OSPAR Contracting Parties' experts attending this workshop (CP in blue, nominative list in annex 1):

Table of contents

Executive Summary

The SUPER COBAM workshop was organised by the leads of the expert groups that work within ICG-COBAM (under OSPAR's Biological Diversity Committee) -see below. It was attended by about 35 experts from 10 Contracting Parties mainly from the expert groups on food webs, benthic habitats, pelagic habitats and non-indigenous species.

The expert group leads are:

• Marine mammals: Anita Gilles <anita.gilles@tiho-hannover.de> • Food webs: Ulrike Schueckel <ulrike.schueckel@lkn.landsh.de> • Benthic habitats: Laurent Guerin <laurent.guerin@mnhn.fr> and Cristina Vina-Herbon <Cristina.Herbon@jncc.gov.uk> • Pelagic habitats: Abigail McQuatters-Gollop abigail.mcquatters-gollop@plymouth.ac.uk • Non-Indigenous Species: Paul Stebbing paul.stebbing@cefas.co.uk • Marine birds -Ian Mitchell ian.mitchell@jncc.gov.uk The aim of the workshop was to help the expert groups prepare and plan for the QSR2023, given that each group will be required to produce assessments of common indicators and thematic assessments by the end of 2021. The workshop enabled experts from different expert groups to discuss common topics and challenges and to develop consistent approaches that will be taken forward over the next 2.5 years. The workshop covered topics that are relevant across the expert groups such as:

• QSR Guidelines including requirements of thematic assessments • State/pressures/activities data availability and requirements, • Integrated assessment, • Threshold setting, • Coordinated/joint monitoring. This full report from the meeting will be presented at ICG-COBAM 2019 in November, and also to ICG-POSH 2019 in December, which will take the workshop outputs into account in developing proposals to BDC 2020 or EIHA 2020 as relevant. To provide an overview of the outputs of the meeting in the interim, the key messages from the workshop are summarised below.

Key messages

Ways of working

The progress made during SUPER COBAM strongly suggests that further science-focused workshops, involving multiple disciplines, will be key to progressing the biodiversity common indicators and for achieving consistency and coherence across the biodiversity thematic assessments. We would recommend holding repeat SUPER COBAM's or similar technical scientific workshops in lieu of more formal COBAM meetings in the spring of 2020 and 2021. We would welcome attendance by the ICG-COBAM co-convenors and by OSPAR-nominated members of JWGBIRD, the OSPAR Marine mammal Expert Group (MMEG) and the OSPAR Fish expert group. We recognise that this will require some additional resources from Contracting Parties to support the attendance of their experts, but aiming to capitalise expert works for technical QSR in 2021.

Development of relevant assessments through the QSR 2023 process will also benefit considerably from early opportunities for discussion between experts and OSPAR policy leads, and where relevant national MSFD policy leads, such as members of ICG-MSFD, as soon as possible to agree on priorities for indicator assessments and thematic assessments. Experience from the EcApRHA project suggests the involvement of policy leads early in the assessment process would be extremely beneficial. It will help us manage expectations of what it is technically possible to deliver with current resources through the thematic assessments and to make sure that what we deliver is policy-relevant and easily understood by policy makers. Such interactions (e.g. a meeting or workshop) could be planned within the QSR2023 timeline. SUPER COBAM welcomed the development of bow-tie analyses by ICG-Eco-C to assess cumulative impacts in the QSR 2023. COBAM experts are keen to work much closer with ICG-Eco-C, in order to better understand the analyses and to contribute to their outputs.

The way and process how to work closer with other OSPAR groups and committees still need to be clarified. The need for cooperation and interaction with several working groups, inside and outside OSPAR process is thus crucial and has to be planned and managed in terms of coordination, complementarity of terms of References and dedicated expert time involved.

Indicator thresholds

With the exception of birds, marine mammals and fish, most of the other biodiversity common will not be assessed using thresholds during the QSR 2023. Despite not having thresholds, many of these indicators will show the extent of change over time (i.e. trend-based indicators) and will be critical for informing management decisions. Links with EU TG Seabed expert group for benthic habitats is important.

Thematic Assessments

Super-COBAM considered the ICG-QSR guidance on the thematic assessments. The introduction of integrated assessments of ecosystem components and the emphasis on state/pressure relationships and management, represent considerable additional work compared to IA2017. Expert groups will further consider what can be delivered in each of the biodiversity thematic assessments with current resources and will provide a proposed structure and content for development at COBAM in Nov 2019. COBAM experts will require guidance from BDC and ICG-QSR on how to reflect information on the implementation of measures in their assessments and how to draw conclusions on effectiveness of measures. Consistency with work of TG-MAP on implementation and effectiveness of measures will also be important.

ICG-Eco-C's bow-tie analyses of cumulative impacts will be very useful for identifying key management recommendations as part of the thematic assessments. Therefore, we think ICG-QSR and ICG-Eco-C could consider incorporating the relevant bow-tie analyses into each the biodiversity thematic assessments, rather than having separate chapter on cumulative impacts. This would involve communication with expert group leads to ensure products make sense. This could provide greater coherence to the report structure. Integration can be descriptive as well as quantitative and we are likely to have descriptive thematic assessments for non-species components. We hope to deliver some examples to BDC 2021.

The conveners of ICG-COBAM and ICG-Eco-C could invite each other to them respective next meetings to discuss the above proposals.

Resources

We acknowledge that the ICG-QSR timeline requires expert groups to complete indicator assessments and thematic assessments by the end of 2021. We recognise that this gives us insufficient time to apply for funding from external bodies (e.g. EU) to support this work. This means the majority of resources to deliver biodiversity assessments for QSR2023 will need to come from Contracting Parties and are needed as soon as possible for work to commence and deliver on time. Many experts and even expert group leads are on short term contracts that lack stable funding, which makes it difficult to progress the COBAM work.

In order for some experts to justify their input into the QSR2023 they will be required by their institutions to produce a citable product. The decision to not permit scientific authorship citations in the QSR2023 will therefore have resource implications. Some experts will inevitably need to produce additional papers in scientific journals as well as the assessments in the QSR2023. This is additional work in a short period of time which is likely to slow the production of the assessments, but is essential to ensure continuation of expert involvement, including expert group leads, in the COBAM processes under scientific quality and robustness.

Co-ordinated monitoring

The current biodiversity CEMP guidelines provide minimum monitoring requirements for each indicator. But not all contracting parties are collecting data in line with CEMP guidelines, which is limiting the delivery of some indicators.

There are numerous opportunities to co-ordinate, or even better joint, monitoring of biodiversity across contracting-parties and on regional scale. In most cases this is technically possible. In order to achieve co-ordinated monitoring there needs to be agreement between contracting parties on sharing standards, regional sampling schemes, and resources and data for joint monitoring. Therefore, the barriers that need being overcome to ensure co-ordinated or joint biodiversity monitoring across OSPAR can only be solved by OSPAR policy leads and not by technical experts. If there is sufficient will across contracting parties to co-operate in monitoring, then the technical experts can recommend where the greatest gains in evidence collection can be made. It should be made clear as soon as possible from decision committee (e.g. BDC) what would be the resources and level of expectation for coordinated and/or joint monitoring for each biodiversity component, and between them.

It is already very late to provide any new guidance for MSFD reporting (2020), to enable any significant progress. However, it will be important to boost and progress works towards coordinated/joint monitoring on regional level, as this is the first gap to fill to have more complete and more relevant data for next QSR and other assessment cycles.

Indicator development

A table, in Session 7 paragraph below, lists those indicators that will require agreement on by CPs for the promotion of candidate indicators to 'common', expansion of existing indicators into new regions and the adoption of regional thresholds. Proposals will be drafted by the relevant expert groups and presented for COBAM to consider forward submission to BDC. An additional candidate Indicator on contaminants in marine mammals will be proposed by the Marine Mammal Expert Group to HASEC 2022, for inclusion in QSR2023. Some indicators, such as PH1, PH2, PH3, BH1, BH2 and BH3 are technically ready for expansion, but actually implementing their expansion will require additional resources and data.

Tuesday 18 th June (9:30 -17:30)

Session 1: Introduction -aims and context of this workshop

At last meeting of the OSPAR intersessional correspondence group on coordinated biodiversity assessment and monitoring (COBAM, Nov. 2018, Madrid), it was decided that next COBAM will be held in November 2019, to give time for expert groups to meet and work inter-sessionaly.

COBAM expert group leads discussed the opportunity to have back to back and joint meetings, as it was considered very useful during the EcApRHA1 project, by groups involved in this project (benthic, pelagic and food webs). The current OSPAR priorities to work towards a more ecosystem-based approach and thematic assessments for next Quality Status Report are other strong reasons to enhance interaction between expert groups.

The benthic habitat, pelagic habitat, food webs and non-indigenous species groups' leads decided to have a 3 day joint workshop, mixing respective experts, to compare and progress work. The OSPAR Secretariat, Marine mammals, Seabirds and Fish groups' leads contributed to the preparation of the workshop and participated in it.

There were also opportunities for several expert groups to meet the day before and/or the day after this joint workshop (See final agenda in annex 2). This report summarise the main outcomes, key messages and concrete recommendations which were produced by the about 35 experts, from the OSPAR maritime area, during this "SUPER COBAM" joint workshop which was held in Paris 18-20 June 2019, at the kind invitation of the French Natural History Museum and the French Agency for Biodiversity.

The meeting was co-chaired by Anita Gilles (chair Marine Mammals, Germany), Abigail McQuatters-Gollop (chair Pelagic Habitats, United Kingdom), Laurent Guérin (co-chair Benthic Habitats, France), Ian Mitchell (chair Seabirds, United Kingdom), Ulrike Schueckel (chair Food Webs, Germany), Paul Stebbing (chair Non Indigenous Species, United Kingdom), Cristina Vina-Herbon (co-chair Benthic Habitats, United Kingdom) and attended by representatives of the following 10 OSPAR Contracting Parties: Belgium, Denmark, France, Germany, the Netherlands, Norway, Republic of Ireland, Spain, Sweden and the United Kingdom.

The draft agenda was presented and discussed on the order and specific expected outcomes from the meeting, in particular to compare work plans and progress made by each expert group, to evaluate how to progress towards a more integrated assessment for the next Quality Status Report 2023 of OSPAR maritime area. Information was previously circulated to all experts through the following working documents: This session started with short interactive presentations of overview of groups to deliver draft QSR (i.e. end 2021). The content was based on the work and documents prepared at the last COBAM (Madrid, Nov. 2018) and the updates received from experts before and during this workshop.

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• Pelagic habitats -Presentation by Abigail (annex 3) An aspirational scenario would be to organise data call and data flows, to update 2017 intermediate assessment (IA), but also to test and expend current pelagic indicators to more OSPAR Regions. Results could then be discussed through expert workshops to propose targets and GES values and develop integration methods for a more integrated assessment: "thematic assessment" of OSPAR pelagic habitats But with current resources, the minimal scenario is for now only to update 2017 IA of each indicator through a coordinated data call, and progress as much as possible assessment methods of each indicator to submit and publish updated documentation (CEMP guidelines) for the next QSR.

• Benthic habitats -Presentation by Laurent (annex 3) A short term vision (with current resources) of what may be possible for QSR 2023, based on available data for some selected habitats is: -BH3 should include other pressure(s) than physical disturbance. With current resources we can continue with fisheries and include some other pressures (depending on data availability from Contracting Parties).

-BH2-A = to be updated by last Water Framework Directive reporting (and Norway specific programme). It will require coordinating a data call and processing data at OSPAR regional scale. -BH2-B = contribution from other pressure-habitat type: case studies and discuss results to update method and state-pressure relationships; to be conducted and compared with BH1.

-BH1 = work in progress from other pressure-habitat type case studies and results and comparison with BH2 results; possible extent to Region II (testing in progress)? -Find a lead for BH5 (Spain offered during this workshop session to take this lead).

-Integration: concept and methods to be further worked through OBHEG in line with works at EU level.

-Monitoring: overview and analyse on the Art.11 MSFD reporting (to be completed for non EU Member States) about current/planned benthic monitoring programs in the OSPAR maritime area and adequacy and gaps with OSPAR assessment methods = simple statement on current adequacy and gaps.

-Review, participate as much as possible, and take into account information and outcomes from other relevant working groups (e.g. TG Seabed, WKBEDPRES, WKBEDLOSS, WGFBIT, BEWG, etc).

A longer term vision (or with additional or project resources), after possible revision of OSPAR CEMP and national monitoring programmes, is: -BH3: To update the sensitivity layer and develop quantitative assessment, which requires more exact pressure data. Furthermore, the geographical coverage should be improved and the indicator should be implemented in the whole OSPAR maritime area.

-BH2 & BH1: These indicators should be integrated with BH3, i.e. update the sensitivity layer of BH3. This update demands the definition of pressure/state relationships, which result in quantitative thresholds, which could help to propose targets and GES values.

-BH4: to be discussed and decided (Germany and UK co-leading).

-BH5: to be discussed and decided (Spain leading).

-Integration: Case study on the overall approach: See presentation in integration session on Elliott et al. ( 2017), annex 7. Assessment area has to be defined according to data and resources available. Monitoring: overview and analyse on the Art.11 MSFD reporting (to be completed for non EU Member States) about current/planned benthic monitoring programs in the OSPAR maritime area and make recommendation on potential evolution/adaptation to fit with OSPAR assessment methods = work towards a joint/coordinated monitoring and recommendation for adaptations (see also Van Hoey et al., 2019).

• Food Webs -Presentation by Ulrike (annex 3)

• Non-indigenous species -Presentation by Paul (annex 3)

The structure, timeline, planed synergies with other groups/committees and current expectations for the next QSR were presented by Ian Mitchell and Lena Avelan (OSPAR Secretariat).

• Last updates on OSPAR process for the next QSR -Presentations by Ian and Lena (annex 3) Main milestones:

-2019: Concept and scope agreed -Data collection and analyses for assessment -Spring 2022: Committees to agree indicators and thematic assessments -Summer 2022: OSPAR to consider draft QSR -Summer 2023: QSR to be agreed by OSPAR and published There are differences between the QSR and the IA 2017, looking in particular at level of impacts instead of just being focused on status. The QSR will have a section on climate change and ocean acidification, but it is not yet clear which group will be responsible for this, and how it will interact with COBAM for biodiversity aspects. COBAM expert groups should be proactive to recommend format and length of related documents, and identify any elements contributing in biodiversity assessments.

Period of time for the assessments is supposed to include data from 2016-2021, but will potentially not include final year since latest (rolling) assessment should be finalised in autumn 2021. As several indicators are trend-based, would it be possible to compare back to QSR 2010, and QSR 2000? As indicators were not developed at this time, comparison will be limited and mainly descriptive. If relevant data from this assessment period would be made available, retrospective analysis could be done, but it would require then even more resources to conduct these additional analyses.

The OSPAR secretariat explained that it would also be an option to use the IA 2017 assessment for certain indicators, in case no new or relevant data is available.

• QSR and thematic assessments -Presentation by Ian (annex 4) A table, based on the QSR guidance document, was presented in plenary to collect views on what would be possible for the next QSR, according to current or potential additional resources. It was noted to keep in mind as a starting point the "action plan" deliverable from EcApRHA for benthic, pelagic and food webs and respective multi-year work plans when available. This table was filled by each expert group during the afternoon. Detailed results for each group are in annex 4 and key messages are included in the box below.

Key outcomes from the discussions after the QSR session

• As experts had no authorships in IA 2017 and in the next OSPAR QSR, the production of scientific articles has to be included in the work conducted by those experts who have to justify and valorise time spent for OSPAR work. This would also help and reinforce the robustness and quality of assessment produced. • More frequent and direct (e.g. workshops) science / policy interactions are needed, as early as possible in the process, to align expectations with possible work during timeline and milestones. This will be also needed to deliver relevant and clear thematic assessments.

EcApRHA (WorkPackage 4 with Science-policy workshops) should be used as a model for this process. This session aimed to continue discussions on possible concrete contribution to the next QSR, with a special focus on data and synergies with other OSPAR groups, notably to incorporate cumulative effects and links with measures.

• The "bow-tie" approach -Presentation by Cristina on behalf of Adrian Judd (annex 5)

This presentation introduced state/pressure relationships, and links with works done by the intersessional correspondence group on Ecosystem Assessment Outlook -Cumulative Effects Assessment (ICG EcoC). It illustrated the "bow-tie" approach and data requirements. This pragmatic and risk-based approach was already considered during EcApRHA project, and links and interaction with ICG EcoC were encouraged.

The marine mammal EG provided a first feedback and noted: "Where MMEG saw value in the approach, it was noted that, for marine mammals, the challenges are often a) the lack of ability to assess what is a direct or indirect impact; b) that these are unlikely to be independent of one another, and c) that the magnitude of the impact will vary between these potential pathways. This would ultimately lead to a complex, and somewhat difficult to interpret, bow tie diagram, unless certain aspects of the assessment are packaged more broadly. As such, bow tie diagrams may assist in basic visualization of a multiple effects assessment when qualitatively considering multiple assessments of impacts in isolation. However, these do not provide a method for quantitatively assessing cumulative effects of the multiple pressures/stressors that marine mammals are exposed to."

• Data requirements table -Presentation by Cristina (annex 5)

The structure of a table was presented in plenary to collect information on data requirements for biodiversity and human activities assessments (assuming also informing on climatic changes) to contribute to the next QSR, according to current or potential additional resources. This table was filled by each expert group during the afternoon. Detailed results for each group are in annex 5 and key messages are contributing to the box below.

Key outcomes from the discussions after the thematic and data requirements sessions

• Expert group will have to be also pro-active on possible structure and content of respective thematic assessments, for development at COBAM 2019. • The bow-tie approach is useful to illustrate and analyse conceptual links between data and information needed for assessments, and science-policy communication. However, there were doubts about the ability to distinguish direct and indirect impacts, and to really quantify respective contributions of activities/pressures on states, and also cumulative effects/impacts. Closer cooperation and exchange is required between COBAM and EcoC expert groups in order to develop "bow-tie" cumulative assessments products on State/Pressure/Activities. These should be incorporated into the thematic assessments (e.g. per biodiversity components) to provide coherence and complementarity in the report, rather than being in a separate chapter. • The work and products developed as "Measures Action Plan" were not clear during discussions. More information and links between groups are needed to incorporate implementation and effects of measures to biodiversity assessments. It is recognised that links with measures is a key element for adaptation and communication of biodiversity assessments.

• The way and process to work closer with other groups still need to be clarified.

Communication, meetings preparation and mutual attending of EcoC, MAP and COBAM convenors and expert group leads could be a minimal requirement until the next QSR? To be discussed and concluded at next COBAM and BDC. • According to data subgroups tables, much progress could be made in each expert group on many indicators. As mentioned before, it will strongly depend on organisation and resources available.

Wednesday 19 th June (9:30 -18:00)

Session 4: Food Webs

This session aims to present in more detail current work conducted and planned under the recently reactivated expert group on Food Webs. Food webs are a key thematic link to progress integration inside and between each ecosystem components, and for ecosystem structure and functioning aspects. It was thus important, notably at this joint workshop, that all experts have this minimum background knowledge of work under progress, to be linked with work planned in each expert group and following discussions on integration, monitoring and QSR thematic assessments.

• Food Webs -Presentation by Ulrike (annex 6)

Session 5: Integration and approaches to set thresholds

This session aims to introduce and initiate discussion on integration and threshold setting methods, as the ultimate technical elements towards ecosystem-based assessments for policy/measures guidance. Several parts of these methodological elements have been progressed, and are at different stage of development, in several groups. Presentations were made to introduce these various approaches and potential next steps to contribute to thematic assessments.

• Benthic indicators integration -EcApRHA approach -Presentation by Laurent (annex 7) To date, for OSPAR or MSFD, assessment is carried out on an indicator-by-indicator basis. However, the integration of indicators is required to undertake a holistic assessment of the state of the marine environment. An ecosystem-based integration method linking OSPAR condition and area-based indicators was developed during the EcApRHA project (2015-2017) and reported several times to OBHEG and ICES/Benthic Ecology Working Group. This method still needs to be tested at wide scale on relevant datasets, and specific knowledge gaps have been identified. This could be one of the concrete tasks to test it in a small area where relevant data exist. This would also probably require extra resources to be coordinated and secured at (sub-) regional scale. But within this conceptual method, four OSPAR benthic habitat indicators relating to biodiversity (D1) and sea-floor integrity (D6) descriptors are linked together. Benthos, environmental and anthropogenic pressure data are required for integration. State indicators are assessed along a gradient of pressure to facilitate threshold values to be quantified and provide advice on management measures. The method also includes a feedback system whereby best available evidence on benthos, its sensitivity and disturbance assessments can be replaced with ground-truthed data. The proposed method can be expanded to include other related indicators under the different descriptors (e.g. non indigenous species (D2), commercial fish and shellfish (D3), food webs (D4) and eutrophication (D5)), where relevant. This concept was published (Elliott et al., 2017) as a first step towards integration of OSPAR (benthic) indicators and could also be applied to monitoring requirements under other Directives such as the Habitat or Water Framework Directive.

• Seabirds indicator integration method -Presentation by Ian (annex 7)

• Seals indicator integration method -Presentation by Ian (annex 7)

• Seabirds indicator thresholds methods -Presentation by Ian (annex 7)

• Marine mammals indicator thresholds methods -Presentation by Anita (annex 7)

The power to detect trends for marine mammals may be increased by good survey design, and by incorporating multiple data sources, which may also improve understanding of any changes. A key issue is to avoid setting impossible targets. In general, targets need to be set in relation to reference levels and conservation objectives, while recognising the limits of statistical power to detect change based on logistically feasible monitoring.

Power analyses highlights the fact that 1% declines in abundance (as specified by the EU Habitats Directive) would be almost impossible to detect for wide-ranging cetaceans using any realistically feasible monitoring programme and, indeed, that only much larger declines are likely to be detectable in the shorter term (i.e. six yearly reporting period). The process of setting targets will need to take this into account and consider a much longer time frame; e.g. the IUCN approach of using three generations, noting that it is evidently not necessary to wait for the three generations or 10 years to measure the trend. For any species in which 3 generations is less than 35 years, the IUCN criterion implies a rate of decline greater than 1% per year, i.e. a rate that should be easier to detect than a 1% decline. Example: For the harbour porpoise, a 30% decline over 3 generations corresponds to an annual decline of 1.77% or just over 9% over the 6-year reporting cycle.

Given the limitations of available methodology and the cost and infrequency of large-scale surveys, a practical solution could be to accept lower confidence for trend detection.

• Food webs group approach on thresholds -Presentation by Ulrike (annex 7)

• Non Indigenous Species group approach on thresholds -Presentation by Paul (annex 7)

In the afternoon, participants split in subgroups to discuss food webs, integration and thresholds topics. 175 -191). There is a need to undertake a validation of models, some matrices are fixed but it includes long-term data series. Case studies using empirical data could be a first step to see how models are performing. Parametrisation of benthic parameters, perhaps have new data could be used to see the performance of models. Work on ICES ecoregions based on Ecopath models, and Ecosim models looking at time series of data, other environmental variables could be added. Irish Sea ecopath. Several case studies were discussed for potential use in the QSR: We need to be clear on what case studies are going to be proposed, what questions we are trying to address, how the information will be used. ICES organising stakeholders' workshops to see what policy or managers would like to know, perhaps the feedback form the workshop could help to guide the case studies. Case studies should be question driven, but aware of data limitations, -what are the nodes at risk, which keystones elements are declining. A case study could be a comparison of models in the Kattegat between ICES Ecopath and ENA but has limitations as the ICES models have no spatial resolution Certain habitat types were a proportion of the community is removed could be an interesting case study, perhaps on infralittoral sublittoral sands. Suggested area: Dogger Bank region sandy areas (not necessarily the MPA) as there are good datasets from several countries Looking at the links with some of the traits with BH1, this could be done in region IV or other areas. The models are also split into functional groups to see how the species are performing, so this could be an important link between FW and benthic work.

Validation -sensitivity analysis, using a series models on biomass or other to indicators. We can also cross-validate with different years Also, looking at changes and variations on the trophic cascade. Assessment areas -there are data limitations, so not going to be sufficient overlaps to allow for full assessments in regions or subregions, but we will need to go through the process to understand what results are being produced. Another potential datasets is from Norway. The Atlas project is looking at Deep-sea and FW. This aspect was not explored further as the Norwegian benthic expert was not available. Conclusion: several potential case studies could be explored for QSR assessments: A comparison between FW modelling approaches on the Kattegat and or in a North Sea subregion FW and Benthic: ENA incorporating benthic parameters in the North Sea (Dogger Bank area), potentially some areas of Bay of Biscay, linking with BH1 work, and on the Norwegian area.

Group B: Methods for integrationchair Ian, rapporteur Laurent

It was important at the beginning to distinguish 3 aspects linked to integration:

• Aggregation of data (to gather data for assessment at wider scales)

• OSPAR/MSFD thematic rules of reporting: from GES criteria -> Species/habitat -> Species/Habitat (functional) Group -> to biodiversity component • Various types of integration at indicator level:

-Food webs = is integrating by definition different component and biodiversity aspects -Intra-indicator (PH1=FW5) = information which can be used for different component -Inter-indicators (BH3=f[BH2; BH1]) for better benthic assessment -Inter indicators/components (e.g. BH with ENI, Food Web, etc. aspects or indicators)

Several aspects were then discussed, which could be summarised under these topics:

• Integration basic principles: Biodiversity (and food webs) are integrating by definition multiple pressures (anthropogenic and natural) so the state of a component already reflects an overall assessment. The challenge is to distinguish effects of each pressure type to guide management measures on specific activities. Splitting Biodiversity into "components" is useful for conservation issues, but an ecosystem-based management needs links and functions. Indicators are useful to summarize information but are just a "piece of the machine" and more work, since integration is needed to have a more refined and useful understanding of the ecosystem (component). Integration methods, whatever they are, have to be transparent, without hiding underpinning information, with possibility to go back ("disintegrate", or stop integrating at too high levels) to sources of data to understand results. This is part of the expert judgement required to interpret and conclude on results of the integrated assessment.

• Assessment area/scales: Relevant and well-defined assessment areas/scales per (sub-)region are the basic knowledge for each component and indicator. Integration methods will have to take into account and be built on these elementary spatial units. Current indicators may have very different assessment scales, even for the same component, but it is useful then for a better understanding. For example, there are broad scale assessments for the pelagic, mostly driven by climate changes, versus local scale assessments, like for Water Framework Directive, assessing disturbances due to nutrients and organic enrichments. It is interesting for habitats to note that pelagic and benthic indicators have indicators that currently can be used at both broad scale (PH1, PH2, BH3) and finer scale (PH1, PH2, PH3, BH2, BH1). Furthermore, the pelagic hydrodynamic landscapes, used for assessment at any scale, are conceptually similar to the broad benthic habitat types or biogeographic strata, which drives reporting and assessment of any benthic indicator (Van Hoey et al., 2019). Works towards linking these pelagic landscapes and broad habitat types, to food webs and mobile "species habitats" would be a stepping stone towards a more ecosystem-based assessment, trans-component.

• Thresholds versus trends: The level of integration to which a trend or threshold is observed is important for interpretation. With current gaps of knowledge, and the few resources to progress, it is anticipated that few habitat and food web indicators may have thresholds for the next QSR assessments. However, a trend-based assessment already makes sense and is informative, for science and management. Furthermore, long-term series of data (e.g. pelagic) enable to interpret more recent changes, locally (chronic disturbances) or at wider scale (climate change). And this information on the variations of the status of biodiversity components, at various scales, is important when compared together to interpret and conclude on ecosystem general status.

• Way forward on integration to contribute to the next QSR: From the most simple to the more complex integration method, the question is just about the state of operationalisation of the methods, data and resources availability and way to communicate results. How to communicate about, for example, "plankton is changing"? Besides, integration is not only bringing together assessment results, it is also forming coherent narrative between state, pressures, impact, managements and links. It doesn't always need to be quantitative. We could imagine a narrative explanation of assessment, cross-component, illustrated by case studies, as it was already imagined between NIS and benthic, food webs and several others. Decision tree and conditional rules are also pragmatic and operational tools which could be elaborate for communication and decision guidance for management. All this will imply strong science/policy direct interactions to develop tools and methods adapted to the current possibilities and overall requirements. Different level and process of communication will be needed to progress current scientific and technical gaps, to understand and adapt current methods and prioritise management requirements. Communication will also have to be adapted for a wider public. All these aspects may have to be deal at various integration levels (e.g. higher for wider public).

Group C: Methods for thresholdschair Paul, rapporteur Anita

According to the definition from Article 2 of the Commission Decision 2017/848/EU "a threshold is a value or range of values that allows for an assessment of the quality level achieved for a particular criterion, thereby contributing to the assessment of the extent to which good environmental status is being achieved". The break-out group started to intensively discuss the definition of thresholds as such; and how thresholds relate to targets. Different examples and approaches from pelagic to benthic indicators were presented. Common issues with respect to MSFD were discussed; what if OSPAR decides to set different thresholds than EU MS? What about inclusion of climate change?

In the middle of the afternoon, experts split in subgroups by ecosystem component to further discuss food webs, integration and thresholds, with a focus on these specific components.

Group A: Benthic -chair Cristina & Laurent

For benthic habitats, it is good to remember that last OBHEG workshop report (Santander, June 2018) already provides many elements and recommendations for all these topics (integration, thresholds, monitoring, etc.). Besides, a working group (TG Seabed) is mandated at EU level to work on thresholds for D6 aspects. It is then important to follow and communicate with this group, rather than duplicate this work.

A tour de table was made on elements, case studies, ideas or key messages discussed in different groups. Each participant had to highlight an outcome which seems to her/him important about these topics. Here are gathered the views of each benthic expert:

Food webs aspects:

• A case study was discussed and planned mixing benthic and Food webs aspects, in Dogger Bank and Kattegat. It would imply comparison between EcoPath and Ecological Network Analysis (ENA), FW4 and FW9 including benthic data. • There is a plan from UK to contact Norway and Spain to propose case studies for Region I and IV for FW9 (ENA) with benthic communities' data and biological traits. It would then be concluded if a specific data call is needed to involve other OSPAR CPs.

Integration aspects:

• Biological traits are an important aspect to connect with Food Webs, even if it was recognised since longs that there are huge knowledge gaps for many species of the OSPAR maritime area. An ENA diet matrix would enable a concrete link for combined analysis. • It would be important as a starting point to work on the assessment units for each of the biodiversity components (notably broad habitat types and biogeographic strata versus pelagic landscapes), to enable assessments between components. • Integration is key for communication. Science-policy interaction is definitely needed all along future works for OSPAR QSR. • According to presentations made, there is potentially data and methods which could be applied to a case study mixing pelagic, benthic (D1), non-indigenous species (D2C3) and food webs (D4) aspects. A data call could be made to identify a local area with sufficient data and illustrate a multi-descriptors assessment. But it should be part of a project-based work.

Thresholds aspects:

• The concept of threshold is quite confusing and should be clarified/specified when applied to indicators, criteria or group, level or distribution of pressure, targets, etc. We should make clear definitions also on the use of alternative words, like assessment values, (environmental) targets, GES, etc. • There may be also a question of scale for thresholds (e.g. local versus national versus subregional). And a need to distinguish its use between state assessment (with climate change background) and pressure/state assessment (at various scales). • There are now implicitly 2 different thresholds in MSFD D6 from 2017 GES Decision: The percentage of area affected, and how we define, quantify and set a limit on "adversely affected". Logically, works should be progressed on the second one first. • Besides quantitative thresholds, trends analyses should be conducted if sufficient time series are available, as it already enables interpretation and recommendation for management. Evolution of pressure disturbance and intensity is informative for exposed benthic habitats.

Others:

• We should do more meetings like this (joining different expert groups) It is really opening mind and boosting ideas, notably for a more ecosystem-based approach!

Group B: Pelagic -chair Abigail

Thresholds: For pelagic, thresholds shouldn't determine GES but can be used to give structure to our narrative for interpreting observed trends. We somehow have to ensure that the message for policy doesn't contradict the message from the eutrophication assessments. Eventually, we could test threshold ideas around magnitude of change linking to GES/not GES, but this will have to wait until we have resources.

Integration: Pelagic group will use a narrative to discuss and interpret indicator results rather than a numerical integration that is dependent on thresholds. A negative of numerical integration is we lose detail from the individual indicators, including geographic information which is useful for putting in management measures. A narrative allows us to retain this information and frame results in a useful and informative way.

Group C: Food Webs -chair Ulrike -Is Food Webs (the FW group and the indicators they produce) perhaps the place where integration across themes (e.g. benthic -pelagic) should happen? (don´t do double/extra integration work across themes outside the FW group?)

-The group felt that the FW group needs to (also) focus (at the moment) on demonstrating their value with showcases and at the same time raise and manage the right type of expectations with policy makers.

-Is FW9 an indicator? The output indices might be, but the model itself is more like a full enveloping integrator of all indicators. We need to be clear on terminology and deliverables.

-The underlying question or overarching message of an assessment should be leading in determining the degree of integration (needs to be meaningful in the first place). Integration is about creating and facilitating a narrative.

-Combined assessment of pelagic and benthic habitats in the same geographical location is also a form of integration perhaps worth looking at: is this an effort that should (if it is ever made) fall under the umbrella of FW?

-There might be a chapter on coupling observations from several indicators and working groups (example just to paint picture: nutrients-primary production -zooplankton parameter -herring abundance). Would this be part of the food web chapter, or a separate chapter?

-Take care that important (e.g. temporal or spatial) is not lost when integrating. An infograph produced after compressing all the data into one integrated bit of information needs to be comprehensive, allowing for trends over time, space and within/between monitored variables to be visible (or do we want to leave such jobs to "the science writers").

Group D: NIS and friends -chair Paul

Main outcomes of discussion are summarised in the key outcomes below Key outcomes from the discussions after the food webs, integration and thresholds sessions

• Most indicators may not have thresholds but are still critical for management decisions and must be included in the next OSPAR QSR. These include trend-based indicators. • Integration can be descriptive as well as (semi)quantitative. For "non-species" biodiversity assessments, according to current works and resources, we are likely to mainly develop descriptive thematic assessments, per ecosystem component. Depending of data and resources available, some local case studies could be developed to illustrate this. Groups will aim to deliver some draft examples to BDC 2021. • Besides scientific and technical gaps to fill, the way to communicate, and the need of strong science/policy direct interactions are crucial to elaborate relevant and useful assessments. • Integration methods, whatever they are, have to be transparent, without hiding underpinning information, with possibility to go back to sources of data to understand results. This is part of the expert judgement required to interpret and conclude on results of any integrated assessment.

Thursday 20 th June (9:30 -17:30)

Session 6: Monitoring

Monitoring is an important step as it is the basis to provide survey and observational data for any biodiversity indicator and integrated assessments. Spatial and temporal designs and resolutions have to be adapted to each assessment method to be used. Reporting in monitoring programmes to support data provision for assessments is also part of the next round of reporting cycle for MSFD (2020 for EU Member States). The definition of the monitoring programs is the responsibility of the member states, but should be ideally imbedded on a regional scale level (Van Hoey et al., 2019). This should lead to more cost-efficient monitoring and more coherent assessments on the right spatial and temporal scale.

• NIS and monitoring -Presentation by Paul (annex 8)

• Table and illustration to initiate thoughts on monitoring -Presentation by Laurent (annex 8) A table was presented with some information for some indicators on needs/possibilities for joint or coordinated monitoring. It was submitted as a working document. The schematic of the "feedback loop" of the (EcApRHA) integration method for benthic indicators was presented to illustrate the use of fine scale monitoring to inform on wider scales assessment for benthic habitats.

After plenary, expert groups met alternatively by pairs, to discuss and share national examples, experiences and potential common or specific aspects of monitoring. Main outcomes are summarised here:

Group Food Webs + Pelagic CPR (Continuous Plankton Recorder) is a joint monitoring solution. Data are needed for pelagic, food webs, NIS throughout all 5 OSPAR regions but the CPR is primarily funded by the UK and is therefore vulnerable (recently the survey has lost routes and sampling due to loss of UK funding). How can we ask OSPAR contracting parties to support this survey? Quality assurance and consistency are already accounted for in this survey. Can we use CPR data for FW2 (phytoplankton production), FW6 (zooplankton something), FW9 (Eco Net Analysis)?

Group Benthic + NIS Benthic NIS monitoring is currently quiet opportunistic in most of countries, from benthic surveys and for other concerns. Several countries (including France, Germany, Netherlands and Sweden) are testing dedicated NIS monitoring in risk-areas like harbours, canals or marine culture. There were past (Marinex) and project INTERREG programmes between France and UK for specific monitoring in harbours of the Channel (GenSys) and between UK, France, Belgium and the Netherlands for specific monitoring in estuaries of the southern North Sea (SEFINS). Assessment scale/area, methods and spatio-temporal sampling design is very important to have comparable baseline of NIS introductions/occurrences, and thus be able to assess trends. At OSPAR sub-region scale, a joint/coordinated monitoring is thus needed to have comparable baselines and trends assessments. Renewable marine energy should include (benthic) NIS monitoring as it is a potential support and relay for dispersion of benthic species. In the Greater North Sea, most of harbours are already well and frequently connected by marine traffic. Bio-contamination (NIS occurrence) on windfarms would then probably be similar with those harbours which are used to import/export its infrastructures. Monitoring of benthic NIS is important for early detection and potential eradication measures, but moreover to assess effects of measures on vectors (e.g. ballasts or biofouling treatments). New technologies, as biomolecular tools, are promising for NIS detection. There is thus a challenge and interest to increase benthic species barcoding besides classical taxonomic determination. Citizen science could also contribute, notably on distribution and occurrences of NIS along OSPAR maritime coasts. Assessment of NIS impacts on benthic habitats (MSFD D2C3 criteria) should be part of benthic habitats loss (D6C4) or disturbance (D6C5) assessment. There are currently preliminary thoughts and work plans (NIS-EG and COBAM/EIHA) to develop method and case studies for this. This will also depend of resources available.

Group Food Webs + NIS Main outcomes of discussion are summarised in the key outcomes below Group Benthic + Pelagic Benthic monitoring requires environmental data, notably pelagic, to be interpreted. Besides, many benthic species have a pelagic larval stage which is critical for their dispersion. Information on both benthic and pelagic is also important for NIS and food webs issues. In Sweden, some "intensive monitoring areas" were defined recently where several components are monitored in a coordinated way, including benthic, pelagic, fish, NIS, hydrological parameters, etc. Currently there is already a coordinated monitoring for benthic and pelagic, at EU scale, but with the specific objective of the Water Framework Directive. Very coastal (1 nautical mile) benthic and pelagic data are monitored as quality elements, and integrated (one out all out rule), to assess coastal and transitional water bodies' quality status. These data (as quality element, before integration) are also re-used for BH2-A and PH3 and contributed to OSPAR 2017 intermediate assessment. For more offshore habitats (both benthic and pelagic), monitoring is currently very heterogeneous and with many gaps in most of the OSPAR maritime area. There is a need and great interest to work towards a coordinated or joint monitoring for benthic and pelagic habitats, also for MSFD descriptors D1, D2, D4 and D6. There are some long term series of benthic and pelagic monitoring, sometimes close to each other, in several countries. The CPR is a great example of this, but the survey is financially vulnerable and needs concerted funding from OSPAR countries. In the benthic realm, long-term monitoring is also declining in some countries, as stations are reduced and time frame between sampling enlarged (to sometimes once every 3 years). It provides important information for long term trends and understanding global changes as climate or ocean acidification. A coordinated/joint monitoring network of long term series stations should be encouraged and sustained. Information on toxic or harmful plankton blooms is important as it may have an impact on benthic species and communities. It would help to interpret changes due to plankton compared to other pressures (natural or anthropic). There are a lot of environmental impact studies (e.g. for various industries) using benthic and pelagic monitoring, but which are most often not coordinated, even nationally. National and regional/European standards should be systematically recommended and used for these EIA studies (Van Hoey et al., 2019). Structure and accessibility of databases is also crucial to facilitate and develop future coordinated benthic and pelagic monitoring.

Group Food Webs + Benthic

Main outcomes of discussion are summarised in the key outcomes below Group NIS + Pelagic Again, CPR data can provide info on 'native' and NIS species, including time of introduction. Main other outcomes of discussion are summarised in the key outcomes below

Key outcomes from the discussions after the monitoring session

• CEMP guidelines currently only give minimum monitoring requirements for some indicators but are not delivered or implemented for all indicators, preventing assessments. • Thematic guidelines (e.g. plankton, benthic, NIS, etc.) would be more efficient, less redundant and more practical to guide monitoring and assessment of each biodiversity component, rather than per indicator. • There is a big add-on value to coordinate monitoring between biodiversity components, notably for food webs but also to help interpret changes observed in each component. This is an important part of the ecosystem-based assessment towards which OSPAR and MSFD aims to be implemented. • Most decisions around coordinated monitoring are actually policy decisions or short-term scientific projects. Expert groups can work towards recommendations and guidance, but only policy people can save budget and make decisions to implement it. It should be made clear as soon as possible from decision committee (e.g. BDC) what would be the resources and level of expectations for coordinated and/or joint monitoring for each biodiversity component, and between them. • It is already very late to provide any new guidance for MSFD reporting (2020), to enable any significant progress. But it will be important to boost and progress works towards coordinated/joint monitoring on regional level, as this is the first gap to fill to have more complete and more relevant data for next QSR and other assessment cycles.

Session 7: Synergies and feedback from the group

Discussions in previous sessions highlighted the need for cooperation and interaction with several working groups, inside and outside the OSPAR process (see previous session's conclusions). Each group lead informed on links and synergies made by his group's Terms of References. In this session, feedback from 2.5 previous days was also collected from participants on this workshop and more generally COBAM works and process.

• Example of synergies for OSPAR-HELCOM-ICES Seabirds -Presentation by Ian (annex 9)

As an example, the joint OSPAR-HELCOM-ICES Seabirds expert group was presented to illustrate context and process of this joint group. Each of the 40-50 members of this group (around 20 physically attending the annual meeting) is nominated by OSPAR, HELCOM or ICES. Terms of Reference have to be discussed and agreed by all institutions. There are also links with CAFF (Conservation of Arctic Fauna and Flora) and AEWA (Agreement on the conservation of African-Eurasian Migratory Waterbirds), notably on the assessment of kittiwake populations.

The case for the marine mammal expert group is a bit different. The ICES WG on Marine Mammal Ecology is a WG with a long history and is, as such, a very active group on its own; currently holding a membership number of about 70 experts. There is considerable overlap with the, in Oct 2018, reactivated OSPAR marine mammal EG (about 85% overlap), however, for the moment it is thought to keep the groups separate, also given the urgent work for QSR.

For Benthic habitat expert groups, there are only links with other expert groups by common members sharing information. Some members are also part of HELCOM (Baltic Sea), BARCON (Mediterranean See) or various ICES expert groups. There was recently decided to include a common task in OSPAR/OBHEG and ICES/Benthic Ecology Working Group to highlight years of cooperation and facilitate preparation, communication and strengthen complementarity of respective works.

For Non Indigenous Species experts group, there are also common members from the HELCOM, BARCON and ICES group. There is a formal link for a joint OSPAR/HELCOM group, but only for the Ballast water and sediments Convention of the International Maritime Organization.

• Debriefing and feedback from group -Presentation by Ian & Cristina (annex 9)

-Did you find it useful? -Have you learnt or improved your understanding of other working areas? -What did work so well? -Should we do it again? -Should we do it differently? -Messages to COBAM?

An open discussion was held in plenary around these questions and main outcomes are summarised in the key messages below.

Key outcomes from the discussions after synergies and feedback session

• Science-focused workshops, such as this one, are key to progress monitoring and assessment methods and interpretation of data analysed. Science-policy interactions are also key to adapt methods developed to aims and level of expectations, and communicate in an efficient and clear way results, knowledge gaps, conclusions and recommendations. Timeline and products deadlines are correlated with available resources (long-term and short-term, like projects, for boosting works). • This workshop was appreciated by most of experts, even if it was recognised that works in expert groups on more focused and technical issues are also required. • An option could be to have at least one scientific workshop of each expert group workshop in spring 2020 and 2021, and COBAM only in autumns of these years. Possibilities to have back to back, or like here joint workshops, should be encouraged for specific issues to be solved, notably for more integrated assessment in the next QSR. • It would be great if at least one of the COBAM co-convenors and from EIHA and ICG-C could attend these spring workshops. • Science-policy interactions, notably workshops, should be discussed and proceed as soon as possible by decision committees (notably BDC, COG and ICG-MSFD)

• Key tasks table -Feedback by expert groups leads There was a request from COBAM to fill a table on key tasks on each indicator towards next COBAMs. This table was filled in plenary by expert groups' leads and experts involved in indicators development: BH1 typical benthic species (OSPAR II & III), BH2 condition of benthic habitat communities & BH3 extent of physical damage to predominant and special habitats (OSPAR I and V?), FW4 Change in average trophic level of marine predators (OSPAR II) FW3 is already used in every OSPAR region, but FC1-3/FW3/FW7 miss data from Celtic Sea, possible to use new survey data FW7 could be expanded to OSPAR region IV by mid-2020 Proposal for promotion to common indicator FW7 Fish biomass and abundance of dietary functional groups BH4? (Depending on resources and case study) FW9 is being put forward as a candidate and will be decided at BDC 2022 for inclusion in QSR2023 Indicator on contaminants in marine mammals to be proposed as candidate to HASEC 2022 for inclusion in QSR

Conclusion and next steps

The report of this workshop will be drafted by expert group leads and submitted to participants for review in September. The final report will then be submitted to COBAM (19-21 November 2019) and OSPAR Secretariat. The deadline for submission to COBAM of the final report is 25 th of October 2018. All aspects developed and highlighted as key outcomes of this workshop will be discussed and formatted during COBAM to raise key messages and requests to Biodiversity Committee (March 2020). Depending of conclusions made at COBAM and BDC, Terms of Reference and work plans of each expert group will be potentially updated. Next meetings and workshops will depend on updates made. Expert group leads will interact with each other to communicate to experts form each group the next meetings and workshops planned.

List of Annexes

Annex 1: List of attending participant Annex 2: Final agenda of 2018 OBHEG workshop Annex 3: Presentations of expert groups' leads overviews on works to be done towards next QSR Annex 4: Presentations and tables on expert groups' views on contribution to QSR and thematic assessments Annex 5: Presentations and tables on expert groups' views on data requirements for data calls Annex 6: Presentation on Food Webs session Annex 7: Presentations on integration and thresholds session Annex 8: Presentations and table structure on monitoring session Annex 9: Presentations on synergies and feedback session

Page

  Executive summary and key messages Session 1: Introduction -aims and context of this workshop Session 2: Towards next OSPAR Quality Status Report Session 3: State/pressure/Activities and Data requirements Session 4: Food Webs Session 5: Integration and approaches to set thresholds Session 6: Monitoring Session 7: Synergies and feedback from the group Conclusions and next steps List of Annexes

  Group A: Food Webs discussionschair Ulrike, rapporteur CristinaCase studies for the QSR looking at interconnections across different ecological elements: FW4 Change in average trophic level and FW9 -ENA . Both indicators use the same data products. The ENA could develop scenarios and look at changes within different compartments. Only FW4 and FW9 give you ecosystems assessments. It needs to be clear how the data are going to be used, in particular for management. Review of ecosystem models done by Chiara Piroddi et al (2015)(Ecological indicators 58 (2015)

  empirical thresholds (timeseries based, but not for all areas) for: FW3 Size composition in fish communities, FC3 Mean maximum length of demersal fish and elasmobranchs, and FW7 Fish biomass and abundance of dietary functional groups B3 Marine bird breeding success (change to existing thresholds) M4 Cetacean abundance & distribution? M6 Marine mammal bycatch? Proposal of indicator expansion NIS trends in New Records of Non-Indigenous Species introduced by Human Activities (OSPAR I and V?) PH1/FW5 Change in plankton communities & PH2 Change in plankton abundance and biomass (OSPAR I & V) PH3 Change in plankton diversity (OSPAR II & IV) M3 Seal abundance and distribution (OSPAR I & III) M5 Grey seal pup production (OSPAR I & III)

Session 2: Towards next OSPAR Quality Status Report (QSR)

	Statusoverview_biodiversity_indicators.docx
	 2019-20 COBAM Key expert group tasks.docx
	 DRAFT_QSR2023_guidance_document.docx
	 COBAM_data_stream_overview.docx
	 Elliott et al_2018_integrating-benthic-indicators.pdf
	 Overview_coordinated and joint monitoring_190611.xlsx
	 seabed_JAMPproduct.docx
	 Practical-approach-for-funding-opportunities.docx

•

  According to the OSPAR process, there are only 2.5 years left to deliver technical content for the draft QSR end 2021. With current resources the expert groups will coordinate and produce some work on methods development, however, to reach the current level of expectation on the next QSR, with updated data computing and assessment, and a more integrated and ecosystem-based work layer, extra resources are urgently needed (postdoctoral positions, workshops, inter-component interactions and project managing). Remaining time does not even enable to candidate on potential future EU call for project.• COBAM expert groups should be proactive to recommend format and length of related documents, and identify any elements contributing in biodiversity assessments •

It seems that, as an OSPAR process, only OSPAR can now decide and organise funding of its expert groups to reach the current level of expectation on next QSR. Session 3: State/Pressure/Activities and Data requirements

https://www.ospar.org/work-areas/bdc/ecaprha

ANNEX 1: List of SUPER-COBAM workshop participants (18-20 June 2019) Attendees: From OSPAR Pelagic Habitats Expert Group: Abigail McQuatters-Gollop (chair, United Kingdom) Felipe Artigas (France) Laetitia Petit (France) Jacob Bedford (United Kingdom) Marie Johansen (Sweden) Hans Jakobsen (Denmark) Hans Ruiter (Netherlands, chair ICG-EUT) Birgit Heyden (Germany) Jos Schilder (Netherlands) From OSPAR Benthic Habitats Expert Group: Laurent Guérin (co-chair, France) Cristina Vina-Herbon (co-chair, United Kingdom) Mats Blomqvist (Sweden) Paul Coleman (Ireland) Grete Elisabeth Dinesen (Denmark) Jørgen L.S. Hansen (Denmark) Maarten de Jong (The Netherlands) Izaskun Preciado (Spain) Hans Ruiter (The Netherlands) Alberto Serrano (Spain) Gert Van Hoey (Belgium) Sander Wijnhoven (The Netherlands) From OSPAR Food Webs Expert Group: Ulrike Schueckel (chair, Germany) Felipe Artigas (France) Andrea Belgrano (Sweden) Laetitia Petit (France) Izaskun Preciado (Spain) Jos Schilder (Netherlands) From OSPAR Non Indigenous Species Expert Group: Paul Stebbing (chair, United Kingdom) Laurent Guérin (France) Saa Kabuta (The Netherlands) Debbie Murphy (United Kingdom) Peter Staehr (Denmark) From OSPAR Fish and Cephalopods Expert Group: Maurice Clarke (Ireland) Vicky Sarrazin (Germany) From OSPAR Marine Mammal Expert group: Anita Gilles (chair, Germany) Farah Chaudry (UK) Jan Haelters (Belgium; only 18.06.) Begoña Santos (Spain) Inger van den Bosch (the Netherlands) From OSPAR Seabirds Expert Group: Ian Mitchell (chair, United Kingdom) From OSPAR Secretariat: Lena Avellan (OSPAR Secretariat)

Assessing Biodiversity Status Under

Expert groups meetings (See dedicated agenda and MNHN rooms' map):

• Marine mammals (all day): Room "Baleine 2" (9:30 -18:00) • Food webs (all day): Room "Claude Hélène" (9:30-18:00) • Benthic habitat (afternoon): Room "Petit Entomo" (9:30 -17:30) • Pelagic habitat (afternoon):Room "Baleine 3" (13:30 -18:00) Tuesday 18 th , 9:30 -17:30: Friday 21 th :

Expert group meetings (See dedicated agenda and MNHN rooms' map):

• Benthic habitat (morning): Room "Petit Entom" (9:30 -13:30)

• Pelagic habitat (all day):Room "Baleine 3" (9:30 -13:30)

• NIS (morning): Room "Grand Entomo" (9:30 -13:00)

Each group will welcome any other Super-COBAM expert who would like to attend!


Sara Tabrizinejadas

Anis Younes

Hussein Hoteit

Jerome Carrayrou

Marwan Fahs
email: fahs@unistra.fr

Coupled fluid flow, solute transport and dissolution processes in discrete 2 fracture networks: an advanced Discontinuous Galerkin model 3 4

Keywords: Dissolution processes, Fractured rocks, Discrete Fracture Network, 51 Discontinuous Galerkin, advection-dominated transport. 55

Modeling dissolution processes in discrete fracture networks (DFNs) is a challenging task. 25 Challenges are related to the highly nonlinear coupling between flow, mass transport, and 26 reactive processes associated with fracture aperture evolution by dissolution. Further, 27 advection-dominated transport due to fast fluid flow in fractures renders the problem more 28 complex from a computational point of view, as traditional numerical methods may introduce 29 unphysical oscillations or excessive numerical diffusion. The Discontinuous Galerkin (DG) 30 method is known to be suitable for the simulation of advection-dominated transport. In this 31 work, an advanced DG model is developed to model transport with dissolution in DFNs. We 32 propose an upwind formulation to deal with the upstream concentration at the intersection of 33 several fractures. The upstream concentration at an intersection node is calculated based on 34 the average nodal concentrations of all the fractures having an inflow at that node, weighted 35 by the volumetric fluxes of these fractures. The dispersion term is discretized with the Mixed 36 Finite Element (MFE) method, which ensures the continuity of the dispersive flux at the 37 intersection of fractures with different apertures. The obtained nonlinear coupled flow-38 transport-dissolution equations are discretized in time with a high-order scheme via the 39 method of lines (MOL). Numerical examples and comparisons with standard finite element 40 (FE) and finite volume (FV) solutions are performed to investigate the correctness and 41 efficiency of the developed model. Results show that the new DG-DFN model avoids 42 unphysical oscillations encountered with the standard FE method and strongly reduces the 43 numerical diffusion observed with the upwind FV scheme. The DG-DFN model is then used 44 to investigate the effect of the dissolution rate on the flow, transport, and aperture evolution 45 processes for a single fracture and for a DFN. A quasi-linear evolution of the fracture aperture 46 is observed for low dissolution rates. For high dissolution rates, a funnel-shaped enlargement 47 is observed with a significant widening for the fractures near the inlet and minor effects for 48 those away from the injection location.

49 50

Introduction 53

The flow of water in fractured rocks is usually associated with dissolution processes and 54 transport of the dissolved species (Liu et al., 2020). Naturally existing fractures as well as coupled flow and mass transport processes in fractured porous media with no reactive 103 processes and with constant fracture aperture. To the best of our knowledge, the DG method 104 has never been used for modeling coupled flow, mass transport and reactive dissolution 105 processes in a discrete fracture network.

106

The objective of this paper is to develop an advanced numerical model based on the DG 107 method for the simulation of dissolution processes in DFNs, and to take advantage of this 108 model for investigating the effects of geochemical dissolution rate on fracture evolution, flow 109 and transport processes. The upwind P1-DG scheme developed by Younes et al. (2009) is 110 adopted to simulate the advection processes in the network of 1D fractures. With this scheme, 111 the degrees of freedom are the mean concentration on elements and the concentration 112 gradient. The Riemann solver is then used to evaluate the concentration at the nodes. The The flow process in a fracture with a variable aperture   bL is governed by the fluid mass 145 conservation equation:

146     .0 q b b t       (1)
and the Darcy law:

147 2 00 12 q g gb HH           (2)
where,   HL is the hydraulic head,   tT is the time and 1 .

LT    q is the Darcy velocity,   bL 148 is the local fracture aperture,     is the porosity, 2 . g L T    is the gravity acceleration, (Witherspoon et al., 1980;Graf and Therrien, 2007;He et al., 151 2021).

152

Under isothermal conditions and no precipitation processes, the mass conservation of a 153 contaminant species through a fracture, taking into account the dissolution process, is ruled by 154 the advection-dispersion-reaction equation (Detwiler and Rajaram, 2007):

155       . . ( )
qD bC b C b C R C t          (3)
where,

LT   

D

is the velocity-dependent dispersion tensor for a fracture filled 157 by a porous medium.

158

The transport Eq. (3) writes

159       . . . ( ) q q D b C b C b b C b C R C tt                  (4)
which, using Eq. ( 1), simplifies to

160   . . ( ) qD C b b C b C R C t          (5)
In the case of one-dimensional fracture, D is given by:

161 Lm DD     q (6)
where,

 

L L  is the longitudinal dispersivity in the fracture and

166

In this work, under the assumption of no precipitation processes, the reaction term   RC 167 representing the dissoulution processes is modeled using a first-order approximation with a 168 constant reaction rate (Hanna and Rajaram, 1998;Detwiler and Rajaram, 2007;Steefel and 169 Lasaga, 1994;[START_REF] Steefel | Multicomponent reactive transport in discrete fractures[END_REF]:

    CS R C K C C  (8)
where,

The numerical model 173

To solve the set of equations (1-8) for flow, transport, and aperture evolution, we selected 174 numerical methods that provide accurate and consistent solutions for each kind of equation.

175

Thereby, the spatial discretization is based on the combination of the MFE method for flow and dispersion, the upwind DG method for advection, and the FV method for reaction. We summarize the main steps of the spatial discretization that allows for obtaining a system of 178 coupled ordinary differential equations. This system is then solved with the DASPK time The flow in the fracture network is discretized with the MFE method. Thus, for a fracture k 187 of length k and width k b , the velocity is approximated with linear test functions as follows:

188 2 1 k k k jj j q q w    (9)
where, k q is the velocity inside the fracture k, 1 191

The continuity Eq. ( 1) is integrated over the fracture k yielding the following mass 192 conservation equation:

193 12 0 k k k k k b qq t       (10)
The variational formulation of Darcy's law Eq. ( 2) using k i w as a test function gives:

194   2 2 0 1 00 12 kk k k k k k j i j i j gb q w w Hw         (11)
Integration by part leads to:

195     2 2 0 0 1 00 12 kk k k x k k k k k j i j i i x j gb q w w H w Hw                  (12)
Using the trapezoidal rule for the evaluation of the left integral yields:

196     2 0 2 12 k k k k k i i k gb b q TH NH      (13)
Eq. ( 13)is then substituted into Eq. ( 10) to obtain:

197     3 0 12 20 6 k k k k k k k k gb b NH NH TH t           (14)
To close system (14), mass conservation is written at each node of fracture intersection. At the 198 node i surrounded by n fractures, we have:

199 n* ii n qQ   (15)
where * i Q is the pumped/injected quantity at the intersection node i. For a given fracture network, the flow system is formed by writing Eq. ( 14) for all the

Spatial discretization of the transport 207

The DG method, which is well adapted for transport with sharp interface fronts, is employed 208 for the discretization of the advection equation. With this method, we assume a linear 209 discontinuous approximation of the concentration:

210       12 k k k k k kx C x,t | x TC x C      (18)
where k C is the concentration at the fracture k , which has two degrees of freedom:

213     12 1, kk k x x x x     (19)
where k

x is the center of the fracture k .

214

The weak formulation of the transport Eq. ( 5) writes:

215       0 0 0 0 0 0 q q q D k k k k k k k k k k k i i i i i i C b b . C b C . b C . b C R C t                          (20)
In the following, we develop the calculation of the second term, for which a specific treatment 216 is developed to solve the Riemann problem, and the fifth dispersive term, which is calculated fractures.

219

The second term is transformed into a boundary integral where the Riemann problem is 220 solved at the interface as follows:

221     1 1 2 2 0 0 q k k k k k k , * k k , * i i i xx b . C b q C q C         (21)
The upstream concentration fractures n sharing the node j and having a positive flux n j q as follows:

228 0 n j nn j j ,in k n j ,out n j n q q NC NC q     (24)
Thus, the second integral in Eq. ( 20) can be written in the following form:

          1 1 2 2 12 12 0 1 1 1 1 2 2 2 2 12 11 11 q k k k k k kk ,in ,in k k k k k i k k k k k k k k kk ,out ,out NC NC b . C b q b q NC NC                                                    (25)
where

k j  is such that 1 k j   if 0 k j q  , else 0 k j   .

230

Using the MFE approximation for the dispersive flux q D C    , the fifth dispersive integral 231 in Eq. ( 20) writes:

232       12 12 0 0 0 0 k k k kk kk i i i k qq qq . bD C . bq                    (26)
where, k j q is the dispersive flux at the node j of the fracture k , calculated in a similar 233 manner to the Darcy flux Eq. ( 13):

234 2 k j kk jk k TC NC q b D   (27)
where j NC is the concentration at the node j . which yields:

238 n n n n n j n n n n b D TC NC b D    (29)
Thus, Eq. ( 27) becomes:

2 n n kn n k n jk n k n n n b D TC b q D TC b D          (30)
If the fracture k is filled by a porous medium, the dispersion coefficient is approximated by:

240 k k L k m D q D   (31)
where, k L  is the longitudinal dispersivity through the fracture k and

  21 2 kk k k qq q b  
is the 241 mean Darcy velocity in k .

242

Finally, the calculation of all integrals of the transport Eq. ( 20) gives

243                 11 1 11 1 1 1 1 1 22 2 12 22 2 2 2 2 2 1 1 1 1 0 0 k kk k ,in kk k k k k k k ,out x kk k k kk kk ,in kk k k k k k k ,out x TC NC t M b q NC C t NC TC qq R TC b q M NC C                                                                   (32)
where the terms of the  

22  local matrices are 1 0 k k k k k ,ij i j Mb      and 244   2 1 2 00 kk k k k k k k k ,ij i j j i M q q b           q , the expressions of 1 k ,in NC and 1 k ,out
NC are given by 245

Eq. ( 23) and Eq. ( 24) and the dispersive fluxes 1 k q and 2 k q are given by Eq. ( 30).

246

If dissolution is considered, the aperture of the fracture can evolve with time, as ruled by Eq. 247 (7). The integration of this equation on the fracture k gives

248   0 k k k k r b R TC t     (33)
Plugging Eq. ( 8) into Eq. ( 33) yields

  0 k k r C S b K C TC t       (34)
The final coupled nonlinear flow-transport-dissolution system to solve is formed by: (i) the 250 flow Eq. ( 14) in which we substitute Eq. ( 17) yielding the hydraulic head at the fracture cells 251 of the DFN, (ii) the transport Eqs. ( 23), ( 24), ( 30) and ( 32), which yield the mean and the 252 variation of the concentration in each fracture and the (iii) the dissolution Eq. ( 34), which

253

gives the aperture for each fracture.

254

The obtained nonlinear system is discretized in time, via the method of lines. The main idea 255 of this method is to keep the time derivative in its continuous form and to discretize the space 256 derivatives. This results in a system of ODEs. The ODE system is solved using the DASPK 257 solver which is based on a higher time integration scheme (Backward differentiation formula

258
or Adams method). The resulting nonlinear system is solved using the Newton-Raphson

0 H  0 0 H  0 0 H  Reaction rate       5 10 C K   m/s Initial concentration 0 0 C  0 0 C  0 0.1768 C  mol/m 3 Inlet concentration 35 inj C  g/l 35 inj C  g/l 0 inj C  300
The distribution of dimensionless concentration in the fracture network after 14 hours with 301 DG and FE models are shown in Figures 3a and3b, respectively. The dimensionless 302 concentration is calculated as the ratio of the concentration to the concentration of injected Table 1.

317

A mesh sensitivity analysis is performed with the DG, FV and FE methods. It is observed that 318 with the DG scheme, a mesh-independent solution is obtained with a relatively coarse mesh

319

(272 nodes). The time variation of concentration at the observation point O2 obtained with DG 320 using a coarse mesh formed by 272 nodes is compared to the solution of FE and FV using two that time, all the fracture enlarges (Figure 11c) and the equivalent permeability of the fracture 471 strongly increases, yielding a highly increasing velocity (Figure 11b). As a consequence, the

Conclusion

Modeling dissolution processes in a DFN is a computationally challenging problem because 587 of the nonlinear coupling between flow, transport and reactive processes, introduced by the 588 impact of dissolution on the fracture aperture. The challenge is accentuated by the fact that in 589 the fractures, the transport is advection dominated. In such a case, standard FE formulations

113

  main challenge in applying this technique for a DFN is the evaluation of the concentration at 114 nodes of intersection of several fractures. A new formulation is developed in this work where 115 the upstream concentration at a fracture intersection node is calculated using the average of 116 the concentrations of all fractures providing flow to that node, weighted by the flow rate in the 117 corresponding fractures. 118 Darcy's law combined with the cubic law is used to simulate flow within the fractures. The 119 flow equations are discretized with the hybrid formulation of the Mixed Finite Element 120 (MFE) method (Younes et al., 2009). The mass lumping technique developed by Koohbor et 121 al. (2020) is employed to avoid over-and under-shoots observed in transient flow simulations 122 with small time steps. The MFE method is also used for the discretization of the dispersion 123 term to ensure the continuity of the dispersive flux at nodes where several fractures with 124 different apertures intersect. The highly nonlinear coupled equations of fluid flow, advection-125 dispersion transport and aperture evolution due to dissolution are solved simultaneously in 126 order to avoid operator-splitting errors. The time discretization is performed using a high

  is the density of the rock and     is a stoichiometric coefficient that 165 represents the mass of mineral entering solution for a unit mass of dissolved rock.

179Figure 1 .

 1 Figure 1. Flow and transport notations in a fracture k .

  using Eq. (17). This system is solved for 204 the head traces k TH at all mesh edges. Hence, the flow system has the number of fracture 205 cells as degrees of freedom (DOF).

  206

  average value of concentration in the fracture k and k x C is the concentration 212 variation along the fracture direction. The corresponding interpolation functions are:

235 jNC

 235 is calculated by imposing the continuity of the dispersive flux of all the fractures 236 (including k ) sharing the node j . For a node j shared by

  259method. The linear system arising at each time step is solved with the preconditioned Krylov 260 iterative method. The solver adapts both the time step size and the order of the time 261 integration scheme in order to reach the prescribed accuracy. Time step and order of 262 integration are updated based on error control. In this work the accuracy is prescribed with a 263 relative tolerance of 10 -6 . Details of the MOL and the use of DASPK for nonlinear coupled 264 flow transport systems are given inYounes et al. (2011;[START_REF] Viswanathan | From Fluid Flow to Coupled Processes in Fractured Rock: 769 Recent Advances and New Frontiers[END_REF].

265 4 .

 4 Accuracy of the DG-DFN model 266 This section aims at verifying the correctness of the developed DG-DFN model and 267 evaluating its performance for the simulation of advection dominant transport with dissolution 268 in a fracture network. To this aim, the results of the DG-DFN model are compared to the 269 results of COMSOL Multiphysics, which is based on the standard FE method, and to an in-270 house upwind FV model. Three examples are investigated. The two first examples deal third example deals with coupled flow, transport, and aperture fracture evolution due to 273 dissolution in a single fracture with high diffusion.

  with high dispersion in a DFN (example 1) 275 Analytical solutions are often of great interest for the verification of numerical codes. For 276 coupled flow, transport and dissolution processes, some analytical and reference solutions 277 were developed under simplified conditions (Hayek et al., 2012; Suk 2016). However, these 278 solutions cannot deal with fractured domains. Verification in fractured domains cannot be 279 performed against analytical solution. Therefore, to verify our newly developed code, we use 280 a standard FE numerical model developed in COMSOL Multiphysics software and an in-281 house model based on the upwind FV method. The generation of the stochastic network is 282 performed with the "Discrete Fracture Network Add-In" which is available in the recent 283 versions of COMSOL. This Add-In creates a randomized distribution of position, size, 284 orientation and aperture for the fracture network. We used power law stochastic rule to create 285 the network as in Barton and Zoback (1992) and Hooker et al., (2009). The network of 286 fracture for the Example 1 is shown in Figure 2a. A constant head gradient is imposed on the 287 network from left to right. The horizontal domain is initially free of contaminant. The left 288 inlet boundary of the domain has a fixed concentration. An outflow boundary condition is 289 considered for the right side of the domain. Impermeable boundary conditions are considered 290 on the top and bottom boundaries. The parameters for Example 1 are given in Table 1. This 291 first example involves high values of dispersion and diffusion to avoid unphysical 292 oscillations.293The results of the numerical models are compared on two observation points (O1 and O2) and 294 for a monitoring fracture (F1) which is highlighted in Figure2b.

Figure 2 .

 2 Figure 2. Problem description: (a) fracture network and boundary conditions, (b)

Figure 3 .

 3 Figure 3. Results for Example 1: distributions of the dimensionless concentration with

  at investigating the advantages of the developed DG-DFN model in the 314 case where the transport is advection dominated because of the fast fluid flow inside the 315 fractures. The example is similar to Example 1, but we assume very little diffusion and no 316 dispersion. The input parameters for Example 2 are given in

Figure 4 .

 4 Figure 4. Comparison between DG, FE and FV for Example 2: (a) Time variation of the

359 Figure 5 ..

 3595 Figure 5. Conceptual model for dissolution in a single fracture.

Figure 6 .

 6 Figure 6. Example 3: Comparison between the FE, FV and DG results for dissolution in a

  new DG model to 397 assess the effect of the dissolution rate on the fracture aperture evolution. The problem is

Figure 7 .

 7 Figure 7. Fracture aperture evolution: (a) for low (

Figure 8 .

 8 Figure 8. Dimesnionless concentration (a), aperture (b) and velocity (c) along the fracture at

Figure 9 .Figure 10 .

 910 Figure 9. Time evolution of the dimensionless concentration (a), velocity (b) and aperture (c)

Figure 11 .

 11 Figure 11. Time evolution of dimensionless concentration (a), velocity (b) and aperture (c) at

  470

  fracture (Figure11a) strongly reduces after * t due to the high advection 473 flux of freshwater arriving from the left boundary.

4744. 2

 2 Effect of the dissolution rate in the case of a DFN475This section extends the discussion of the previous section to a DFN. We consider a network 476 of connected horizontal and vertical fractures, as in Figure12.

Figure 12 .

 12 Figure 12. Conceptual model for flow, dissolution and transport in a network of fractures.

Figure 14 .

 14 Figure 13. Results for the low dissolution rate (

  Figure15shows the concentration, aperture and velocity distribution in the case of high

Figure 15 :

 15 Figure 15: Results for the high dissolution rate (

  575

  16e). However, contrarily to the low dissolution case, the flow rate in the two fractures shows 576 a non-monotonic evolution with time (Figures16c and 16e). Indeed, the flow rate in the 577 a decrease until around 5 months and an increase after that, whereas the 578 flow rate in the fracture B depicts the opposite behavior, thus the sum of the two flow rates 579 remains constant. This parabolic evolution of the flow rate is probably related to the change of 580 the permeability distribution during the simulation due to dissolution in the DFN.

Figure 16 :

 16 Figure 16: Aperture (a), velocity (b) and flowrate (c) evolutions in the fracture A and aperture

590

  introduce unphysical oscillations that can lead to convergence issues. The upwind FV 591 formulation give stable results but introduces a large amount of numerical diffusion. In this 592 work, we developed a new model based on advanced numerical schemes to simulate 593 dissolution processes in DFNs. The model is based on coupling the MFE method for flow 594 with the DG scheme for transport. The DG method is known to be suitable for advection-595 dominated problems, as it avoids unphysical oscillations and reduces numerical diffusion. A 596 new formulation of the DG was proposed for the Riemann solver at the intersection of 597 fractures. The newly developed scheme calculates the upstream concentration based on the 598 average of the nodal concentration of all fractures having an inflow at the intersection node, 599 weighted by the water fluxes through these fractures. The dispersion term is calculated with 600 the MFE method which allows to ensure the continuity of the dispersive flux at the 601 intersection of several fractures having different apertures. The time integration of the 602 obtained nonlinear coupled flow-transport-dissolution equations is improved by using an 603 advanced solver of ODEs via the MOL. 604 The developed DG model is first verified for linear transport in a DFN by comparison against 605 a standard FE solution obtained with COMSOL Multiphysics and an upwind FV model. Good 606 agreement is obtained between the three models in the case of high diffusion. For advection-607 dominated transport configurations, often encountered because of the rapid flow in fractures, 608 the DG-DFN model avoids the unphysical oscillations observed with FE results and allows 609 for capturing sharp concentration fronts with a relatively coarse mesh. The upwind FV

deformable rock fracture, Water Resour.Res. 16 (1980Res. 16 ( ) 1016Res. 16 ( -1024. .

718

Liu, Min, Vitalii Starchenko, Lawrence M. Anovitz, and Andrew G. Stack. "Grain

638

The model considered in this study is limited to dissolution processes, but the numerical 639 scheme can be generalized to dissolution/precipitation processes. Precipitation processes may 640 occur and could be important under non isothermal conditions. Thus, a future extension of 641 this work could be including precipitation and thermal processes.

Water