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Monitoring the distribution of marine nonindigenous species is a challenging task. To support this monitoring, we developed and validated the specificity of 12 primer-probe assays for detection of environmental DNA (eDNA) from marine species, all nonindigenous to Europe. The species include sturgeons, a Pacific red algae, oyster thief, a freshwater hydroid from the Black Sea, Chinese mitten crab, Pacific oyster, warty comb jelly, sand gaper, round goby, pink salmon, rainbow trout and North American mud crab. We tested all assays in the laboratory, on DNA extracted from both the target and non-target species to ensure that they only amplified DNA from the intended species. Subsequently, all assays were used to analyse water samples collected at 16 different harbours across two different seasons during 2017. We also included six previously published assays targeting eDNA from goldfish, European carp, two species of dinoflagellates of the genera Karenia and Prorocentrum, two species of the heterokont flagellate genus Pseudochattonella. Conventional monitoring was carried out alongside eDNA sampling but with only one sampling event over the one year. Because eDNA was relatively fast and easy to collect compared to conventional sampling, we sampled eDNA twice during 2017, which showed seasonal changes in the distribution of nonindigenous species. Comparing eDNA levels with salinity gradients did not show any correlation. A significant correlation was observed between number of species detected with conventional monitoring methods and number of species found using eDNA at each location. This supports the use of eDNA for surveillance of the distribution of marine nonindigenous species, where the speed and relative easy sampling in the field combined with fast molecular analysis may provide advantages compared to conventional monitoring methods. Prior validation of assays increases taxonomic precision, and laboratorial setup facilitates analysis of multiple samples simultaneously. The specific eDNA assays presented here can be implemented directly in monitoring programmes across Europe and potentially worldwide to infer a more precise picture of the dynamics in the distribution of marine nonindigenous species.

Marine ecosystems are under high demand for human use, giving concerns about how pressures from human activities may affect their structure, function, and status. In Europe, recent developments in mapping of marine habitats and human activities now enable a coherent spatial evaluation of potential combined effects of human activities. Results indicate that combined effects from multiple human pressures are spread to 96% of the European marine area, and more specifically that combined effects from physical disturbance are spread to 86% of the coastal area and 46% of the shelf area. We compare our approach with corresponding assessments at other spatial scales and validate our results with European-scale status assessments for coastal waters. Uncertainties and development points are identified. Still, the results suggest that Europe’s seas are widely disturbed, indicating potential discrepancy between ambitions for Blue Growth and the objective of achieving good environmental status within the Marine Strategy Framework Directive.

Claims for ocean space are growing while marine ecosystems suffer from centuries of insufficient care. Human pressures from runoff, atmospheric emissions, marine pollution, fishing, shipping, military operations and other activities wear on habitats and populations. Ecosystem-based marine spatial planning (MSP) has emerged worldwide as a strategic instrument for handling conflicting spatial claims among competing sectors and the environment. The twofold objective of both boosting the blue economy and protecting the environment is challenging in practice and marine planners need decision support. Cumulative Impact Assessment (CIA) was originally developed to provide an overview of the human imprint on the world's ocean ecosystems. We have now added a scenario component to the CIA model and used it within Swedish ecosystem-based MSP. This has allowed us to project environmental impacts for different planning alternatives throughout the planning process, strengthening the integration of environmental considerations into strategic decision-making. Every MSP decision may entail a local shift of environmental impact, causing positive or negative consequences for ecosystem components. The results from Swedish MSP in the North Sea and Baltic Sea illustrate that MSP certainly has the potential to lower net cumulative environmental impact, both locally and across sea basins, as long as environmental values are rated high and prevailing pressures derive from activities that are part of MSP. By synthesizing innumerous data into comprehensible decision support that informs marine planners of the likely environmental consequences of different options, CIA enables ecosystem-based MSP in practice.

We have analyzed the development of “Broad-Scale Seabed Habitat Maps” (BSHM) and their potential use in a European context with regard to the EU Marine Strategy Framework Directive (MSFD) implementation, MPA designation and network assessment as well as other applications of BSHMs. The analyses are anchored in BSHMs developed by a series of interlinked EU projects (e.g. UKSeaMap, BALANCE, MESH, Mesh Atlantic, EUSeaMap 2012, and EUSeaMap 2016) and all maps are based on environmental data. Some EU Member States have used BSHMs as part of their MSFD Initial Assessments published in 2012. However, we conclude that BSHMs are a prerequisite for another key MSFD activity, i.e. mapping of potentially cumulative effects of multiple human stressors. Further, BSHMs seem to play a growing role with regard to evidence-based assessments of MPAs. With the upcoming second round of MSFD Initial Assessments due in 2018, including assessment of potentially cumulative pressures, there seems to be an increasing need for more BSHMs nationally, regionally and on a European scale.

We modelled and assessed the past, present and predicted future eutrophication status of the Baltic Sea. The assessment covers a 350-year period from 1850 to 2200 and is based on: (1) modelled concentrations of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorous (DIP), chlorophyll-a, Secchi depth, and oxygen under four different of nutrient input scenarios and (2) the application of a multi-metric indicator-based tool for assessment of eutrophication status: HEAT 3.0. This tool was previously applied using historical observations to determine eutrophication status from 1901 to 2012. Here we apply HEAT 3.0 using results of a biogeochemical model to reveal significant changes in eutrophication status from 1850 to 2200. Under two scenarios where Baltic Sea Action Plan (BSAP) nutrient reduction targets are met, we expect future good status will be achieved in most Baltic Sea basins. Under two scenarios where nutrient loads remain at 1997-2003 levels or increase, good status will not be achieved. The change from a healthy state without eutrophication problems in the open waters took place in the late 1950s and early 1960s. Following introduction of the first nutrient abatement measures, recovery began in some basins in the late 1990s, whilst in others it commenced in the beginning of the 21st century. Based on model results, we expect that the first basin to achieve a status without eutrophication will be Arkona, between 2030 and 2040. By 2060-2070, a status without eutrophication is anticipated for the Kattegat, Bornholm Basin and Gulf of Finland, followed by the Danish straits around 2090. For the Baltic Proper and Bothnian Sea, a good status with regard to eutrophication will not be expected before 2200. Further, we conclude that two basins are not likely to meet the targets agreed upon and to attain a status unaffected by eutrophication, i.e. the Gulf of Riga and Bothnian Bay. These results, especially the prediction that some basins will not achieve a good status, can be used in support of continuous development and implementation of the regional ecosystem-based nutrient management strategy, the HELCOM Baltic Sea Action Plan.

Efforts to attain good environmental status in the marine realm require decisions which cannot be done without knowledge of effects of different management measures. Given the wide diversity of marine ecosystems, multitude of pressures affecting it and the still poor understanding on linkages between those, there are likely no models available to give all the required answers. Hence, several separate approaches can be used in parallel to give support for management measures. We tested three completely different methods – a spatial impact index, a food web model and a Bayesian expert method. We found that a large uncertainty existed regarding the ecosystem response to the management scenarios, and that the three different modelling approaches complemented each other. The models indicated that in order to reach an improved overall state of the ecosystem nutrient reductions are the more effective of the two management variables explored, and that cumulative effects of the management of nutrient inputs and fishing mortality are likely to exist.

The objectives of this study are 1) to map the potential cumulative impacts of multiple human activities and stressors on the ecosystems in the transition zone between the North Sea and Baltic Sea, for Danish waters 2) to analyse differences in stressor contribution between the European Union’s Marine Strategy Framework Directive (MSFD, off-shore waters) and Water Framework Directive (WFD, coastal waters), and 3) to assess the local relative importance of stressors for 14 areas along a land-sea gradient, from inner fjords or coastal areas to offshore waters. The mapping of cumulative impacts is anchored in 35 datasets describing a broad range of human stressors and 47 ecosystem components ranging from phytoplankton over benthic communities to fish, seabirds and marine mammals, which we combined by means of a widely used spatial human impact model. Ranking of the stressor impacts for the entire study area revealed that the top five stressors are: ‘Nutrients’, ‘Climate anomalies’, ‘Non-indigenous species’, ‘Noise’ and ‘Contaminants’. The gradient studies showed that some stressors (e.g. ‘Nutrients’, ‘Shipping’ and ‘Physical modification’) have a relatively higher impact within the fjord/estuarine systems whilst others (e.g. ‘Fisheries’, ‘Contaminants’ and ‘Noise’) have relatively higher impact in the open waters. Beyond mapping of cumulative human impacts, we discuss how the maps can be used as an analytical tool to inform ecosystem-based management and marine spatial planning, using the MSFD and WFD as examples.

BEAT 3.0 is a multi-metric indicator-based tool for integrated assessments of marine biodiversity status implemented in R. It follows the structure and requirements of the EU Marine Strategy Framework Directive and allows for use of monotonic, unimodal, conditional, trend-based and qualitative indicators. The tool handles tabular data files (.txt format), in which the assessment structure and indicator results are specified. Integration of indicators is primarily based on weighted averaging, where both spatial assessment scale and ecosystem level are considered. Parallel to the biodiversity status assessment, a confidence assessment is also included. BEAT 3.0 uses HELCOM Assessment units and HELCOM core indicators as default but can be customized for use in any geographical region and any set of indicators. Funding Statement: BEAT 3.0 was developed in the HELCOM coordinated EU co-financed project ‘Baltic Sea project to boost regional coherence of marine strategies through improved data flow, assessments, and knowledge base for development of measures (BalticBOOST)’ EU grant number 11.0661/2015/712632/SUB/ENVC.2.

Much of the Baltic Sea is currently classified as 'affected by eutrophication'. The causes for this are twofold. First, current levels of nutrient inputs (nitrogen and phosphorus) from human activities exceed the natural processing capacity with an accumulation of nutrients in the Baltic Sea over the last 50-100 years. Secondly, the Baltic Sea is naturally susceptible to nutrient enrichment due to a combination of long retention times and stratification restricting ventilation of deep waters. Here, based on a unique data set collated from research activities and long-term monitoring programs, we report on the temporal and spatial trends of eutrophication status for the open Baltic Sea over a 112-year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the eutrophication status assessment based on a systematic quantitative approach using coefficients of variation in the observations. The classifications in our assessment indicate that the first signs of eutrophication emerged in the mid-1950s and the central parts of the Baltic Sea changed from being unaffected by eutrophication to being affected. We document improvements in eutrophication status that are direct consequences of long-term efforts to reduce the inputs of nutrients. The reductions in both nitrogen and phosphorus loads have led to large-scale alleviation of eutrophication and to a healthier Baltic Sea. Reduced confidence in our assessment is seen more recently due to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem-based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan.

The EU Marine Strategy Framework Directive (MSFD) requires that GoodEnvironmentalStatus (GEnS), is achieved for European seas by 2020. These may deviate from GEnS, its 11Descriptors, targets and baselines, due to endogenic managed pressures (from activities withinan area) and externally due to exogenic unmanaged pressures (e.g. climate change). Conceptualmodels detail the likely or perceived changes expected on marine biodiversity and GEnSDescriptors in the light of climate change. We emphasise that marine management has toaccommodate ‘shifting baselines’ caused by climate change particularly during GEnSmonitoring, assessment and management and ‘unbounded boundaries’ given the migration anddispersal of highly-mobile species. We suggest climate change may prevent GEnS being met,but Member States may rebut legal challenges by claiming that this is outside its control, forcemajeure or due to ‘natural causes’ (Article 14 of the MSFD). The analysis is relevant tomanagement of other global seas.

This study follows up on a previous assessment of eutrophication status in the Baltic Sea, which covered the period 2001–2006. The updated assessment is based on new eutrophication targets, an improved eutrophication assessment tool (HEAT 3.0) as well as monitoring data for the period 2007–2011. Based on classifications of eutrophication status in all Baltic Sea sub-basins, we reveal that during the assessment period 2007–2011, the entire open Baltic Sea was affected by eutrophication. This is a different conclusion compared to earlier assessments and studies. Whilst the confidence of the assessment was high or moderate in most basins, there were indications of declining confidence in some assessment units and improved confidence in others. The problems in confidence were mainly related to scarcity of in situ monitoring data on chlorophyll-a and Secchi depth. The potential implications of our results, e.g. the expansion of the eutrophic zone and declining confidence in the classifications of eutrophication status, are discussed in relation to the existing Baltic Sea-wide nutrient management strategy as well as future assessment activities.

People are dependent on the ocean and coasts and their resources for their survival and well-being. Coastal ecosystems of the Nordic countries, such as kelp forests, blue mussel beds, eelgrass mead ...

Nutrient enrichment of coastal marine waters caused by losses of nitrate (NO3 −) from agriculture is an increasing global problem. In the European Union, the Nitrates Directive (ND) of 1991 was meant to be a cornerstone in reducing eutrophication effects in coastal waters downstream from intensively farmed catchments. Although reductions in losses of nitrate have been attained, very few Member States have yet been able to reduce eutrophication effects caused by inputs of NO3 − from agriculture. We report trends in concentrations of NO3 − and chlorophyll-a (Chl-a) in Danish coastal and open marine waters during the period from 1996 to 2011 together with an assessment of eutrophication status based on multiple indicators (e.g. nutrient concentrations, Chl-a, submerged aquatic vegetation and benthic macroinvertebrates). Despite decreasing concentrations of both NO3 −and Chl-a, Danish coastal waters are not yet to be classified as ‘unaffected by eutrophication’. In order to improve future pan-European evaluations of the effectiveness of the ND, we argue for the added value of including indicators and assessment principles from other European Directives, i.e. the Water Framework Directive and the Marine Strategy Framework Directive.

Ever more extensive use of marine space by human activities and greater demands for marine natural resources has led to increases in both duration and spatial extent of pressures on the marine environment. In parallel, the global crisis of decreasing biodiversity and loss of habitats has revitalized scientific research on human impacts and lead to methodological development of cumulative pressure and impact assessments (CPIA). In Europe alone, almost 20 CPIAs have been published in the past 10 years and some more in other sea regions of the world. In this review, we have analyzed 40 recent marine CPIAs and focused on their methodological approaches. We were especially interested in uncovering methodological similarities, identifying best practices and analysing whether the CPIAs have addressed the recent criticism. The review results showed surprisingly similar methodological approaches in half of the studies, raising hopes for finding coherence in international assessment efforts. Although the CPIA methods showed relatively few innovative approaches for addressing the major caveats of previous CPIAs, the most recent studies indicate that improved approaches may be soon found.

Traditional and emerging human activities are increasingly putting pressures on marine ecosystems and impacting their ability to sustain ecological and human communities. To evaluate the health status of marine ecosystems we need a science-based, integrated Ecosystem Approach, that incorporates knowledge of ecosystem function and services provided that can be used to track how management decisions change the health of marine ecosystems. Although many methods have been developed to assess the status of single components of the ecosystem, few exist for assessing multiple ecosystem components in a holistic way. To undertake such an integrative assessment, it is necessary to understand the response of marine systems to human pressures. Hence, innovative monitoring is needed to obtain data to determine the health of large marine areas, and in an holistic way. Here we review five existing methods that address both of these needs (monitoring and assessment): the Ecosystem Health Assessment Tool; a method for the Marine Strategy Framework Directive in the Bay of Biscay; the Ocean Health Index (OHI); the Marine Biodiversity Assessment Tool, and the Nested Environmental status Assessment Tool. We have highlighted their main characteristics and analyzing their commonalities and differences, in terms of: use of the Ecosystem Approach; inclusion of multiple components in the assessment; use of reference conditions; use of integrative assessments; use of a range of values to capture the status; weighting ecosystem components when integrating; determine the uncertainty; ensure spatial and temporal comparability; use of robust monitoring approaches, and address pressures and impacts. Ultimately, for any ecosystem assessment to be effective it needs to be: transparent and repeatable and, in order to inform marine management, the results should be easy to communicate to wide audiences, including scientists, managers, and policymakers.

We review approaches and tools currently usedin Nordic countries (Denmark, Finland, Norway andSweden) for integrated assessment of ‘ecological status’sensu the EU Water Framework Directive as well asassessment of ‘eutrophication status’ in coastal and marinewaters. Integration principles for combining indicatorswithin biological quality elements (BQEs) and combiningBQEs into a final-integrated assessment are discussed.Specific focus has been put on combining different types ofinformation into indices, since several methods arecurrently employed. As a consequence of the variety ofmethods used, comparisons across both BQEs and watercategories (river, lakes and coastal waters) can be difficult.Based on our analyses, we conclude that some principlesand methods for integration can be critical and that aharmonised approach should be developed. Further, weconclude that the integration principles applied withinBQEs are critical and in need of harmonisation if we want abetter understanding of potential transition in ecologicalstatus between surface water types, e.g. when riverinewater enters a downstream lake or coastal water body.

In the 1980s, Danish coastal waters suffered from eutrophication and several nutrient management plans have been implemented during the years to improve ecological status. This study aims at giving a holistic ecosystem perspective on 25 years of mitigation measures. We report trends of nutrient inputs and the responses to these in various chemical and biological components. Nutrient inputs from land were reduced by ~50 % for nitrogen (N) and 56 % for phosphorus (P) since 1990. These reductions resulted in significant and parallel declines in nutrient concentrations, and initiated a shift in the dominance of primary producers towards reduced phytoplankton biomass (chlorophyll a concentration) and increased cover of macroalgae in deeper waters. In the last 5 years, eelgrass meadows have also expanded towards deeper waters, in response to improving water clarity. An expected improvement of bottom water oxygen conditions has not been observed, presumably because more frequent stratification and higher water temperatures have counteracted the expected positive effects of reduced nutrient inputs. The biomass of the benthic macrofauna decreased as expected, but it was composed of a drastic decline of filter feeders paralleled by a more moderate increase of deposit feeders. This shift was most likely induced by increasing stratification. The reduced benthic filtration along with the limited eelgrass cover probably kept relatively more particles in suspension, which can explain why improvements in the Secchi depths were modest. Overall, several ecosystem components demonstrated clear signs of improvement, suggesting that at least partial recovery is attainable. On this basis, we propose a conceptual scheme for recovery of shallow coastal ecosystems following marked reductions in nutrient inputs.

We report the development and application of a prototype tool for integrated assessment of chemical status in aquatic environments based on substance- and matrix-specific environmental assessment criteria (thresholds). The Chemical Status Assessment Tool (CHASE) integrates data on hazardous substances in water, sediments and biota as well as bio-effect indicators and is based on a substance- or bio-effect-specific calculation of a 'contamination ratio' being the ratio between an observed concentration and a threshold value. Values1.0 indicate areas potentially 'unaffected', while values1.0 indicate areas potentially 'affected'. These ratios are combined within matrices, i.e. for water, sediment and biota and for biological effects. The overall assessment used a 'one out, all out principle' with regard to each matrix. The CHASE tool was tested in the Baltic Sea and the North Sea in 376 assessment units. In the former, the chemical status was1.0 in practically all areas indicating that all areas assessed were potentially affected. The North Sea included areas classified as unaffected or affected. The CHASE tool can in combination with temporal trend assessments of individual substances be advantageous for use in remedial action plans and, in particular, for the science-based evaluation of the status and for determining which specific substances are responsible for a status as potentially affected.

The eutrophication status of the entire Baltic Sea is classified using a multi-metric indicator- based assessment tool. A total of 189 areas are assessed using indicators where information on reference conditions (RefCon), and acceptable devi- ation (AcDev) from reference condition could be combined with national monitoring data from the period 2001-2006. Most areas (176) are classified as 'affected by eutrophication' and only two open water areas and 11 coastal areas are classified as 'unaf- fected by eutrophication'. The classification is made by application of the recently developed HELCOM Eutrophication Assessment Tool (HEAT), which is described in this paper. The use of harmonized

Many studies have tried to explain spatial and temporal variations in biodiversity status of marine areas from a single-issue perspective, such as fishing pressure or coastal pollution, yet most continental seas experience a wide range of human pressures. Cumulative impact assessments have been developed to capture the consequences of multiple stressors for biodiversity, but the ability of these assessments to accurately predict biodiversity status has never been tested or ground-truthed. This relationship has similarly been assumed for the Baltic Sea, especially in areas with impaired status, but has also never been documented. Here we provide a first tentative indication that cumulative human impacts relate to ecosystem condition, i.e. biodiversity status, in the Baltic Sea. Thus, cumulative impact assessments offer a promising tool for informed marine spatial planning, designation of marine protected areas and ecosystem-based management, and may prove useful for setting limits on allowable levels of human impact on ecosystems. Many studies have tried to explain spatial and temporal variations in biodiversity status of marine areas from a single-issue perspective, such as fishing pressure or coastal pollution, yet most continental seas experience a wide range of human pressures. Cumulative impact assessments have been developed to capture the consequences of multiple stressors for biodiversity, but the ability of these assessments to accurately predict biodiversity status has never been tested or ground-truthed. This relationship has similarly been assumed for the Baltic Sea, especially in areas with impaired status, but has also never been documented. Here we provide a first tentative indication that cumulative human impacts relate to ecosystem condition, i.e. biodiversity status, in the Baltic Sea. Thus, cumulative impact assessments offer a promising tool for informed marine spatial planning, designation of marine protected areas and ecosystem-based management, and may prove useful for setting limits on allowable levels of human impact on ecosystems.

In the past 2 decades significant measures have been taken to reduce nitrogen and phosphorus discharges from Denmark by 50% and 80%, respectively. These nutrient reduction targets now appear within reach after several consecutive reduction measures are fully implemented, particularly toward diffuse discharges, and reduced nutrient concentrations are beginning to be observed in estuaries and the Danish straits. Phosphorus concentrations have declined by 22% to 57% from the early 1990s, mainly owing to improved treatment of urban and industrial wastewater. Changes in nitrogen concentrations, following reduction measures toward diffuse sources, were more recent and partly masked by large interannual variations in freshwater discharge. The response in marine nitrogen concentrations was delayed relative to the decline in riverine concentrations, most likely owing to large internal loading from the sediments. Two consecutive dry years appeared to be the triggering mechanism for nitrogen concentrations to decline. In the last 5 yr, nitrogen levels in estuaries and coastal waters have decreased up to 44% when interannual variations in freshwater discharge were accounted for. These first signs of environmental recovery were most pronounced in estuaries and coastal waters but also were apparent in open waters of the Kattegat, the Sound, and the Belt Sea. This case study is the first to document significant decreases in nutrient concentrations on a large regional scale resulting from an active management strategy to reduce nutrients from both diffuse and point sources.

Assessing the environmental status of marine ecosystems is useful when communicating key messages to policymakers or the society, reducing the complex information of the multiple ecosystem and biodiversity components and their important spatial and temporal variability into manageable units. Taking into account the ecosystem components to be addressed (e.g., biological, chemical, physical), the numerous biodiversity elements to be assessed (e.g., from microbes to sea mammals), the different indicators needed to be studied (e.g., in Europe, 56 indicators of status have been selected), and the different assessment scales to be undertaken (e.g., from local to regional sea scale), some criteria to define spatial scales and some guidance on aggregating and integrating information is needed. We have reviewed, from ecological and management perspectives, the approaches for aggregating and integrating currently available for marine status assessment in Europe and other regions of the world. Advantages and shortcomings of the different alternatives are highlighted. We provide some guidance on the steps toward defining rules for aggregation and integration of information at multiple levels of ecosystem organization, providing recommendations on when using specific rules in the assessment. A main conclusion is that any integration principle used should be ecologically-relevant, transparent and well documented, in order to make it comparable across different geographic regions.

Integrated assessment of the status of marine biodiversity is and has been problematic compared to, for example, assessments of eutrophication and contamination status, mostly as a consequence of the fact that monitoring of marine habitats, communities and species is expensive, often collected at an incorrect spatial scale and/or poorly integrated with existing marine environmental monitoring efforts. The objective of this Method Paper is to introduce and describe a simple tool for integrated assessment of biodiversity status based on the HELCOM Biodiversity Assessment Tool (BEAT), where interim biodiversity indicators are grouped by themes: broad-scale habitats, communities, and species as well as supporting non-biodiversity indicators. Further, we report the application of an initial indicator-based assessment of biodiversity status of Danish marine waters where we have tentatively classified the biodiversity status of Danish marine waters. The biodiversity status was in no areas classified as “unaffected by human activities.” In all the 22 assessment areas, the status was classified as either “moderately affected by human activities” or “significantly affected by human activities.” Spatial variations in the biodiversity status were in general related to the eutrophication status as well as fishing pressure. &nbsp

Deoxygenation is a global problem in coastal and open regions of the ocean, and has led to expanding areas of oxygen minimum zones and coastal hypoxia. The recent expansion of hypoxia in coastal ecosystems has been primarily attributed to global warming and enhanced nutrient input from land and atmosphere. The largest anthropogenically induced hypoxic area in the world is the Baltic Sea, where the relative importance of physical forcing versus eutrophication is still debated. We have analyzed water column oxygen and salinity profiles to reconstruct oxygen and stratification conditions over the last 115 y and compare the influence of both climate and anthropogenic forcing on hypoxia. We report a 10-fold increase of hypoxia in the Baltic Sea and show that this is primarily linked to increased inputs of nutrients from land, although increased respiration from higher temperatures during the last two decades has contributed to worsening oxygen conditions. Although shifts in climate and physical circulation are important factors modulating the extent of hypoxia, further nutrient reductions in the Baltic Sea will be necessary to reduce the ecosystems impacts of deoxygenation.

The EU Marine Strategy Framework Directive requires Member States to estimate the level of human impacts on their marine waters. We report the first attempt to quantify the magnitude and distribution of cumulative impacts of anthropogenic pressures for an entire regional sea, the Baltic Sea. We used a method which takes account of the sensitivity of different ecosystem components and gives scores for potential impacts in 5 km × 5 km areas. Our quantification of impacts was based on data layers of anthropogenic pressures and ecosystem components. The classification of the anthropogenic pressures follows the MSFD and the outcome of the index was targeted to facilitate the implementation of the directive. The study presents the cumulative impacts over the entire sea area and shows that the highest estimated impacts were in the southern and south-western sea areas and in the Gulf of Finland. The lowest index values were found in the Gulf of Bothnia. The results coincide with the population densities of the adjacent catchment areas. Fishing, inputs of nutrients and organic matter and inputs of hazardous substances comprised 25%, 30% and 30%, respectively, of the total cumulative impact. The approach used is transparent and the results are useful in regard to ecosystem-based management, e.g. for area-based management and assessments. Examples of uses are given together with analysis of the strengths and weaknesses of the approach.

Ferreira, João G. ... et al. -- 15 pages, 2 figures, 5 tables, In 2009, following approval of the European Marine Strategy Framework Directive (MSFD, 2008/56/EC), the European Commission (EC) created task groups to develop guidance for eleven quality descriptors that form the basis for evaluating ecosystem function. The objective was to provide European countries with practical guidelines for implementing the MSFD, and to produce a Commission Decision that encapsulated key points of the work in a legal framework. This paper presents a review of work carried out by the eutrophication task group, and reports our main findings to the scientific community. On the basis of an operational, management-oriented definition, we discuss the main methodologies that could be used for coastal and marine eutrophication assessment. Emphasis is placed on integrated approaches that account for physico–chemical and biological components, and combine both pelagic and benthic symptoms of eutrophication, in keeping with the holistic nature of the MSFD. We highlight general features that any marine eutrophication model should possess, rather than making specific recommendations. European seas range from highly eutrophic systems such as the Baltic to nutrient-poor environments such as the Aegean Sea. From a physical perspective, marine waters range from high energy environments of the north east Atlantic to the permanent vertical stratification of the Black Sea. This review aimed to encapsulate that variability, recognizing that meaningful guidance should be flexible enough to accommodate the widely differing characteristics of European seas, and that this information is potentially relevant in marine ecosystems worldwide. Given the spatial extent of the MSFD, innovative approaches are required to allow meaningful monitoring and assessment. Consequently, substantial logistic and financial challenges will drive research in areas such as remote sensing of harmful algal blooms, in situ sensor development, and mathematical models. Our review takes into account related legislation, and in particular the EU Water Framework Directive (WFD – 2000/60/EC), which deals with river basins, including estuaries and a narrow coastal strip, in order to examine these issues within the framework of integrated coastal zone management, The authors are grateful to the European Commission, International Council for the Exploration of the Sea, and the EU Joint Research Centre for the opportunity to develop this work. We would particularly like to thank Ana Cristina Cardoso (JRC), Carlos Berrozpe-Garcia and Sif Johansson (EC), and Claus Hagebro (ICES). We also wish to thank Mike Elliott for comments on an earlier version of the text

Development of a methodological approach to define and characterise type areas of selected elements of the ecosystems in the open parts of the Skagerrak and Kattegat. The selected elements are aquatic vegetation on hard substrate and macrozoobenthos. Furthermore, the project will develop quantitative ecological relationships and empirical models that describe the relationship between anthropogenic pressures and biological elements.

The Second International Symposium on Research and Management of Eutrophication in Coastal Ecosystems took place 20–23 June 2006 in Nyborg, Denmark. The Symposium was attended by more than 200 persons with a specific interest in eutrophication processes as well as a common interest in science-based management and implementation of nutrient reduction strategies. More than 120 oral presentations were made, mostly focussing on both science and management of nutrient enrichment and eutrophication. The papers in this Special Issue of Hydrobiologia are all based on presentations made at the Symposium.

We report the development of a prototype tool for modeling the risks of spreading of non-indigenous invasive species via ballast water. The tool constitutes of two types of models: a 3D hydrodynamical model calculates the currents in the North Sea and Danish Straits, and an agent-based model estimates the dispersal of selected model organisms with the prevailing currents calculated by the 3D hydrodynamical model. The analysis is concluded by a postprocessing activity, where scenarios of dispersal are combined into an interim estimate of connectivity within the study area. The latter can be used for assessment of potential risk associated with intentional or unintentional discharges of ballast water. We discuss how this prototype tool can be used for ballast water risk management and outline other functions and uses, e.g., in regard to ecosystem-based management and the implementation of the EU Marine Strategy Framework Directive.