Coast Of Norway Research Articles

Resolving tsunami wave dynamics: Integrating sedimentology and numerical modelling

AbstractTsunamis are a major hazard along many of the world's coastlines. To understand the impact of these events, a sufficiently long record of previous events is needed, which can be provided by their sedimentary deposits. A number of past events have left extensive sedimentary deposits that can be used to understand the hydrodynamics of the tsunami. The ca 8.15 ka Storegga submarine slide was a large, tsunamigenic mass movement off the coast of Norway. The resulting tsunami had estimated run‐up heights of around 10 to 20 m on the Norwegian coast, over 30 m in Shetland and 3 to 6 m on the Scottish mainland coast. New cores were taken from the Ythan Valley in North‐East Scotland, where Storegga tsunami deposits have previously been found. High‐resolution sedimentary analyses of the cores, combined with statistical (changepoint) analysis, shows signatures of multiple waves. Moreover, detailed CT scans of the erosional basal surface reveal sole marks called skim marks. Taken in conjunction with the grain size and sedimentary fabric characteristics of the tsunami deposits, this indicates that the flow exhibited a high‐concentration basal component, with an initial semi‐cohesive phase and that deposition was dominantly capacity driven. A multiple wave hypothesis is tested by creating a high‐resolution numerical model (metre‐scale) of the wave inundation, coupled to a previously published regional model. The inundation model confirms that multiple waves passed over the site in agreement with the sedimentological analysis. The sensitivity of the model to the reconstructed palaeocoastal geomorphology is quantitatively explored. It is concluded that local palaeogeomorphological reconstruction is key to understanding the hydrodynamics of a tsunami wave group in relation to its sedimentary deposit. Combining sedimentological data with high‐resolution inundation modelling is a powerful tool to help interpret the sedimentary record of tsunami events and hence to improve knowledge of their risks.

Valve gaping behaviour in the European oyster (Ostrea edulis) in response to changes in light intensity when combined with variations in salinity and seawater temperature

Valve gaping behaviour in bivalve molluscs controls the flow of water across gills that provides both food, and oxygen for respiration. Closure of the valves also provides protection from predators and poor-quality water conditions. Research presented here used a flow through seawater system with controlled changes in salinity and temperature, combined with continuous measurement of valve gape using Hall effect sensors, to study how changes in these variables affect the valve movements of the European oyster (Ostrea edulis) held under controlled long day-length conditions. A clear relationship between periods of reduced light intensity and maximum valve gape was recognised in preliminary studies and provided a benchmark against which to compare how changes in environmental conditions linked to climate change may alter the behaviour of these coastal marine bivalves. Oysters collected from the southwest coast of Norway in August 2022 were held for 72 h at full seawater salinity of 33.6 and a temperature of 15.8 ± 0.5 °C prior to exposure to a reduction in salinity down to 18.2 over a 3 h period. Oysters showed an initial reduction in valve gape width as salinity reached 31.4, with valve gape decreasing further as salinity fell to 28.8. All valves were fully closed at salinity 20.5. Oysters remained in this condition throughout the subsequent 21 h exposure period with salinity at 18.2. Thereafter salinity was increased in 3 steps. In the first step, salinity reached 24.2 over 2 h, and was held there over the following 22 h. All oysters commenced re-opening valves between salinity 22.8 and 24.2. When salinity was further increased to 27.3 over the subsequent 24 h, oysters returned to approximately their pre-exposure valve gape widths. When salinity 33.8 was delivered to the tanks there were 2 d during which maximum valve gape was significantly reduced, after which valve gape width returned to a pre-exposure condition. The predicted pattern of valve opening during reduced light intensity periods was maintained when seawater temperature was raised from 15.8 °C up to 20.1 °C in approximately 1 °C steps every 24 h. However, reduction of temperature from 20.1 °C in similar sized increments altered the expected patterns of behaviour. The results indicate that increasing occurrences of fluxes in salinity and temperature due to climate change have the potential to disrupt normal valve gaping behaviour in European oysters, creating an additional challenge to those they already face from invasive species and disease.

Caught in the trap: over half of the farmed Atlantic salmon removed from a wild spawning population in the period 2014-2018 were mature

Whilst aquaculture continues its global expansion, containment of fish in sea cages remains a persistent environmental challenge. Within Atlantic salmon Salmo salar farming, widespread escapes over several decades have left a legacy of ecological and genetic impacts on wild populations. Quantifying the characteristics of escapees, and how they vary in time and space, is important to understand how environmental impacts will vary and how mitigation strategies need to be tuned. Using a fish trap located in the River Etne on the west coast of Norway, we created an ecological and genetic profile for 616 escapees entering the river. The most important findings of the present study were (1) the annual number of escapees entering the trap declined in the period 2014-2018; (2) more than half of the escapees entering the river were mature; (3) the vast majority of escapees entering the river were categorised as recent escapees; (4) nearly all (96%) of the early escapees were mature upon entry to the river, while just over half (55%) of the recent escapees were mature; and (5) the escapees originated from multiple sources every year. We conclude that without the fish trap, this population would have been at risk of exposure to further spawning and introgression of domesticated salmon. Furthermore, the current findings of maturation status and escape history highlight the fact that mitigation efforts to reduce escape of smolts, post-smolts and larger fish all need continued attention from the management authorities and aquaculture industry.

4-dimensional seismic interpretation to monitor CO2 injection in carbon capture & storage project of Sleipner field, North Sea, Norway using inversion method

Sleipner is the world's first commercial Carbon Capture and Storage (CCS) project, located off the coast of Norway, with the goal of reducing carbon emissions by capturing CO2 and storing it in a utsira saline aquifer sandstone reservoir capable of storing up to 600 billion tonnes of CO2. The CO2 injection in these projects increases year after year, so the CO2 development must be monitored to see the distribution pattern and its implications for the reservoir zone. The purpose of this research is to calculate and model the CO2 distribution resulting from acoustic impedance inversion using 4-dimensional inversion, to calculate the repeatability from seismic data between baseline and monitor using the Normalized Root Mean Square attribute. In the processing, baseline and monitor data must be matched in the overburden zone using a cross-equalization process so that the inversion process. The results revealed a correlation between the two seismic data sets (baseline and monitor) with the classification of Reasonable Repeatability, and CO2 distribution in a securely stored reservoir that spreads laterally and does not leak.

4D Seismic Inversion and Rock Physic Modeling to Monitor CO2 Injection at Carbon Capture and Storage Project in The Utsira Formation, Sleipner Field, North Sea, Norway

Carbon Capture and Storage (CCS) is used at Sleipner Field due to the implementation of a carbon emission tax off the coast of Norway. This project causes the fluid at the Utsira Formation as a reservoir to be replaced by CO2, so the elastic property of the reservoir rock will change. Because of that, the 3D seismic survey was carried out in 1994 (baseline) and re-acquisition in 2001 (monitor) to observe CO2 distribution and changes in rock properties. This study aims to monitor the distribution of CO2 as well as changes in reservoir rock's acoustic and elastic parameters. This research performed the cross-equalization, 4D Seismic Inversion model-based, and rock physics modeling process. From data processing, obtained information that CO2 spreads laterally, then moves to the northeast and does not penetrate the overburden. Also, we get the NRMS value of 0.443068 and the cross-correlation value of 0.907426. 4D Inversion results reveal a change in the reflector at the reservoir zone, as indicated by the velocity pushdown caused for a decrease in seismic velocity owing to CO2. In addition, rock physics modeling provides that changes occur in bulk modulus, Vp, Vs, density, and AI. From the process, there are differences in AI values where the Inversion results show a decrease in AI values of 2.9%, while rock physics modeling shows a 12% reduction.

Living through changing climates: Temperature and seasonality correlate with population fluctuations among Holocene hunter-fisher-gatherers on the west coast of Norway

The use of archaeological proxy records representative of population dynamics is paramount for a richer understanding of prehistoric cultural change, but its use require a dialectic assessment between proximate climatic drivers and ultimate cultural responses. Focusing on the Stone Age archaeological record of Western Norway (11,500–4300 cal. BP), this paper presents an exhaustive empirical curation and statistical testing between changing climates and demographic responses among coastal hunter-fisher-gatherers. The results connect long-term demographic fluctuations with changes in annual mean temperatures and seasonality and the results are discussed in relation changes in technology, subsistence and mobility. The paper also highlights the process of population decline and cultural loss towards the end of the Late Mesolithic (ca. 7000–6000 cal. BP) and emerging cultural novelties and population re-growth during the Early and Middle Neolithic (ca. 6000–4300 cal. BP). However, despite its strong correlation, the archaeological record of Western Norway lacks sufficient detail to ascribe an exclusive explanatory role to climate change, especially in episodes of significant population decline. This helps to emphasise that changing climates, while evidently central, form but a part of a larger system of interactions leading to demographic fluctuations and cultural change, the substantiation of which requires significant empirical improvements to the archaeological record.

Археология Кольского Севера: обзор на 2022 год

Up until now the book by N.N. Gurina released in 1997 is the only general work about the ancient history of the Kola Peninsula. This article is a brief summary of the archeology and history of the Kola North with an emphasis on research over the past 25 years. Modern scientific ideas suggest two ways of how the first humans initially populated the Kola Peninsula in the Mesolithic: "western" — along the coast of Norway from southern Scandinavia, "eastern" — from areas to the south and /or east of Kola Peninsula. The transition to the Neolithic, marked by the appearance of pottery, takes place in the second half of the 6th millennium BC. In the middle of the 3rd millennium BC the Gressbakken culture appears, which exists until the middle of the 2nd millennium BC. In the 1st millennium BC elements of the Saami culture are known, which develops up to the modern times. At the same time common archaeological cultures existed at all times on the Kola Peninsula and the North of Scandinavia and Finland. Ancient Russian culture comes to this region no later than the 12th century.

Solving a maritime inventory routing problem under uncertainty using optimization and simulation

The problem studied in this paper is inspired by one of the world’s largest producers of aluminium. The company produces alumina in South America that needs to be transported to aluminium production plants along the west coast of Norway. The problem is to determine the optimal shipping plan that satisfies the production plants’ alumina demand at minimum cost while satisfying requirements on inventory levels. Both departure time from the loading ports and sailing times are subject to uncertainty. We present a combined optimization and simulation framework for solving this maritime inventory routing problem under uncertainty. We solve the problem heuristically with an iterative solution approach that combines optimization with simulation: In phase 1 of our approach we solve a deterministic optimization model to generate a candidate solution. The performance of this solution is then evaluated in phase 2 by a simulation over a set of realizations of the uncertain parameters, resulting in an expected cost of uncertainty for this solution. The expected cost of uncertainty is then included in the phase 1 model and associated with the simulated solution, before the model is solved again. This process is repeated until no new solution is found. We apply this approach to a case based on real-world data. The results show that our approach finds solutions that perform considerably better under uncertainty than solutions resulting from a purely deterministic planning approach.

Coastex wave calculation — A cost-efficient method for computing high-resolution wave conditions in coastal regions

Accurate and reliable information about ocean surface waves is crucial for marine activities in coastal regions. In areas with complex coastlines, where fjords, islets and strong bathymetry gradients affect the wave field, a high-resolution computational grid is needed to generate model results that agree with observations. For traditional wave modelling this requires enormous computational power, often resulting in insufficient spatial resolution at the most complex fjord and coastal regions. We present an alternative method for coastal wave calculation, the Coastex Wave Calculation, where the wave field is calculated from a set of predefined sea states given by wave properties at an offshore position and the local wind field. We assess four different versions of the Coastex method, using wave observations from five measurement sites at the western coast of Norway, and two control runs using a traditional model setup on a high-resolution computational grid. For our study area we find that deviations between the results of the Coastex calculations and the control runs are small: At the most exposed location the mean error, the mean absolute error and the root mean square error of the significant wave height are in the range 0.06 m to 0.10 m, 0.26 to 0.28 m and 0.34 m to 0.36 m, respectively (Coastex) and 0.08 m to 0.10 m, 0.24 m to 0.26 m and 0.31 m to 0.33 m for the control runs. At the most sheltered location the mean error of the Coastex hindcast ranges from −0.07 m to −0.02 m, compared to −0.05 m for the control runs, the mean absolute error is 0.08 m and 0.09 m (Coastex) and 0.07 m (control runs) and the root mean square error is 0.11 m and 0.12 m (Coastex) and 0.10 m for the control runs.

Evaluating the transport of surface seawater from 1956 to 2021 using 137Cs deposited in the global ocean as a chemical tracer

Abstract. We analyzed the spatiotemporal variations in the 137Cs activity concentrations in global ocean surface seawater from 1956 to 2021 using the HAMGlobal2021 (Historical Artificial radioactivity database in Marine environment, Global integrated version 2021) and other published data. The global ocean was divided into 37 boxes. When observing the 0.5-year median value of 137Cs in each box in the Pacific Ocean, we noticed that the values gradually increased or had almost constant levels in the 1950s and 1960s, and then decreased exponentially in 1970–2010, immediately before the Fukushima Daiichi Nuclear Power Plant Station (F1NPS) accident. In the northern North Atlantic Ocean and its marginal sea, the 0.5-year median values of 137Cs showed large variations in the directly discharged 137Cs from the reprocessing plants. The 137Cs inventory in the surface mixed layer in 1970, when 137Cs was released into the surface seawater, was estimated to be 184±26 PBq. In 1975 and 1980, the 137Cs inventory increased to 201±27 and 214±11 PBq, respectively, due to direct discharge from the Sellafield and La Hague nuclear fuel reprocessing plants. In 2011, the 137Cs inventory in the global ocean mixed layer increased to 50.7±7.3 PBq compared to that before the F1NPS accident, in which the contribution from the accident was estimated to be approximately 15.5±3.9 PBq. Mass balance analysis indicates that 137Cs deposited by the global fallout in the western North Pacific Ocean moved to the eastern North Pacific Ocean. Subsequently, 137Cs was transported southwards, followed by westward transport in the subtropical and equatorial Pacific Ocean, and then inflowed into the Indian Ocean via the Indonesian Archipelago. The longer apparent half-residence times in the Indonesian Archipelago (36.7 years from 1973 to 1997) and central Atlantic Ocean (38.0 years from 1992 to 2016) also support the interpretation of the global-scale transport of 137Cs from the western North Pacific Ocean to the Indian (20–30 years) and Atlantic oceans (30–40 years). In the northern North Atlantic Ocean and its marginal sea, 137Cs discharged from nuclear reprocessing plants is transported to the North Sea, Barents Sea and coast of Norway, and Arctic Ocean on a decadal scale. The dataset is available at https://doi.org/10.34355/CRiED.U.Tsukuba.00085 (Aoyama, 2021), https://doi.org/10.34355/Ki-net.KANAZAWA-U.00149 (Inomata and Aoyama, 2022a), https://doi.org/10.34355/Ki-net.KANAZAWA-U.00150 (Inomata and Aoyama, 2022b), and https://doi.org/10.34355/Ki-net.KANAZAWA-U.00151 (Inomata and Aoyama, 2022c).

Energy transfer from sub-inertial Kelvin waves to continental shelf waves at a transverse bottom escarpment

We consider barotropic coastally-trapped Kelvin waves of tidal origin along a straight coast that propagate from deeper water across a transverse bottom escarpment into a more shallow region. The M2 component, which has a frequency above the inertial frequency f, is modified by crossing the escarpment, but continues basically as a Kelvin wave into the shallow region. For tidal components that have frequencies smaller than f, like K1, some of the energy in the Kelvin wave is converted into a continental shelf wave (CSW) that follows the escarpment with shallow water to the right (in the northern hemisphere). The theory is applied to the shelf north-west of Norway where the deep Norwegian Sea is separated from the much shallower Barents Sea by an escarpment reaching from the north-Norwegian coast towards Spitsbergen. By introducing an idealized bottom topography and coastal geometry, analytical calculations and numerical modeling are used to investigate the energy flux in CSWs towards Spitsbergen caused by sub-inertial Kelvin wave motion along the west coast of Norway. Both analytical and numerical calculations indicate that the CSW energy flux towards Spitsbergen is about eighty percent of the incident sub-inertial Kelvin wave energy flux, and that only twenty percent of the energy flux is transmitted into the Barents Sea in the form of sub-inertial Kelvin waves.

Surface-based observations of cold-air outbreak clouds during the COMBLE field campaign

Abstract. Cold-air outbreaks (CAOs) are characterized by extreme air–sea energy exchanges and low-level convective clouds over large areas in the high-latitude oceans. As such, CAOs are an important component of the Earth's climate system. The CAOs in the Marine Boundary Layer Experiment (COMBLE) deployment of the US Department of Energy Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) provided the first comprehensive view of CAOs using a suite of ground-based observations at the northern coast of Norway. Here, cloud and precipitation observations from 13 CAO cases during COMBLE are analyzed. A vertical air motion retrieval technique is applied to the Ka-band ARM Zenith-pointing Radar (KAZR) observations. The CAO cumulus clouds are characterized by strong updrafts with magnitudes between 2–8 m s−1, vertical extents of 1–3 km, and horizontal scales of 0.25–3 km. A strong relationship between our vertical air velocity retrievals and liquid water path (LWP) measurements is found. The LWP measurements exceed 1 kg m−2 in strong updraft areas, and the vertical extent of the updraft correlates well with the LWP values. The CAO cumulus clouds exhibit eddy dissipation rate values between 10−3 and 10−2 m2 s−3 in the lowest 10 km of the atmosphere, and using a radar Doppler spectra technique, evidence of secondary ice production is found during one of the cases.

Population structure and connectivity in the genusMolvain the Northeast Atlantic

AbstractIn fisheries, operational management units and biological data often do not coincide. In many cases, this is not even known due to the lack of information about a species’ population structure or behaviour. This study focuses on two such species, the common ling Molva molva and the blue ling M. dypterygia, two Northeast Atlantic gadoids with overlapping geographical distribution, but different depth habitats. Heavily exploited throughout their ranges, with declining catches, little is known about their population structure. Genotyping-by-sequencing at thousands of genetic markers indicated that both species are separated into two major groups, one represented by samples from the coasts of western Scotland, Greenland, and the Bay of Biscay and the other off the coast of Norway. This signal is stronger for the deeper dwelling blue ling, even though adult dispersal was also identified for this species. Despite small sample sizes, fine-scale patterns of genetic structure were identified along Norway for common ling. Signatures of adaptation in blue ling consisted in signs of selections in genes involved in vision, growth, and adaptation to cold temperatures.

Future Projections of EURO‐CORDEX Raw and Bias‐Corrected Daily Maximum Wind Speeds Over Scandinavia

AbstractTwenty historical and future Coordinated Regional Climate Downscaling Experiment ensemble for Europe simulations are bias corrected to investigate the future changes in the daily maximum wind speed over Scandinavia. We use quantile mapping to adjust the wind for the historical period (1985–2014) and quantile delta mapping for two future periods (2041–2070, 2071–2100, RCP8.5) with the 3‐km spatial resolution NORA3 hindcast as the reference data set. Decomposing the variance, we find that most of the inter‐model spread in the bias and the response to climate change is due to the regional climate model over land and mainly to the general climate model over sea. On average, the mean daily maximum wind speed is projected to increase everywhere except along the western coast of Norway and Denmark. In summer, we see an opposite sign over Sweden and Finland. The Norwegian Sea experiences weaker mean and high wind whereas the Baltic Sea experiences a strengthening. Bias correction influences the amplitude of the response, not the response pattern. Wind speed distributions can have different shapes in the future, with, for example, a flattening of the distribution off the coast of Norway with more frequent weak and very strong winds. Apart from a few locations in Norway, we find an increase in the number of days in the local highest historical wind category. Overall, summer exhibits opposite signals compared to the three other seasons. At country scale, the sign of the change in the mean and 98th percentile varies greatly depending on the region and among the simulations, especially for Norway.

Prey predictability and preparation versus recovery breathing strategies in European shags Gulosus aristotelis (L.) diving in different habitats

AbstractA recent study on the diving behaviour of European shags (Gulosus aristotelis (L.)) foraging in kelp forests off rocky coasts of Norway suggests surface durations are related only to the duration of the preceding dive, and hence are being used for respiratory recovery. These results contrast with earlier reports concerning shags foraging in highly tidal estuarine waters off the coast of Lundy Island, SW England, where there was a stronger relationship between dive durations and preceding pre‐dive surface durations, suggesting the use of preparatory variation in oxygen loading. These two datasets were collected using different methods, and statistically analysed in quite different ways, so the contrasting results here could be due to different methodologies rather than the ecological differences between the two foraging environments. Here, we re‐analyse the two datasets using similar statistical methods, and we confirm the contrasting results produced by the two datasets. We, therefore, conclude that shag breathing strategies do differ between these two marine environments, presumably reflecting adaptive facultatively plastic responses to differences in predictability of foraging dive durations. Off the Norwegian coast, unpredictable variation in the depth and availability of pelagic prey in complex environments may require more responsive post‐dive respiratory recovery on the surface after each dive. In the more uniform English near‐shore environment, however, pre‐dive preparatory oxygen loading customised to match predictable dive‐to‐dive variation in benthic prey depths and foraging durations, may be more time and energy efficient.

Spatial variation in the evolutionary potential and constraints of basal metabolic rate and body mass in a wild bird.

An organism's energy budget is strongly related to resource consumption, performance, and fitness. Hence, understanding the evolution of key energetic traits, such as basal metabolic rate (BMR), in natural populations is central for understanding life-history evolution and ecological processes. Here we used quantitative genetic analyses to study evolutionary potential of BMR in two insular populations of the house sparrow (Passer domesticus). We obtained measurements of BMR and body mass (Mb ) from 911 house sparrows on the islands of Leka and Vega along the coast of Norway. These two populations were the source populations for translocations to create an additional third, admixed 'common garden' population in 2012. With the use of a novel genetic group animal model concomitant with a genetically determined pedigree, we differentiate genetic and environmental sources of variation, thereby providing insight into the effects of spatial population structure on evolutionary potential. We found that the evolutionary potential of BMR was similar in the two source populations, whereas the Vega population had a somewhat higher evolutionary potential of Mb than the Leka population. BMR was genetically correlated with Mb in both populations, and the conditional evolutionary potential of BMR (independent of body mass) was 41% (Leka) and 53% (Vega) lower than unconditional estimates. Overall, our results show that there is potential for BMR to evolve independently of Mb , but that selection on BMR and/or Mb may have different evolutionary consequences in different populations of the same species.

Distribution and Phylogenetic Position of the Antarctic Ribbon Worm Heteronemertes longifissa (Nemertea, Pilidiophora)

To date, a total of 23 valid species of heteronemerteans belonging to 15 genera have been recorded in Antarctic and Subantarctic waters. The ribbon worm Heteronemertes longifissa (Hubrecht, 1887) is the only heteronemertean species reported to have bipolar distribution, but this statement is doubtful. The phylogenetic relationships of H. longifissa to other heteronemerteans remain uncertain. A genetic analysis of specimens from Antarctica has shown that the name H. longifissa refers to two sibling species with an uncorrected p-distance of 5.3% in COI. These species differ in body color: one is whitish, and the other is grayish-pink. The species with the whitish body has been reliably identified from off the Norway coast (as Cerebratulus sp. NemBar1383 (BOLD: ACM5920)), i.e., it has a bipolar distribution. A molecular phylogenetic analysis of Lineidae based on five gene markers (COI, 16S, 18S, 28S, and histone H3) has shown the genus Heteronemertes to belong to Lineage D of Clade 2 sensu Kajihara et al., 2022 (crown Lineidae). The phylogenetic positions of four more species of unidentified lineids are currently under discussion.

Rapid Response of the Norwegian Atlantic Slope Current to Wind Forcing

Abstract We explore drivers of variability in the Norwegian Atlantic Slope Current, which carries relatively warm Atlantic Water toward the Barents Sea and Arctic Ocean, using Copernicus Marine Environment Monitoring Service (CMEMS) satellite altimetry data and TOPAZ4 ocean reanalysis data. Previous studies have pointed to a variety of causes, on a variety of time scales. We use data with daily resolution to investigate day-to-day changes in ocean transport across three sections crossing the shelf-slope of Norway (Svinøy, Gimsøy, and the Barents Sea Opening). The highest (lowest) extremes in transport at all sections develop over two days as a cyclonic (anticyclonic) atmospheric pressure system approaches from the southwest, piling up (extracting) water at the coast of Norway. The actual peak is reached when the pressure system passes the site of measurement, and the transport then relaxes for the next two days as the system continues northward along the coast. Other sources of short-term variability, such as propagating continental shelf waves and baroclinic instability, are unlikely to yield covariability over large separations. Monthly variability in the current can also be explained by passing weather systems since their numbers and intensity vary greatly from month to month. Many studies of longer-term variability, especially in the Barents Sea Opening, have pointed to the North Atlantic Oscillation (NAO) as the main cause of variability. Our results show that passing weather systems offer a better explanation of month-to-month variability.

Sea level response to late Pliocene-Quaternary erosion and deposition in Scandinavia

Erosion and deposition can perturb regional sea level significantly by altering the Earth's surface and by redistributing mass. However, no studies have investigated the importance of these geomorphic processes for glacial settings on glacial-interglacial time scales, despite large erosion rates and the inherent importance of sea-level changes for ice-sheet dynamics and stability. Here we quantify how glacial erosion and depositional processes have affected relative sea level in western Scandinavia where glacial activity has reoccured periodically throughout the late Pliocene-Quaternary. By comparing offshore sediment volumes with onshore topographic relief, we quantify erosion and deposition for the last two glacial cycles as well as the entire late Pliocene-Quaternary. Specifically, we develop a history of erosion and deposition for the last two glacial cycles by scaling the erosion rate with the normalised global ice volume through time. We use the ice model ICE6G_C as a global ice history and calculate sea-level changes through time as a result of ice, water, and sediment loading using a global gravitationally self-consistent sea-level model. Our results show that geomorphic mass redistribution, excluding direct changes in ocean depth owing to erosion and deposition, has caused a sea-level fall of ≈50–100 m along the southern coast of Norway during the last two glacial cycles reaching ≈120 m in the offshore Skagerak region. During the late Pliocene-Quaternary, the total sea-level fall reach as much as ≈ 310 m in Skagerak. These results showcase the importance of erosion and deposition for the relative sea-level history of Scandinavia with implications for studies of ice-sheet history and regional glacial rebound in this region and elsewhere.

Viral Haemorrhagic Septicemia Virus (VHSV) Isolated from Atlantic Herring, Clupea harengus, Causes Mortality in Bath Challenge on Juvenile Herring.

Viral hemorrhagic septicaemia virus (VHSV) has been demonstrated to cause high mortalities in a wide range of teleosts, farmed as well as wild. In Europe, VHSV of genotypes Ib, Id, II, and III have been detected in wild fish, including Atlantic herring Clupea harengus, but disease outbreaks have not been observed in Atlantic herring and the effects on wild stocks are not well documented. Here, we have tested two VHSV isolates from herring (genotypes Ib and III, from the western coasts of Norway and Denmark, respectively) in a challenge experiment with herring (mean weight 2.59 g, SD 0.71 g) caught on the west coast of Denmark. The Norwegian genotype Ib isolate (NO-F-CH/2009) showed an accumulated mortality of 47% compared to 6% mortality with the Danish genotype III isolate 4p168 and zero in the unchallenged control group. In both groups, we found positive rt-RT-PCR and positive immunohistochemistry of VHSV from days 6 and 8 onward. With both isolates, the organs mainly affected were the heart and kidney. The results demonstrate the susceptibility of Atlantic herring to VHSV, and both genotypes gave pathological findings in several organs. Genotype III showed a low mortality rate, and the importance of this genotype for herring is therefore not determined. Genotype Ib showed both high prevalence and mortality, and this genotype is therefore likely to have a negative effect on wild Atlantic herring stocks. Further examinations to determine how VHSV can affect wild Atlantic herring stocks are needed.