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Marine litter is a global problem that requires soon management and design of mitigation strategies. Marine litter monitoring is an essential step to assess the abundances, distributions, sinks and hotspots of pollution as well as the effectiveness of mitigation measures. However, these need to be time and cost-efficient, fit for purpose and context, as well as provide a standardized methodology suitable for comparison among surveys. In Europe, the Marine Strategy Framework Directive (MSFD) provides a structure for the effective implementation of long-term monitoring. For beaches, the well-established 100 m OSPAR macrolitter monitoring exists. However, this method requires a high staff effort and suffers from a high spatio-temporal variability of the results. In this study, we test the potential of aerial drones or Unmanned Aerial Vehicles (UAVs) together with a Geographic Information System approach for semi-automatic classification of meso- (1–25 mm) and macrolitter (>25 mm) at four beaches of the southern Baltic Sea. Visual screening of drone images in recovery experiments (50 m2 areas) at 10 m height revealed an accuracy of 99%. The total accuracy of classification using object-based classification was 45–90% for the classification with four classes and 50–66% for the classification with six classes, depending on the algorithm and flight height used. On 100 m beach monitoring transects the accuracy was between 39–74% (4 classes) and 25–74% (6 classes), with very low kappa values, indicating that the GIS classification method cannot be regarded as a reliable method for the detection of litter in the Southern Baltic. In terms of cost-efficiency, the drone method showed high reproducibility and moderate accuracy, with much lower flexibility and quality of data than a comparable spatial-OSPAR method. Consequently, our results suggest that drone based monitoring cannot be recommended as a replacement or complement existing methods in southern Baltic beaches. However, drone monitoring could be useful at other sites and other methods for image analysis should be tested to explore this tool for fast-screening of non-accessible sites, fragile ecosystems, floating litter or heavily polluted beaches.

In the North Sea, many oil and gas fields will reach the end of their productivity and their associated structures will be decommissioned. OSPAR decision 98/3 prescribes removal of all disused offshore structures as the only acceptable decommissioning option. This policy is the legacy of the 1995 Brent Spar incident, which resulted in the current dominant discourse of ‘Hands off the Oceans,’ ruling out the conversion of oil and gas rigs into artificial reefs (Rigs-to-Reefs (RtR)). The shift from a conservation to a restoration paradigm could open up the RtR debate. In this paper, a discourse analysis is carried out to discern whether and how ideas about RtR and ecosystem restoration are articulated to challenge the dominant ‘Hands off the Oceans’ discourse and thereby bring about change in North Sea decommissioning policy. A discourse analytic framework is applied to elucidate whether an ‘RtR as Restoration’ discourse can be distinguished and how competing claims are presented in the various storylines. Our analysis shows an ‘RtR as Restoration’ discourse, consisting of four different storylines. Given the fragmented nature of this discourse, the ‘RtR as Restoration’ discourse will not overcome the dominant ‘Hands off the Oceans’ discourse.

Anthropogenic litter in aquatic ecosystems negatively impacts ecosystems, species and economic activities. Rivers play a key role in transporting land-based waste towards the ocean. A large portion however is retained within river basins, for example in the estuary, in sediments and on the riverbanks. To effectively identify litter sources, sinks and transport mechanisms, reliable data are crucial. Furthermore, such data can support optimizing litter prevention mitigation and clean-up efforts. This paper presents the results of a 2-year monitoring campaign focused on riverbank macrolitter (>0.5 cm) in the Dutch Rhine–Meuse delta. Between 2017 and 2019, volunteers sampled 152 415 litter items at 212 unique locations. All items were categorized based on the River-OSPAR method (based on the OSPAR beach litter guidelines), which includes 110 specific item categories across ten parent categories. The median litter density was 2060 items/km, and the most observed items were foam, hard, and soft plastic fragments (55.8%). Plastic bottles, food wrappings and packaging, caps, lids and cotton swabs were the most abundant specific items. The litter density and most abundant items vary considerably between rivers, along the river, and over time. For both rivers however, the highest litter density values were found at the Belgian (Meuse) and German (Rhine) borders, and at the Biesbosch National Park, the most downstream location. With this paper, we aim to provide a first scientific overview of the abundance, top item categories, and spatiotemporal variation of anthropogenic litter on riverbanks in the Dutch Rhine–Meuse delta. In addition, we evaluate the used River-OSPAR method and provide suggestions for future implementation in (inter)national long-term monitoring strategies. The results can be used by scientists and policy-makers for future litter monitoring, prevention and clean-up strategies.

The data and results of the UK second application of the OSPAR Common Procedure (COMP) for eutrophication were used as a case study to develop a generic system i) to assess an observational network from a multi-variable point of view, ii) to introduce additional datasets in the assessment and iii) to help reduce the cost of the monitoring programme. The method consisted of tools to analyse, by means of simple statistical techniques, if any reduction of the available datasets could correspond to the published assessments, with reduced costs (and limited loss in confidence). The data reduction scenarios included the removal of an existing dataset or the inclusion of freely available third-party data (ferrybox, satellite observations) combined with a subset of existing datasets. Merging different datasets was problematic due to the heterogeneity of the techniques, sensors, scales, and a cross validation was carried out between the different datasets out to assess possible biases between the different datasets. The analysis of the results showed that there was little margin to remove any of the available datasets and that the use of extensive datasets, such as satellite data, has an important effect, leading very often to a change in the results of the assessment with respect to the thresholds, generally in the sense of moving from threshold exceedance to the opposite.This suggested that the results of the original assessment might be biased to the sampling location and time and emphasized the importance of monitoring programmes covering extensive spatial and temporal scales, and the opportunity to improve assessments by combining observations, satellite data and model results.

International audience; The Marine Strategy Framework Directive requires EU Member States to assess the Good Environmental Status (GES) of their marine waters in a coherent and strategic manner. For the regional assessment of biodiversity, the OSPAR Intersessional Coordination Group of Biodiversity Assessment and Monitoring (ICG-COBAM) provides substantial advice. Through expert working groups, phytoplankton indicators are currently being developed to measure the state and the change in pelagic diversity, to quantify food web dynamics and to measure the extent of eutrophication impacts. We developed a multi-metric indicator that is compliant with the common OSPAR indicator “Changes in plankton diversity” (PH3). The aim was to describe the structure of the phytoplankton community (alpha diversity) and to detect significant temporal changes (beta diversity) to evaluate the health of pelagic habitats. In this pilot study, we used three coastal time-series in the Western Channel and the north of the Bay of Biscay (North Atlantic, France) to test the efficiency and the performance of several existing diversity indices. We validated two alpha diversity indices, namely the Menhinick Index (D) and the Hulburt Index (δ), based on their complementary ecological information, their strong relationship with habitat characteristics, and their relative ease of interpretation for stakeholders. Temporal shifts or rate of change in community structure were detected by the Local Contributions to Beta Diversity index (LCBD; a beta diversity measure). For the years where significantly high LCBD values were found, the Importance Value Index (IVI) was calculated to potentially identify the taxa (genus) responsible for the “unusual” community structure. For example, at the Ouest Loscolo site in 2008, an elevated LCBD (0.45) coincided with a high dominance value (Hulburt’s Index) caused by the occurrence of a monospecific bloom of Leptocylindrus spp. (IVI = 73%) in July (2.22 × 106 cells L−1) and October (8 × 106 cells L−1). In this way, PH3 informs on different aspects of phytoplankton diversity from a community to a genus level. At the current stage of development, however, PH3 acts as a “surveillance” rather than an operational indicator since the relationship to GES is not directly tracked. In the future, by additional testing of PH3 and extending the geographical scope, the robustness of the assessment could be further determined across the OSPAR Maritime Area.

Increased plastic consumption and poor waste management have resulted in litter representing an ever-increasing threat to the marine environment. To identify sources and evaluate mitigation measures, beach litter has been monitored. Using data from two citizen science protocols (CSPs) and OSPAR monitoring of Norwegian beaches, this study 1) identifies the most abundant litter types, 2) compares OSPAR to citizen science data, and 3) examines how to improve the management relevance of beach litter data. The dominant litter types were; food and drink- and fishery related items, and unidentifiable plastic pieces. Data from CSPs are consistent with OSPAR data in abundance and diversity, although few OSPAR beaches limit verification of CSP data. In contrast to OSPAR, the CSPs estimate the weight of the litter. CSPs lack important variables which could explain why some litter types are abundant in some particular areas. The latter could be improved by recording GPS positions.

The aims of this study are to develop an optimized method for regional benthic fauna assessment of the Southern North Sea which (a) is sensitive and precise (quantified as the slope and the R2 value of the pressure-impact relationships, respectively) for the anthropogenic pressures bottom fishing and organic enrichment, (b) is suitable for estimating and modelling reference values, (c) is transparent, (d) can be efficiently applied using dedicated software; and to apply this method to benthic data from the Southern North Sea. Margalef diversity appeared to be the best performing benthic index regarding these criteria, even better than several Multi-Metric Indices (MMIs) containing e.g. AMBI (AZTI Marine Biotic Index) and ITI (Infaunal Trophic Index). Therefore, this relatively simple and very practical index, including a new reference value estimation and modelling method, and BENMMI software were selected as a common OSPAR (Oslo Paris convention) method for the benthic fauna assessment of the Southern North Sea. This method was applied to benthic fauna data from the Southern North Sea collected during the period 2010–2015. The results in general show lower normalized Margalef values in coastal areas, and higher normalized Margalef values in deeper offshore areas. The following benthic indices were compared in this study: species richness, Margalef diversity, SNA index, Shannon index, PIE index, AMBI, ITI. For each assessment area, the least disturbed benthic dataset was selected as an adjacent 6 year period with, on average, the highest Margalef diversity values. For these datasets, the reference values were primarily set as the 99th percentile values of the respective indices. This procedure results in the highest stable reference values that are not outliers. In addition, a variable percentile method was developed, in which the percentile value is adjusted to the average bottom fishing pressure (according to data from the International Council for the Exploration of the Sea, ICES) in the period 2009–2013. The adjusted percentile values were set by expert judgement, at 75th (low fishing pressure), 95th (medium fishing pressure) and 99th (high fishing pressure) percentile. The estimated reference values for Margalef diversity correlate quite well with the median depth of the assessment areas using a sigmoid model (pseudo-R2 = 0.86). This relationship between depth and Margalef diversity was used to estimate reference values in case an assessment area had insufficient benthic data .For testing the effects of bottom fishing pressure, normalized index values (NIV; index value divided by reference value) were used. The rationale for using NIVs is the assumption that, although a certain level of bottom fishing pressure will have a larger absolute effect on more biodiverse benthic communities in deeper waters than on more robust and less biodiverse coastal benthic communities, the relative effects (tested using NIVs) are comparable. A clear exponentially decreasing relationship (R2 = 0.26–0.27, p 2 cm, respectively) and normalized Margalef diversity values, with an asymptotic normalized Margalef value of 0.45 at a subsurface fishing activity >2.3 sweeps/year. This asymptotic value is predominantly found in coastal waters, and probably shows that the naturally more robust coastal benthic communities have been transformed into resilient benthic communities, which rapidly recover from increasing fishing pressure.

International audience; Grey (Halichoerus grypus) and harbour seals (Phoca vitulina) are sympatric seal species, but they display distinct strategies of habitat use and connectivity between haulout sites. The distribution patterns and variations in relative abundance of both species were investigated along the French coast of the English Channel, at the southern limit of their range where seal numbers are increasing. Regular censuses conducted at all main haulout sites in mainland France showed significant seasonal variations at most sites, with more harbour seals counted during summer (breeding and moulting seasons), and more grey seals during summer only in the eastern English Channel. Trends in maximum haulout numbers at haulout sites showed a significant increase over the last five years, ranging from 9.7 to 30.9% per year for harbour seals, and from 5.8% (in the western English Channel) to 49.2% (in the eastern English Channel) per year for grey seals. These rates of increase in grey seal numbers are not linked to local pup production and most probably result from seal movements from the southwest British Isles and the North Sea, respectively. Aerial surveys conducted across the English Channel showed that most seal observations at sea were concentrated in the north-eastern English Channel. Telemetry showed that the 28 harbour seals tracked remained highly coastal, within a radius of 100 km from their haulout sites, and did not move to other known colonies. Grey seals moved much greater distances, reaching up to 1200 km from their capture site. More than half of the 45 grey seals tracked crossed the English Channel, especially during the breeding season, moving to known colonies in the southwest British Isles and the North Sea. Combining individual tracks and long-term surveys of the seal populations allowed a better understanding of the dynamics of these populations and their connectivity at a larger regional scale. The findings provide direct information for the management of grey and harbour seals within the frame of the Marine Strategy Framework Directive, and highlight focus areas where potential interactions between the two species should be monitored.

peer-reviewed, We detail the calculations of North Sea Large Fish Indicator values for 2009–2011, demonstrating an apparent stall in recovery. Therefore, recovery to the Marine Strategy Framework Directive's good environmental status of 0.3 by the 2020 deadline now looks less certain and may take longer than was expected using data from 2006 to 2008.

Marine Protected Areas (MPAs) are considered key elements to the achievement of conservation and sustainable marine management targets. Yet, even if recently the number of MPAs has increased rapidly worldwide, the area of ocean under some type of MPA classification is far behind the international targets (e.g. Convention on Biological Diversity) considered essential for conservation of the world's oceans. Furthermore, coherence, representativeness and effectiveness of existing MPAs are largely unknown or even weakly defined. In this study, general characteristics of MPAs from Portugal, Spain and France were collected and used to evaluate conservation progress in this geographic area. In addition, an online questionnaire was administered to the MPAs managers, and focused on multiple processes inherent to each MPA, namely on the characteristics and suitability of planning, management, monitoring, governance and enforcement. Obtained responses were used to calculate the overall level of MPA management effectiveness, and multivariate analyses were used to identify the factors that most contributed to differences in effectiveness. Most MPAs are adjacent to the coast, are small in area (near 50% have less than 20 km2) and were established with multiple goals concerning species conservation and sustainable development of economic activities (e.g. fisheries). Only 9% of analysed MPAs are larger than 1000 km2 and are unequally distributed among the study area. Overall, 46% of MPAs and 59% of total area covered were established during the last five years, while only 3 of the 35 no-take areas (22% in area) were implemented during this period. High MPA effectiveness (i.e. the extent to which an MPA is protecting values and achieving its goals and objectives) was related with high levels of stakeholders support, with suitable goals, management and enforcement. Results highlighted the need to improve MPA coverage taking into account other existing MPAs to increase coherence and representativeness of networks, that new no-take areas should be implemented in key conservation sites and that management strategies (e.g. enforcement and monitoring) should be strengthened. These findings are applicable to the study area yet methodology and outcomes are pertinent to MPA management worldwide. Ultimately, strategies aiming at maximizing MPA performance are probably as important as the increase of MPA coverage.

Many maritime countries in Europe have implemented marine environmental monitoring programmes which include the measurement of chemical contaminants and related biological effects. How best to integrate data obtained in these two types of monitoring into meaningful assessments has been the subject of recent efforts by the International Council for Exploration of the Sea (ICES) Expert Groups. Work within these groups has concentrated on defining a core set of chemical and biological endpoints that can be used across maritime areas, defining confounding factors, supporting parameters and protocols for measurement. The framework comprised markers for concentrations of, exposure to and effects from, contaminants. Most importantly, assessment criteria for biological effect measurements have been set and the framework suggests how these measurements can be used in an integrated manner alongside contaminant measurements in biota, sediments and potentially water. Output from this process resulted in OSPAR Commission (www.ospar.org) guidelines that were adopted in 2012 on a trial basis for a period of 3 years. The developed assessment framework can furthermore provide a suitable approach for the assessment of Good Environmental Status (GES) for Descriptor 8 of the European Union (EU) Marine Strategy Framework Directive (MSFD)., SI

Candidate OSPAR/ICES recommended biomarkers at the level of the individual in Mytilus edulis for determination of good environmental status for MSFD were evaluated against contaminant levels at sites around Ireland. The sites chosen ranged from moderate to low pollution levels, but the actual ranking of the sites varied according to the contaminant levels present. At the most contaminated site, Cork, 4 out of 16 contaminants exceeded the EAC, while at Shannon, no EACs were exceeded. The SOS assay suggested that Cork was the healthiest site with a LT50 of 17.6 days, while SOS for Shannon was 15.6 days. Likewise, condition factors varied among sites and did not always correspond to contaminant-based status. There may be uncertainty in assigning status around the not good:good boundary. This raises potential difficulties not only in the biomarker/contaminant load relationship but also in the reliability of the biomarkers themselves and hence barriers meeting compliance levels., Peer-reviewed., This work was carried out under the Sea Change strategy with the support of the Marine Institute and the Marine Research Sub-Programme of the National Development Plan 2007–2013.

Shephard, S., Reid, D. G., and Greenstreet, S. P. R. 2011. Interpreting the large fish indicator for the Celtic Sea. – ICES Journal of Marine Science, 68: 1963–1972. The large fish indicator (LFI) was developed in the North Sea as a size-based indicator of fish community state. It is now established as OSPAR's fish community Ecological Quality Objective (EcoQO) metric and will be applied across all OSPAR regions. To produce a protocol for use when developing regional LFIs, the North Sea experience is interpreted using data from the Celtic Sea. Differences in fish community species composition and size distribution were reflected in a different species complex and large fish threshold (50 cm) for the Celtic Sea LFI. However, a lag of 12–14 years in the relationship between assemblage-averaged fishing mortality Fcom,y and the LFI suggested similar underlying ecological mechanisms to the North Sea. The indicator responded to changes in small fish biomass that follow fishing-induced changes in the level of predation by large demersal piscivores. The Celtic Sea LFI showed maximum observed values >0.40 before 1990, and 0.40 is here proposed as an EcoQO. Development of regional LFIs demands a flexible process rather than a strictly prescriptive protocol.