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Longline mussel farming has been proposed as a tool to remove nutrients and counteract the negative effects of eutrophication in coastal waters. In this study, we use coupled 3D hydrodynamic and ecological modelling in combination with measurements from a full-scale mitigation farm to assess the environmental effects of mitigation cultures in Skive Fjord, Denmark, a shallow eutrophic estuary. The results show that mitigation cultures decrease chl a concentration and increase Secchi depth especially in the surroundings of the farms but also on a basin scale. Fecal production by the mussels increases sedimentation below the farms but reduces ambient sedimentation, resulting in a net decrease in sedimentation of organic material on a basin scale. Comparisons with nutrient load reduction scenarios indicate that nutrient removal by mitigation cultures have a higher short-term impact on water quality parameters (chl a, Secchi depth and sedimentation) than nutrient removal using land-based measures.

Overvågningen af den marine bundvegetation foregår i dag hovedsageligt ved transekt observationer, som er dyre og tidskrævende, og som ikke giver overblik over den arealmæssige udbredelse af vegetationen. Nye teknologier, som fx droner og satellitter, bliver i stigende omfang anvendt i kystzonen og i SeaStatus projektet har vi undersøgt om og hvordan disse nye teknologier kan bidrage til at forbedre overvågningen af den marine bundvegetation.

This study aims to understand the economic and bio-physical conditions under which mussel farming is a cost-effective mitigation measure to improve water quality related to excess nitrogen in fjords and coastal areas. We set-up a mixed-integer optimization model including every farm in three agricultural catchments surrounding Limfjorden, the largest fjord in Denmark. We include a number of relevant nitrogen abatement measures, including agricultural land-use measures and mussel farming in the sea. The aim is to model the least costly combination of mitigation measures to improve water quality when agricultural, environmental and market conditions vary. We run three scenarios varying environmental conditions for mussel productivity and market opportunities for mussel-based products as organic animal feed. We analyze the resulting marginal abatement costs and draw insights about the potential scale of mussel farming for the different catchments. We show that mussel farming is a cost-effective option for 2 of the 3 catchments, but that decreasing mussel productivity over time may make the measure ineffective for one of the catchments, if a market for feed is not available. The possibility of a market for mussel-based organic feed significantly increases the share of nitrogen reduction done by mussels and decreases overall costs by up to 65%. Ultimately, the results indicate that, for catchments where environmental conditions are adequate, mussel farming can be a cost-effective nutrient reduction measure. Therefore, mussel farming can potentially increase the cost-effectiveness of incentive schemes aimed at reducing eutrophication in fjords and coastal waters.

Worldwide, coastal and marine policies are increasingly aiming for environmental protection, and eutrophication is a global challenge, particularly impairing near-coastal marine water bodies. In this context, mussel mitigation aquaculture is currently considered an effective tool to extract nutrients from such water bodies. Mussel mitigation farming using longline systems with loops of collector material is a well-developed technology and considered promising in the western Baltic Sea. Besides several spatially limited field studies, a suitable spatial model for site-specific implementation is still lacking. In this study, we present a modular spatial model, consisting of a spatial and temporal habitat factor model (Module 1), blue mussel growth model (Module 2), mussel farm model (Module 3), and an avoidance of food limitation model (Module 4). The modules integrate data from in situ monitoring, mussel growth experiments, and eco-physiological modelling for the western Baltic Sea, to estimate spatially explicit nutrient reduction potentials. The model is flexible with respect to farm setups and harvest times and considers natural variability, model uncertainty, and required hydrodynamics. Modelling results proved valid at all scales and modules, and point out key areas for efficient mussel mitigation farms in Danish, German and Swedish areas. Modelled long-term mean mitigation potentials for harvest in November reach up to 0.88 t N/ha and 0.05 t P/ha for a farm setup using 2 m depth-range of the water column and 3.0 t N/ha and 0.17 t P/ha using up to 8 m, respectively. For Danish water bodies, we demonstrate that in efficient areas, mitigation farms (18.8 ha, 90 km collector substrate in loops with 2 m depth-range) required

Effects of excess loading of nutrients to the marine environment can be mitigated by mussel cultures, basically through nutrient removal from the marine environment when shellfish are harvested. Shellfish farming also provide other goods and services to the marine environment primarily through the impact on water transparency caused by shellfish filtration. There is an increasing awareness of the mitigation potential in mussel culture in relation to eutrophication, but so far practical examples of culture on full scale devoted to mitigation are few. Further, impact of mussel farming on nutrient cycling, e.g. in the sediments below the culture units, has raised concerns. In this review, we clarify concepts in relation to nutrient mitigation and discuss goods and services delivered by mussel mitigation cultures and their impact on an ecosystem scale based primarily on results from studies in heavily eutrofied estuaries. A multi-criteria approach for site selection is presented based on experiences from Danish waters, and economic aspects of mitigation cultures are analysed in relation to use of the produced mitigation mussels. Future perspectives for extractive cultures are discussed in relation to source of excess nutrients.

The fate of anthropogenic reactive nitrogen (N) is often described as a cascade of different nitrogen forms and effects throughout the environment. In order to describe the fate in detail, a holistic approach covering the flow between the main environmental compartments is needed. Therefore a new management tools has been setup for an area in Denmark. A holistic approach is attempted by linking models for the main compartments (atmosphere, watershed and aquatic) and including a common emission scenario. The scenario describes a new technique for reducing ammonia emissions and at the same time increase N availability for crops using acidification of liquid manure and use of air cleaners in pig and poultry houses. Here the first results from a pilot study in Northern Jutland, Denmark, will be presented.

The multiple hydrodynamic and ecological processes characterizing estuarine systems make ecological modelling an essential tool for ecosystem-based management by increasing the understanding of the complex interactions and by quantifying the effects of various natural and anthropogenic pressures. The modelling technique used is dominated by computational simple box model approaches with a low spatial resolution and coupled 3D hydrodynamic-ecological models with high computational requirements. In this paper we present a novel concept (Flexsem) which combines the computational simplicity and condensed hydrodynamics from box models with a high spatial resolution characterizing coupled 3D models. The modelling framework Flexsem is a fast, flexible and user-friendly tool specifically targeted towards scientific and management challenges of the complex biogeochemical processes in coastal zone ecosystems. We use Flexsem to simulate the physical conditions in a typical Danish estuary, Horsens Fjord utilizing unstructured computational meshes to vary the complexity of grid geometry and resolution. The results showed that the model was able to reproduce the physical conditions in the estuary and provide reliable estimates for the tracer residence time.

PEG-aspariginase is a backbone chemotherapy agent in pediatric acute lymphoblastic leukemia and in some non-Hodgkin lymphoma therapies. Nurses lack standardized guidelines for monitoring patients receiving PEG-asparaginase and for educating patients/families about hypersensitivity reaction risks. An electronic search of 6 databases using publication years 2000-2015 and multiple professional organizations and clinical resources was conducted. Evidence sources were reviewed for topic applicability. Each of the final 23 sources was appraised by 2 team members. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) system was used to assign a quality and strength rating for each recommendation. Multiple recommendations were developed: 4 relating to nurse monitoring of patients during and after drug administration, 8 guiding hypersensitivity reaction management, and 4 concerning patient/family educational content. These strong recommendations were based on moderate, low, or very-low-quality evidence. Several recommendations relied on generalized drug hypersensitivity guidelines. Additional research is needed to safely guide PEG-asparaginase monitoring, hypersensitivity reaction management, and patient/family education. Nurses administering PEG-asparaginase play a critical role in the early identification and management of hypersensitivity reactions.

Nutrient loading of aquatic ecosystems results in more food for benthic macrofaunal communities but also increases the risk of hypoxia, resulting in a reduction or complete loss of benthic biomass. ...

Eelgrass depth limits and water clarity in the Skive Fjord estuarine system have not improved despite nutrient input reductions of 30%. Long-term monitoring data (1989–2010) were used to investigate the underlying causes. Dissolved inorganic and organic nitrogen concentrations decreased significantly over time, whereas particulate organic nitrogen concentration, assumed to consist primarily of phytoplankton and phytoplankton detritus and calculated as a proportional factor to chlorophyll a, did not change. Total organic carbon, mostly of autochthonous origin, remained constant despite reduced nitrogen concentrations, resulting in an increasing C:N ratio of the organic material in the water column. Phytoplankton primary production also remained constant suggesting that phytoplankton growth was only limited by nitrogen to a minor degree. Alleviated grazing pressure caused by a reduction in the blue mussel standing stock and a pelagic food web dominated by jellyfish may have contributed to the constantly high phytoplankton levels. Particulate inorganic matter, likely reflecting sediment resuspension, increased over time, most probably in response to removal of blue mussels and declining eelgrass cover. The Skive Fjord estuarine system is affected by multiple pressures—nutrient enrichment, mussel dredging and climate change that must be addressed together for water clarity to improve and eelgrass to recover.

The relative importance of nutrient inputs from streams and the open sea for the water quality is a key issue for an effective management of eutrophication problems in estuaries. In order to resolve this question we have developed a coupled 3D hydrodynamic–ecological model with numerical nitrogen tracking for Horsens estuary, which is a typical Danish estuary that is shallow and well ventilated with water from the adjacent open sea. The nitrogen tracking technique revealed that nitrogen discharges from local streams accounted for the major part (40%–90%) of the nitrogen in NO3, NH4 and detritus whereas only 15% to 50% of the nitrogen in phytoplankton originated from streams. Effects of nitrogen loading reductions were most pronounced for nutrient concentrations and Chl a concentrations whereas the light condition was only slightly improved. The impact of stream nitrogen reductions on nitrate concentrations, Chl a concentrations and light attenuation was respectively 7, 2 and 3 times higher than the impact of open sea nitrogen reductions. Hence, even in estuaries that are well ventilated with water from the adjacent sea significant environmental improvements can be expected after reduction in local nutrient discharges.

The development of off-shore wind farms along the coastline of north-west Europe is rapidly increasing; it is therefore important to study how this will affect the marine environment. The present study modelled the growth and feed-backs of blue mussels in natural beds and on turbine foundations in an off-shore wind farm (OWF) located in a shallow coastal ecosystem by coupling a dynamic energy budget (DEB) model to a small-scale 3D hydrodynamic–biogeochemical model. The model results showed that blue mussels located higher up in the water column on turbine pillars achieved a 7–18 times higher biomass than those located on the scour protection because the former experience an enhanced advective food supply. Secondly, the high biomasses of blue mussels on foundations created local ‘hot spots’ of biological activity and changed ecosystem dynamics due to their feed-backs e.g. ingestion of microplankton and copepods, excretion of ammonium and egestion of faecal pellets. The model results were supported by field measurements around foundations of Chl a concentrations and biomasses of the fauna community. Our study emphasised that OWFs seem to be particularly favourable for blue mussels in the western Baltic Sea and that the functioning of the OWFs as artificial reef ecosystems depends upon how the blue mussels interact with their local pelagic and benthic environment.

The effects of 2 polychaetes, Nereis diversicolor and Arenicola marina, on the microbial mineralization of the organic contaminant pyrene, a polycyclic aromatic hydrocarbon (PAH), were followed over 44 d. We also examined whether the effect of the polychaetes was caused by enhanced oxygen supply, altered pyrene bioavailability and/or a changed abundance or activity of pyrenedegrading bacteria. The presence of polychaetes enhanced microbial pyrene mineralization by 180 to 200% compared with defaunated sediment. Collectively, the replicates of the different treatments showed that mineralization rates were positively correlated with the amount of oxidized sediment, which comprised mainly the 3 mm surface layer and zones around burrows (burrow sediment). The biogenic sediment structures had similar mineralization potential and abundance of pyrene-degrading bacteria as surface sediments. Pyrene mineralization potential in bulk (reduced and presumably anoxic) sediment was significantly lower than for surface and burrow sediments. However, when the bulk sediments were oxidized, mineralization rates increased rapidly. Collectively, these data indicate that oxygen availability controlled pyrene mineralization in these experiments. On the other hand, the presence of the polychaetes significantly reduced the bioavailability of pyrene to the microbial degraders. Pyrene bioavailability in burrow sediment was always lower than the bioavailability in both surface and bulk sediments. In addition, N. diversicolor and especially A. marina decreased the bioavailability of pyrene in surface sediments compared with that of surface sediments in the non-bioturbated control. In conclusion, these polychaetes enhanced microbial pyrene mineralization significantly and this enhancement seemed to be caused by the increased oxygen supply due to burrow construction and irrigation. In contrast, these worms decreased pyrene bioavailability and, hence, counteracted to some extent the stimulating effect of irrigation.

New agricultural technologies can reduce the emissions of ammonia associated with e.g. manure spreading. Reduced emissions to the atmosphere have the potential to limit the negative impacts of reactive nitrogen (Nr) on terrestrial ecosystems and human health. But could the new technologies transfer more Nr to the watershed instead and hence lead to increased eutrophication in the aquatic environment? In order to answer questions like this a holistic approach is necessary. Therefore a new management tools is under development at the Danish Center for Energy and Environment (DCE), Aarhus University, where models describing the fate of Nr in the relevant compartments (atmosphere, watershed and aquatic systems) are linked.

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.

The bioavailability of the PAH (polycyclic aromatic hydrocarbon) model compound pyrene to the deposit-feeding polychaete Arenicola marina was studied at pyrene concentrations ranging from 0 to 10 ppm. By manipulating the sediment organic content, different distributions of pyrene between particle-associated pyrene, pyrene bound to dissolved organic matter (DOM) and freely dissolved pyrene were obtained at the same pyrene concentration in bulk sediment. The results showed that organic matter influenced the partitioning of pyrene in the sediment matrix. The concentration of dissolved pyrene in porewater and overlying water was higher in sediment with a high organic content, probably due to an increased DOM concentration. In contrast, the concentra- tion of freely dissolved pyrene was, as expected, higher in sediment with low organic content. Bio- accumulation of pyrene correlated very well with the amount of pyrene passing through the gut, indi- cating that particle-associated pyrene is bioavailable and that ingestion is an important uptake route. Body burden was correlated neither with total dissolved pyrene nor with freely dissolved pyrene, leading one to reject the hypothesis that pyrene uptake is due to simple diffusion processes from water to sediment. Furthermore, no relation between bioaccumulation and dissolved pyrene passing through the gills via irrigation was observed. Bioconcentration factors relative to sediment and water declined with increasing external pyrene concentrations, enhancing the likelihood of sediment toxi- city being underestimated when using these factors in risk assessment.

I forbindelse med udarbejdelsen af det faglig grundlag for næste generation af vandplaner, har vi udviklet et koncept, som inddrager en række forskellige kriterier for at vurdere miljøtilstanden i marine områder. Kriterierne er: 1) forekomst af iltsvind, 2) potentiel kvælstofbegrænsning, 3) lyssvækkelse i vandsøjlen i forhold til dybdeudbredelse af ålegræs, 4) økologiske effekter af iltsvind og 5) klorofyl koncentration. I projektet er anvendt både empiriske og dynamiske modeller for at kvantificere sammenhængen mellem miljøtilstand og næringsstoftilførsler. I denne præsentation beskrives, hvordan miljømål kan kvantificeres, og hvordan en vægtet model for ovenstående kriterier er anvendt for at beregne den maksimalt acceptable tilførsel (måltilførsel) for opnåelse af ’god økologisk tilstand’. Konceptet er anvendt på 29 vandområder. I præsentationen viser vi, hvordan konceptet virker for områder, som er tæt på ’god økologisk tilstand’ og i områder, hvor der er behov for en meget betydelig reduktion af de nuværende tilførsler. Endvidere kvantificerer vi det samlede indsatsbehov i forbindelse med næste generation af vandplaner. I forbindelse med udarbejdelsen af det faglig grundlag for næste generation af vandplaner, har vi udviklet et koncept som inddrager en række forskellige kriterier for at vurdere miljøtilstanden i marine områder. Kriterierne er: 1) forekomst af iltsvind, 2) potentiel kvælstofbegrænsning, 3) lyssvækkelse i vandsøjlen i forhold til dybdeudbredelse af ålegræs, 4) økologiske effekter af iltsvind og 5) klorofylkoncentration. I projektet er anvendt både empiriske og dynamiske modeller for at kvantificere sammenhængen mellem miljøtilstand og næringsstoftilførsler. I denne præsentation beskrives, hvordan miljømål kan kvantificeres, og hvordan en vægtet model for ovenstående kriterier er anvendt for at beregne den maksimalt acceptable tilførsel (måltilførsel) for opnåelse af ’god økologisk tilstand’. Konceptet er anvendt på 29 vandområder. I præsentationen viser vi, hvordan konceptet virker for områder, som er tæt på ’god økologisk tilstand’ og i områder, hvor der er behov for en meget betydelig reduktion af de nuværende tilførsler. Endvidere kvantificerer vi det samlede indsatsbehov i forbindelse med næste generation af vandplaner.

Miljømålet for god økologisk tilstand i de marine vandområder er bestemmende for hvilken belastning områderne kan tåle (dvs. for målbelastningen). Det er derfor en forudsætning for vandplanerne, at man har fastsat grænsen mellem God og Moderat (G-M) tilstand.G-M grænserne for sommerklorofylkoncentrationer kan fastlægges ud fra kendskab til klorofylkoncentrationer i en referencesituation og en såkaldt interkalibreret EQR værdi, som definerer den tilladelige forskel mellem referencesituationen og G-M grænsen. For danske kystområder er referenceniveauet for klorofyl undersøgt ved at anvende de modeller, der er udviklet til den marine Vandplans-værktøjskasse. Undersøgelsen er baseret på estimater af referencebelastningen, der bygger på basis af data fra DCE/Aarhus Universitet og data fra Baltic Nest Institute. Hvor det er muligt er der anvendt en ensemble tilgang, hvor referencetilstandens klorofylniveau er beregnet med begge de 2 typer af modelværktøjer, statistiske modeller og mekanistiske modeller, der indgår i værktøjskassen (se abstract om disse). På basis af resultaterne og en typeopdeling af havområder er G-M grænsernefastlagt for de enkelte vandområder. Denne præsentation vil gennemgå de beregninger der er foretaget og diskutere resultater og usikkerheder. Miljømålet for god økologisk tilstand i de marine vandområder er bestemmende for hvilken belastning områderne kan tåle (dvs. for målbelastningen). Det er derfor en forudsætning for vandplanerne, at man har fastsat grænsen mellem God og Moderat (G-M) tilstand.G-M grænserne for sommerklorofylkoncentrationer kan fastlægges ud fra kendskab til klorofylkoncentrationer i en referencesituation og en såkaldt interkalibreret EQR værdi, som definerer den tilladelige forskel mellem referencesituationen og G-M grænsen. For danske kystområder er referenceniveauet for klorofyl undersøgt ved at anvende de modeller, der er udviklet til den marine Vandplans-værktøjskasse. Undersøgelsen er baseret på estimater af referencebelastningen, der bygger på basis af data fra DCE/Aarhus Universitet og data fra Baltic Nest Institute. Hvor det er muligt er der anvendt en ensemble tilgang, hvor referencetilstandens klorofylniveau er beregnet med begge de 2 typer af modelværktøjer, statistiske modeller og mekanistiske modeller, der indgår i værktøjskassen (se abstract om disse). På basis af resultaterne og en typeopdeling af havområder er G-M grænserne fastlagt for de enkelte vandområder. Denne præsentation vil gennemgå de beregninger der er foretaget og diskutere resultater og usikkerheder.

Irrigation by the lugworm Arenicola marina has a major impact on solute transport and distributions in nearshore environments due to the subsurface injection of overlying water at depth (typically 15-20 cm) and the resulting advective water flow within the sediment back toward the sediment surface. A mechanistic one-dimensional diffusion and advection model which emphasizes the injection and advective transport of solutes within the sediment not described in previous irrigation models was developed to describe irrigation by A. marina. The model was verified by comparing its results to measured pore-water tracer (Br) profiles and it is concluded that the model adequately described the experimental tracer profiles, including the characteristic subsurface peaks often observed in sediments inhabited by lugworms. There are three model output parameters, P(t), K and β, which contain biological information about irrigation. P(t) is the pumping rate of A. marina [ml/h]. K describes the ratio between the area of the advective transport zone (i.e. zone affected by the return advective transport of irrigation water) and the total area of the sediment core [dimensionless]. Finally, β is a measure of the increased effectively diffusive transport due to the presence of A. marina [cm 2 /h]. Pumping rates were estimated to 8.8-21.3 mL H 2 O/g/h which are within the range of reported values for A. marina. Model calculations of K were between 0.1 and 0.53, equivalent to areas of 5.5 to 29 cm 2 , indicating that water was more or less locally transported to the sediment surface. In all simulations β was greater than 1 indicating that diffusion-like transport was enhanced by lugworms, affecting solute transport.

Coastal ecosystems worldwide are under pressure from human-induced nutrient inputs, fishing activities, mariculture, construction work, and climate change. Integrated management instruments handling one or more of these problems in combination with socioeconomic issues are therefore necessary to secure a sustainable use of resources. In the Limfjord, a temperate eutrophic estuary in Denmark, nutrient load reductions are necessary to fulfill EU regulations such as the Water Framework Directive (WFD). The expected outcome of these load reductions is an improved water quality, but also reduced production of the abundant stock of filter-feeding blue mussels, Mytilus edulis. This is expected to have significant economic consequences for the million-euro mussel fishing industry taking place in the Limfjord today. We developed a bioeconomic model that can be used to explore the consequences of load reductions for mussel fishery as practiced today, as well as potential management options, to obtain an economically and ecologically sustainable mussel fishery. Model simulations clearly demonstrate a substantial decrease in mussel production after the nutrient load reductions necessary to obtain the targets in the WFD. With today's practice, the mussel fishery in the Limfjord will not be profitable in a future, less eutrophic estuary. However, model simulations also revealed that mussel fishery can be profitable after implementation of the WFD with a reduction in the total fishing quota, fewer fishing vessels, and a higher fishing quota per vessel.

Long-line mussel farming has been proposed as a mitigation tool for removal of excess nutrients in eutrophic coastal waters. A full-scale mussel farm optimized for cost efficient nutrient removal was established in the eutrophic Skive Fjord, Denmark where biological and economic parameters related to nutrient removal was monitored throughout a full production cycle (1 yr). The results showed that it was possible to obtain a high area specific biomass of 60 t WW ha(-1) eqvivalent to a nitrogen and phosphorus removal of 0.6-0.9 and 0.03-0.04 t ha(-1)yr, respectively. The analysis of the costs related to establishment, maintenance and harvest revealed that mussel production optimized for mitigation can be carried out at a lower cost compared to mussel production for (human) consumption. The costs for nutrient removal was 14.8 € kg(-1)N making mitigation mussel production a cost-efficient measure compared to the most expensive land-based measures.

Invasive species and bottom-water hypoxia both constitute major global threats to the diversity and integrity of marine ecosystems. These stressors may interact with unexpected consequences, as invasive species that require an initial environmental disturbance to become established can subsequently become important drivers of ecological change. There is recent evidence that improved bottom-water oxygen conditions in coastal areas of the northern Baltic Sea coincide with increased abundances of the invasive polychaetes Marenzelleria spp. Using a reactive-transport model, we demonstrate that the long-term bioirrigation activities of dense Marenzelleria populations have a major impact on sedimentary phosphorus dynamics. This may facilitate the switch from a seasonally hypoxic system back to a normoxic system by reducing the potential for sediment-induced eutrophication in the upper water column. In contrast to short-term laboratory experiments, our simulations, which cover a 10-year period, show that Marenzelleria has the potential to enhance long-term phosphorus retention in muddy sediments. Over time bioirrigation leads to a substantial increase in the iron-bound phosphorus content of sediments while reducing the concentration of labile organic carbon. As surface sediments are maintained oxic, iron oxyhydroxides are able to persist and age into more refractory forms. The model illustrates mechanisms through which Marenzelleria can act as a driver of ecological change, although hypoxic disturbance or natural population declines in native species may be needed for them to initially become established. Invasive species are generally considered to have a negative impact; however, we show here that one of the main recent invaders in the Baltic Sea may provide important ecosystem services. This may be of particular importance in low-diversity systems, where disturbances may dramatically alter ecosystem services due to low functional redundancy. Thus, an environmental problem in one region may be either exacerbated or alleviated by a single species from another region, with potentially ecosystem-wide consequences.

Effects of bioturbation by the common lugworm Arenicola marina on the fate of oil hydrocarbons (alkanes and PAHs) were studied in situ during a simulated oil spill in a shallow coastal area of Roskilde fjord, Denmark. The fate of selected oil compounds was monitored during 120 d using GC-MS and bioturbation activity (feces production and irrigation) was measured regularly during the experiment and used as input parameters in a mechanistic model describing the effects of A. marina on the transport and degradation of oil compounds in the sediment. The chemical analytical data and model results indicated that A. marina had profound and predictable effects on the distribution, degradation and preservation of oil and that the net effect depended on the initial distribution of oil. In sediment with an oil contaminated subsurface-layer A. marina buried the layer deeper in the sediment which clearly enhanced oil persistence. Conversely, A. marina stimulated both the physical removal and microbial degradation of oil compounds in uniformly oil contaminated sediments especially in deeper sediment layers (10-20 cm below the surface), whereas the fate of oil compounds deposited in surface layers (0-5 cm) mainly was affected by removal processes induced by wave actions and other bioturbating infauna such as Nereis diversicolor, Corophium volutator and Hydrobia spp. present in the experimental plots.

"Growth of human activities often conflict with nature conservation requirements and integrated assessments are necessary to build reliable scenarios for management. In the Limfjord, Denmark???s largest estuary, nutrient loading reductions are necessary to fulfill EU regulations criteria, such as the Water Framework Directive (WFD). Cuts in nutrient loadings do not necessarily result in corresponding reductions in eutrophication impacts or in improving primary and higher trophic-level production. Similarly, the socioeconomic consequences of a mussel fishery and aquaculture production are complex and hard to predict. This study focuses on the usefulness of a System Approach Framework (SAF) implementation for stakeholder understanding of complex systems and development of sustainable management. Ecological-social-economic (ESE) model simulations clearly demonstrated the potential problems of WFD implementation for mussel fishers and mussel farmers. Simulation of mussel fishery closures resulted in a tenfold increase in the hitherto fishable mussel biomass and a similar decrease in the biomass of shallow-water mussels and medium-sized ones in deep water. A total closure of the mussel fishery could result in an annual profit loss of ~???6.2 million. Scenario simulation of the introduction of one, two, three, and four mussel culture farms of ~19 ha showed that the introduction of line-mussels would decrease the biomass of wild mussels both in shallow and deep waters, affecting the catch and profit of fishers. The SAF, which included consultation with stakeholders at all stages, differs from the traditional public consultation process in that (1) communication was verbal and multilateral, (2) discussion among stakeholders was facilitated, and (3) stakeholder opinions and priorities formed the focus of the ESE assessment."

Eutrophication of coastal water bodies by massive anthropogenic nutrient inputs is a serious global challenge. For Denmark, a range of mitigation measures has successfully led to reduced amounts of nutrients and algal biomass within its surrounding coastal water bodies over the past decades. At the same time, however, a considerable decline in the abundance of benthic filter feeders, in particular of blue mussels (Mytilus edulis), was observed. Blue mussels play a substantial role in filtering different kinds of particles out of the water and this strongly contributes to reduced phytoplankton concentrations and improved light conditions in the aquatic environment.The implementation of blue mussel farms in Danish coastal water bodies has therefore been recently suggested as a potentially effective tool for mitigating coastal eutrophication on a national scale. The general idea in this study is to utilize the capability of these strong suspension-feeders to extract large amounts of suspended particle loads and algal biomass from the water column. Incorporated nutrient loads in harvested mussels will be recycled as organic protein source and bottom light conditions in the water will improve. Blue mussel farming itself, of course, requires to be economically feasible and cause least constrains to other important utilizations of Danish coastal waters. In a national-scale spatial context, we therefore asses (a) potential yields of blue mussel farms by numerical and spatial modelling, (b) possible risks of loss to the farms by e.g. predators and physical exposure, (c) possibly conflicting interests such as protected areas, economic utilization, tourism/recreation, and public acceptance. These evaluations will be based on a range of layered spatial datasets. Finally, we aim to develop a multi-criteria site selection tool for optimized and scientifically based decision-making for blue mussel farms as an effective mitigation tool in Danish coastal waters.

Vandrammedirektivet foreskriver, at medlemsstaterne skal indsamle oplysninger om type og omfang af de signifikante menneskeskabte belastninger og deres virkninger på kystvandenes tilstand. Forskning har tidligere vurderet, at den mest betydende presfaktor er belastningen med N og P. En række andre presfaktorer kan imidlertid belaste det marine miljø, men der findes ikke en samlet vurdering af betydningen af disse presfaktorer for miljøtilstanden i kystvandene, som den defineres i VRD. For at forbedre plangrundlaget i 3. generations vandplaner har Miljøstyrelsen derfor iværksat indsatser til belysning af andre presfaktorer.I denne analyse har vi på baggrund af strukturerede reviews analyseret presfaktorerne: Råstofindvinding, klapning og graveaktiviter, fysiske konstruktioner, fiskeri, skibstrafik, plastik, miljøfarlige stoffer og invasive arter. De invasive arter er repræsenteret ved 4 karakteristiske arter. Analysen har taget udgangspunkt i, at tilstedeværelse alene ikke er tilstrækkelig, der skal være en påvirkningsmekanisme på et eller flere af kvalitetselementerne (fytoplankton, makroalger, angiospermer og bundfauna) og/eller støtteparametrene (iltforhold og sigtdybde), for at det kan siges, at presfaktorerne har en virkning jf. VRD. Da indsatser for at forbedre vandmiljøet bliver planlagt på niveau af vandområder, skal effekten af presfaktoren endvidere kunne detekteres på dette niveau. For at kunne beskrive og dokumentere en evt. betydende påvirkning af en given presfaktor på kvalitetselementerne i et vandområde er det endvidere nødvendigt, at der er et tilstrækkeligt datagrundlag til at analysere den konkrete sammenhæng mellem presfaktoren og kvalitetselementerne/støtteparametrene.På baggrund af kriterier om dokumenteret påvirkningsmekanisme, potentiel væsentlighed og datagrundlag er de nævnte presfaktorer blevet gennemgået og vi præsenterer her resultater og anbefalinger vedrørende inkludering af presfaktorerne i analyserne i 3. generations vandplaner.

Eutrophication of coastal water bodies by massive anthropogenic nutrient inputs is a serious global challenge. Suspended mitigation cultures of blue mussels have been suggested as a tool to remove nutrients through harvesting from eutrophic systems like the Western Baltic Sea. The general idea of mitigation mussel farming is that the mussels remove nutrients contained in particles (mainly phytoplankton) directly from the water through their feeding activity and incorporate them into animal tissue during growth. In the present study, mussel farm production and nutrient mitigation potential was estimated for the Western Baltic Sea.We integrated data from field experiments and national monitoring programs within a sequence of numerical, statistical, and spatial models. Mussel individual growth was estimated by a dynamic Energy Budget (DEB) model and the results were used to make a more simple statistical model of mussel growth versus monthly data of temperature, salinity and chlorophyll-a (Chl a) concentrations. A spatial model estimated long-term (2008-2017) monthly means of environmental variables on 1km2 scale based on monitoring data from Denmark, Sweden and Germany. The statistical growth model was imposed on the spatial environmental data and up-scaled to farm production taking bathymetry (farm depth) and mussel densities into account. For the whole study area, water quality affects the growth of individual mussels in the following order of impact: salinity > Chl-a > temperature. When selecting the 10% of sites with highest farm production and nutrient mitigation potentials, the north-west coast of Sweden, the Limfjorden, Mariager Fjord, Isefjord and the area ranging from the Danish Belt Sea to the Kiel Bay in Germany are part of the selection. Site-selection for marine mitigation aquaculture can be an important part of sustainable marine spatial planning considering both farm production potential, as well as environmental and socio-economic goals and interests.