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The EU Water Framework Directive (WFD) requires the achievement of good ecological and chemical status in European river basins. However, evidence is increasing that a majority of European water bodies will not achieve this goal. Nutrient emissions and related eutrophication together with hydromorphological alterations have been suggested as the major driving forces of this insufficient ecological status. MODELKEY (511237 GOCE, FP6) provides strong evidence that toxic chemicals also affect the ecological status of European rivers. This was demonstrated in the case study rivers Elbe, Scheldt and Llobregat on different scales. This paper summarises key findings of MODELKEY including recommendations for WFD implementation. We • provide evidence of toxic stress in aquatic ecosystems, • provide evidence that impairment of ecological status results from impact of multiple stressors, • suggest a tiered approach to assess impact of chemicals on ecological status, • suggest a new approach for deriving candidate compounds for monitoring and prioritisation, • call for consideration of bioavailability and bioaccumulation in chemical status assessments, • suggest improvements for WFD water quality monitoring programmes, • provide new integrated tools for basin-scale risk assessment and decision making, • developed a Decision Support System to support river basin management. These key results will be presented in a series of ten integrated sections; for the scientific details please refer to publications listed on the MODELKEY website (/). This article also looks beyond MODELKEY and proposes a combination of MODELKEY diagnostic tools with recent ecological methods to further improve effectiveness of river basin management. [ABSTRACT FROM AUTHOR]

Between 1992 and 1997 the effects of contaminated sediment on an aquatic community were studied in outdoor mesocosms (2m3), one filled with 'naturally' polluted sediment from the sedimentation area 'Ketelmeer', the other with relatively clean sediment from the shallow lake 'Oostvaardersplassen'. Negative effects of the contaminatedsediment were observed on the population development of the amoeba species Arcella megastoma and Difflugia accuminata, the mysid shrimp Neomysis integer, the microlepidopteran Cataclysta lemnata and the cladoceran community, whereas the biting midge Culex sp. showed a preference for the contaminated system. The reduction of the grazing capacity of the cladoceran community resulted in higher algal densities in the 'Ketelmeer' mesocosm despite the fact that nutrient concentrations in the water column of both mesocosms were comparable. (c) 1998 IAWQ. Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]

Marine and freshwater mesocosm-scale experiments with contaminated sediments have shown that there is a direct relationship between the accumulated contaminant levels and the feeding habits of the organismsused. The highest levels of PAHs and PCBs were found in the sedimentfeeding lugworm Arenicola marina and in Tubifex worms. The levels ofcontaminants in the suspension feeding mussels Mytilus edulis and the zebra mussels, Dreissena polymorpha, were not influenced by the contaminant content of the sediments, but were related instead to level of contaminants in the sea water above. Intermediate levels were found in the baltic tellin, Macoma balthica, which is a filter feeder as well as a deposit feeder, depending on the availability of food. The results show that there is no simple relationship between contaminantconcentration in the sediments and bioavailability. Higher levels ofcontaminants do not necessarily lead to higher levels of these contaminants in Arenicola, due to differences in the sediment structure and the ageing of the contamination. On the other hand. toxic effects are related to the internal concentrations of certain chemicals. The internal concentrations observed in Arenicola may provide a good estimation of the true bioavailability of sedimentary contaminants and canalso be used as an indicator for potential environmental effects. (c) 1998 IAWQ. Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]

In order to assess the importance of the mode of feeding for the bioaccumulation of contaminants from sediments, three marine benthic invertebrates, with different feeding habits, were exposed to contaminated sediments in outdoor mesocosms. Residue analyses were carried out for several polychlorinated biphenyls and polycyclic aromatic hydrocarbons after exposure periods of 60 to 140 days. It was shown that sediment ingestion is a major uptake route for the sediment-feeding lugworm, Arenicola marina, and for the facultative deposit-feeding baltictellin, Macoma balthica. Residues in the filter-feeding mussel, Mytilus edulis, appeared to be independent of contaminant concentrations in the sediment. The difference between deposit and filter-feeding bivalves was confirmed in experiments involving the baltic tellin, withdifferences in the food availability in the overlying water. A simple linear regression model was used to describe contaminant concentrations in sediment-feeding invertebrates as a function of concentrations in sediment. A correction for the accumulation from water was made by subtracting the concentrations in filter feeders. It was concludedthat chemical equilibrium partitioning alone is not sufficient for the assessment of the risks of contaminated sediments to sediment-feeding invertebrates, but that feeding habits should also be considered. [ABSTRACT FROM AUTHOR]

The commercial farming of Atlantic salmon, Salmo salar, may require the periodic application of emamectin benzoate (EB) treatments to reduce the effects of biological pests, such as sea lice. As a result, EB is detected in sediments beneath these fish farms at considerable levels. Literature sediment toxicity data for EB for marine benthic species is only available for 10-day sediment toxicity tests, which might be too short to assess field effects. Here, we present a sediment toxicity test to determine 28-day mortality and growth effect concentrations for the non-target polychaete worm Arenicola marina, the crustacean Corophium volutator and the mollusk Cerastoderma edule using a marine microcosm setup. Results indicate that no concentration-dependent increase of mortality and growth rate was apparent to A. marina and C. edule. But for C. volutator, a concentration-dependent increase in mortality was observed, resulting in a calculated 28-d LC50 of 316 μg/kg dry sediment (95% confidence interval: 267-373 μg/kg dry sediment). There were significant effects on C. volutator growth rate at concentrations of 100 μg/kg dry sediment and above (NOEC = 30 μg/kg dry sediment). These observations show that C. volutator is more sensitive to EB than A. marina, which differs from results reported in previous studies. Comparison to the most sensitive NOEC (30 μg/kg dry sediment) found for C. volutator (organisms of 8-11 mm length), shows that the Environmental Quality Standard, derived by the Scottish Environment Protection Agency in 2017 which based on freshwater species data (NOEC = 1.175 μg/kg dry sediment), are relatively strict and is sufficiently protective for the marine species tested in this paper., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

This study combines published datasets with unpublished data on plastic ingestion in several North Sea fish species. The combined dataset of 4389 individuals from 15 species allows the analysis of spatial distribution and temporal variability of plastic uptake in fish. Airborne fibre contamination was observed to be the main contributor to fibres encountered in the samples. The number of fibres in samples was strongly related to the time needed to process a sample, not to the number of individual fishes in the sample. Accurate correction for secondary fibre contamination was not possible, but corrections required would be similar to fibre numbers observed in the samples. Consequently, all fibres were omitted from further analysis. The frequency of occurrence and the average number of plastics in fish is generally low (1.8% and 0.022 pieces per organism respectively), with only cod having a higher prevalence (12.3%). While latitude of catch locations influences plastic uptake in fish, no correlation with the distance to the coast was found. Slightly less plastics were ingested in winter, and a decrease in plastics ingested was observed between 2009 and 2018. These factors should be considered when fish species, catch location and time are discussed as indicators for plastic pollution in the European Marine Strategy Framework Directive. We recommend considering demersal cod and pelagic sprat as two species suitable for monitoring plastic ingestion in biota, both on the seafloor and in the water column., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Researcher and media alarms have caused plastic debris to be perceived as a major threat to humans and animals. However, although the waste of plastic in the environment is clearly undesirable for aesthetic and economic reasons, the actual environmental risks of different plastics and their associated chemicals remain largely unknown. Here we show how a systematic assessment of adverse outcome pathways based on ecologically relevant metrics for exposure and effect can bring risk assessment within reach. Results of such an assessment will help to respond to the current public worry in a balanced way and allow policy makers to take measures for scientifically sound reasons.

The Predicted No Effect Concentration (PNEC) for dissolved copper based on the species sensitivity distribution (SSD) of 24 marine single species tests was validated in marine mesocosms. To achieve this, the impact of actively maintained concentrations of dissolved copper on a marine benthic and planktonic community was studied in 18 outdoor 4.6m(3) mesocosms. Five treatment levels, ranging from 2.9 to 31μg dissolved Cu/L, were created in triplicate and maintained for 82days. Clear effects were observed on gastropod and bivalve molluscs, phytoplankton, zooplankton, sponges and sessile algae. The most sensitive biological endpoints; reproduction success of the bivalve Cerastoderma edule, copepod population development and periphyton growth were significantly affected at concentrations of 9.9μg Cu/L and higher. The No Observed Effect Concentration (NOEC) derived from this study was 5.7μg dissolved Cu/L. Taking into account the DOC concentration of the mesocosm water this NOEC is comparable to the PNEC derived from the SSD., (Copyright © 2015. Published by Elsevier B.V.)

Marine filter feeders are exposed to microplastic because of their selection of small particles as food source. Baleen whales feed by filtering small particles from large water volumes. Macroplastic was found in baleen whales before. This study is the first to show the presence of microplastic in intestines of a baleen whale (Megaptera novaeangliae). Contents of its gastrointestinal tract were sieved, dissolved in 10% potassium hydroxide and washed. From the remaining dried material, potential synthetic polymer particles were selected based on density and appearance, and analysed by Fourier transform infrared (FTIR) spectroscopy. Several polymer types (polyethylene, polypropylene, polyvinylchloride, polyethylene terephthalate, nylon) were found, in varying particle shapes: sheets, fragments and threads with a size of 1mm to 17cm. This diversity in polymer types and particle shapes, can be interpreted as a representation of the varying characteristics of marine plastic and the unselective way of ingestion by M. novaeangliae., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

As the industrial production of nanoplastic and the degradation of microplastic into smaller particles at sea increase, the potential amount of nanoplastics in the marine environment rises. It has been reported that mussels uptake 100-nm polystyrene (PS) beads; to date, however, the effects of this uptake on the organism are unknown. In the present study, the authors investigated the effects of 30-nm PS on the feeding behavior of the blue mussel (Mytilus edulis) by exposing the organism to different nano PS and different algae (Pavlova lutheri) concentrations. The state of nano PS aggregation in the exposure medium was assessed using dynamic light scattering. In all treatments that contained nano PS, M. edulis produced pseudofeces. The total weight of the feces and pseudofeces increased with increasing nano PS and increasing algae concentration. Furthermore, M. edulis reduced its filtering activity when nano PS was present but still caused a decrease in the apparent nano PS concentration in the water. The presence of nano PS around the foot of M. edulis after the bioassay confirmed that the organism removed nano PS from the water. Chronic effect studies are therefore needed to investigate the effects of nanoplastics in M. edulis and possible consequences for its predators, including humans., (Copyright © 2012 SETAC.)

During the development of an embryo into a juvenile, the physiology and behavior of a fish change greatly, affecting exposure to and uptake of environmental pollutants. Based on experimental data with sole (Solea solea), an existing bioaccumulation model was adapted and validated to calculate the development of concentrations of persistent organic pollutants in the tissue of developing fish. Simulation revealed that toxic tissue concentrations of pollutants with log octanol-water partition ratio (K(OW)) > 5 peak at the moment when the larvae become free-feeding, when the lipid reserves are depleted. This may explain the delayed effects observed in fish early-life-stage experiments with exposed eggs. In the field, eggs can be exposed through maternal transfer to adult pollutant tissue concentrations, which will increase in the larva to peak tissue concentrations, exceeding those of the adult fish. The results demonstrate the risk of underestimating the effects of lipophilic persistent organic pollutants with log K(OW) > 5 in short-term, early-life-stage fish tests and underscore the importance of maternal transfer as an exposure route in the field situation., (Copyright © 2012 SETAC.)

Dichlofluanid (N-dichlorofluoromethylthio-N'-dimethyl-N-phenylsulphamide) is used as booster biocide in antifouling paints. The occurrence of dichlofluanid and its metabolite DMSA (N'-dimethyl-N-phenyl-sulphamide) was monitored in seawater and marine sediment from three Greek marinas. Seawater and sediment samples were collected at three representative positions and one suspected hotspot in each marina and shipped to the laboratory for chemical analysis. As part of the project, an analytical method had been developed and validated. Furthermore, some additional experiments were carried out to investigate the potential contribution of paint particle bound dichlofluanid on the total concentration in the sediment. As expected, given its known high hydrolytic degradation rate, no detectable concentrations of dichlofluanid were measured in any of the seawater samples. DMSA was detected in seawater samples at very low concentrations varying from <3 ng l(-1) (LOD) to 36 ng l(-1). During method validation, it had already been demonstrated that dichlofluanid is unstable in sediment and can therefore only be determined as its metabolite DMSA. In a separate experiment, in which marine sediment was spiked with artificial paint particles containing dichlofluanid and then analysed according to the validated method, it was demonstrated that if there is any dichlofluanid originating from paint particles, this would be determined as DMSA. No DMSA was detected in any of the sediment samples. It could therefore be concluded that there were no significant concentrations of dichlofluanid in the sediment samples.

The cockle Cerastoderma edule was exposed to sediments variously comprised of pulverised fuel ash (PFA) for two consecutive periods of 3 and 9 months. Chronic effects of PFA on this filter feeding bivalve were studied by examining changes in cellular and tissue pathology with the aid of a screening procedure developed for analysing histopathology conditional. The mortality rate was high, up 43% for the 100% PFA sediment and growth of the individual bivalves was low. The accumulation of metals appeared to be low at 1-10 times background tissue levels. Signs of cellular stress were seen in the digestive gland after the first 3 months. However, after 9 months, this same organ was in fairly good condition. Reproduction was delayed due to slow oocyte maturation.