North Sea Area Research Articles

Cross-border stratigraphy of the Northern, Central and Southern North Sea: a comparative tectono-stratigraphic megasequence synthesis

Abstract The Devonian–Recent tectono-stratigraphic history of the Northern, Central and Southern North Sea is here reviewed at a regional scale and four novel cross-border pseudo-Wheeler diagrams are presented to summarize the stratigraphic evolution of the cycles of basin fill and uplift/erosion. In this scheme, six first-order megasequence boundaries have been defined, characterized by extensive and long-lasting erosional hiatuses and major coastal regressions: (1) Caledonian (or Base Devonian) Unconformity; (2) Variscan–Saalian (or Base Permian) Unconformity; (3) Mid Cimmerian (or Intra-Aalenian) Unconformity; (4) Late Cimmerian (or Base Cretaceous) Unconformity; (5) Atlantean (or Near-Base Tertiary) Unconformity; and (6) Eridanos (or Mid-Miocene) Unconformity. These surfaces have been linked to regional causal factors ranging from orogenesis-related compressional uplifts, in either active plate margin settings (1) or foreland basin settings (2), to intra-plate dynamically supported uplifts associated with the development of mantle plumes (3, 5 and 6) and the end-of-rifting and associated widespread erosion of tilted fault block crests (4). The aforementioned megasequence boundaries punctuate the geodynamic evolution of the North Sea area and facilitate the subdivision of the entire the North Sea sedimentary basin fill into six megasequences, named here A–F. All of the lithostratigraphic units of the North Sea (formations and members) have been described within the context of this first-order tectono-stratigraphic framework. The correlation powers of certain stratigraphic markers are also compared and contrasted, together with the potential cross-border equivalence of sedimentary units on different sides of the political median lines.

A Brief Climatology of Dunkelflaute Events over and Surrounding the North and Baltic Sea Areas

In the coming decades, the European energy system is expected to become increasingly reliant on non-dispatchable generation such as wind and solar power. Under such a renewable energy scenario, a better characterization of the extreme weather condition ‘Dunkelflaute’, which can lead to a sustained reduction of wind and solar power, is important. In this paper, we report findings from the very first climatological study of Dunkelflaute events occurring in eleven countries surrounding the North and Baltic Sea areas. By utilizing multi-year meteorological and power production datasets, we have quantified various statistics pertaining to these events and also identified their underlying meteorological drivers. It was found that almost all periods tagged as Dunkelflaute events (with a length of more than 24 h) are in November, December, and January for these countries. On average, there are 50–100 h of such events happening in each of these three months per year. The limited wind and solar power production during Dunkelflaute events is shown to be mainly driven by large-scale high-pressure systems and extensive low-cloud coverage. Even though the possibility of simultaneous Dunkelflaute events in neighboring countries can be as high as 30–40%, such events hardly occur simultaneously in all the eleven countries. Through an interconnected EU-11 power system, the mean frequency of Dunkelflaute drops from 3–9% for the individual countries to approximately 3.5% for the combined region, highlighting the importance of aggregating production over a wide area to better manage the integration of renewable energy generation.

Basement fault trends in the Southern North Sea Basin

The Southern North Sea Basin (SNS) contains the regional Zechstein megahalite, a highly deformed Upper Permian salt layer, which partly obscures the Palaeozoic basement structures. This study provides a comprehensive and systematic analysis of pre-salt basement fault trends in the SNS mapped at the top Rotliegend level. We utilize a consistent fault mapping methodology with seismic attribute-based fault mapping techniques and GIS-based image tracing. The results are compared with published maps from the Southern North Sea area. Data analysis is performed on a supra-regional time-migrated 3D seismic dataset located offshore Netherlands and the United Kingdom. Statistical directional analysis of fault trends in the study area confirms the published dominant NW-SE basement trend and allows quantifying its contribution at approximately 51% of all fault segments. Basement fault trend distributions in individual sub-basins in the SW SNS are highly similar and show a strong NW-SE trend dominance despite different tectonic histories of those sub-basins. This may imply their joint origin prior to Caledonian accretion of the Laurussian continent. In the NE sub-basins, NE-SW, W-E and N–S trends are locally important and may represent the structural inheritance of smaller pre-Caledonian terranes.

Evidence of difference in landings and discards patterns in the English Channel and North Sea Rajidae complex fishery

Bycatch species such as skates and rays are for most of them not subject to analytical stock assessment. However, their life history characteristics increased their vulnerability to fisheries. In the English Channel and North Sea area, the three main landed Rajidae species are Raja clavata, Raja brachyura and Raja montagui. The current management measure is a global TAC, common for all Rajidae species. Data to process analytical stock assessment are not available for these species, particularly discards data. A Bayesian multispecies biomass production model, following separately the landings and discards was applied to these stocks. This model provided proxies of reference points (MSY and BMSY) per species. All stocks were depleted in 1990 and are now rebuilding. However, rebuilding speeds are different within the complex, R. clavata being the fastest and R. brachyura the slowest. Furthermore, the proportion of the discards and landings to biomass differ between species, highlighting species specific fishing strategies. Differences in vulnerabilities within the Rajidae complex might be caused by the variability of life history parameters between species as well as landings and discards pattern differences. This second factor, usually not considered for data limited stock assessment, is particularly relevant for highly discarded chondrichthyans species, and might be considered when choosing new methodology to asses Rajidae stocks.

Marine Citizen Science: Current State in Europe and New Technological Developments

Marine citizen science is emerging with promising opportunities for science, policy and public but there is still no comprehensive overview of the current state in Europe. Based on 127 projects identified for the North Sea area we estimate there might be as much as 500 marine and coastal citizen science projects running in Europe, i.e., one marine citizen science project per ∼85 km of coastline, with an exponential growth since 1990. Beach-based projects are more accessible and hence most popular (60% of the projects), and the mean duration of the projects is 18–20 years. Current trends, topics, organizers, aims, and types of programme in terms of participation are presented in this overview. Progress in marine citizen science is specially enabled and promoted through technological developments. Recent technological advances and best practise examples are provided here, untapping the potential of smart mobile apps, do-it-yourself (DIY) technologies, drones, and artificial intelligence (AI) web services.

Semi Quantitative Risk Analysis Of Well Blowout During Reactivation Phase Using Relief Well Technique

The oil and gas field development was carried out by PT X located in the Of shore North West Java Block, in the North Sea area of West Java. Y Well is one of the development wells drilled by PT X with the aim of producing gas to increase the company's production. With the case study in the Y well in the Java Sea, drilling activity was completed in 2011. In 2019 the well reactivation activity was carried out. During the reactivation activity, gas bubbles appear in the surface of of shore platform and Rig Z. To overcome the problem of blowout relief well was drilled. Research methodology in this paper is carried out by identifying hazards in the process planning and executing of Relief Well and describing them in possibilities and consequences also developing strategies and mitigations that can be carried out to reduce the risks that might occur at the level with a high risk assessment. Risk analysis in this paper uses Risk Scoring Index with Crystal Ball simulation software to simulate the risk value. In the Risk Scoring Index model, the significant probability risk value consists of: subsurface risk, NPT (Non Productive Time) of drilling equipment, blowout and combined with the consequences consisting of: safety, the environment, financial impacts that may arise, and the company's reputation. Based on calculation results simulation, the average risk value of 12.3 at the high level is obtained and by evaluating and mitigating preventive measures, the risk value can be reduced to average of 7.3 at the medium level. The most influential value on the level of risk is the uncertainty factor in the subsurface condition, where the weight of the assessment for the possibility of risk factors is considered high.

Efficient Removal of Magnetic Contamination From Drilling Fluids: The Effect on Directional Drilling

Abstract Magnetic debris in a drilling fluid have a significant influence on the ability of the drilling fluid to maintain its function. Down hole logging can suffer from poor signal to noise ratios. Directional drilling in areas close to the magnetic North Pole, such as in the Barents Sea, Northern Canada, or Russia, can suffer because of magnetic contamination in the drilling fluid. Magnetic particles in the drilling fluid introduce additional errors to the magnetic surveying compared to those normally included in the ellipsoid of uncertainty calculation. On many offshore drilling rigs, there are mounted ditch magnets to remove metallic swarf from the drilling fluid. These magnets normally only remove the coarser swarf. In this project, we use a combination of strong magnets and flow directors to significantly improve the performance of the ditch magnets. This combination, together with proper routines for cleaning the ditch magnets, significantly helps to clean the drilling fluid. Through the combined use of flow directors and ditch magnets, it was possible to extract more than five times as much magnetic contamination from the drilling fluid as normal compared with other proper ditch magnet systems. This is verified by comparing the ditch magnet efficiencies from two drilling rigs drilling extended reach drilling (ERD) wells in the North Sea area. In this paper, it is discussed how the accuracy of directional drilling and well position effected by various interferences can be improved by the use of a drilling fluid with minimal effect to the measurement while drilling (MWD) measurement.

Spatio-temporal patterns in harbour porpoise density: citizen science and conservation in UK seas

Fisheries-induced mortality poses a threat to the conservation of small cetaceans, particularly those found in productive coastal waters. Harbour porpoisesPhocoena phocoenaare ubiquitous in UK seas, but despite their prevalence, knowledge gaps remain on fine-scale space use. A deeper understanding of how distributions vary in space and time is required for appropriate management. Citizen science programs which collect standardized data aboard platforms of opportunity can help uncover patterns and identify higher density areas in the time between surveys of absolute abundance. Here, we analyze citizen science data collected from ferries to investigate spatio-temporal patterns in porpoise densities along routes in UK waters. Region-specific detection functions and generalized additive models were used to estimate abundance and elucidate relationships between distributions and environmental variables. The highest densities during the study period (2006-2017) were found southwest of Cornwall, followed by the North Sea and the English Channel. Average density in the North Sea increased substantially during this time, suggesting new high-use areas along these routes. Density surface models showed strong relationships with coastal waters, sea surface temperature, chlorophyll, and water column dynamics. Contrasting preferences for stratified waters in the North Sea and well-mixed areas in the channel suggest distinct foraging behaviours. Higher density areas were identified in the southwestern and northeastern UK, indicating priority areas for conservation efforts, especially in Cornish waters where porpoises are highly vulnerable to bycatch. Findings highlight how citizen science, together with robust density estimation, can contribute to the conservation management of a common, although threatened, species.

Optimising Carbon Capture and Storage Supply Chains for the European Industry

Abstract Carbon capture and storage is considered of fundamental importance to achieve a remarkable decarbonisation of steel, cement and refining sectors. To operate carbon capture and storage at scale and address its inherent complexity, mathematical programming techniques can be exploited to optimise such systems. This contribution proposes a Europe-wide, spatially-explicit, time-dependent, carbon capture and storage chains optimisation, based on mixed integer linear programming architecture. Capture plants can be installed in all significant industrial CO2 emitters, which comprise 25 steel mills, 111 cement plants and 59 refineries. A techno-economic description of capture plants is provided, based on scale effects and different options. Transport can be operated through pipelines and offshore storage is taken into account in the North Sea and Adriatic area. The analysis allows identifying the most promising sectors and optimal specific plants where capture should be operated, and the evolution of the system throughout the time horizon. Considering a time-varying carbon reduction target, the avoidance cost is 75.6 €/t of CO2 for a North Sea targeted network, and decreases by 1.9% when sequestration in the Adriatic Sea is also taken into account.

The potential contribution of small coastal streams to the conservation of declining and threatened diadromous fishes, especially the European eel

AbstractHuman‐generated pressures are continuing to have a detrimental effect on diadromous fishes, resulting in legislative initiatives to conserve and manage these species. Field studies to inform these initiatives focus almost exclusively on larger marine, estuarine, and inland waters, neglecting the role of small coastal streams and tributaries in population recovery. As an example of the potential contribution of very small coastal streams to diadromous fish recruitment, we report here on the densities and distribution of European eel Anguilla anguilla L. and flounder Platichthys flesus (L.) in one such stream, “La Warenne,” in northeast France in October 1998 and 1999. Both species were found mainly in downstream sites in both years—flounder were captured in low numbers only, but mean CPUE values for eel were similar to the highest densities reported in the ICES WGEEL database for larger rivers of Great Britain, France and Spain in the Interreg Atlantic and North Sea areas. This small dataset illustrates that small coastal streams may represent an important, but overlooked, role in conservation strategies for European eel, and possibly flounder, indicating the need for further field studies and investigations of existing data sources to evaluate the contributions to diadromous fish recruitment of these poorly studied water courses.

Abrupt last glacial dust fall over southeast England associated with dynamics of the British-Irish ice sheet

Loess deposits in southern Britain contain a record of dust, climate and landscape dynamics over the last glacial, yet their age and accumulation rate remain poorly known. Furthermore, the environmental controls on the loess-soil stratigraphy shown in the thickest deposits in southeast England are still debated. Here we apply the first high sampling resolution quartz optically stimulated luminescence study of dust accumulation and loess formation in Britain at the Pegwell Bay site in east Kent. We couple this to mineral magnetic, particle size and geochemical analyses to understand climate, environment and post depositional modification of the loess. The luminescence ages and Bayesian age modelling results suggest two phases of greatly enhanced dust accumulation at the site. Loess began to accumulate around c. 25–23.5 ka, coinciding with Heinrich event 2, and after subsequent lower accumulation rates, a second enhanced phase of deposition occurred at around 20–19 ka. We propose a model where the dynamics of the British-Irish and Fennoscandian Ice Sheets, associated glacial lake drainage, and linked reorganisations of atmospheric circulation, all controlled loess accumulation in southern Britain. Accumulation in the first phase was triggered by increased sediment supply from initial retreat of the North Sea ice lobe, and drainage of Dogger Lake. Loess accumulation during this phase was enhanced by easterly winds from Atlantic depressions tracking to the south of Britain, caused by the maximum extent of the Irish Sea Ice Stream at c. 25–24 ka. The subsequent retreat of the western part of the British Irish Ice Sheet then allowed storm tracking further north, which reduced effectiveness of dust transporting winds across southern Britain, while sediment supply and availability was reduced in North Sea source areas. A second retreat of the maximum extent of the North Sea Lobe of ice after c. 21–20 ka would have led to another abrupt input of sediment-rich ice dammed lake and meltwater from eastern England and the North Sea into the exposed southern North Sea area. This would have again dramatically increased sediment availability for transport and deposition as loess in SE England, resulting in the second dust accumulation phase. We also propose that the abrupt stratigraphic change from calcareous to non-calcareous loess up section at Pegwell Bay was driven, not by these changes in dust input, but rather deepening of the permafrost active layer after c. 21 ka. This deepening was associated with warmer and wetter conditions driven by Atlantic storms tracking further north following the regression of the Irish Sea Ice Stream and overall ice sheet retreat. As such, last glacial dust dynamics and loess accumulation in Britain is highly influenced by the interaction of the British Irish Ice Sheet the Fennoscandian Ice sheet, Atlantic storm tracks, and the topography and drainage of the exposed North Sea.

A new stratigraphic framework for the Miocene – Lower Pliocene deposits offshore Scandinavia: A multiscale approach

Here, we present an updated stratigraphic subdivision of the Oligocene to Pleistocene succession (880–610 m) in the newly proposed type well for the Molo Formation, the industrial 6407/9‐5 well, located on the continental shelf in the eastern Norwegian Sea. Furthermore, new data from the Danish North Sea wells Nora‐1, Vagn‐2, and Tove‐1 are presented. The studied succession in the 6407/9‐5 well is composed of five sedimentary units separated by hiati. The dating of these five units is based on correlation to the stratigraphically more complete Neogene succession in the (Danish) central North Sea area. In this study, a robust stratigraphic framework of these five units, based on a combination of dinoflagellate cysts (dinocyst) stratigraphy and seismic data, is established. The Oligocene succession is referred to the NSO zonation of Van Simaeys et al., Review of Palaeobotany and Palynology, 2005, 134, 105–128, while the Miocene–Pliocene succession is referred to the dinocyst zonation of Dybkjær and Piasecki, Review of Palaeobotany and Palynology, 2010, 161, 1–29. In well 6407/9‐5 the two lowermost units, located below the Molo Formation, comprise a Rupelian (Lower Oligocene) succession up to 803 m, and an Aquitanian/Burdigalian (Lower Miocene) succession from 803 to 787 m, respectively. Both of these units are referred to the Brygge Formation. The Molo Formation is separated from the underlying Brygge Formation by an unconformity. Furthermore, and in contrast to previous studies, our study shows that the Molo Formation (787–703 m) has an unconformity within it. The lower part of the formation (787–724 m) is dated to late Tortonian (Late Miocene), and referred to the Hystrichosphaeropsis obscura dinocyst Zone. The upper part (724–703 m) is dated to Zanclean (Early Pliocene), and referred to the Melitasphaeridium choanophorum dinocyst Zone. The uppermost unit studied (703–670 m) in the well is referred to the Gelasian (Lower Pleistocene) and is included in the Naust Formation. The regional correlation of this stratigraphy with the complete succession in the Danish North Sea reveals that the hiati found in the Miocene succession on the Norwegian Sea shelf are controlled by tectonism, while the internal depositional patterns of the Molo Formation were controlled by eustatic sea‐level changes.

Paleozoic-Mesozoic tectono-sedimentary evolution and magmatism of the Egersund Basin area, Norwegian central North Sea

This study focuses on the tectonic evolution of the greater Egersund Basin in the Norwegian central North Sea, with special emphasis on Late Paleozoic extensional tectonics following Caledonian collapse and the Variscan Orogeny, and the impact of the basement structural grain on this evolution. The Caledonian collapse likely resulted in development/rejuvenation of the deepest E-W trending structures/depocenters by Late Devonian time. Thus, a late Devonian-?early Carboniferous age can be assigned to the initial extension, which was associated with the development of an E-W striking basin system, to be overprinted by N–S extensional structures of similar age. A phase of regional magmatism at the Carboniferous-Permian transition (≈300 Ma) may be associated with a large igneous province centred on the Skagerrak area. Faulting during late Carboniferous-early Permian was minor within the study area as reflected by uniform sedimentary thicknesses of the uppermost Carboniferous and lower Permian sequences. Major normal faults, mainly trending N–S, were active during a late Permian-Early Triassic rift phase affecting large parts of the central and northern North Sea area. A later phase of extension was initiated in late Middle Jurassic time and the Egersund Basin proper formed during the Late Jurassic-Early Cretaceous. The depocenters that developed during this phase was influenced by the deep Late Paleozoic (sub-salt) structural grain, including strike-slip movements along the Sorgenfrei-Tornquist Zone. Later events include mild inversion along the northern flank of the Egersund Basin, possibly as a Late Cretaceous response to far-field Alpine compression, and Cenozoic regional tilting.

A new and working petroleum source rock on the UK Continental Shelf (Upper Permian, offshore Yorkshire)

We report on the discovery of oil from the Boulby Mine and its likely productive source rock from Yorkshire in NE England, located to the west (<30 km) of the newly licensed petroleum exploration areas in the vicinity of the Mid-North Sea High. Oil samples from the mine, dripping out of halite in the roof, have likely been generated from Zechstein Group Kirkham Abbey Formation (KAF) sapropelic carbonate rock as indicated by aliphatic and aromatic hydrocarbon biomarkers. Other potential source rocks of Carboniferous (Westphalian, Namurian, Viséan coals and mudrocks) and Jurassic (the Jet Rock, Bituminous Shales, Kimmeridge Clay Formation) age are ruled out on the basis of organic geochemical data. Boulby oil was generated in the peak-to-late oil-window and it is characterised by the high abundance of C32 and C34 homohopanes, slight even-over-odd predominance (EOP) of C20-25n-alkanes indicating restricted carbonate-evaporite depositional conditions, and C29 ethyl-diacholestane 20 S likely implying a clay-rich source rock. The structural framework and tectonic history of the Permian strata reveal the presence of several fault systems which served as conduits for migrating petroleum. Similar Zechstein-sourced oil is known from Poland and Germany, but the occurrence at Boulby is the first positive identification of oil derived from Zechstein source rock in the North Sea area. The Boulby oil is reservoired in Zechstein 3 (Z3) Brotherton Formation dolomite and sealed by Z3 evaporite rocks. The proven oil occurrence at Boulby has significant implications in terms of reducing the risk of a lack of oil mature source rock for acreage offered in the neighbouring North Sea during the UK's 30th and 31st licensing rounds.

Here are the polyps: in situ observations of jellyfish polyps and podocysts on bivalve shells.

Most Scyphozoan jellyfish species have a metagenic life cycle involving a benthic, asexually reproducing polyp stage and a sexually reproducing medusa stage. Medusae can be large and conspicuous and most can be identified using morphological characteristics. Polyps on the other hand are small, live a cryptic life attached to hard substrates and often are difficult or impossible to distinguish based on morphology alone. Consequently, for many species the polyp stage has not been identified in the natural environment. We inspected hard substrates in various habitats for the presence of Scyphozoan polyps. Three polyps were found on Dogger Bank, Central North Sea, attached to the inside of the umbo of empty valves of the bivalves Mactra stultorum and Spisula subtruncata. One polyp was accompanied by four podocysts. With this knowledge, the inside of bivalve shells washed ashore in Oostende (Belgium) was inspected and supposed podocysts on the inside of empty valves of Cerastoderma edule and Spisula elliptica were found. Polyps and podocysts were identified to species level by 18S rDNA and mitochondrial COI sequencing. The three polyps found on Dogger Bank all belonged to the compass jellyfish Chrysaora hysoscella. One podocyst from the Oostende beach also belonged to this species but another podocyst belonged to Cyanea lamarkii. These are the first in situ observations of C. hysoscella and C. lamarckii polyps and podocysts in the natural environment. Mactra, Cerastoderma and Spisula species are abundant in many North Sea regions and empty bivalve shells could provide an abundant settling substrate for jellyfish polyps in the North Sea and other areas. Several new strategies to increase the detection of polyps on bivalve shells are presented.

High resolution biostratigraphic zonation for the UK central North Sea Paleocene

Abstract This paper presents the high resolution biostratigraphic zonation scheme for the Paleocene of the Central North Sea area (UK) and the application to formation characterization, well correlation, reservoir modelling and wellsite activities. The scheme is developed from detailed and consistently recorded palynological events, supported by microfossil data, which have been applied successfully to the majority of proprietary biostratigraphic studies from the basin. Nine zones and 29 subzones have been defined based on First Downhole Occurrence (FDO) or abundance events with chronostratigraphic significance and can be consistently correlated across the studied area. The nine biozones are described based on a dominant palynological marker, from base upward: Senoniasphaera inornata and Spiniferites magnificus (Danian), Isabelidinium? viborgense and Palaeoperidinium pyrophorum (Selandian), Cordosphaeridium gracile, Spiniferites fentonii, Spiniferites rhomboideus, Areoligera gippingensis and base Apectodinium spp. (Thanetian). The defined bioevents have been consistently linked with the published lithostratigraphy, stratigraphic sequences and interpreted depositional environments.

An investigation of the regional correlation gradients between Euro‐Atlantic atmospheric teleconnections and winter solar short wave radiation in northwest Europe

AbstractIncreased use of solar photovoltaic electricity requires a better understanding of the impact of large‐scale atmospheric teleconnections on incident short wave (SW) solar radiation. Our focus is on the relationship between winter (December to February) SW radiation in northwest Europe and the dominant Euro‐Atlantic atmospheric teleconnection patterns using multiple multi‐decadal observational and gridded reanalysis datasets, with a focus on the islands of Ireland and Britain. Our study reveals that the previously reported west–east seesaw in the correlation pattern between the winter North Atlantic Oscillation (NAO) index and winter SW radiation across the United Kingdom is complex, involving several zonal changes in the sign of the NAO–SW correlations (multiple seesaws). By comparison with the NAO, the east Atlantic pattern exerts only a weak control on winter SW radiation across the United Kingdom and Ireland, although in the western part of the Iberian Peninsula and adjacent Atlantic Ocean significant positive correlations occur. High values of the Scandinavian pattern index result in higher than average winter SW radiation in much of northern Europe, although it is evident that some regions (e.g. northeast England, east Scotland and the adjacent North Sea area) exhibit the opposite behaviour. Inter‐seasonal variations in the dominant atmospheric flow and moisture transport directions, steered by large‐scale atmospheric pressure patterns, combined with orographic uplift and rainout effects on the windward side of hills and mountains are interpreted to be the physical drivers of the observed zonal variations and correlation sign reversals between winter SW anomalies and the NAO index.

De Vendelhelm uit Hallum: wat doet deze helm in Friesland?

The Vendel helmet from Hallum: What is this helmet doing in Friesland? The helmet with copper-alloy animal heads found at Hallum (province of Friesland), which was presented in two previous volumes of Paleo-aktueel, is here interpreted in its historical context. An attempt is made to explain what a Scandinavian-type Vendel helmet is doing at a terp site in present-day Friesland. Three options are discussed: (1) local manufacture in Friesland; (2) war booty from a military expedition in the North Sea area; and (3) a gift from a Scandinavian king to a Frisian warrior who had undertaken an adventurous journey to central Denmark or Sweden. Option 1 is seen as unlikely, because Scandinavian-style helmets from England are executed in a style that is local to the region, as is Scandinavian-style jewellery from Friesland. Option 2 is seen as more probable, although no other Vendel helmet is recorded for the North Sea area, where military expeditions from Friesland are expected to have taken place. Option 3 is seen as the most probable: a Frisian warrior – like Beowulf – undertook an adventurous journey to central Denmark or Sweden, was rewarded with a Vendel helmet, and brought this helmet back to his homeland. Although the further history of the helmet cannot be reconstructed, an additional fastening hole in the lower part of each of the animal heads is proof that these mounts were removed at some point, probably to be attached to a new helmet. In this way, the mounts referred to the deeds of an adventurous Frisian warrior predecessor, whose fame now supported a young warrior in his quest to prove himself.

Likely and High-End Impacts of Regional Sea-Level Rise on the Shoreline Change of European Sandy Coasts Under a High Greenhouse Gas Emissions Scenario

Sea-level rise (SLR) is a major concern for coastal hazards such as flooding and erosion in the decades to come. Lately, the value of high-end sea-level scenarios (HESs) to inform stakeholders with low-uncertainty tolerance has been increasingly recognized. Here, we provide high-end projections of SLR-induced sandy shoreline retreats for Europe by the end of the 21st century based on the conservative Bruun rule. Our HESs rely on the upper bound of the RCP8.5 scenario “likely-range” and on high-end estimates of the different components of sea-level projections provided in recent literature. For both HESs, SLR is projected to be higher than 1 m by 2100 for most European coasts. For the strongest HES, the maximum coastal sea-level change of 1.9 m is projected in the North Sea and Mediterranean areas. This translates into a median pan-European coastline retreat of 140 m for the moderate HES and into more than 200 m for the strongest HES. The magnitude and regional distribution of SLR-induced shoreline change projections, however, utterly depend on the local nearshore slope characteristics and the regional distribution of sea-level changes. For some countries, especially in Northern Europe, the impacts of high-end sea-level scenarios are disproportionally high compared to those of likely scenarios.

Strongholds of Ostrea edulis populations in estuaries in Essex, SE England and their association with traditional oyster aquaculture: evidence to support a MPA designation

AbstractThe flat oyster Ostrea edulis has declined significantly in European waters since the 1850s as a result of anthropogenic activity. Ostrea edulis was designated a UK Biodiversity Action Plan Species and Habitat in 1995, and as a Feature of Conservation Importance (FOCI) within the UK Marine &amp; Coastal Access Act 2009. To promote the recovery of oyster beds, a greater understanding of its abundance and distribution is required. Distribution of O. edulis across the proposed Blackwater, Crouch, Roach and Colne MCZ in Essex was determined between 2008 and 2012. Ostrea edulis were present in four estuary zones; with highest sample abundance in the Blackwater and Ray Sand zones. Size structure of populations varied, with the Ray Sand and Colne zones showing a significant lack of individuals with shell height &lt;39 mm. Ostrea edulis occurred in highest number on shell substratum, followed by silty sediments. There were no significant associations between O. edulis abundance or size structure with water column Chl a, suspended solids, oxygen, nitrate or ammonium concentrations, temperature or pH. Highest abundance and most equitable population shell-size distribution for O. edulis were located within, or adjacent to, actively managed aquaculture zones. This suggests that traditional seabed management contributed to the maintenance or recovery of the species of conservation concern. Demonstration that the Essex estuaries were a stronghold for Ostrea edulis in the southern North sea area led to the designation of the Blackwater, Crouch, Roach and Colne estuaries Marine Conservation Zone in 2013.