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Albretsen, J., Aure, J., Sætre, R., and Danielssen, D. S. 2012. Climatic variability in the Skagerrak and coastal waters of Norway. – ICES Journal of Marine Science, 69: 758–763.The Institute of Marine Research in Norway collects marine data from all national waters. Data are primarily collected from vessels, but observation buoys, manual measurements, and oceanographic gliders are also used. The most valuable long-term data for elucidating decadal hydrographic variability in the Skagerrak and along the Norwegian coast are the time-series from the transect between Norway and Denmark, and observations carried out at eight fixed coastal stations in the region. The time-series date back to the 1950s and the 1930s, respectively, and the observation frequencies range from approximately once a month to 3–4 times per month. The hydrographic data and their long-term fluctuations have been used in several studies, with particular emphasis on the increased salinity and temperature of the 1990s. Trends during the past decade, however, indicate that warming has continued but that a salinity increase is less evident, implying signs of regional warming in parallel with the global warming observed both on land and in the sea. The overall temperature increase off the Norwegian coast at deeper layers from the 1961–1990 period to the 2000–2009 decade is ∼0.8°C, but some of this can be related to natural variability in the North Atlantic circulation pattern. [ABSTRACT FROM PUBLISHER]

Abstract: The Kattegat–Skagerrak region on the Swedish west coast is home to an abundant harbour seal population (Phoca vitulina) and a small scattered grey seal population (Halichoerus grypus). In addition, grey seal from the growing population in the Baltic Sea frequently migrate into the Kattegat–Skagerrak. Harbour seals on the west coast of Sweden show relatively high population growth (approximately 9%) compared to the Baltic grey seal in ice-free habitats (approximately 6%), which, in theory, makes harbour seal the stronger competitor of the two in this region. However, incidents of disease in harbour seals that lower population growth are becoming more frequent. These epidemics are primarily caused by the Phocine Distemper Virus (PDV), and may reduce population size with up to 70%. This study models the average development under potential scenarios of competing harbour- and Baltic grey seal populations using Leslie matrices and the Lotka–Volterra model of inter-specific competition. The model is parameterised with previously published data, and resource overlap is incorporated through density dependent pup survival. Using numerical methods short- and long-term abundances are simulated under weak, moderate and strong competition and for different frequencies of PDV epidemics. Results show that the harbour seals are resilient to competition while exerting a negative effect on grey seal abundance under moderate to strong competition. Hence Baltic grey seal benefit from weaker levels of competition. Under moderate and strong competition grey seal abundance is a direct function of the PDV frequency as this reduces the competitive strength of harbour seals. Theoretically this means that higher frequencies of PDV or other pathogens epidemics could facilitate an expansion of Baltic grey seal into Kattegat–Skagerrak. Independent of interaction strength and frequency of epidemics the projected changes to abundances are slow (50–100years), and even in exceedingly stable populations very long time-series of population size estimates are necessary to determine interaction strength. From a management perspective, a more permanent grey seal population in Kattegat–Skagerrak is likely to increase the predation pressure on overfished regional cod populations, and also lead to higher prevalence of the cod parasite Pseudoterranova decipiens, which uses grey seal as end host. From a population ecology perspective, abundant Baltic grey seal in this region would facilitate the mixing of grey seals from the North Atlantic and the Baltic Sea, with unknown implications for the genetically divergent Baltic population. [Copyright &y& Elsevier]

Recent analyses of historical data of fish abundance and distribution have shown the importance of a long temporal perspective in the evaluation of the current status of fish populations, but pose numerous difficulties such as fragmentation and inhomogeneities in the amount of available information in space and time. Using mixed-effects models in a multiscale analysis, we identified an appropriate spatiotemporal scale of investigation of a high-quality, spatially explicit historical data set, and we reconstructed the long-term spatial dynamics of Atlantic cod ( Gadus morhua) in the Kattegat-Skagerrak along the 20th century. We identified a northern and southern main aggregation of adult cod in the study area, corresponding to the Skagerrak portion of the North Sea and the Kattegat cod stocks, respectively. The stocks showed specificities in their spatial dynamics, but common extensive loss of coastal aggregations during the last decades when only 13% (Kattegat) and 35% (Skagerrak) of the estimated early century cod biomass was left. Our reconstruction showed that the collapse of the cod stocks in the area followed the peak in landings in the 1960s-1970s, suggesting that the postwar development of the industrial fisheries played a major role in the decrease of local abundances and disappearance of local adult cod aggregations. [ABSTRACT FROM AUTHOR]

Investigating how individuals are affected by environmental pollution is relatively straightforward, for example through conducting field studies or laboratory toxicity tests. Exploring such effects at a population level is considerably more difficult. Nonetheless, the exploration of population-level effects is important as the outcomes may differ from those seen at the individual level. Eelpout (Zoarces viviparus L.) have been used for several years as a bioindicator for hazard substances in both the field and laboratory tests, and individual effects on reproduction have been reported. However, the influence of these effects at the population level remained unexplored. In this study, four Leslie matrix models were parameterized using data from non-polluted eelpout populations (Skagerrak, Baltic Proper, Gulf of Bothnia and Gulf of Finland). The four sites represent an environmental gradient in salinity. Furthermore, life-history data revealed differences between the sites with growth rate, fecundity, age at maturity and longevity being the most significant. The effect of pollution on natural eelpout populations was then simulated by combining the outputs from the Leslie matrices with data from laboratory and field studies exploring reproductive impairment in contaminated environments. Our results show that despite differences in life-history characteristics between sites, survival of early life stages (i.e. larvae and zero-year-old fish) was the most important factor affecting population growth and persistence for all sites. The range of change in survival of larvae necessary to change population dynamics (i.e. growth) and persistence is well within the range documented in recipient and experimental studies of chemicals and industrial waste waters. Overall, larval malformation resulting from environmental pollution can have large effects on natural populations, leading to population losses and possibly even extinction. This study hereby contributes valuable knowledge by extending individual-level effects of environmental contaminants to the population level. [Copyright &y& Elsevier]

Abstract: Due to a continuous increase in human activities occurring throughout marine and coastal areas worldwide (e.g., marine traffic and construction), the lack of in-depth information on vast marine areas is problematic. However, the spatial informatics field has enabled the development of new applications based on pre-existing spatial data. This paper discusses the physical structure and complexity of the continental shelf seafloor, using geospatial modelling and GIS analysis to gain insight into the physical environment of the Baltic Sea seafloor as a basis for ecosystem management. We demonstrate the mapping of coherent features over a broad region and identify geomorphic features of the seabed by analysing and modelling bathymetric, seabed substrate, and photic depth datasets. The analysis was performed at the kilometre scale using a grid size of 200 m. In total, 18 unique seabed geomorphic features were identified from the entire Baltic Sea (including the Skagerrak). The features are similar to geomorphic seafloor structures typically occurring on glaciated continental shelves. The Baltic Sea is primarily characterized by various plains and basins, and on average, one-third of the seafloor can be regarded as a sediment accumulation area. Other seabed geomorphic features are mainly present in certain local sub regions. The archipelagos as well as the coastal areas of southern Sweden and the Bothnian Bay have a heterogeneous seafloor environment. These areas are characterized by sea valleys and holes, sea troughs, and bedrock elevations, partly due to a crystalline basement and glacial erosion. In addition, the shallow coastal areas suffer from intense wave exposure and have erosional features that differ from those in open sea areas. Effective transnational marine spatial planning requires extensive knowledge of the environmental characteristics of the region in question. Background data for marine spatial planning can be obtained through an analysis of seabed geomorphic features, which provides consistent information on the physical marine environment over a broad area. [Copyright &y& Elsevier]

Nielsen, J. R., Lambert, G., Bastardie, F., Sparholt, H., and Vinther, M. 2012. Do Norway pout (Trisopterus esmarkii) die from spawning stress? Mortality of Norway pout in relation to growth, sexual maturity, and density in the North Sea, Skagerrak, and Kattegat. – ICES Journal of Marine Science, 69: 197–207.The mortality patterns of Norway pout (NP) are not well understood. It has been suggested that NP undergo heavy spawning mortality, and this paper summarizes and provides new evidence in support of this hypothesis. The very low–absent fishing activity in recent years provides a unique opportunity to analyse the natural life-history traits of cohorts in the NP stock in the North Sea. Based on the ICES trawl survey abundance indices, cohort mortality is found to significantly increase with age. We argue that this cannot be explained by selectiveness in the fishery, potential size-specific migrations out of the area, higher predation pressure on older individuals, or differences in survey catchability by NP age from before to after spawning and that it is higher in the main spawning areas than outside. We found that natural mortality (M) is significantly correlated with sexual maturity, sex, growth, and intraspecific stock density. All of this is consistent with a greater mortality occurring mainly from the first to the second quarter of the year, i.e. spawning mortality, which is discussed as being a major direct and indirect cause of stock mortality. [ABSTRACT FROM PUBLISHER]

A high-resolution multiproxy study of core MD99-2286 reveals a highly variable hydrographic environment in the Skagerrak from 9300 cal. yr BP to the present. The study includes foraminiferal faunas, stable isotopes and sedimentary parameters, as well as temperature and salinity reconstructions of a c. 29 m long radiocarbon-dated core record. The multivariate technique fuzzy c-means was applied to the foraminiferal counts, and it was extremely valuable in defining subtle heterogeneities in the foraminiferal faunal data corresponding to hydrographic changes. The major early-/mid-Holocene (Littorina) transgression led to flooding of large former land areas in the North Sea, the opening of the English Channel and Danish straits, and initiation of the modern circulation system. This is reflected by fluctuating C/N values and an explosive bloom of Hyalinea balthica. A slight indication of ameliorated conditions between 8000 and 5750 cal. yr BP is related to the Holocene Thermal Maximum. A subsequent increase in freshwater/Baltic water influence between 5750 and 4350 cal. yr BP is reflected by dominance of Bulimina marginata and depleted δ18O values. The Neoglacial cooling (after 4350 cal. yr BP) is seen in the Skagerrak as enhanced turbidity, increasing TOC values and short-term changes in an overall Cassidulina laevigata-dominated fauna suggesting a prevailing influence of Atlantic waters. This is in agreement with increased strength of westerly winds, as recorded for this period. The last 2000 years were also dominated by Atlantic Water conditions with generally abundant nutrient supply. However, during warm periods, particularly the ‘Medieval Warm Period’and the modern warming, the area was subject to a restriction in the supply of nutrients and/or the nutrient supply had a more refractory character. [ABSTRACT FROM PUBLISHER]

A bacterial community may be resistant to environmental disturbances if some of its species show metabolic flexibility and physiological tolerance to the changing conditions. Alternatively, disturbances can change the composition of the community and thereby potentially affect ecosystem processes. The impact of disturbance on the composition of bacterioplankton communities was examined in continuous seawater cultures. Bacterial assemblages from geographically closely connected areas, the Baltic Sea (salinity 7 and high dissolved organic carbon [DOC]) and Skagerrak (salinity 28 and low DOC), were exposed to gradual opposing changes in salinity and DOC over a 3-week period such that the Baltic community was exposed to Skagerrak salinity and DOC and vice versa. Denaturing gradient gel electrophoresis and clone libraries of PCR-amplified 16S rRNA genes showed that the composition of the transplanted communities differed significantly from those held at constant salinity. Despite this, the growth yields (number of cells ml-1) were similar, which suggests similar levels of substrate utilization. Deep 454 pyrosequencing of 16S rRNA genes showed that the composition of the disturbed communities had changed due to the recruitment of phylotypes present in the rare biosphere of the original community. The study shows that members of the rare biosphere can become abundant in a bacterioplankton community after disturbance and that those bacteria can have important roles in maintaining ecosystem processes. [ABSTRACT FROM AUTHOR]

Abstract: Sugar kelp (Saccharina latissima) forests have an important ecological function in the coastal zone, as they inhabit a high number and a specific composition of fauna. In 2002, a large-scale disappearance of sugar kelp was observed in Skagerrak and parts of the south-western coast of Norway, and the perennial sugar kelp forests were replaced by opportunistic and ephemeral filamentous algae. For management purposes, including identifying areas for restoration initiatives, maps of where sugar kelp forests are supposed to be found and where and under what conditions they have disappeared are needed. Based on modelled and field-measured geophysical variables and presence/absence/loss data of sugar kelp, we therefore developed spatial predictive probability models (i.e. maps) for sugar kelp potential distribution under natural conditions and areas of kelp loss. The influence of geophysical factors was analysed using generalized additive models (GAMs). Using the Akaike Information Criterion (AIC) for model selection, we found that wave exposure, depth, light exposure and slope best explained the potential distribution of sugar kelp. Areas of sugar kelp disappearance were identified by the combined effect of wave and light exposure. These models were developed into maps presented to the managers. [Copyright &y& Elsevier]

Abstract: Despite the common incorporation of iodine in the biological cycle and occurrence of huge contamination of the radioactive isotope 129I in the Baltic Proper, Skagerrak and Kattegat, there is no data on chemical speciation of iodine in these waters. We here present first time data on iodine isotopes 129I and 127I species as iodide and iodate in surface seawater samples collected from 16 locations in August 2006 and 19 locations in April 2007 in the Baltic Proper, Skagerrak and Kattegat. After extensive separation methods, the isotopes concentrations were determined using accelerator mass spectrometry (AMS) technique for the 129I and inductively coupled plasma mass spectroscopy (ICP-MS) for 127I. High concentrations of both isotopes species were found in the Skagerrak–Kattegat basins, whereas the values in the Baltic Proper are low for both species. The ratios of 129I−/129IO3 − and 127I−/127IO3 − significantly increase from south to central Baltic Sea, and iodide (both isotopes) appears as the predominant inorganic iodine species along the Baltic Sea. The results show insignificant change in 129I and 127I speciation and suggest that reduction of iodate and oxidation of iodide in Skagerrak and Kattegat may be a slow process. Additionally, the positive correlation between salinity and iodide and iodate (both isotopes) may reflect effective control of Skagerrak water mass on iodine distribution in surface water of the Baltic Sea. [Copyright &y& Elsevier]

The article presents a study on the genetic mixed-stock analysis of the populations of Atlantic herring in a mixed feeding area. The researchers gathered and analyzed data for mixed feeding aggregations, after which they recorded the age and hatching season for the subsets of the fish after the same procedure for spawning samples. They also genotyped mixed-stock and baseline individuals for nine tetra-nucleotide microsatellites. They found that Rügen fish significantly contributed to most collections in summer.

Summary 1. We estimated the biomass and production of juvenile anadromous brown trout ( Salmo trutta) and Atlantic salmon ( Salmo salar) (parr) in 12 streams in the Skagerrak area of Norway to identify controlling environmental factors, such as land-use and water chemistry. 2. Production estimates correlated positively with fish density in early summer, but not with the size of the catchment. The summer biomass of age-0 brown trout and Atlantic salmon was smaller than that of age-1 and constituted 27.4 and 25.7%, respectively, of the total biomass of the two groups. 3. Mean production of brown trout from July to September varied between streams, but in most cases it was below 2 g 100 m−2 day−1. Yearly cohort production from age-0 in July to age-1 in July was 10 g m−2 or less, with mean annual production of 1.32 g 100 m−2 day−1, equivalent to 4.8 g m−2 year−1. The corresponding annual cohort production of Atlantic salmon was 0.38 g 100 m−2 day−1 or 1.4 g m−2 year−1. Annual production to biomass ratio ( P/ B) for brown trout of the same cohort in the various streams was between 1.47 and 4.37; the overall mean (±SD) for all streams was 2.25 ± 0.94. Mean turnover rate of Atlantic salmon was 2.73 ± 0.24. 4. Production of 0+ brown trout during the summer correlated significantly with the percentage of agricultural land and forest/bogs in the catchment, with maxima at 20 and 75%, respectively. Age-0 brown trout production also correlated with concentration of nitrogen and calcium in the water, with maxima at 2.4 and 14 mg L−1, respectively. 5. The results support the hypothesis that brown trout parr production reflects the quality of their habitat, as indicated by the dome-shaped relationship between percentage of agricultural land and the concentration of nitrogen and calcium in the water. [ABSTRACT FROM AUTHOR]

Erbs-Hansen, D. R., Knudsen, K. L., Gary, A. C., Jansen, E., Gyllencreutz, R., Scao, V. & Lambeck, K. 2011: Late Younger Dryas and early Holocene palaeoenvironments in the Skagerrak, eastern North Atlantic: a multiproxy study. Boreas, 10.1111/j.1502-3885.2011.00205.x. ISSN 0300-9843 A high-resolution study of palaeoenvironmental changes through the late Younger Dryas and early Holocene in the Skagerrak, the eastern North Atlantic, is based on multiproxy analyses of core MD99-2286 combined with palaeowater depth modelling for the area. The late Younger Dryas was characterized by a cold ice-distal benthic foraminiferal fauna. After the transition to the Preboreal ( c. 11 650 cal. a BP) this fauna was replaced by a Cassidulina neoteretis-dominated fauna, indicating the influence of chilled Atlantic Water at the sea floor. Persisting relatively cold bottom-water conditions until c. 10 300 cal. a BP are presumably a result of an outflow of glacial meltwater from the Baltic area across south-central Sweden, which led to a strong stratification of the water column at MD99-2286, as also indicated by C. neoteretis. A short-term peak in the C/N ratio at c. 10 200 cal. a BP is suggested to indicate input of terrestrial material, which may represent the drainage of an ice-dammed lake in southern Norway, the Glomma event. After the last drainage route across south-central Sweden closed, c. 10 300 cal. a BP, the meltwater influence diminished, and the Skagerrak resembled a fjord with a stable inflow of waters from the North Atlantic through the Norwegian Trench and a gradual increase in boreal species. Full interglacial conditions were established at the sea floor from c. 9250 cal. a BP. Subsequent warm stable conditions were interrupted by a short-term cooling around 8300-8200 cal. a BP, representing the 8.2 ka event. [ABSTRACT FROM AUTHOR]

The seismically active Skagerrak region in the border area between Denmark and Norway has traditionally been associated with uncertain earthquake locations due to the limited station coverage in the region. A new seismic station in southern Norway and a recent update of the earthquake database of the Danish National Network have led to a much more complete and homogeneous data coverage of the Skagerrak area, giving the possibility of improved earthquake locations in the region. In this study, we relocate earthquakes in the Skagerrak area to obtain a more exact picture of the seismicity and investigate well-recorded events to determine the depth distribution. Hypocenter depths are found to be generally in the range 11-25 km. Furthermore, new composite focal mechanisms are determined for clusters of events with similar waveforms. Results indicate that the Skagerrak seismicity is associated with shallow, crustal faults oriented in the NS direction south of the Sorgenfrei-Tornquist Zone (STZ) as well as with the STZ itself. Mainly reverse faulting mechanisms along NE-SW oriented faults indicate maximum horizontal compression in the NW-SE direction. This is in agreement with World Stress Map generalizations, most likely associated with ridge push forces from the mid-Atlantic ridge, though modified probably by local crustal weaknesses. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of the present study was to explore the composition and variation of the pico-, nano- and micro-plankton communities in Norwegian coastal waters and Skagerrak, and the co-occurrence of bacteria and viruses. Samples were collected along three cruise transects from Jæren, Lista and Oksøy on the south coast of Norway and into the North Sea and Skagerrak. We also followed a drifting buoy for 55h in Skagerrak in order to observe diel variations. Satellite ocean color images (SeaWiFS) of the chlorophyll a (chl a) distribution compared favorably to in situ measurements in open waters, while closer to the shore remote sensing chl a data was overestimated compared to the in situ data. Using light microscopy, we identified 49 micro- and 15 nanoplankton sized phototrophic forms as well as 40 micro- and 12 nanoplankton sized heterotrophic forms. The only picoeukaryote (0.2–2.0μm) we identified was Resultor micron (Pedinophyceae). Along the transects a significant variation in the distribution and abundance of different plankton forms were observed, with Synechococcus spp and autotrophic picoeukaryotes as the most notable examples. There was no correlation between viruses and chl a, but between viruses and bacteria, and between viruses and some of the phytoplankton groups, especially the picoeukaryotes. Moreover, there was a negative correlation between nutrients and small viruses (Low Fluorescent Viruses) but a positive correlation between nutrients and large viruses (High Fluorescent Viruses). The abundance of autotrophic picoplankton, bacteria and viruses showed a diel variation in surface waters with higher values around noon and late at night and lower values in the evening. Synechococcus spp were found at 20m depth 25–45 nautical miles from shore apparently forming a bloom that stretched out for more than 100 nautical miles from Skagerrak and up the south west coast of Norway. The different methods used for assessing abundance, distribution and diversity of microorganisms yielded complementary information about the plankton community. Flow cytometry enabled us to map the distribution of the smaller phytoplankton forms, bacteria and viruses in more detail than has been possible before but detection and quantification of specific forms (genus or species) still requires taxonomic skills, molecular analysis or both. [Copyright &y& Elsevier]

The article focuses on an otolith geochemical study of the deep-sea fish Coryphaenoides rupestris in the North Atlantic Ocean. Fish otoliths are described as acellular, metabolically inert calcified cephalic structures that play a role in the hearing, balance and orientation of the fish. Results show significant trace element differences across sites which increase with age and in between life stages. One finding indicates that the highest concentrations of manganese (Mn) were recorded from the Skagerrak while the lowest observed Mn concentrations came from the Mid-Atlantic Ridge (MAR) while another finding shows that barium (Ba) concentrations were the lowest in the Skagerrak.

Abstract: A White Paper on a new integrated management plan for the Norwegian Sea was launched by the Norwegian government in May 2009. Following international guidelines for ecosystem-based management, the plan provides an overall framework for managing all human activities (mainly oil and gas industry, fishing, and shipping) in the area to ensure the continued production and function of the ecosystem. The plan is based on an assessment of the present and projected future impact of human activities and of the interactions between them, taking into account deficits in current knowledge of ecosystem state and dynamics. Areas of particular value in terms of biodiversity or biological production were identified. In each of these valuable areas, any access for substantial human activity is to be carefully managed. To monitor the overall development of the Norwegian Sea, a set of indicators with associated environmental quality objectives have been selected. The approach used builds upon experience gained from the first integrated Norwegian management plan for a marine area, the Barents Sea–Lofoten region, developed in 2002–2006. Work towards a Norwegian management plan for the North Sea, including Skagerrak, was initiated in 2009. [ABSTRACT FROM AUTHOR]

Mertens, K. N., Dale, B., Ellegaard, M., Jansson, I.-M., Godhe, A., Kremp, A. & Louwye, S. 2010: Process length variation in cysts of the dinoflagellate Protoceratium reticulatum, from surface sediments of the Baltic-Kattegat-Skagerrak estuarine system: a regional salinity proxy. Boreas, 10.1111/j.1502-3885.2010.00193.x. ISSN 0300-9483. Results are presented from a regional comparison of average process length variation in cysts of Protoceratium reticulatum and Lingulodinium polyedrum, extracted from surface sediments in the Skagerrak-Kattegat-Baltic estuarine system, with the environmental variables of seawater temperature and salinity. Although too few cysts of Lingulodinium polyedrum were recovered from the sediments to make reliable correlations, cysts of Protoceratium reticulatum were well represented, and average process length was correlated significantly with both salinity and temperature. Owing to dominant summer surface production, and regional covariation between salinity and density, we propose the use of the significant correlation with summer sea surface salinity (SSS) by the equation SSS=3.16 × average process length −0.84 ( R=0.8). Application of this equation down-core in Limfjord (northern Denmark) shows its usefulness as a regional palaeosalinity proxy. [ABSTRACT FROM AUTHOR]

Compliance and enforcement are important issues from an economic point of view because management measures are useless without a certain level of enforcement. These conclusions come from the well-established theoretical literature on compliance and enforcement problems within fisheries. This paper contributes to the literature by investigating compliance and enforcement in the empirical case of a mixed trawl fishery targeting Norway lobster in Kattegat and Skagerrak located north of Denmark with help from a simulated model. The paper presents results from two simulation models of the case study: one for a single output and a single enforcement tool and one for multiple outputs and multiple enforcement tools. The results of the simulation models are compared to the benchmark case, defined as the enforcement situation in the baseline year. The paper discusses the consequences of policy intervention at the level of compliance and the private and social benefits of varying enforcement intensities, penalties and management measures as well as combinations thereof. The empirical investigation of the case study indicates the current level of control is too low compared to the optimal level of enforcement. Another conclusion from the case study is that only small welfare effects are obtained by increasing enforcement efforts to reduce non-compliance. [ABSTRACT FROM AUTHOR]

Abstract: We present the first complete sections of humic substance fluorescence (HSfl)-values and total organic carbon (TOC) concentrations through the extended estuary of the Baltic Sea, Kattegat, and Skagerrak. Both HSfl-values and TOC concentrations correlated strongly with salinity, indicating terrestrial runoff as the main source for both components. However, their distributions do not result from a simple two end-member mixing and the two pools have different controls. In the Baltic Sea, surface water HSfl-values decreased from north to south, while TOC concentrations remained relatively constant, indicating an increasingly biologically-labile TOC pool from north to south. Both HSfl-values and TOC concentrations decreased strongly from the Baltic Sea to Kattegatt and Skagerrak. There were no major net sources or sinks for HSfl or TOC in Kattegat. However, the Jutland Current was an HSfl and TOC source for Skagerrak, probably derived from Danish rivers. Fraction of forested area in drainage basins of the Baltic Sea correlated positively with HSfl-values in freshwater end-members, but not with TOC concentrations. Land-runoff-volume relative to basin volume correlated positively with HSfl-values in surface waters, but not with TOC concentrations. In the Baltic Proper, deepwater oxygen concentrations correlated negatively with HSfl-values, indicating a significant source for HSfl (but not TOC) in suboxic and anoxic deepwaters. Photobleaching decreased HSfl-values in surface waters of the Baltic Proper, but had no effect on TOC concentrations. Despite terrestrial material being the main source for both TOC and HS, differences in control mechanisms result in a partial decoupling of their concentrations within the estuary. [Copyright &y& Elsevier]

Abstract: This paper presents an ongoing project with the aim to assess a CO2 infrastructure in the Skagerrak/Kattegat region (the sea bordered by north of Denmark, south coast of Norway and the west coast of Sweden). The area comprises 10–12 CO2 emission sources of more than 0.5 Mt/year. The geological and geophysical assessment of CO2 storage potential in the described area as well as reservoir modelling and simulations are performed in work package (WP) 1. The results from WP1 are used in the other work packages. Candidate storage sites are matched with those point sources in the region that are technically and economically feasible for CO2 capture, together with an assessment of the connecting infrastructure needs. WP2 focuses on identifying optimal technological CO2 infrastructure solutions. Sources-to-sink solutions are in the process of being developed based on input from WP1 and WP3. Assessment of the build-up of a complete CCS infrastructure from a system perspective is the overall focus of WP3, covering economical, practical and judicial aspects. The project group explores the economic potential for capture at each individual site including looking at other CO2 mitigation options and propose relevant capture technology with cost estimations. Dissemination of project results is organized in a separate work package, WP4. [Copyright &y& Elsevier]

Abstract: Reduction of CO2 emissions is regarded as necessary to limit the consequences of increased CO2 in the atmosphere. Carbon capture and storage will play an integral part in future reduction of CO2 emissions together with energy optimization. Development of an efficient CCS infrastructure is the key to reaching proposed emission goal. In the current project the focus is on CO2 emissions in the Skagerrak-Kattegat region. The project encompasses all aspects of CCS, but in this article the focus is on CO2 transport infrastructure. Different infrastructure scenarios are proposed and costs are compared. This will be an iterative process and a final recommendation will be given by the end of the project period. Preliminary results will be provided in this article and are limited by the specified assumptions. Currently two scenarios, storage in the Skagerrak-Kattegat region and one outside, are estimated and compared. Both scenarios assumed that all the CO2 emitted in the region is available simultaneously and that no ramp-up is necessary. Storage in relatively close proximity to the emission sources is preferable in an economic perspective and the initial estimations indicate this. [Copyright &y& Elsevier]

Abstract: This paper provides some initial results from the project “CCS in the Skagerrak/Kattegat-region” which is an intraregional CCS project partly funded by the EU. The project assesses the prospects for Carbon Capture and Storage (CCS) from industry and power plants located in the Skagerrak region which comprises northern Denmark, south-east coast of Norway and the west coast of Sweden. The project is a joint cooperation between universities, research institutes and industries in the region. The methodology used in one of the project work packages is presented together with some initial results on legal aspects. CCS in the Skagerrak region may potentially account for a third of combined emission reduction commitments by 2020 in the three countries involved in the project. Yet, much of the emissions in the region occur from industry (in addition to power plants) and it is still not clear how these industries will be treated under the ETS. Based on current knowledge, a good storage option would be in the Hanstholm aquifer on Denmark’s northwest coast. The phasing-in of capture plants over time is central to the development of a cost efficient CCS infrastructure. However, many of the sources in the region are located at a port facilitating use of boat transport through the build-up period. The initial legal analysis show that significant regulatory uncertainties exist in the region with regard to CCS and it is not obvious that the implementation of the EU CCS directive into national law by June 2011 will alleviate these uncertainties. Finally, the project may provide a significant test case for what type of political and regulatory cooperation that will be required if CCS is to be deployed in a transboundary context under conditions of sufficient public acceptance and well-designed regulation. [Copyright &y& Elsevier]

The article discusses research done on the life history characteristics of fjord cod Gadus morhua in Skagerrak, Norway. Life history changes are considered as stress indicators in harvested populations. The study procedure included the measurement of the fork length of the fish and the identification of the maturity state from the visual inspection of the gonads. The data gathered indicated the shift of age and length distributions towards larger and older fish, contrary to expectations with the historic sample.

The European eel (Anguilla anguilla L.) is distributed in coastal and inland habitats all over Europe, but spawns in the Sargasso Sea and is thus affected by both continental and oceanic factors. Since the 1980s a steady decline has been observed in the recruitment of glass eels to freshwater and in total eel landings. The eel is considered as critically endangered on the International Union for the Conservation of Nature and Natural Resources Red List of species. The Skagerrak beach seine survey from Norway constitutes the longest fishery-independent dataset on yellow/silver eels (starting in 1904). The Skagerrak coastal region receives larvae born in the Sargasso Sea spawning areas that have followed the Gulf Stream/North Atlantic Drift before they penetrate far into the North Sea. The Skagerrak coastal time series is therefore particularly valuable for exploring the impacts of oceanic factors on fluctuations in eel recruitment abundance. Analyses showed that Sargasso Sea surface temperature was negatively correlated with eel abundance, with a lag of 12 years revealing a cyclic and detrimental effect of high temperatures on the newly hatched larvae. The North Atlantic Oscillation index and inflow of North Atlantic water into the North Sea were negatively correlated with eel abundance, with a lag of 11 years. Increased currents towards the North Atlantic during high North Atlantic Oscillation years may send larvae into the subpolar gyre before they are ready to metamorphose and settle, resulting in low recruitment in the northern part of the distribution area for these years. The Skagerrak time series was compared with glass eel recruitment to freshwater in the Netherlands (Den Oever glass eel time series), and similar patterns were found revealing a cycle linked to changes in oceanic factors affecting glass eel recruitment. The recent decline of eels in the Skagerrak also coincided with previously documented shifts in environmental conditions of the North Sea ecosystem. [ABSTRACT FROM AUTHOR]

Abstract: Microreticulate dinoflagellate cysts are a major component of latest Holocene (Subatlantic) sediments from the Skagerrak and Kattegat, off the west coast of Sweden. They first appear about 4000yearsBP, become more prominent from 2000yearsBP to about 300yearsBP, before they decline to their present minor occurrence in modern sediments. In particular they occur in at least two major pulses and one minor pulse, where their numbers exceed 5000 cysts per gram of sediment, seemingly correlating to times toward the end of the Roman Warm Period, to between the Roman and Medieval warm periods, and with the Little Ice Age. The minor pulse occurs within the Medieval Warm Period. Originally thought to be assignable to the species Gymnodinium catenatum Graham 1943 these cysts were interpreted as an indication of warmer waters, warmer climates and significant changes within the hydrology of the region. Opinion amongst palynologists and phycologists now favour assignment of these cysts to Gymnodinium nolleri Ellegaard and Moestrup 1999, based mainly upon their dimensions; this cautions against earlier environmental interpretations. Further study of microreticulate cysts from core material recovered in the Kattegat and Skagerrak (Gullmar Fjord) supports the identification of these cysts as G. nolleri and emphasises an environmental interpretation that does not solely depend upon possible temperature change but that other factors may be involved. This study also emphasises the importance of these microreticulate cysts to the biostratigraphy of the Subatlantic in offshore west coast Sweden. [Copyright &y& Elsevier]

Eigaard, O. R., and Munch-Petersen, S. 2011. Influence of fleet renewal and trawl development on landings per unit effort of the Danish northern shrimp (Pandalus borealis) fishery. – ICES Journal of Marine Science, 68: 26–31. Recent stock assessments of the Pandalus stock in the Skagerrak (ICES Division IIIa) and the Norwegian Deep (Division IVa east) have relied largely on a time-series of landings per unit effort (lpue) calculated from Danish logbook data. Because of fleet renewal and trawl-size changes, the relationship between nominal effort data as recorded in logbooks (days fishing) and effective effort is likely to have changed, so to standardize the nominal lpue time-series, trawl-size development has been taken into account using generalized linear modelling. As logbooks do not provide trawl-size information, this standardization was made possible by retrieving technical trawl and vessel data from industry order books. These data demonstrated an approximately linear relationship between vessel engine power and Pandalus trawl size, so validated the use of vessel horsepower from the logbooks as a proxy for an unknown trawl size. Standardized lpue time-series for the past 20 years indicated a lesser increase in stock size than nominal lpue, the modelling results demonstrating that vessel lpue increased by 9.5% with each 100 hp of engine power. [ABSTRACT FROM PUBLISHER]

Frandsen, R. P., Madsen, N., and Krag, L. A. 2010. Selectivity and escapement behaviour of five commercial fishery species in standard square- and diamond-mesh codends. – ICES Journal of Marine Science, 67: 1721–1731. The Danish fishery for Nephrops (Nephrops norvegicus) is often conducted in a mixed-species setting, characterized by high rates of discards of several target species, including Nephrops and cod (Gadus morhua). Experiments were conducted to investigate and compare the selective properties of a standard 70 mm square-mesh codend (standard SMC) and a standard 90 mm diamond-mesh codend (standard DMC). Selectivity estimates for five commercial species are provided for both codends. The standard SMC yielded higher estimates of length at 50% retention/mesh size (hereafter SF) for Nephrops and roundfish than did the standard DMC, but no effect of codend type on SF was found for plaice (Pleuronectes platessa). Moreover, a novel codend cover design allowed assessment of the preferred direction of escapement in the codend. Whiting (Merlangius merlangus) and Nephrops showed pronounced, but opposite, vertical preference in the direction of escapement, with whiting escaping upwards and Nephrops downwards. A significant (p < 0.05) difference in the direction of escapement between the two codends was found for haddock (Melanogrammus aeglefinus) and whiting. Owing to the relatively small catches, the outcome is probably most applicable to Nephrops-directed fisheries under similar conditions, and caution should be taken not to extrapolate the results to other fisheries. [ABSTRACT FROM PUBLISHER]

Abstract: Individual tracking of commercial fishing vessels from vessel monitoring systems (VMS) is now widely available across Europe for scientific purposes. This enables analyses of the spatial and temporal distribution of disaggregated fishing activity as well as high resolution determination of the consequent relative fishing pressure on stocks, provided that an accurate method can link these data with the declaration of catches (logbooks). In the present study, logbook analyses to allocate the fishing activity due to various fisheries (fleet segments) are integrated with processing of raw satellite-recorded data for identifying trips at sea and fishing sequences. Both data sources are linked into one output dataset. A robust method is developed to allocate logbook catches to VMS positions, with focus on potential mismatch. The method is applied to data on the Danish Skagerrak–Kattegat fishing fleets from 2005 to 2008, where 52–56% of the VMS total effort perfectly matched (representing approximately 80% of landings); 14–18% partially matched; and 30% failed to match the logbook data, which was partially related to fleet type, area and year. Comparison of three methods for generating high resolution determination of grid-based fishing effort demonstrated only minor differences, suggesting a mainly equal dispatch of landings between each of the merged fishing positions. Despite possibly poor matching success for this particular region, we demonstrate that the approach can cope with the potentially large sources of error in the data, including the current low accuracy of available VMS pre-processing algorithms and the possible misreporting of areas and catch dates in fishermen''s logbook declarations. [Copyright &y& Elsevier]

Abstract: The importance of the coastal seas as areas of CO2 uptake from the atmosphere has gained more attention during recent years. This study utilizes dissolved inorganic carbon and hydrographic data collected in the Skagerrak for 10months in 2006 to assess the carbon dynamics over the year. The surface water is under-saturated in CO2 relative to the atmosphere during the first half of the year and stays close to equilibrium at least until November. Consequently primary production compensates for the increase in pCO2 caused by the temperature increase from ∼2 to ∼10°C in spring. Integrating the annual air–sea CO2 flux as computed using the Wanninkhof (1992) parameterization gives a net uptake of 1.2molm−2 year−1 which, if representative for the whole Skagerrak area, equals 3.7∙1010 molyear−1 or 0.45 TgCyear−1. Converting the nitrate consumption in the surface mixed layer from January to May to carbon units through the RKR ratio () gives a drawdown of 6gCm−2. This number increases by a factor of two if primary productivity also occurs in the waters below the surface mixed layer, i.e. an increase in depth from 10 to 25m as a seasonal average.We estimated the effect of salinity, biological processes and air–sea CO2 exchange on the monthly DIC change. We found that salinity was one of the major drivers for the DIC change. [ABSTRACT FROM AUTHOR]

We consider results from two 27-year-long simulation pairs derived using two different ocean models. We focus on the Skagerrak/North Sea area. Each pair consists of the two terrain-following coordinate models ROMS and MIPOM. The first pair utilizes an eddy-permitting grid, that is, a grid in which the Rossby radius is barely resolved. The second pair utilizes an eddy-resolving grid in which the Rossby radius is truly resolved. The goal is to compare the quality of the two models and the two pairs. To this end we derive statistical properties such as probability density functions and compare them with similar statistics derived from observations. Thereby we obtain insight into whether a truly eddy-resolving model is required to realistically capture the mesoscale statistics. We find that eddy resolution is critical to get the mesoscale statistics correct, in particular, the strength of the current jets. Our results also indicate that the improvement gained by employing the eddy-resolving grid is mostly due to a better resolved topography. In particular, we find that this is the case in areas exhibiting prominent topographic features, such as the deep Norwegian Trench cutting into the heart of the northern North Sea/Skagerrak area. The results also highlight the advantage of first performing quality assurance investigations when implementing a new model for a new area. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated a clear year-round diel vertical migration pattern (DVM) of juvenile coastal cod Gadus morhua from the Skagerrak coast in Norway. It is stated that light intensity, ambient temperature and food availability were determinants to the diel vertical migration of coastal cod. Ultrasonic receivers and transmitters were used to plot every fish. The authors concluded that seasonal shift in the timing of DVM was related with the seasonal shift in sunrise and sunset.

Abstract: Gear selectivity with regard to cod (Gadus morhua) needs to be improved in the Kattegat and Skagerrak Norway lobster (Nephrops norvegicus) fishery. One way to achieve this goal is to improve the selectivity of an escape window (henceforth window) in the gear. Our gear development focused particularly on moving the window further back, gaining more stability in the codend to avoid loss of Norway lobster through the window, making a relatively narrow section where the window is located, and testing larger mesh sizes in the window. We designed a four-panel sorting section—the sorting box—where a 300mm window is placed at the top section at about 3–6m from the codline. Acoustic release technology was used to avoid catch loss during gear retrieval. Sea trials were conducted in the Skagerrak and Kattegat from a commercial trawler. The sorting box yielded a high reduction of the cod catch, but no improvement was observed for cod that came into contact with the window after reducing the distance from the window to the codline. The sorting box also showed a high reduction of flatfish and other roundfish species. The retention of Norway lobster above minimum landing size in the sorting box was higher compared to a general selection model. [Copyright &y& Elsevier]

For many years, the planning and management of terrestrial areas has been supported by a detailed knowledge of the distribution of habitats and their associated species. However, the detailed mapping of biological resources in extent coastal areas, such as the Norwegian coastal zone, is unrealistic due to its enormous coastline. Here, we present a useful and feasible approach and a set of simple, cost-effective methods which are suitable for providing a broad-scale overview of marine habitats and fish resources. This approach was developed in conjunction with a pioneer study conducted along the southern coast of the Skagerrak, where we combined knowledge gathered from local fishermen with scientific knowledge of important species and nature types to establish a coastal sea mapping program. GIS modeling tools were used in both the mapping program and to integrate local and scientific knowledge into digital maps made available to local area management. This multi-faceted approach, which combines local knowledge and scientific methods, provides valuable information with respect to marine biodiversity, and has been used extensively by local environmental management. [ABSTRACT FROM AUTHOR]

In the Baltic Sea, the broadly distributed brown alga Fucus vesiculosus coexists in sympatry over part of its range (south west Gulf of Bothnia) with the Baltic endemic F. radicans sp. nov, while further north in colder and lower-salinity areas of the Baltic F. radicans occurs alone (north west Gulf of Bothnia). F. radicans appears to have arisen via rapid speciation from F. vesiculosus within the recent history of the Baltic (ca. 7500 BP). Possible functional divergence between the two species was investigated by comparing stress-responsive gene expression in a common-garden experiment. The experiment used two allopatric populations of Fucus vesiculosus from the Skagerrak (North Sea) and Central Baltic, as well as F. radicans from the same Central Baltic site. The two species in sympatry displayed divergent heat shock responses, while F. vesiculosus populations from allopatric sites did not. F. radicans was more sensitive to heat shock at 25°C, either alone or together with high irradiance and desiccation, than Baltic or Skagerrak F. vesiculosus. The results indicate that rapid functional divergence in the inducible heat shock response has occurred between sympatric species on a timescale of thousands of years. [ABSTRACT FROM AUTHOR]

Information on the temporal stability of genetic structures is important to permit detection of changes that can constitute threats to biological resources. Large-scale harvesting operations are known to potentially alter the composition and reduce the variability of populations, and Atlantic herring (Clupea harengus) has a long history of heavy exploitation. In the Baltic Sea and Skagerrak waters, the census population sizes have declined by 35–50% over the last three decades. We compared the genetic structure of Atlantic herring in these waters sampled at least two different times between 1979 and 2003 by assaying 11 allozyme and nine microsatellite loci. We cannot detect any changes in the amount of genetic variation or spatial structure, and differentiation is weak with overall FST=0.003 among localities for the older samples and FST=0.002 for the newer ones. There are indications of temporal allele frequency changes, particularly in one of five sampling localities that is reflected in a relatively small local Ne estimate of c. 400. The previously identified influence of selection at the microsatellite locus Cpa112 remains stable over the 24-year period studied here. Despite little genetic differentiation, migration among localities appears small enough to permit demographic independence between populations. [ABSTRACT FROM AUTHOR]

Abstract: New data support our previously published propagule dispersal hypothesis and show that propagules of some benthic foraminiferal species can survive for two years before growth commences. Following exposure to simulated shallow-water conditions, shallow-water species of benthic foraminifera appeared and grew in large numbers (commonly >100 ind/12ml sediment) in the <32µm-size sediment fraction collected from 320m water depth in the Skagerrak basin (North Sea). None of the shallow-water species that grew abundantly (Planorbulina mediterranensis, Morulaeplecta bulbosa, Bolivina pseudoplicata, Cuneata arctica, Eggerelloides scaber, Gavelinopsis praegeri) seem to grow or reproduce at or in the vicinity of the sampling site. Consequently, they must have been transported there as <32µm-sized individuals. Their sudden appearance when exposed to shallow-water conditions suggests that they had been transported to the sampling site as propagules and that they could survive in the sediments until conditions became suitable for growth and, for some, reproduction. The lack of agglutination on the proloculi of the agglutinated taxa that appeared in the growth-chambers may enhance their passive transport via currents and, thereby, dispersal. Of all the indigenous foraminiferal species that occur at the sampling site, only Textularia earlandi and Bolivinellina pseudopunctata continued to grow and reproduce when transferred from bathyal (320m) to simulated shallow-water (0m) conditions. The former is considered a highly opportunistic species. According to the literature, most of the morphospecies which grew in the experiments are cosmopolitan. Our results indicate substantial inter-specific differences in dispersal potential and support previous suggestions that among free-living species, some serial forms have the potential for long-distance dispersal. Still, oceanographic, physical and ecological boundaries and barriers constrain the distribution of most species. In addition to benthic foraminifera, Gromia spp. (rhizarian protists related to the foraminifera) grew in >60% of the experimental growth-chambers. [Copyright &y& Elsevier]

Abstract: The polychaete Arenicola defodiens, or black lug, was recently described as a morphologically highly similar species alongside the blow lug Arenicola marina. So far it was only known from the British Isles. A double spawning peak was observed earlier in lugworms of the western Wadden Sea. Here, we test the hypothesis that the two spawning peaks represent the two species in sympatry. This hypothesis is refuted on the basis of both morphological and mitochondrial DNA data; both spawning peaks are attributed to A. marina. In spite of this, we confirm, on the basis of new collections as well as re-examination of museum collections, the presence of A. defodiens in the western Wadden Sea, North Sea and also the Skagerrak; its distribution is restricted to habitats which are either submerged or have short emersion times, have relatively coarse sediments and high and stable salinities. Sympatry is common. The species differ strongly in the mitochondrial DNA fragment examined; the observed 14% uncorrected minimum difference amounts to an estimated 33–63million years since sequence divergence. The amount of intraspecific molecular variation is larger for A. defodiens than for A. marina. This is evidence to suggest that A. marina may have undergone more recent and/or more severe population size bottlenecks. [Copyright &y& Elsevier]

Abstract: Morphology, total sulfur content and stable sulfur isotopic composition of Zostera marina were examined in the Baltic Sea–Skagerrak transition zone through surveys. The seagrass meadows were denser and less productive at the low salinities in the Baltic Sea (salinity 6–7psu), and total sulfur accumulations in plants were lower and δ34 S values were higher compared to the west coast of Sweden (salinity 21–29psu). The δ34 S values of the three plant compartments (leaves, rhizomes, roots) indicated lower sulfide invasion at low salinities, which was mainly due to environmental conditions (e.g. low epiphytic biomass, low sediment organic matter and low sulfate concentration) and plant characteristics (productivity, shoot morphology). Between 13% and 63% of the sulfur in the plants was derived from sediment sulfides with highest percentages in the roots (27–63%) and lower in rhizomes (13–50%) and leaves (14–51%). The high sulfide invasion on the west coast of Sweden was coincident with high sediment organic matter, probably increasing sulfide pressure on the plants, and high epiphytic biomass, probably constraining the oxygen dynamics in the plants and enhancing sulfide invasion. Regional and spatial variability in the δ34 S were extensive, emphasizing the need for detailed analysis of local sources when applying stable sulfur isotopes in food web analyses. The observed invasion of sulfides suggests sulfide as a contributing factor to reported declines of Z. marina in the Skagerrak region. [Copyright &y& Elsevier]

Abstract: Study of rate process responses and carbon transfer rates in the plankton is a well developed field, but attention has focused on seasonal or longer scales and knowledge on variability patterns and modulating mechanisms at shorter scales is very limited. Here we investigated variability in pelagic carbon transfer rates on daily and seasonal scales in the Gullmar Fjord, Sweden. Hierarchical sampling was carried out in five campaigns in different seasons each of which consisted of 8–12d with sampling every other day. Algal ingestion, copepod egg and pellet production and vertical flux measured as pigments and pellets varied significantly between days as well as between seasons. Algal ingestion was highest in autumn (weight-specific rate: 0.3–1d−1) and at the start of the spring bloom (0.3–1.5d−1), while egg production was highest in summer–autumn (0.1–0.5d−1). Vertical flux peaked in summer with 4–6mg pigmentm−2 d−1 and up to 150mg pelletCm−2 d−1. Consonant responses between species were observed indicating a common food source for the mesozooplankton. Changes in trophic functions occurred on scales of days and the coupling between pelagic processes and vertical flux was strong. There were, however, both positive and negative responses which could not be explained by simple predator–prey interactions. The food quality in terms of prey type and biochemical composition are suggested as crucial factors for the variability both within the pelagic environment as well as for the vertical flux out of the upper layers in the ocean. [Copyright &y& Elsevier]

Mapping the seabed along the Norwegian coast is costly and time consuming. Hence, finding a modeling method to separate rocky seabed from other substrate types will provide digital maps that may be used to develop cost-effective sampling designs to predict species and habitat distribution. Our approach was to use geophysical data that were quantitative and objectively defined, generalized additive models (GAMs), and Akaike information criterion (AIC) to develop statistical models and select among them. We found that slope, terrain curvature, wave exposure, and depth predicted rocky seabed occurrence with a high degree of certainty. [ABSTRACT FROM AUTHOR]

Abstract: Significant faunal changes reported from recent, coastal environments, which are not directly influenced by urban and industrial impact, are rarely seen. In Gullmar Fjord on the Swedish west coast, a significant foraminiferal fauna change occurred in connection with severe low-oxygen conditions that evolved in the winter of 1979/1980. A foraminiferal fauna marked by common Skagerrak–Kattegat species, which had previously characterised the deep fjord basin, was replaced by the opportunistic, low-oxygen tolerant species Stainforthia fusiformis (Williamsson). To study this phenomenon further we performed stable oxygen and carbon isotope analyses on the indicator species itself, S. fusiformis, both on specimens from sediment cores representing approximately the last 85years and on living (stained) individuals taken from a transect across the deep fjord basin. Our purpose was to detail how and why S. fusiformis, came to dominate the fauna. The oxygen isotope results suggest that salinities and temperatures in the deep basin have been relatively constant over the last c. 85years, while the carbon isotopes show a significant change towards more negative values in association with the faunal shift of 1979/1980. The combined results from both the cores and the surface sediments suggest that S. fusiformis did not inhabit the deep basin until 1980. Before then, almost all specimens of S. fusiformis were small sized and their carbon isotope values suggest they were re-deposited shallow-water specimens that had been transported down to the central, deep basin as part of a suspension load. After a major faunal extinction in 1979–1980, S. fusiformis of all sizes suddenly appeared in large numbers and their carbon isotopic values were similar to the signal from registered in the recent, living fauna within the deep basin. This suggests that the opportunistic S. fusiformis established itself in the deep basin as a consequence of the severe low-oxygen event and the faunal crash of the previously dominating Skagerrak–Kattegat fauna. [Copyright &y& Elsevier]

Abstract: A previously presented objective method to calculate each species sensitivity to disturbance is here slightly modified and implemented in the Benthic Quality Index (BQI) for marine benthic invertebrates. A framework for assessment of water bodies based on multi-site BQI-values is also presented, where a certain variation of BQI-values is allowed to cover the heterogeneity within each water body. The 20th percentile, using bootstrapping, from the available sites’ BQI-values is compared with the status boundaries for quality assessment. The reliability of the assessment depends on the background information available for the boundary setting as well as the number of sampling sites included in the assessment. Agreement between time series of quality assessments in areas with known changes in anthropogenic disturbances is encouraging. Problems associated with water body assessment based on few or no samples, as well as multiple sampling occasions during the 6-yr WFD cycle are discussed. [Copyright &y& Elsevier]

The Norwegian Coastal Administration (NCA) is responsible for monitoring the environmental risk created by shipwrecks in Norwegian waters. If the risk is found to be unacceptable, corrective measures will be recommended to the Norwegian Ministry of Fisheries and Coastal Affaires. Approval and funding of such corrective measures will be decided by the Ministry. The NCA has been tasked to execute a program to find the shipwrecks that constitute the highest environmental risk from substances other than oil. The NCA's Wreck Data Base (2,300 wrecks) is the basis for the study. The emphasis of this article is on activities connected to ships loaded with chemical weapons (CWs) dumped in the Skagerrak. The article gives information on the surveys carried out by the Norwegian Defense Research Establishment (FF1) in 1989 and 2002. A number of the wrecks containing CWs are unaccounted for. FF1 recommended in the 2002 report that an effort should be made to find the remaining CW wrecks. To find and possibly identify the missing CW wrecks in Skagerrak, a search program will be developed. The NCA is testing a new concept this autumn: is it possible to identify a sunken ship by class or name based on information from an underwater vehicle? The test of FFI's HUG IN 1000 HUS autonomous underwater vehicle is expected to provide information on the suitability of the vehicle in providing data for wreck location and identification. [ABSTRACT FROM AUTHOR]

Abstract: Patterns in community structure and functioning of motile epibenthic fauna were investigated in shallow (0–1m) sediment habitats along the Skagerrak–Baltic estuarine gradient (salinity range from 4 to 34). The study area was divided into five regions, reflecting different sea-basins along the 1260km coastline, and fauna was collected at six sites within each region. Ten replicate samples of motile epibenthic fauna were taken randomly at each site with a portable drop trap (bottom area 1m2) in June and September in 2004. All together, 110 taxa were found, of which 45 had a marine and 65 a limnic origin. The marine species decreased along the salinity gradient while the limnic showed the opposite pattern. Number of species and abundance of epibenthic fauna exhibited considerable local and regional variation, with a trend of increase with decreasing salinity. Fauna biomass, on the other hand was significantly higher (six times) in the Skagerrak–Kattegat area compared to the Baltic. There was a significant difference in fauna composition among regions and season, but with high similarity within the five regions, which implies that management of such coastal habitats should preferably be based on scales of a region (ca. 100km) or smaller. Predators were the dominant functional group in all coastal regions, with a species shift from Crustacea to Insecta along the salinity gradient and with gobid fish occurring in all regions. Grazers were the second most important group in the Skagerrak–Kattegat area, but planktovores were more important in two of the Baltic regions. The importance of shallow sediment bottoms as feeding and nursery grounds for coastal fish assemblages is discussed and compared throughout the investigated area. [Copyright &y& Elsevier]

The paper develops a biological-economic evaluation tool to analyse the consequences for trawl fishers of implementing more selective fishing technologies. This is done by merging a dynamic biological population model and an economic cost–benefit evaluation framework to describe the consequences for the fish stocks, fishermen and society. The bio-economic evaluation is applied to the case of the Danish trawl fishery in Kattegat and Skagerrak, which experiences a high level of discards and bycatches of several species. Four different kinds of selectivity scenarios are evaluated in comparison with a baseline. The results from the evaluation are indicators for the consequences on ecological and economic levels. The results show that implementation of different selective fishing gear in the Kattegat and Skagerrak mixed trawl fisheries generally implies a trade off over time between rebuilding the stocks and economic loss. Moreover, the analysis shows that implementation of more selective gear is not always beneficial. [Copyright &y& Elsevier]

Changes in phenotypic variability in natural populations have received little attention in comparison with changes in mean trait values. This is unfortunate because trait diversity may influence adaptive evolutionary change and population stability. We combine two unique data sets to illuminate complex trait changes in Atlantic cod along the Norwegian Skagerrak coast: (i) an annual beach seine survey starting in 1919, monitoring juvenile body size and abundance and (ii) capture–mark–recapture data from which we estimated selection on juvenile body size and growth. We demonstrate that the variability of juvenile size has been steadily decreasing across nine decades, with no evidence for a similar trend in mean size. We also report that small, slow-growing fish as well as large, fast-growing fish are selected against. Together, these results suggest long-term stabilizing selection acting on Atlantic cod, and emphasize the need for further studies evaluating the full complexity of trait changes in wild populations. [ABSTRACT FROM AUTHOR]