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Eutrophication and persistent pollutants are two of the main environmental problems in European marine and freshwater ecosystems. As theytend to co-occur, interactive processes between eutrophication and contaminants are suggested, that may lead to environmental effects that cannot be predicted from each process alone. In order to predict the consequences of remedial measures (changing the input of organic matter, nutrients and contaminants) it is important to understand mech-anisms that alter the bioavailability and fate of contaminants. The environmental risks will depend on the speciation of contaminants and their association to media and matter and by that means affect exposure. Furthermore, the risks will depend on the mobility of the substances and their pathways in food chains. In 1995, the Swedish Environmental Protection Agency initiated a 5-year research program Interactions between EUtrophication and CONtaminants (EUCON). A background document was prepared listing a number of relevant questions and hypotheses. On the basis of this document a program was launched, addressing the prob-lems related to the interaction between eutrophication and contaminants (persistent organic compounds and trace metals) in the marine environment, with focus on the Baltic Sea, and in lakes. This paper summarizes the state-of-the-art, hypotheses and highlights from the research program with emphasis on the implications and applications of the results. [ABSTRACT FROM AUTHOR]

O[sub2] plays a key role in early sedimentary diagenetic processes, but the effect of most macrofaunal species on the pathways and rates of supply of O[sub2] into the seabed are not well known. We investigated the effect of the ophiuroid Amphiura filiformis, one of the dominant macrobenthic species on soft bottoms in the northeast Atlantic, at depths of ∼ 15-100 m, in a laboratory environment. We determined how the presence of the ophiuroid changed the total O[sub2] uptake of macrofauna-free sediment by combining measurements from a microcosm approach and an approach that uses microelectrodes and a flushed aquarium. We suggest that natural populations of A. filiformis can account for 80% of the total flux of O[sub2] into the soft bottom. At least 67% of this portion is due to the diffusion of O[sub2] across additional sediment-water interfaces excavated by the brittle star. [ABSTRACT FROM AUTHOR]

Human activities, especially increased nutrient loads that set in motion a cascading chain of events related to eutrophication, accelerate development of hypoxia (lower oxygen concentration) in many areas of the world's coastal ocean. Climate changes and extreme weather events may modify hypoxia. Organismal and fisheries effects are at the heart of the coastal hypoxia issue, but more subtle regime shifts and trophic interactions are also cause for concern. The chemical milieu associated with declining dissolved oxygen concentrations affects the biogeochemical cycling of oxygen, carbon, nitrogen, phosphorus, silica, trace metals, and sulfide as observed in water column processes, shifts in sediment biogeochemistry, and increases in carbon, nitrogen, and sulfur, as well as shifts in their stable isotopes, in recently accumulated sediments. [ABSTRACT FROM AUTHOR]

Abstract: Ecologists studying coastal and estuarine benthic communities have long taken a macroecological view, by relating benthic community patterns to environmental factors across several spatial scales. Although many general ecological patterns have been established, often a significant amount of the spatial and temporal variation in soft-sediment communities within and among systems remains unexplained. Here we propose a framework that may aid in unraveling the complex influence of environmental factors associated with the different components of coastal systems (i.e. the terrestrial and benthic landscapes, and the hydrological seascape) on benthic communities, and use this information to assess the role played by benthos in coastal ecosystems. A primary component of the approach is the recognition of system modules (e.g. marshes, dendritic systems, tidal rivers, enclosed basins, open bays, lagoons). The modules may differentially interact with key forcing functions (e.g. temperature, salinity, currents) that influence system processes and in turn benthic responses and functions. Modules may also constrain benthic characteristics and related processes within certain ecological boundaries and help explain their overall spatio-temporal variation. We present an example of how benthic community characteristics are related to the modular structure of 14 coastal seas and estuaries, and show that benthic functional group composition is significantly related to the modular structure of these systems. We also propose a framework for exploring the role of benthic communities in coastal systems using this modular approach and offer predictions of how benthic communities may vary depending on the modular composition and characteristics of a coastal system. [Copyright &y& Elsevier]

Abstract: An experimental mesocosm was used to investigate the feeding behaviour, particle size selectivity, gut throughput time and dietary selection of two holothurian species, Stichopus tremulus (Gunnerus) and Mesothuria intestinalis (Ascanius). Specimens usually only present at depths >1000m in the North-eastern Atlantic Ocean were collected from a relatively shallow (<100 m) cold-water fjordic system in Sweden and maintained in the laboratory. Both species exhibited a similar strategy for retrieving sediment particles from the sediment surface; feeding tentacles were used in a ‘grasping’ motion to pick up sediment particles. The rate at which the feeding tentacles were placed onto the sediment surface, however, differed between species (S. tremulus was three times quicker than M. intestinalis) resulting in a significant difference in gut throughput time. Both species, when offered different sized sediment particles, showed a preference for finer sediment and for nutritionally rich, pigment-enhanced, food patches. [Copyright &y& Elsevier]

Marine ecosystems world-wide are threatened by oxygen deficiency, with potential serious consequences for ecosystem functioning and the goods and services they provide. While the effects of hypoxia on benthic species diversity are well documented, the effects on ecosystem function have only rarely been assessed in real-world settings. To better understand the links between structural changes in macro- and meiofaunal communities, hypoxic stress and benthic ecosystem function (benthic nutrient fluxes, community metabolism), we sampled a total of 11 sites in Havstensfjord and Askeröfjord (Swedish west coast) in late summer, coinciding with the largest extent and severity of seasonal hypoxia in the area. The sites spanned oxic to anoxic bottom water, and a corresponding gradient in faunal diversity. Intact sediment cores were incubated to measure fluxes of oxygen and nutrients (NO 3 −, NO 2 −, NH 4 +, PO 4 3−, SiO 4) across the sediment-water interface. Sediment profile imaging (SPI) footage was obtained from all sites to assess structural elements and the bioturbation depth, and additional samples were collected to characterise sediment properties and macro- and meiofaunal community composition. Bottom-water O 2 concentration was the main driver of macrofauna communities, with highest abundance and biomass, as well as variability, at the sites with intermediate O 2 concentration. Meiofauna on the other hand was less sensitive to bottom-water O 2 concentration. Oxygen was the main driver of nutrient fluxes too, but macrofauna as well meiofauna were also significant predictors; DistLM analyses indicated that O 2 concentration, macrofaunal abundance or biomass, and meiofaunal abundance collectively explained 63%, 30% and 28% of the variation in sediment O 2 consumption, NH 4 +flux and PO 4 3− flux, respectively. The study provides a step towards a more realistic understanding of the link between benthic fauna and ecosystem functioning, and the influence of disturbance on this relationship, which is important for management decisions aimed at protecting the dwindling biodiversity in the coastal zones around the world. • Hypoxia decimates macrofauna, but fauna can still contribute to nutrient cycling. • Meiofauna is less sensitive to hypoxia compared with macrofauna. • The link between community structure and ecosystem function is mediated by context. [ABSTRACT FROM AUTHOR]

The Benthic Quality Index, BQI, is widely used for benthic quality assessment. Here, we investigated if spatial variation in the BQI can be reduced by accounting for the environmental factors instead of having different boundaries for different salinity regimes between status classes in the EU Water Framework Directive and Marine Strategy Framework Directive. For this purpose we tested salinity, sediment structure, and depth in a regression model to test their contribution to variations in BQI. The spatial variation in BQI was better explained by depth than by salinity or sediment structure. The proposed assessment method uses the residuals from the regression model between BQI and depth. With this method the variance in BQI between samples was reduced by 50% to 75% in the majority of situations. A method to establish the boundary between good and moderate status and how to derive EQR-values according to the WFD is presented., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)

A challenging aspect of benthic quality indices used for assessing the marine environment has been to compile reliable measures of the species' sensitivity to disturbances. Sensitivity values and their uncertainties can be calculated, but a problem to cope with is that the results may depend on the actual proportion of samples from disturbed and undisturbed environments. Here we calculated sensitivity values for each species along an artificial disturbance gradient created by bootstrapping varying numbers of samples from disturbed and undisturbed environments. The values were increasing, decreasing, or more or less constant along this gradient. The lowest value with the lowest uncertainty was adopted as the species sensitivity value. Analyses of the uncertainties indicated that the accuracy rather than the precision might be a concern. We suggest a method to exclude species for which the uncertainty is outside predefined limits as a precaution to reduce bias in the environmental status classification., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)