypothesis posed by Cartwright and Dewhurst [Geol. Soc. Am. Bull. 110 (1998) 1242] best explains the distribution and initiation of the analysed fault system.3D seismic attribute maps reveal an orthogonal intersection relationship between polygonal faults and tectonic faults in the study area. This relationship is interpreted to indicate that local stress perturbations around the tectonic faults influenced the propagation of the polygonal faults. [Copyright &y& Elsevier]

The aim of this paper is to evaluate the current availability of port reception facilities within the North Sea area. The evaluation is based primarily on original survey data from the summer of 2001, supplemented by existing information from surveys conducted by the International Maritime Organization. The EU Directive on port reception facilities for ship-generated waste etc. (Directive 2000/59/EC) requires that all ports provide facilities to meet the needs of those vessels normally calling in at them. In order for the Directive to be implemented effectively, the physical availability of such facilities is vital. This paper audits the wide range of port types within the region and also outlines the wide range of vessel types using these ports, and their requirements for a range of facilities. On the basis of this analysis, conclusions are drawn about the extent to which the provision requirement of the Directive is already being met. [Copyright &y& Elsevier]

Recent reconstructions suggest that the British-Irish and Fennoscandian ice sheets coalesced and covered the central and northern North Sea from ca. 26 cal. ka BP and until ca. 19 cal. ka BP. At ca. 19 cal. ka BP the Norwegian Channel Ice Stream started to retreat and the ice sheets broke apart at ca. 18.7 cal. ka BP. This led to a drainage of an ice-dammed lake in the southern North Sea northwards via the Norwegian Channel into the SE Nordic Seas. In this paper we combine information from high resolution TOPAS profiles, bathymetric records and shallow borings to study the ice-dammed lake outburst, a common deglaciation process but which rarely has been evidenced in such a detail from the marine realm. A 12 m deep and 3 km wide incision at the northeastern part of the Dogger Bank is suggested to represent the point where the ice-dammed lake breached. The glacial lake outburst flood, which had an estimated peak discharge of 9.8 × 10 4 –2.9 × 10 5 m 3 /s and lasted for about 5–15 months, flowed between the withdrawing British-Irish and Fennoscandian ice sheets following the crest of the Ling Bank northwards. Along this path, about 300 km downstream of the break-through point, an up to 10 m thick sediment package with a prograding-aggrading sedimentation pattern, typical for ice-dammed lake outburst deposits, has been deposited. This sediment package was deposited in a high-energy environment, immediately following extensive erosion of the underlying till unit of Last Glacial Maximum age. An oxygen isotope anomaly and an associated ultra-rapidly deposited meltwater plume on the Norwegian continental margin, dated to ca. 18.7 cal. ka BP, also witness this lake outburst. The ice-dammed lake outburst flood occurred when evidence suggest a sea level at least 110 m lower than at present in the region. As the sea level rose, following the melting of the Last Glacial Maximum ice sheet, the Ling Bank Delta developed on top the outburst deposits. The delta, indicating a sea level close to 80 m below present, has an extent of 80 km and up to 12 m deep fluvial channels are associated with the topset beds. This fluvial environment may have lasted until the end of the Younger Dryas time period when the Ling Bank was submerged and attained its present water depth. [ABSTRACT FROM AUTHOR]

The Lower Palaeolithic hominin occupation of northwest Europe occurred during a period of significant climatic change. In Britain, hominin populations were present discontinuously, from strongly continental sites to those characterised by a balmy Mediterranean environment. Whilst apparently able to survive a range of conditions, the configuration of the associated landscapes, in particular the presence or absence of a land connection with the continent, would have had a fundamental impact on the density of hominin occupation in Britain at any given time. Similarly, the environments once present in the now-drowned North Sea Basin and Channel regions would presumably have played an important role in attracting and sustaining hominin populations. However, our understanding of the physical and environmental character of these landscapes, as well as the timing of marine transgressive and regressive periods, remains frustratingly murky, hindering the ability to imagine how these landscapes may have been used. A growing body of data from recent research and commercial offshore development is beginning to help researchers understand this issue, but there is still an immense amount of work to do. With the contribution that evidence from these lost landscapes could provide to Lower Palaeolithic archaeology as a focus, this paper begins with a review of the current state of affairs with regard to commercial and research methods and practices. It then discusses the ways that we are moving this forward through specific archaeological projects, providing tentative suggestions for how current methods could be developed and the kinds of information that these could provide. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to analyse the socio-economic justification of implementing a Nitrogen Emission Control Area (NECA), starting 2021, for ships in the Baltic Sea and/or the North Sea and English Channel. We analyse the potential for emission reduction, emission control costs, and monetised benefits following the introduction of a NECA. Costs and benefits are compared for 2030. We compile new data on emission control costs for shipping, use the GAINS model for calculations of emission dispersion, and the Alpha-RiskPoll model for estimating monetary values of health impacts. The model results show that costs to conform to the NO X regulations of a NECA in the Baltic Sea, North Sea or both sea regions would be 111 (100–123), 181 (157–209), and 230 (195–273) million € per year, respectively. Corresponding benefits from reduced emissions are estimated to be 139 (56–294), 869 (335–1882), and 1007 (392–2177) million € per year, respectively. Calculated benefits surpass costs for most scenarios, but less convincingly for a Baltic Sea NECA. Conforming to the NECA regulations by using Liquefied Natural Gas (LNG) propulsion engines is estimated to give the highest net benefits but also the largest variation (costs: 153 (88–238), benefits: 1556 (49–3795) million €/year). The variations are mainly due to uncertainties in the valuation of avoided fatalities and climate impacts. It is concluded that the NECAs for the Baltic and North Seas can be justified using CBA under all but extreme assumptions. [ABSTRACT FROM AUTHOR]

The sudden disappearance of Atlantic bluefin tuna in northern Europe in the 1960’s, after its frequent occurrence in the preceding period, has often been discussed in the scientific literature. Remarkably enough, the question whether the figures from the beginning of the 20th century have always been at the same high level in earlier periods, has so far only been poorly investigated. The answer to this question is crucial to define realistic targets for conservation measures aiming at the return of bluefin tuna to this feeding area. Taking account of texts from 16th to 19th century authored by naturalists and zoologists, and scientific papers by fishery biologists in the early 20th century, it is concluded that tuna has frequently been present over the last centuries but their abundance has not been consistently high. This conclusion is supported by national newspaper databases which help to learn more about age group distribution, fishery, and local differences in consumer acceptance with regard to tuna in the 1910’s. These sources revealed two new ecological insights to bluefin tuna ecology in the region. First, the documents showed an earlier phenology than can be seen from most of the 20th century commercial catch statistics, with occasional sightings and strandings during March-June. Second, schools of bluefin tuna appeared in the Rhine-Scheldt estuary in the first decades of the 20th century. [ABSTRACT FROM AUTHOR]

A likely side-effect of introducing the landing obligation of the 2013 Common Fisheries Policy into mixed fisheries is the occurrence of the “choke species” problem. When discarding no longer is an option, leasing quota or changing fishing practices remain important tools to avoid choke species. Here, the scale and tactics linked to using avoidance behaviour to reduce choke species is investigated by analysing the fishing behaviour of a single demersal trawler in the North Sea. Analysis combined qualitative information collected from through interviews with the vessel owner and skipper, along with quantitative analysis on fisheries data. From the interviews, saithe and cod were identified as potential choke species and subsequent analysis focused on these two species. The analysis of catch and quota composition showed that cod would choke the fishery early if no catch-quota balancing options were available, resulting in a 87% reduction in revenue, while saithe could choke the fishery later, resulting in a 43% reduction in revenue. Avoidance behaviour was difficult to detect from fisheries data, which was explained by avoidance taking primarily place through very fine-scale tactical choices rather than large displacements. Catch composition showed that saithe is distributed more patchily than cod, with most hauls containing small amounts of saithe and a few hauls containing large amounts. In conclusion this paper supplies an view on the choke species problem seen from the perspective of an individual fisher and highlights the amount of real-time tactical decisions and trade-offs that need to be made when operating in mixed-fisheries. [ABSTRACT FROM AUTHOR]

This paper assesses different concepts for efficient supply of power and heat to specific offshore installations in the North Sea, with the objective of cutting carbon dioxide emissions. The concepts analyzed include solutions with on-site power generation, full plant electrification, and hybrid solutions where power can be either generated locally or taken from the onshore grid. A detailed modeling of the power generation system was carried out, enabling design and off-design simulations. Plant power and heat demand profiles were used to evaluate the various concepts throughout the entire field’s life. A first analysis of the common on-site power generation systems revealed the possibility of cutting carbon dioxide emissions simply by optimizing the operating strategy. Overall, the assessment of the different concepts showed that full plant electrification and the implementation of an offshore combined cycle have the potential to substantially reduce cumulative carbon dioxide emissions. A sensitivity analysis of the carbon dioxide emission factor, associated with the grid power, stressed how this parameter has a strong influence on the analysis outputs and, thus, needs to be thoroughly assessed. Similarly, the impact of increased plant heat demand was evaluated, showing that advantages connected to the plant electrification tend to diminish with the increase in heat requirements. [ABSTRACT FROM AUTHOR]

This paper describes the distribution of the razor clam Ensis directus in the Dutch coastal zone with emphasis on its relation to sediment grainsize, in particular silt. The study includes a spatial survey along the coast of North Holland (Netherlands) and an in-situ experiment for the burial of silt. Densities of E. directus appeared highest close to the coast in the siltiest sediment, where also the highest body mass index values (BMI) were found suggesting the best conditions for growth. The largest specimens with the lowest BMI were found at the less silty, outermost off-shore stations. In the shallow (10 m) zone a “lander” frame was deployed at the seabed containing ~ 100 pvc tubes filled with silt free sand that each hosted either a living E. directus , an empty shell, or bare sand. After three 3-weeks periods the silt content in the different tubes was determined and compared. The silt content around a living E. directus appeared 34% (spring) and 12% (autumn) higher than around an empty vertical shell, and 56% (spring) higher than in bare sand. We discuss the different pathways along which silt is brought into subsurface sediment layers and speculate about the potential role of E. directus in the coastal sediment and silt dynamics. It is estimated that E. directus facilitates the (temporal) burial of up to 6 Mton of fine particles in the coastal zone annually. This equals up to 27% of the annual SPM transport along the Dutch coast and is between 45 and 85% of the annual influx into the western Wadden Sea. The results show that the coastal E. directus population has a large impact on mass balance and behaviour of SPM, and on the ecological functioning of Dutch coastal and estuarine ecosystems. [ABSTRACT FROM AUTHOR]

Along the terrestrial margin of the southern North Sea, previous studies of the MIS 2 glaciation impacting eastern Britain have played a significant role in the development of principles relating to ice sheet dynamics (e.g. deformable beds), and the practice of reconstructing the style, timing, and spatial configuration of palaeo-ice sheets. These detailed terrestrially-based findings have however relied on observations made from only the outer edges of the former ice mass, as the North Sea Lobe (NSL) of the British-Irish Ice Sheet (BIIS) occupied an area that is now almost entirely submarine (c.21–15 ka). Compounded by the fact that marine-acquired data have been primarily of insufficient quality and density, the configuration and behaviour of the last BIIS in the southern North Sea remains surprisingly poorly constrained. This paper presents analysis of a new, integrated set of extensive seabed geomorphological and seismo-stratigraphic observations that both advances the principles developed previously onshore (e.g. multiple advance and retreat cycles), and provides a more detailed and accurate reconstruction of the BIIS at its southern-most extent in the North Sea. A new bathymetry compilation of the region reveals a series of broad sedimentary wedges and associated moraines that represent several terminal positions of the NSL. These former still-stand ice margins (1–4) are also found to relate to newly-identified architectural patterns (shallow stacked sedimentary wedges) in the region's seismic stratigraphy (previously mapped singularly as the Bolders Bank Formation). With ground-truthing constraint provided by sediment cores, these wedges are interpreted as sub-marginal till wedges, formed by complex subglacial accretionary processes that resulted in till thickening towards the former ice-sheet margins. The newly sub-divided shallow seismic stratigraphy (at least five units) also provides an indication of the relative event chronology of the NSL. While there is a general record of south-to-north retreat, seismic data also indicate episodes of ice-sheet re-advance suggestive of an oscillating margin (e.g. MIS 2 maximum not related to first incursion of ice into region). Demonstrating further landform interdependence, geographically-grouped sets of tunnel valleys are shown to be genetically related to these individual ice margins, providing clear insight into how meltwater drainage was organised at the evolving termini of this dynamic ice lobe. The newly reconstructed offshore ice margins are found to be well correlated with previously observed terrestrial limits in Lincolnshire and E. Yorkshire (Holderness) (e.g. MIS 2 maximum and Withernsea Till). This reconstruction will hopefully provide a useful framework for studies targeting the climatic, mass-balance, and external glaciological factors (i.e. Fennoscandian Ice Sheet) that influenced late-stage advance and deglaciation, important for accurately characterising both modern and palaeo-ice sheets. [ABSTRACT FROM AUTHOR]

For the first time on the Norwegian Continental Shelf, deeply buried paleoregolith profiles have been identified as part of the petroleum reservoirs in recently discovered oil fields on the Utsira High, Norwegian North Sea. Reservoir properties (porosity and permeability) in the granitic basement on the Utsira High are mainly the result of physical and chemical alteration of the rock occurring in the near-surface environment during sub-aerial exposure of the high in the Mesozoic. Evaluating the reservoir potential of altered basement rocks requires a different approach than in conventional petroleum exploration. In this paper, macroscopic, mineralogical and micromorphological alteration features observed in two deeply buried paleoregolith profiles are compared with surface paleoregoliths from Ivö Klack, Sweden and Georgia, USA. The paleoregolith profiles are subdivided into specific weathering facies (altered coherent rock facies, saprock facies and saprolite facies) based on the rock fabric and mechanical strength. The reservoir potential of each weathering facies is controlled by the type and degree of alteration. In the altered coherent rock facies, porosity and permeability is mainly controlled by joints and microfractures that developed prior to subaerial exposure of the granitic pluton. In the saprock facies, intensified chemical dissolution of plagioclase enhanced porosity and the development of mesofractures improved the connectivity between pores. In the saprolite facies, progressive dissolution of plagioclase creates porosity, but the precipitation of clays within voids and mesofractures has a destructive effect on the overall reservoir properties. The deeply buried paleoregolith profiles from the Utsira High display comparable macroscopic, mineralogical and micromorphological alteration features to what was observed in surface paleoregoliths from Ivö Klack and Georgia. Outcrop studies may therefore be an important tool when evaluating the reservoir potential in subsurface paleoregoliths. [ABSTRACT FROM AUTHOR]

Thick deposits of peat derived from fen environments accumulated in the coastal lowland areas adjacent to the North Sea during the middle and late Holocene. These sediments are frequently used in pollen-based reconstructions of in situ and more distant vegetation. However, discriminating between wetland and dry land originating pollen signals, and between the potential fen communities present in the wetland, is complex. In this study, a suite of analytical approaches are used to explore the pollen signal of modern fen communities and compare them against Holocene pollen assemblages. At two sites in eastern England, Woodwalton Fen and Upton Broad, vegetation composition was recorded around a series of moss polster sampling points. The communities investigated included herbaceous fen communities under different cutting regimes, a grazed area, glades, and woodland with canopies dominated by Alnus glutinosa and Betula . Cluster analysis is used to provide an overview of, and compare the structure within, the datasets consisting of the vegetation, the vegetation converted to palynological equivalents, and the pollen data. It is demonstrated that any loss of taxonomic precision in pollen identifications does not pose particular problems when attempting to identify fen communities, including tall-herbaceous vegetation, in the pollen record. Indices of Association imply pollen presence can be interpreted as indicating the local presence for some taxa, though few of these are confined to a particular community. Herbaceous fen vegetation subject to different management regimes are, however, shown to produce distinctive pollen signatures. Middle and late Holocene pollen assemblages from eastern (Fenland) and southern (Romney Marsh) England, interpreted as derived from fen vegetation, are compared against the modern pollen dataset using ordination. Most of the fossil samples plot out within or adjacent to the groupings produced by the modern samples in the ordinations. While these investigations demonstrate that modern pollen work can help improve the interpretation of Holocene assemblages they also call attention to a number of limitations including the restricted range of communities from which modern samples are currently available and the potential for non-analogous modern vegetation. The paper concludes with ideas to aid the interpretation of pollen data collected from fen peats and suggestions for future work. [ABSTRACT FROM AUTHOR]

The paper reports about the assessment of deteriorated protective coatings and exposed steel surfaces on offshore wind power platforms in the North Sea and the Baltic Sea. A simple procedure for the assessment of coating deterioration and metal loss on exposed steel surfaces is developed. The procedure delivers a protection number N P N C + N S , whereby the term N C characterizes coating deterioration, and the term N S characterizes metal loss at exposed surfaces. For N P = 0, the structure is fully protected, and for N P = 2, the capacity of the corrosion protection system (protective coating combined with corrosion allowance) is completely exhausted. This number is linked to maintenance procedures. A total of 750 inspection results are reviewed and categorized. The majority of coating damages can be attributed to unsuitable constructive design and to mechanical loading. Design specifications and testing scenarios for coating assessment may be updated in order to account for special stresses in addition to corrosive stresses. Color-based digital image processing is applied for the quantitative recording and rating of coating deterioration processes and for the estimation of N C -values. Preliminary investigations reveal that color-based digital image processing opens the opportunity to evaluate fouling, top coat color changes, and early iron corrosion products. [ABSTRACT FROM AUTHOR]

The North Seas offshore grid serves to connect offshore wind power to onshore systems, and to interconnect power systems in Northern Europe. Its development is a priority for the European climate and energy policy, which has led to a number of studies on the subject. Nonetheless, research questions, assumptions and typologies can vary considerably among them, and thus to guide future research this paper reviews the published works that use bottom–up energy models. This review develops a simple and effective methodology that can be applied to other reviews of energy systems models. It jointly considers the studies of interest, the system characteristics, a categorization framework and relevant indicators. The analysis indicates most studies focus on investment and operation of the grid using optimization models, with rare use of other research questions or other model approaches. Moreover, results vary significantly, and their comparability is limited due to differences in assumptions, methodology and detail of results publication. Nonetheless, integrated typologies frequently present economic, operational and environmental benefits, although the reviewed studies do not unambiguously warrant immediate and full cooperation on grid governance. Lastly, future research should be attentive to the presentation and resolution of data, assumptions and results, as well as consider grid characteristics relevant to the research questions. [ABSTRACT FROM AUTHOR]

Despite increasing attention paid to the value of marine resources, in particular marine protected areas (MPAs), their economic valuation focuses mainly on use values of ecosystem services such as fishery and tourism. Furthermore, most MPA related studies are carried out for coastal ecosystems, especially tropical coral reefs. The valuation of remote marine ecosystems is rare. The main objective of this paper is to estimate public willingness to pay (WTP) for alternative management regimes of a network of offshore MPAs in the North Sea under the Marine Strategy Framework Directive (MSFD). In a baseline valuation study carried out just before the adoption of the MSFD, beach visitors and a random sample of coastal and non-coastal residents were asked for their preferences for two alternative management options of three remote, ecologically sensitive areas with multiple use conflicts. Despite the lack of public awareness and familiarity with the offshore marine areas, a majority of 70% is willing to pay extra tax for their protection. Using a conservative value elicitation procedure, Dutch households are willing to pay on average maximum 0.25% of their annual disposable income to ban access and economic use. This serves as an indicator of what a network of remote MPAs in the MSFD is allowed to cost according to the Dutch tax payer. [ABSTRACT FROM AUTHOR]

In this paper, the use of a tidal buoy, equipped with a GNSS, is assessed. The prediction of the tide in the North Sea area is performed by a network of coastal tidal gauges. Long term measurements by these gauges are used to derive tidal constituents and the construction of tidal prediction tables for each separate measurement location. To estimate the tide between these locations, an interpolation is required. However, the quality of this calculation is heavily reduced for offshore predictions. The aim of this research is to deal with this challenge by the deployment of GNSS-buoys on full sea. The focus is on the data processing and the analysis of meteorological influences on the data quality. In this context, a strong correlation between meteorological parameters and the ability to calculate a fixed position will be demonstrated. Based on the results of two separated measurement campaigns, it is stated that the developed data acquisition technique results in highly accurate elevation measurement. [ABSTRACT FROM AUTHOR]

A mixed-method approach was used to assess and value the ecosystem services derived from the Dogger Bank, an extensive shallow sandbank in the southern North Sea. Three parallel studies were undertaken that 1) identified and quantified, where possible, how indicators for ecosystem service provision may change according to two future scenarios, 2) assessed members of the public's willingness-to-pay for improvements to a small number of ecosystem services as a consequence of a hypothetical management plan, and 3) facilitated a process of deliberation that allowed members of the public to explore the uses of the Dogger Bank and the conflicts and dilemmas involved in its management. Each of these studies was designed to answer different and specific research questions and therefore contributes different insights about the ecosystem services delivered by the Dogger Bank. This paper explores what can be gained by bringing these findings together post hoc and the extent to which the different methods are complementary. Findings suggest that mixed-method research brings more understanding than can be gained from the individual approaches alone. Nevertheless, the choice of methods used and how these methods are implemented strongly affects the results obtained. [ABSTRACT FROM AUTHOR]

North Sea oil is overwhelmingly generated in shales of the Upper Jurassic – basal Cretaceous Kimmeridge Clay Formation. Once generated, the oil is expelled and ultimately migrates to accumulate in sandstone or carbonate reservoirs. The source rock shales, however, still contain the portion of the oil that was not expelled. As a consequence such shales and juxtaposed non-source lithofacies can form the targets for the exploration of ‘unconventional oil’. In this paper, we examine part of the Kimmeridge Clay Formation as a hybrid shale resource system within which ‘Hot Shale’ and organic-lean sandstone and siltstone intervals are intimately interbedded. This hybrid system can contain a greater volume of oil because of the increased storage capacity due to larger matrix porosities of the sand-silt interbeds, together with a lower adsorptive affinity in the interbedded sandstone. The relationship between the estimated volume percentages of sand and mudstone and free oil determined from Rock-Eval ® S1 yields is used to place limits on the drainage of oil from source mudstone to reservoir sand at the decimeter scale. These data are used to determine oil saturations in interbedded sand-mudstone sequences at peak oil maturity. Higher values of free hydrocarbon (as evidenced by the S1 value in mudstone) suggest that more oil is being retained in the mudstone, while higher S1 values in the interbedded sands suggest the oil is being drained to saturate the larger pore spaces. High silica content in the interbeds confirms the brittleness in this mudstone–sandstone lithofacies – an important factor to be considered for fracture stimulation to successfully work in a hybrid system. The key points of this hybrid unconventional system are the thickness, storage capacity and the possibility to capture a portion of the expelled, as well as retained oil. [ABSTRACT FROM AUTHOR]

Species commonness is often related to abundance and species conservation status. Intuitively, a “common species” is a species that is abundant in a certain area, widespread and at low risk of extinction. Analysing and classifying species commonness can help discovering indicators of ecosystem status and can prevent sudden changes in biodiversity. However, it is challenging to quantitatively define this concept. This paper presents a procedure to automatically characterize species commonness from biological surveys. Our approach uses clustering analysis techniques and is based on a number of numerical parameters extracted from an authoritative source of biodiversity data, i.e. the Ocean Biogeographic Information System. The analysis takes into account abundance, geographical and temporal aspects of species distributions. We apply our model to North Sea fish species and show that the classification agrees with independent expert opinion although sampling biases affect the data. Furthermore, we show that our approach is robust to noise in the data and is promising in classifying new species. Our method can be used in conservation biology, especially to reduce the effects of the sampling biases which affect large biodiversity collections. [ABSTRACT FROM AUTHOR]

In this paper, we use concentrations of persistent organic pollutants (POPs) and of chlorophyll a to infer POP-induced effects on marine primary production in the Kattegat and the North Sea between the 1990s and the 2000s. To do so, we modelled phytoplankton dynamics using four classical drivers (light and nutrient availability, temperature and zooplankton grazing) and tested whether extending this model with a POP-induced phytoplankton growth limitation term improved model fit to observed chlorophyll a concentrations. Including monitored concentrations of PCBs and pesticides did not lead to a better model fit, suggesting that POP-induced growth limitation of marine phytoplankton in the North Sea and the Kattegat is small compared to the limitations caused by the classical drivers. In an attempt to more fully represent the multitude of POPs in the marine environment, the monitored concentrations were multiplied with a factor 10 and 100. Under these two configurations, region-specific contributions of POPs in the phytoplankton growth limitation were found. The inferred contribution of POPs to phytoplankton growth limitation was ca. 1% in Belgian marine waters, but in the Kattegat POPs explained ca. 10% of the phytoplankton growth limitation. These results suggest that there are regional differences in the contribution of POPs to the phytoplankton growth limitation. [ABSTRACT FROM AUTHOR]

Carbon capture and storage (CCS) – the collection of CO 2 from industrial sources and its injection underground – could potentially contribute to the reduction of atmospheric emissions of greenhouse gases. In this paper, we investigate the sequestration of CO 2 in aquifers with the co-injection of surfactants for foam generation. This is equivalent to the use of foam for conformance control in enhanced oil recovery applications. To study foam-assisted sequestration, we extend an in-house streamline-based simulator to model foam flow. We use two foam models that have been previously suggested in the literature. In both models foam hinders gas mobility through increasing its apparent viscosity. The modified simulator is validated by comparison to analytical solutions. We then investigate the performance of CO 2 sequestration with the co-injection of surfactants. We look at CO 2 sequestration in a North Sea aquifer. We study both simultaneous and alternating surfactant-gas injection at different fractional flows (i.e. water:gas ratios). For cases where a seal provides a reliable trapping mechanism, the simulation results suggest that the use of surfactants to generate foam significantly improves the storage efficiency at a marginal increase in water consumption. In this setting, CO 2 /surfactant simultaneous injection at a 0.5 CO 2 fractional flow was found to be the optimum injection strategy for the case investigated. To the contrary, if the seal is unreliable or not present at the first place, CO 2 /brine simultaneous injection at a 0.85 CO 2 fractional flow was found to be the optimum injection strategy. Although foam-assisted sequestration in this case further improves the storage efficiency, it does that at a significant increase in water consumption. This is since, although foam generation improves the sweep during the sequestration phase, it significantly hinders the sweep during the chase-brine injection phase. Based on that, having a design where the surfactant will degrade just before or during the chase-brine injection phase would provide the optimum sequestration strategy—without reliance on the presence or integrity of the seal. [ABSTRACT FROM AUTHOR]

This paper presents the current state of knowledge on the evolution and depositional history of the River Rhine in the southern part of the North Sea basin during the upper Middle and Late Pleistocene, and its response to climate change, sea-level oscillation and glacio-isostasy. The study focuses on the development of the Eemian interglacial lower-delta in the central Netherlands and its relation to records of climate and sea-level rise, and uses the Saalian and Weichselian pre- and postdating periods to place its development in context. The Rhine fluvial system fills the gradually subsiding North Sea basin, but its development has strongly been affected by the Saalian glaciation and its remaining topography. Ice-pushed ridges originating off the limit of maximum glaciation basically divided the central Netherlands into two sedimentary depocentres: a central depocentre within the former ice-limit, and a southern depocentre south of it. The sedimentary record of the central depocentre, including an incised-valley fill, shows a 20–40 m thick stacked sequence consisting of three units. The incised-valley fill consists of a Late Saalian to early Eemian age lower fluvial unit and a Weichselian age upper fluvial unit, both composed of coarse-grained channel deposits. Sandwiched in-between is a 5–15 m thick record composed of fine-grained fluvial and estuarine (tidal) floodbasin and shallow-marine deposits. It is of Eemian interglacial and Early Weichselian age, and comprises transgressive and highstand deposits that show the drowning of a fluvial system. Inland parts transformed from fluvial to deltaic and estuarine environments, and the most downstream parts transformed to a shallow-marine embayment. Preservation of these units occurred, despite considerable sea-level fall and climate-controlled erosion taking place in the last-glacial. Preservation potential was increased by the fact that the Rhine system avulsed away to the southern depocentre, halfway the Weichselian Pleniglacial. Consequently, the infill of the southern depocentre is of an entire different nature, and last-interglacial transgressive or highstand units are hardly preserved. Because of glaciation and resulting depocentre configuration, the Netherlands in NW Europe thus offers a very good opportunity to study the transgressive interglacial lower-deltaic records and falling-stage preservation thereof – both key elements for understanding sedimentary development over full 100-ky glacial-interglacial cycles of climate and base-level change. [ABSTRACT FROM AUTHOR]

This paper reports result from a survey on 157 navigators (bridge officers) from eight offshore companies operating in the North Sea. The questionnaire measured stress, work pressure and sleep/rest (fatigue). Sleep/rest and work pressure explained around 35% of the variation in stress. Work pressure increases stress, and sleep and rest reduce stress both directly and through reduced work pressure. A positive work climate/supportive culture reduces stress on the bridge substantially through reducing work pressure and improving sleep and rest quality. The research indicates that age and the length of time that respondents have been seafarers do not have any influence on stress. However, a significant difference at the 10% significance level was found in relation to occupation (between first mate and other navigators). Around 30% of the respondents reported unsatisfactory sleep and rest during a normal day. More than 10% of the respondents reported that senior management was not interested in their health and safety, and more than 15% of the officers reported that they took short cuts to get their work done. [ABSTRACT FROM AUTHOR]

Sleipner gas field in the North Sea is the world's first industrial scale CO 2 injection project designed specifically to reduce the emission of greenhouse gas. Here CO 2 separated from natural gas produced at Sleipner gas field is injected into the Utsira sand, which is a major saline aquifer in the North Sea basin. From time-lapse (4D) seismic data, CO 2 plume is observed as a number of bright sub-horizontal reflections within the reservoir. Correlation of log data with the seismic data indicates that CO 2 accumulates within a series of interbedded sandstones and mudstones beneath a thick cap rock of mudstone. Nine reflective horizons have been mapped within the reservoir on the six seismic surveys from 1999 to 2008. Comparison with the baseline seismic survey of 1994 (pre-injection) provides clear impression of the migration of CO 2 plume. In this paper, we attempt to model CO 2 distribution quantitatively within the reservoir by applying a pressure-dependent differential effective medium (PDEM) theory using 4D seismic data. Pre- and post-injection acoustic impedances are calculated by inverting post-stack seismic data of 1994 and 2001 using a model-based inversion technique. A 3D CO 2 saturation volume is estimated using PDEM theory from inverted acoustic impedance of the year 2001 taking the reference of that from the results of pre-injection data of the year 1994. Since the gas distribution type is seldom known, we estimate the saturation distribution using both a homogeneous and a patchy distribution pattern in our rock physics model. We estimate saturation for homogeneous distribution of CO 2 to be 0–20% and for CO 2 as patches of gas as 0–80% of the total porosity within ∼200 m thick reservoir unit. 5–7% uncertainty in the predicted CO 2 saturation is estimated using a Monte-Carlo simulation technique. Our results indicate that a large amount of CO 2 is accumulated as patches of gas within sand layers capped by mud layers, though some amount of gas may have mixed uniformly with water. [ABSTRACT FROM AUTHOR]

Textural and structural facies analysis in the Buchan Field (North Sea) has provided an important potential database for the assessment of parameters controlling the reservoir quality. Nowadays, significant research effort in oilfield reservoirs focused on pore-scale petrophysics, grain distribution, pore geometry and distribution besides the fluid flow circulation. The investigation, we are conducting, is aimed to determine the reservoir type, based on qualitative and quantitative evaluation. This study deals with the upper part of the defined upward channel sequence in the Buchan oilfield (North Sea). In this view, determination of pore geometry and pore aperture sizes which are related to grain size, sorting and packing becomes essential. The pore geometry size and distribution are present but at a microscopical-scale. They constitute the main petrophysical properties of the studied reservoir, since these selected parts of the reservoirs can be qualified as tight or unconventional material type. These investigated deposits are characterized by very low permeability with the presence of reduced pores leading to the probable existence of important interfacial tension forces as well as high capillary pressure. These properties are directly affecting fluid circulation by trapping considerable amount of residual oil leading to a lesser reservoir recovery. In the case study, examination and assessment of this type of reservoirs and their characteristics, responsible for the H/C accumulations and circulation can only be accomplished by the use of very refined equipments such as the Micro-CT or the SEM. Support for this investigation can be credited to the Autopore use. Accordingly, this paper presents the results of a combination of reservoir characteristics determination, the use of the SEM. petrographical investigation for the purpose of detailed examination as well as the MICP application for the physical properties appraisal. The overall will lead to better understanding of the studied section coupled to other reservoir attributes identification. [ABSTRACT FROM AUTHOR]

Continuous operational monitoring by means of remote sensing contributes significantly towards less occurrence of oil spills over European waters however, operational activities show regular occurrence of accidental and deliberate oil spills over the North Sea, particularly from offshore platform installations. Since the areas covered by oil spills are usually large and scattered over the North Sea, satellite remote sensing particularly Synthetic Aperture Radar (SAR) represents an effective tool for operational oil spill detection. This paper describes the development of a semi-automated approach for oil spill detection, optimized for near real time offshore platform sourced pollution monitoring context. Eight feature parameters are extracted from each segmented dark spot. The classification algorithm is based on artificial neural network. An initial evaluation of this methodology has been carried out on 156 TerraSAR-X images. Wind and current history information also have been analyzed for particular cases in order to evaluate their influences on spill trajectory. [ABSTRACT FROM AUTHOR]

Abstract: This paper characterises the soil conditions at the Sheringham Shoal wind farm in the North Sea, in the context of designing foundations for offshore wind turbines. The purpose is to provide a realistic reference case study for research and practice in the emerging field of offshore wind energy. The soil data was obtained between 2005 and 2008 in an investigation program involving field measurements and laboratory experiments. The characterisation focuses on soil properties which are relevant for evaluating the performance of foundations for offshore wind turbines. The soil profile at the Sheringham Shoal site consists of four main units: two clay strata interbedded with a sand layer and underlain by a chalk bed. The heavily overconsolidated state of the clays and the densely compacted state of the sand dictate the behaviour of these soils. The chalk bed is characterised by varying degrees of weathering leading to significant variation in properties ranging from those typical for stiff soil to soft rock. These four main units, though differ considerably in soil composition, share several common characteristics including high shear strength and high stiffness but their shear stiffnesses reduce significantly both at high mobilised static shear strength and at medium to high mobilised strength under cyclic loading. The soil stiffness is an important input parameter for the design of offshore wind turbine foundations and hence the degradation of stiffness is an important issue at this wind farm. A number of soil properties at the site show considerable variability which requires a specific foundation design tailored for each location in order to be both safe and cost-effective. [Copyright &y& Elsevier]

Abstract: From RACs to Advisory Councils analyses the discourse of stakeholders engaged in Europe׳s Common Fisheries Policy (CFP) in a tier of governance known as RACs (Regional Advisory Councils) from 2004 to 2008. The analysis demonstrates a shift towards discursive sharing by participating stakeholders. This fostered inclusion but did not effect a redistribution of the power held by Europe׳s inter-governmental institutions. This more substantive change would require more, and more consistent, discursive consensus from stakeholders. With a reformed CFP for 2014, this paper considers the possibility of a future in which regional stakeholder-based fisheries governance becomes a reality. [Copyright &y& Elsevier]

Abstract: The paper presents a design exercise of upgrading a typical rock armoured revetment by modifying the structure profile and adding structure elements. Several concepts of upgrading are examined. A sea level rise corresponding to the mean of the IPCC 2007 predictions is used together with a slight increase in long-term wind/wave conditions as predicted for the North Sea by the Danish Coastal Authority. Both conditions of non-acceptable and acceptable increase in structure crest level are considered. Moreover, a scenario for steepening of the foreshore due to morphological changes caused by increased wave impacts is included. Only desk study tools are used for the upgrade designs. A simple comparative cost optimization analysis of the various upgrading solutions is presented, and conclusions are given for the preferred upgrading concept valid for the case study structure. A short discussion of the uncertainties related to upgrading design is included. The importance of physical model tests of the structures is underlined due to insufficient desk study tools for rubble mound upgrade design. [Copyright &y& Elsevier]

Abstract: This paper describes a method to trace the origin of nutrients in marine areas and subsequently quantify the optimal reductions of nutrient loads in accordance with eutrophication water quality targets. The tracer method is incorporated in a validated Delft-3D model of the North Sea. For this model, nutrient loads are well characterized. Resulting from the tracer model, nutrient composition matrices are created for each OSPAR area of the North Sea for the year 2002. Water quality targets are also based on OSPAR agreements. The optimal reduction is obtained directly via Linear Programming, which is extremely quick and does not need scenario runs of the full model. The optimum reduction scenario obtained was validated in Delft 3D and showed a similar outcome. Results from the optimization method clearly differ from common practise (uniform reduction of all sources). They also show that some targets are inconsistent spatially or with respect to the DIN to DIP ratio. The method provides a quick and useful tool to quantify the necessary riverine reductions to achieve a healthy ecosystem state. It can be extended to include economic costs per river basin or economic sector and also be applied in combination with other eco-hydrodynamic models or for other substances. [Copyright &y& Elsevier]

Abstract: This paper presents an updated historic oil production analysis as well as an updated future oil production forecast for Norway and Denmark. Previous forecasts conducted by academic and official agencies using a variety of methodologies are contrasted and their accuracy examined. The bottom-up field-by-field methodology is found to be precise in the short-term, as it deviates by less than 1% from actual production. The impact of declining oil production in the North Sea on Sweden is explored as a case study. The historic and future trends regarding Swedish oil imports are presented and their vulnerability assessed using the Herfindahl–Hirschman index. [Copyright &y& Elsevier]

Abstract: Over the last few decades, global warming has accelerated both the rate and magnitude of changes observed in many functional units of the Earth System. In this context, plankton are sentinel organisms because they are sensitive to subtle levels of changes in temperature and might help in identifying the current effects of climate change on pelagic ecosystems. In this paper, we performed a comparative approach in two regions of the North Atlantic (i.e. the Northeast Atlantic and the North Sea) to explore the relationships between changes in marine plankton, the regional physico-chemical environment and large-scale hydro-climatic forcing using four key indices: the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO), the East Atlantic (EA) pattern and Northern Hemisphere Temperature (NHT) anomalies. Our analyses suggest that long-term changes in the states of the two ecosystems were synchronous and correlated to the same large-scale hydro-climatic variables: NHT anomalies, the AMO and to a lesser extent the EA pattern. No significant correlation was found between long-term ecosystem modifications and the state of the NAO. Our results suggest that the effect of climate on these ecosystems has mainly occurred in both regions through the modulation of the thermal regime. [Copyright &y& Elsevier]

Oil and gas platforms in the North Sea region are associated with high power consumption and large CO2-emissions, as the processing and utility plants suffer from significant changes in production rates and performance losses over the field lifespan. In this paper, a generic model of the overall offshore system is described: its thermodynamic performance is assessed by performing an exergy accounting and rules of thumb for oil and gas platforms are derived. Simulations are built and conducted with the tools Aspen Plus®, Dynamic Network Analysis and Aspen HYSYS®. 62–65% of the total exergy destruction of an offshore platform is attributable to the power generation and waste heat recovery system, and 35–38% to the oil and gas processing. The variability of the feed composition has little effect on the split of the thermodynamic irreversibilities between both plants. The rejection of high-temperature gases from the utility and flaring systems is the major contributor to the exergy losses. These findings suggest to focus efforts on a better use of the waste heat contained in the exhaust gases and on the ways in which the gas compression performance can be improved. [ABSTRACT FROM AUTHOR]

This paper assesses historic changes in mean sea level around the coastline of the North Sea, one of the most densely populated coasts in the world. Typically, such analyses have been conducted at a national level, and detailed geographically wider analyses have not been undertaken for about 20years. We analyse long records (up to 200years) from 30 tide gauge sites, which are reasonably uniformly distributed along the coastline, and: (1) calculate relative sea level trends; (2) examine the inter-annual and decadal variations; (3) estimate regional geocentric (sometimes also referred to as ‘absolute’) sea level rise throughout the 20th century; and (4) assess the evidence for regional acceleration of sea-level rise. Relative sea level changes are broadly consistent with known vertical land movement patterns. The inter-annual and decadal variability is partly coherent across the region, but with some differences between the Inner North Sea and the English Channel. Data sets from various sources are used to provide estimates of the geocentric sea level changes. The long-term geocentric mean sea level trend for the 1900 to 2011 period is estimated to be 1.5±0.1mm/yr for the entire North Sea region. The trend is slightly higher for the Inner North Sea (i.e. 1.6±0.1mm/yr), and smaller but not significantly different on the 95% confidence level for the English Channel (i.e. 1.2±0.1mm/yr). The uncertainties in the estimates of vertical land movement rates are still large, and the results from a broad range of approaches for determining these rates are not consistent. Periods of sea level rise acceleration are detected at different times throughout the last 200years and are to some extent related to air pressure variations. The recent rates of sea level rise (i.e. over the last two to three decades) are high compared to the long-term average, but are comparable to those which have been observed at other times in the late 19th and 20th century. [ABSTRACT FROM AUTHOR]

Abstract: Displacement ratio (D r) is the ratio between salt thickness (T v) and sub-salt normal fault displacement (D) (D r = T v/D), and it is typically used to predict the degree of geometric and kinematic linkage between sub- and supra-salt fault populations, and the overall structural style in salt-influenced extensional settings. However, we currently lack natural examples of how D r and the underlying geological controls vary, and how these may control the three-dimensional geometry and evolution of salt-influenced normal fault systems. Furthermore, it is currently unknown if kinematic coherence in salt-influenced extensional settings can be maintained over relatively long length-scales (101–103 m) and for relatively long timeframes, and how this may impact the growth and geometry of large-throw (>500 m), salt-influenced normal fault systems. In this paper we use a 3600 km2, high-quality 3D seismic reflection dataset and borehole data from the Stavanger Fault System (SFS), Egersund Basin, eastern North Sea Basin to investigate; (i) how pre-rift salt thickness (T v) and sub-salt fault throw (T) control the structural style and evolution of a basin-bounding, salt-influenced normal fault system; and (ii) the role salt plays in maintaining kinematic coherence in normal fault systems. We demonstrate that; (i) pre-rift salt distribution (T v), specifically its presence in the proto-footwall (i.e., when T v > 0), is the primary control on partitioning of faulting and (forced) folding along the fault system, and the style of linkage (i.e., hard- or soft-linkage) between sub- and supra-salt fault populations; and (ii) sub- and supra-salt fault populations represent brittle elements of a single, geometrically and kinematically coherent structure, the geometry and evolution of which is related to the ductile translation of strain on a scale (up to 8 km) and duration (c. 65 Myr) that believe is significantly greater and longer than previously documented. [Copyright &y& Elsevier]

Abstract: With the construction of wind farms all across the North Sea, numerous artificial reefs are created. These windmill artificial reefs (WARs) harbour high abundances of fish species which can be attracted from elsewhere or can be the result of extra production induced by these wind farms. To resolve the attraction–production debate in suddenly altered ecosystems (cf. wind farms), the possible consequences of attraction should be assessed; thereby bearing in mind that ecological traps may arise. In this paper we investigated whether the wind farms in the Belgian part of the North Sea act as ecological traps for pouting and Atlantic cod. Length-at-age, condition and diet composition of fish present at the windmill artificial reefs was compared to local and regional sandy areas. Fish data from the period 2009–2012 were evaluated. Mainly I- and II-group Atlantic cod were present around the WARs; while the 0- and I-group dominated for pouting. For Atlantic cod, no differences in length were observed between sites, indicating that fitness was comparable at the WARs and in sandy areas. No significant differences in condition index were observed for pouting. At the WARs, they were slightly larger and stomach fullness was enhanced compared to the surrounding sandy areas. Also diet differed considerably among the sites. The outcome of the proxies indicate that fitness of pouting was slightly enhanced compared to the surrounding sandy areas. No evidence was obtained supporting the hypothesis that the WARs act as an ecological trap for Atlantic cod and pouting. [Copyright &y& Elsevier]