# Ecological assessment of marine systems: How to conclude? Method and application to Western Mediterranean

Marc Igigabel, Olivier Laroussinie, Alan Quentric, Neil Alloncle, Fanny Châles, Sophie Rumin, Antonin Gimard, Maxime Jobin, Séverine Hallot

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Marc Igigabel, Olivier Laroussinie, Alan Quentric, Neil Alloncle, Fanny Châles, et al.. Ecological assessment of marine systems: How to conclude? Method and application to Western Mediterranean. Journal of Environmental Management, In press, 380, pp.124953. 10.1016/j.jenvman.2025.124953. hal-05025867

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Research article

# Ecological assessment of marine systems: How to conclude? Method and application to Western Mediterranean

Marc Igigabel<sup>a, *</sup> <sup>D</sup>, Olivier Laroussinie<sup>a, D</sup>, Alan Quentric<sup>a, D</sup>, Neil Alloncle<sup>a</sup>, Fanny Châles<sup>a, D</sup>, Sophie Rumin<sup>a</sup>, Antonin Gimard<sup>b</sup>, Maxime Jobin<sup>b</sup>, Séverine Hallot<sup>c, D</sup>

## ARTICLE INFO

Handling editor: Lixiao Zhang

**Keywords:**

Assessment of the environmental status
Marine waters
Ecosystem approach
Synthesis
Methodology
Case study
Western Mediterranean

## ABSTRACT

The ecosystem approach is generally considered as the best way to manage human activities impacting the marine environment. Nevertheless, more than 20 years after the emergence of this new paradigm, whereas ecosystem-based management is theoretically implemented through an essentially systemic approach, in practice, it appears that the application of standards and criteria and the use of indicators lead to a predominance of analytical approaches and to reporting formats that are inappropriate for defining action programmes. This paper proposes a new methodological framework to produce, in a synthetic form, integrated ecosystem assessments that go beyond the juxtaposition of sectoral analyses. Its guiding principle is to use the general knowledge of the marine environment (understanding of system dynamics and interactions within the system through a systemic approach) to put into perspective the results obtained through criteria and methodological standards (understanding the state of ecological components and the pressures affecting them through analytical approaches). The new methodological framework includes the identification of appropriate typologies for activities and pressures, as well as for ecological components. An essential point is to group the ecological components within the following compartments: pelagic habitats and food webs; benthic habitats; areas at the land-sea interface; protected species; and commercial species. On each of these compartments, the application of a selection of descriptors is possible. The result is an optimization of analyses in comparison with the indiscriminate use of descriptors on each of the ecological components considered separately. A case study is presented on the French Western Mediterranean.

## 1. Introduction

In the 21st century, humanity faces two major challenges: climate change (Bindoff et al., 2019; IPCC et al., 2021) and biodiversity loss (IPBES et al., 2019). Although human activities, by seriously weakening the resilience of marine ecosystems (Folke et al., 2002, 2004), are at the root of these two main concerns (IPBES et al., 2018; European Environmental Agency, 2019a), the Organisation for Economic Co-operation and Development (OECD, 2016) estimates that between 2010 and 2030 the ocean economy could more than double its contribution to global value added, reaching over US$3 trillion per annum (in 2010, US$1,5 trillion per annum represented approximately 2.5% of world gross value added). In this context, the legislative acts seek not only the preservation of the marine environment, but also economic growth in the maritime

domain. For example, in the United States, these two objectives coexist within the Oceans Act (2000). In Europe, the preservation objective is expressed by the Marine Strategy Framework Directive (MSFD; European Commission, 2008); and the objective of economic development by the reports on the blue economy (European Commission, 2014, 2019, 2021). The definition of these integrated marine policies is based on the idea that better knowledge of the marine environment, improved practices and better coordination of activities would make it possible in the long term to take greater advantage of maritime space, while reducing the impact on the environment (European Commission, 2007; OECD, 2019). Yet, in the first two decades of the 21st century, regulations have not halted degradation of the marine environment, either on a European scale (IPBES et al., 2018; European Environmental Agency, 2019a; European Commission, 2020a), or on a global scale (IPBES et al., 2019).

<footnote><sup>a</sup> Cerema, Technical Division for Risk, Water and Sea, Technopôle Brest Iroise, 155 rue Pierre Bouguer, BP5, Plouzané, 29280, France</footnote>

<footnote><sup>b</sup> Cerema, Territorial Division for the Normandy and Central Regions, 10 Chemin de la Poudrière, Le Grand-Quevilly, 76120, France</footnote>

<footnote><sup>c</sup> Cerema, Strategy and Communication Department, 110 route de Paris, 77171, Sourdun, France</footnote>

<footnote>* Corresponding author.</footnote>

<footnote>E-mail address: marc.igigabel@cerema.fr (M. Igigabel).</footnote>
List of abbreviations

C Criterion

D Descriptor

EFESE French assessment of ecosystems and ecosystem services (in French, *Évaluation Française des Écosystèmes et des Services Écosystémiques*)

ES Ecosystem Service,

IEA Integrated Ecosystem Assessment

MSFD Marine Strategy Framework Directive,

NIS Non-Indigenous Species

PAH Polycyclic aromatic hydrocarbon

SES Social-Ecological System

WFD Water Framework Directive

The marine economy now includes a very broad range of activities in traditional sectors (e.g. fisheries, shipping and tourism), booming sectors (e.g. offshore renewable energy and aquaculture), and emerging sectors (e.g., biotechnology and seabed mining). All of these activities are increasingly putting pressures on marine ecosystems (Jackson et al., 2001; Millennium Ecosystem Assessment, 2005; IPBES et al., 2019; Puharinen, 2023). Therefore, there is a growing need to manage the cumulative and in-combination pressures in a holistic approach (Jackson, 2008; Goulletquer et al., 2013; Korpinen and Andersen, 2016) and no longer to focus on singular pressure-response relationships. Thus, methods have been developed to assess the cumulative impacts of multiple pressures on several ecosystem components (Crain et al., 2008; Ban et al., 2010; Kaplan et al., 2013; Holsman et al., 2017). The ecosystem approach, management and resource planning procedure that integrates the management of human activities and their institutions with the knowledge of the functioning of ecosystems (CBD, 2000), is generally considered as the best way to manage human activities impacting the marine environment (Agardy et al., 2011). This approach is recommended by legislation at national or regional levels that aims to control the potential adverse impacts of marine activities: in USA, Australia or Canada, Oceans Acts; in Europe, Water Framework Directive (European Commission, 2000) (WFD), MSFD (European Commission, 2008) and its associated decision (European Commission, 2010); in South Africa, National Water Act, etc. (Enright and Boteler, 2020). Its implementation consists mainly of assessing the status of ecosystems relative to specific management objectives and to determine management strategies accordingly (Levin et al., 2014). In this perspective, Integrated Ecosystem Assessments (IEAs) are the prevailing methodological framework of the ecosystem approach. IEAs are a stepwise process consisting of goal and target setting, defining indicators, analysis of component status, trends and risk, to arrive at an overall assessment of ecosystem status (Levin et al., 2014). This approach normally includes a first scoping step (systemic approach) followed by three steps (definition of indicators, definition of reference levels and risk assessment) corresponding mainly to an analytical approach (comparison of indicators with reference levels). Major interest of IEAs should be to provide a structured approach to ecosystem assessment to serve as an integrative counterpart to single-species and single-sector assessments (Levin et al., 2009). The review by Borja et al. (2016) of five evaluation and monitoring methods (one of which is for the implementation of the MSFD) confirms that the methods used worldwide have in common to describe the state of the ecosystem in relation to a desired state. However, in these methods, the analyses are preceded, but never followed, by a systemic approach. IEAs therefore generally appear as a juxtaposition of sectoral analyses and do not favour the emergence, in a synthetic form, of transversal propositions, even though the policies dealing with these problems should necessarily be multiobjectives. This may explain why, in practice, using IEA results to define operational measures organised in

a global action plan can be difficult. To address these challenges, legislative revisions may have been initiated. For example, the European Commission revised the MSFD in 2017 (European Commission, 2017a, 2017b), aiming at « (3) [...] a clearer, simpler, more concise, more coherent and comparable set of good environmental status criteria and methodological standards ». This methodological adjustment could have helped to resolve the difficulties identified. However, some methodological difficulties remain (Puharinen, 2023) and the Directive is currently being reviewed by the European Commission (2020b).<fnref n="1" /> These difficulties may be related, as suggested by Borja and Elliott (2013) in the case of Europe, to the fact that the Habitats Directive (1992) and the WFD have imprinted on our cultures structural approaches (focusing mainly on monitoring the number, abundance and/or distribution of species), while the MSFD is a functional approach that requires, in addition to the prerequisites of the structural approach, a good understanding of the relationships between the components of the system.

This article proposes a new methodological framework to produce, in a synthetic form, IEAs in which the analyses are framed by systemic approaches. The first focus is on understanding the functioning of marine and coastal ecosystems. The general knowledge is used upstream to organize and guide the analysis, in order to get the best benefit of long-standing investigations, as well as the latest investigations (including periodic assessments of environmental ecological status). This methodological framework favours systemic approaches, paying particular attention to the description of the marine environment (typology of ecological components and anthropogenic pressures and definition of geographical perimeters and the temporality of analyses). It also aims to improve the dialogue between scientists, managers and decision-makers, by making progress on the transparency of the analysis (origin and processing of data) and on the communicability of the conclusions. For this reason, it is intended for scientists and should strengthen their ability to highlight in the specialized literature essential information for decision-making, including the identification of critical situations. This methodological framework has been experimented on the French Western Mediterranean.

This article presents the types of data needed to develop the methodological framework and its implementation, the definition of the methodological framework and its implementation to the case study. The discussion focuses on the contribution of the methodological framework to operationalization of the ecosystem approach and its replicability in non-European legislative frameworks.

## 2. Data

Information used for the definition and implementation of the proposed methodological framework may be derived from: (i) general knowledge of the marine environment, (ii) legislative acts and associated methodological standards, and (iii) investigations and analyses carried out for a particular IEA.

### 2.1. General knowledge of the marine environment

Given the strong involvement of human communities in marine ecosystems, we will consider them as an integrated system, commonly referred to as a social-ecological system (SES). The functions of such a system arise from the interactions and interdependence of the social and ecological subsystems (Berkes and Folke, 1998; Arctic Council et al., 2016; IPBES et al., 2022). According to Millenn. Ecosyst. Assess. (2005), SESs produce a « bundle » of ecosystem services (ESs), categorized as supporting (e. g., for marine and coastal SESs, nutrient cycling, primary production), provisioning (e. g., fish, algae, salt), regulating (e. g., flood

<footnote n="1">¹ MSFD Art 23; European Commission, The Review of the Marine Strategy Framework Directive (https://ec.europa.eu/environment/marine/eu-coast-and-marine-policy/review_of_the_directive.htm, accessed 27.10.2023).</footnote>
and climate regulation), and cultural services (e. g., recreation and spiritual values). Building on this critical idea, Biggs et al. (2012) define resilience as: « The capacity of an SES to sustain a desired set of ESs in the face of disturbances and ongoing evolution and change ».

The mode of knowledge selection is considered an essential point in the scientific literature devoted to strengthening the resilience of SES. Weichselgartner and Kasperson (2010) emphasise the need to integrate different kinds of knowledge and a variety of experiences. For this purpose, scientists, the public, and decision-makers in policy and practice collaborate to generate not only scientifically reliable, but also context-appropriate, socially robust and actionable knowledge (Weichselgartner and Kelman, 2014). Consistent with this principle, our methodological framework will be based on the results of the research program EFESE (French Assessment of Ecosystems and Ecosystem Services), whose contribution on coastal and marine areas has been produced by Ifremer, the University of Western Brittany and the French Agency for Biodiversity (Mongruel et al., 2019). Indeed, the results have been established by (i) a synthesis of existing assessments, mostly produced within the framework of political or management arrangements (Regional Seas Conventions, European Directives such as the Directive Habitats (European Council, 1992), the WFD (European Commission, 2000), the MSFD (European Commission, 2008), etc.), (ii) a stakeholder consultation on the topic, allowing both to capture complementary, if not different, perspectives and to measure the adequacy between stakeholder perceptions and the current state of scientific knowledge (Scemama et al., 2022).

The EFESE research programme (Mongruel et al., 2019) presents a typology of ecological components (main types of ecosystem, habitat or species group) and the associated ecosystem services (see Fig. 1).

The EFESE research program (Mongruel et al., 2019) also presents typologies of activities and pressures, and specifies the types of pressure exerted by each activity (Table 1).

However, a national research program such as EFESE is not intended to produce assessments directly at the level of marine regions and their subdivisions, as this requires more specific consideration of ecosystems

and human activities in the area under consideration. For this reason, our approach will also draw on the regulatory and normative frameworks for assessing the ecological status of the marine environment, as well as information generated from their application.

## 2.2. Information provided by legislative acts and associated methodological standards

Our methodological framework is intended to be implemented in various contexts, considering however that methodological criteria and standards have already been defined in relation to qualitative descriptors used to determine good environmental status. For example, for the MSFD, the descriptors are defined by Directive (2008)/56 (European Commission, 2008) in Annex I: 1. Biological diversity; 2. Non-Indigenous Species (NIS); 3. Population of fish and other seafood; 4. Marine food webs; 5. Human-induced eutrophication; 6. Seafloor integrity; 7. Alteration of hydrographical conditions; 8. Concentrations of contaminants; 9. Contaminants in fish and other seafood; 10. Marine litter; 11. Energy and underwater noise. Among these descriptors (D), some relate to the state of the environment (D1, D3, D4 and D6), whereas others relate to pressures and impacts. In addition, criteria and methodological standards are set out in the Annex to Decision 2017/848 (European Commission, 2017b). These recommendations provide for cross-references between state and pressure descriptors. For example, for pelagic habitats (under descriptor 1), criterion D1C6 is: “The condition of the habitat type, including its biotic and abiotic structure and its functions [...] is not adversely affected due to anthropogenic pressures.” The associated specifications make explicit reference to the criteria used under the pressure descriptors D2, D5, D7 and D8: “Assessments of the adverse effects from pressures, including under D2C3, D5C2, D5C3, D5C4, D7C1, D8C2 and D8C4, shall be taken into account in the assessments of pelagic habitats under Descriptor 1.”

<figure><img src="image_4.png" /><figcaption>Fig. 1. Typology of ecological components and expert perception of the importance of ecosystem services associated (Mongruel et al., 2019; Scemama et al., 2022).</figcaption></figure>
<caption>**Table 1**</caption>

Activities causing pressures (typologies proposed by Directive, 2017/845 amending the MSFD). Adapted from Mongruel et al. (2019) and MTES (2025, in press; Matrix 1). X = significant contribution of the activity to pressure; x = minor contribution to pressure.

<table><thead><tr><th></th><th>Maritime transport, defence, research, at-sea exploration</th><th>Fishing (seabed trawling)</th><th>Fishing (excluding seabed trawling)</th><th>Agriculture and urbanization</th><th>Industry, coastal housing</th><th>Boating, yachting and bathing activities</th><th>Oil and Mining Exploration, Marine Renewable Energy and Cable Laying</th></tr></thead><tbody><tr><td>Physical habitat loss (smothering, sealing)</td><td></td><td></td><td></td><td></td><td></td><td></td><td>x</td></tr><tr><td>Physical damage (abrasion, material extraction)</td><td>x</td><td>X</td><td>x</td><td></td><td></td><td>x</td><td>x</td></tr><tr><td>Sediment modification, turbidity</td><td>x</td><td>X</td><td></td><td>x</td><td></td><td></td><td>x</td></tr><tr><td>Disturbance, collisions</td><td>X</td><td>x</td><td></td><td></td><td>x</td><td>X</td><td></td></tr><tr><td>Underwater noise disturbances</td><td>X</td><td>x</td><td>x</td><td></td><td></td><td>x</td><td>X</td></tr><tr><td>Marine litter</td><td>X</td><td>x</td><td>X</td><td>x</td><td>x</td><td>x</td><td>x</td></tr><tr><td>Hydrological changes</td><td></td><td></td><td></td><td>x</td><td>x</td><td></td><td></td></tr><tr><td>Contamination by hazardous substances</td><td>X</td><td>x</td><td></td><td>X</td><td>x</td><td></td><td></td></tr><tr><td>Excessive input of nutrients and organic matter</td><td>X</td><td>x</td><td>x</td><td>X</td><td>x</td><td></td><td></td></tr><tr><td>Input of microbial pathogens</td><td>x</td><td></td><td></td><td></td><td>X</td><td>x</td><td></td></tr><tr><td>Input of non-indigenous species</td><td>X</td><td></td><td>X (shellfish culture)</td><td></td><td></td><td>x</td><td></td></tr><tr><td>Extraction of species</td><td>x</td><td>X</td><td>X</td><td></td><td></td><td>x</td><td></td></tr></tbody></table>

**2.3. Information from past assessments of the ecological state of the marine environment**

In accordance with the legislative acts and associated methodological standards, we will consider that at least one assessment of the ecological status of the marine environment has already been undertaken for the area under consideration.

Among the many challenges associated with the production of IEAs, two difficulties are recurrent.

One major challenge is to consider the information relating to the different descriptors together. For example, in the French context, on the first two cycles of MSFD evaluation (2012–2018 and 2018–2024), the criteria were applied without cross-reference between state and pressure descriptors, in particular because the indistinct application of standards and criteria to the many ecological components already generates a very high degree of complexity, without the implementation of these cross-references. This difficulty can be considered major, as it contributes to reducing our overall understanding of the impact of human activities on the marine environment.

Another challenge is the achievement of quantitative results, especially in the absence of large-scale observational programs (Claudet and Fraschetti, 2010; Borja et al., 2013; Micheli et al., 2013; Pandeya et al., 2016; Gissi et al., 2021). For example, in a study conducted in the Mediterranean, Fraschetti et al. (2022) concede that the results of ecological status assessments are significantly affected by the assumption that discrete observations over small spatial scales are representative of the total extension investigated.

The proposed methodological framework aims primarily at meeting the first challenge, by providing a better understanding of the functioning of the system and the impacts of human activities. It should also contribute to long-term progress in solving the second problem, by promoting the definition of an observation program based on this improved understanding.

**3. Methodological framework**

The proposed new methodological framework aims to produce, in a synthetic form, integrated ecosystem assessments that go beyond

juxtaposition of sectoral analyses. It therefore aims, in general, to create conditions conducive to the overall understanding of the system and, more specifically, to promote cross-references between state descriptors and pressure descriptors. For the development of the methodological framework, a study protocol is defined to ensure a controlled use of the different types of data previously identified.

**3.1. Study protocol**

Our methodological framework, both in its definition and implementation, should make optimal use of general marine knowledge, legislative and regulatory frameworks, and local observations and analyses. To make the best use of these three sources of information and to define the role of each in conducting the evaluation, a clear distinction between systemic and analytical approaches is needed.

Two generic principles of risk understanding exist and are generally intended to complement each other: « analytical » approaches and « systemic » approaches (Puccia and Levins, 1985; Kay et al., 1999; Iġigabel et al., 2021). Analytical approaches, originally described by Descartes, 1637, apply preferentially to stable systems, consisting of elements with so-called linear interactions, that is to say which can be described by fixed rules or by continuous mathematical laws. However, marine ecosystems as complex adaptive systems (Hagstrom and Levin, 2017) cannot be understood by analytical approaches alone. Contrary to what analytical approaches imply, in a process of aggregating a set of locally controlled situations, risks can emerge at a higher level (Kay et al., 1999). The examination of linear processes and cause-effect pairs is insufficient to understand the dynamic behavior of the whole system (Cassel-Gintz, 2001; Cassel and Hinsberger, 2017). In addition to analytical approaches, a systemic approach is intended to define « the architecture of a system » (Krob, 2008), that is to say, its invariable part,
which can reasonably be considered as fixed over time.<fnref n="2" /> Systemic and analytical approaches are fundamentally different, to the point that they correspond to two distinct paradigms: a systemic approach aims for a comprehensive understanding, applies to heterogeneous systems, is based on views expressed in a collaborative framework, and produces relative conclusions that take into account external constraints to the system by utilizing logic and systems representation; an analytical approach seeks a complete understanding, applies to homogeneous systems, is based on detailed representation modes, utilizes experts, and concludes with certainty, using scientific disciplines (Krob, 2008; Resilience Alliance, 2010).

On this conceptual basis, it is necessary to recognize the types of approaches to which the three sources of information identified correspond, in order to assess how they can be used within our methodology. Schematically, we will consider that general information from long-standing investigations in various contexts helps to advance the understanding of the functioning of marine and coastal ecosystems. Therefore, these are essentially systemic approaches. The legislative and regulatory framework provides a general framework for the risk assessment approach, combining the systemic approach expressed by the definition of general principles, and analytical approaches expressed by the definition of methodological standards and criteria, as well as associated indicators. Specific observations and analyses, produced using criteria and indicators, provide accurate information, usually corresponding to a measurement over a given territory and period. Therefore, these are essentially analytical approaches.

To make the best use of this information, a study protocol is adopted. Its objective is to define guidelines for the production of synthetic IEAs. These guidelines, which together constitute the “methodological framework”, should be applicable to different marine areas. This protocol consists of three steps, which are graphically represented in Fig. 2.

Step 1 is to group the ecological components into environmental compartments. This step is based on the typologies of ecological components, activities and pressures existing in the scientific literature. One of the principles is to group together ecological components that may be subject to the same types of pressure. This step uses the state of general knowledge about the marine environment.

Step 2 consists of selecting descriptors for each ecological component. A rigorous selection of the descriptors of state and pressure will be carried out using general knowledge and the regulatory and normative corpus.

Step 3 is to optimise the use of selected descriptors in the production of a synthetic IEA for the marine environment. This step is based on the results of the first two steps.

From the three types of data identified, only general knowledge and regulatory and normative frameworks are used in these three steps to develop guidelines for the production of synthetic IEAs in various marine areas. The third type of data corresponds to the latest observations and analyses produced during the last IEA on the studied area (or the last IEAs if several have been conducted and trends are sought). This third type of data will only be used in the implementation of the methodological framework on a specific study area. An example of such an implementation will be presented in Part 4.

## 3.2. Step 1: grouping of ecological components into compartments

The first step is to group ecological components into environmental

compartments, which requires a typology of ecological components and a typology of anthropogenic pressures and activities. In this case, we will consider a marine area located in temperate climate. An equivalent approach can be taken for an area under another climate.

The typologies used, both for ecological components (Fig. 1) and for anthropogenic pressures and activities (Table 1), are borrowed from the EFESE program (Mongruel et al., 2019). The choice of these typologies is justified by their development process involving scientists and various stakeholders, and the resulting benefits in terms of transparency in the conduct of analyses and readability of the results.

It should be noted that MSFD requires in its Annex I the use of qualitative descriptors for determining good environmental status. On the other hand, in its Annex III, the characteristics of the environment, as well as the pressures and impacts are only the subject of indicative lists. This relative flexibility of the European regulatory framework has been maintained in the Directive 2017/845 amending the original Directive 2008/56/EC as regards “the indicative lists of elements to be considered for the preparation of marine strategies”. On this point, the proposed methodology therefore respects the MSFD regulatory framework.

We will consider ecological components as belonging to types of ecosystems, habitats or groups of species. In this, our methodological framework agrees also with the MSFD. Thereafter, we will refer by the common term “environmental compartments” to broad categories of ecological components: “benthic habitats”, “pelagic habitats”, “land-sea interfaces”, “protected species” and “commercial species”, the definitions of which are specified below.

In order to achieve the objective of a territorialized assessment, it is necessary to assess how to attribute the available knowledge to geographically defined areas. Traditionally, in the description of the marine environment, a distinction is made between the pelagic and benthic compartments through the different water bodies (cf. Fig. 3). Since most food chains are initiated in the water column from phytoplankton, we will conventionally associate trophic networks with pelagic habitats.

Particular habitats develop on different substrates and refer to types of ecosystems characterized by their own functioning: herbaria, macroalgae fields, coralligenous habitats, coral reefs, estuaries, lagoons, coastal marshes, beach and dunes, mangroves, extensive aquaculture production areas. Among these environments, we will attribute: (i) to the compartment of benthic habitats: ecological components that belong unambiguously to the seabed, in particular seagrasses, macro-algae fields, coralligenous communities and coral reefs; and (ii) to a specific compartment dedicated to “areas positioned at the land-sea interface”: estuaries and extensive aquaculture production areas, which we shall refer to as “nearshore areas”; and lagoons, coastal marshes, beaches and dunes and mangroves, which we shall refer to as “coastal areas”. These habitats play an essential role in the trophic and functional processes of marine ecosystems (Mongruel et al., 2019). The classification adopted helps to highlight the problems of these areas subject to pressures often particularly intense because of land inputs and the presence of activities specific to the coast (for example, port, beach and boating activities). This methodological choice favours a coherent cartographic representation, the biogenic habitats of the marine environment being naturally integrated into the detailed representation of benthic environments and the land-sea interfaces more naturally integrated into the more global representation of a marine area and its surroundings.

Finally, most species groups cannot be linked to a single ecosystem or habitat type. Our typology will therefore include two additional compartments: (i) protected species including marine birds, marine mammals, turtles and non-commercial species of fish, molluscs or crustaceans; (ii) commercial species including all species intentionally collected from the marine or coastal environment.

The French Office For Biodiversity (OFB, 2021, 2024) confirms that ecological components can be grouped into identified compartments. Table 2 presents the types of EFESE ecological components associated with each of these compartments.

<footnote n="2">² Krob (2008) points out that this way of extending to systems, the concept of architecture as it traditionally exists in urban planning is perfectly consistent with its usual understanding. The architecture of a building is in fact none other than its invariant part, that is, the part that will not change regardless of how the building is occupied and evolves over time.</footnote>
<figure><img src="image_5.png" /><figcaption>Fig. 2. Definition of guidelines for the production of synthetic IEAs in different marine areas - Study protocol.</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>Fig. 3. Diagram of the major components of benthic and pelagic habitats, based on a coastal-offshore gradient and vertical zoning. Credit: Cerema, on the basis of the decree of 17/12/12 on the definition of the good environmental status of marine waters.</figcaption></figure>

### 3.3. Step 2: selection of descriptors for each ecological component

In order to ensure full compatibility with the MSFD, we will refer in the following to the 11 qualitative descriptors used to define the good ecological status listed in Annex I of this directive (descriptors listed in section 2.1). It is possible to consider the use of these descriptors indistinctly on all ecological components. However, the systematic application of the corpus of criteria and methodological norms generates

a large number of analyses. This led the European Commission in its Decision 2017/848 to consider that “(6) [...] the number of criteria that Member States should monitor and assess should be reduced, applying a risk-based approach to the selected criteria to enable Member States to focus their efforts on the main anthropogenic pressures impacting their waters.” For the same reason, the synthesis of the assessment of the ecological state of the marine waters should be organized by (i) ensuring that descriptors and associated criteria and indicators are used only
<table><caption>**Table 2**

Environmental compartments and associated ecological component types.</caption><thead><tr><th>Environmental compartments considered for our method</th><th>Ecological component types (EFESE)</th></tr></thead><tbody><tr><td>Pelagic habitats and trophic networks</td><td>Pelagic habitats (including deep ecosystems) and food webs (including plankton)</td></tr><tr><td>Benthic habitats</td><td>Rocky seafloors, soft seafloors herbaria, macroalgae fields, coralligenous habitats, coral reefs</td></tr><tr><td>Land-sea interface areas</td><td>Estuaries, coastal lagoons and salt marshes, beaches and dunes, extensive aquaculture production areas, mangroves</td></tr><tr><td>Protected species</td><td>Marine birds, marine mammals, turtles and non-commercial species of fish, molluscs or crustaceans</td></tr><tr><td>Commercial species</td><td>Species intentionally collected from the marine or coastal environment</td></tr></tbody></table>

when strictly necessary for the assessment of a component, and (ii) avoiding as much as possible the redundant presentation of the analyses. To apply this principle, the descriptors applicable to the components will be selected using the scientific literature and then, in step 3, the use of these descriptors will be the subject of an optimization research.

The consequences of environmental degradation can be assessed considering, for each ecological component, the impact on its state and its functions, while being attentive to the reductions or losses of associated ecosystem services (Grizzetti et al., 2019). Firstly, this analysis should be carried out on the basis of general knowledge, that is, by using scientific data and stakeholder perceptions. The EFESE programme has the advantage of combining these two approaches. As part of this systemic approach, the focus is first on the functioning of ecosystems, before considering a quantitative approach based on the use of criteria and indicators. To implement this approach, we will rely on two summary results from the EFESE programme: (i) the typology of the

ecological components and the main expected ecosystem services (Fig. 1) and (ii) the typology of key pressures and activities (Table 1).

The most relevant descriptors are identified by considering together the literal descriptions of the main pressures and activities (also extracted from the EFESE programme) with the types of ecological components and associated ecosystem services. Supplementary Table ST1 (cf. Part 12) shows in concrete terms the organization and results of such an analysis for the ecological components of a marine area located in a temperate climate. The same type of analysis can be conducted on mangroves and other components specific to tropical, equatorial or polar climates. It should be noted that in this analysis the cultural and recreational services were not detailed as in Fig. 1 (C1: Support for recreational and leisure activities; C2: Contribution to a pleasant landscape; C3: Contribution to culture and territorial identity), but were considered together. Since the levels of importance of the perceptions by experts of the three services concerned are generally fairly close (as shown in Fig. 1), the loss of information generated by this aggregation can be considered acceptable.

### 3.4. Step 3: Search to optimise the use of selected descriptors

The third step aims to optimise the use of selected descriptors in the production of a synthetic IEA for the marine environment.

The assignment of descriptors as performed in ST1 reveals that analyses common to several types of ecological components can be presented by exploiting their grouping in environmental compartments. Indeed, it appears that the ecological components belonging to the same compartment are characterized by the same set of descriptors. For example, land-sea interface areas, despite their great diversity can be described with a restricted set of descriptors (D1, D2, D5, D8 and D10). This is a significant step forward in organizing the synthesis of the assessment of the ecological state of the marine waters. With this result, the assessment can be organized in three sections (cf. Fig. 4), the first

<figure><img src="image_7.png" /><figcaption>**Fig. 4.** General organization of the assessment of the ecological state for a marine area located in temperate climate. In bold are highlighted descriptors of the state of the marine environment.</figcaption></figure>
one devoted to the pelagic and benthic habitats and food webs, the second to land-sea interface areas, and the third to protected and commercial species.

This organization, with the adjustments that the various contexts may require, defines « the architecture of the system ». Presenting an evaluation following this organization implies a progression in the order of the sections. The lines of force that emerge are: (i) the study of pressures that apply transversally to habitats and food webs: alteration of hydrographic conditions by the effects of climate change, pollution from contaminants and waste, activities degrading the seabed; (ii) additional investigations of land-sea interfaces, areas essential for the functioning of the marine environment and exposed to greater pressures because of their proximity to the coastline; (iii) the study of protected and commercial species particularly sensitive to certain pressures generated by climate change, non indigenous species, contaminants, marine litter, energy and underwater noise.

Table 3 summarizes the direct impacts of different pressures on each of the ecological compartments. The composition of this table is established in particular by considering the objective formulated by the European Commission on the occasion of the revision of the DCSMM in 2017 (European Commission, 2017a): « (4) [...] better linking ecosystem elements, and anthropogenic pressures and impacts on the marine environment with the descriptors used for determining good environmental status ». To facilitate the links between these elements, a row is assigned to each environmental compartment and a column is assigned to the main types of activity. Table 3 is filled based on the pressures identified in Table 1, and using the descriptors that have been selected for each environmental compartment (Fig. 4).

It should be noted that hydrographic conditions, including temperature, acidity and salinity, change on a global scale mainly due to climate change (IPCC et al., 2019). Therefore, developments associated with this descriptor cannot be attributed to particular activities.

In addition, the multitude of contaminants does not permit a uniform attribution of pressures to activities, especially for heavy metals (Anh, 2023) and for Polycyclic aromatic hydrocarbons (PAHs) (Mali et al., 2022). Similarly, the attribution of waste pollution to activities cannot be presented simply in a table, a fortiori when waste is fragmented in the form of meso or micro-debris (de Sciscio et al., 2016; Thushari and Senevirathna, 2020; Cowan and Tiller, 2021).

For NIS, while it may be possible in certain cases to identify the vector of introduction of a given species, it is not possible to make systematically a precise connection with the activities, especially since the implantation of species is also favored by the degradation of the different environmental compartments, including the excessive enrichment of nutrient and organic matter of the water column, the degradation of the seabed, the artificialization of the coasts, overfishing of commercial species and multiple disturbances to protected species (Molnar et al., 2008; Stiger-Pouvreau and Thouzeau, 2015) ...

Lastly, for underwater noise that are also among the most damaging pressures (Leaper and Renilson, 2012; Bittencourt et al., 2014; Borja et al., 2016; European Environmental Agency, 2019b), it can also be difficult to make systematically a precise connection with the activities.

Ultimately, climate change, pollution by various contaminants and marine litter, the development of NIS and underwater noise have multiple causes. These pressures and their impacts should be described and measured. However, except in certain special cases, it is not possible at

<table><caption>**Table 3**
Pressures directly induced by human activities on environmental compartments. The main pressures are shown in bold.</caption><thead><tr><th></th><th>Maritime transport, defence, research, at-sea exploration</th><th>Fishing (seabed trawling)</th><th>Fishing (excluding seabed trawling)</th><th>Agriculture and urbanization</th><th>Industry, coastal housing</th><th>Boating, yachting and bathing activities</th><th>Oil and Mining Exploration, Marine Renewable Energy and Cable Laying</th></tr></thead><tbody><tr><td><strong>Pelagic habitats and food webs</strong><br>Biological diversity (D1)<br>Food web (D4)</td><td><strong>Marine Litter (D10)</strong></td><td><strong>Marine Litter (D10)</strong></td><td><strong>Marine Litter (D10)</strong></td><td></td><td><strong>Marine Litter (D10)</strong></td><td><strong>Marine Litter (D10)</strong></td><td></td></tr><tr><td><strong>Benthic habitats</strong><br>Biological diversity (D1)<br>Seafloor integrity (D6)</td><td>Input of NIS (D2)<br>Loss and physical damage to the seafloor (D6)<br>Contamination (D8)</td><td><strong>Loss and physical damage to the seafloor (D6)</strong><br>Contamination (D8)</td><td>Loss and physical damage to the seafloor (D6)<br><strong>Marine Litter (D10)</strong></td><td>Loss and physical damage to the seafloor (D6)<br><strong>Contamination (D8)</strong></td><td>Contamination (D8)<br><strong>Marine Litter (D10)</strong></td><td>Input of NIS (D2)<br>Loss and physical damage to the seafloor (D6)</td><td>Loss and physical damage to the seafloor (D6)</td></tr><tr><td><strong>Land-Sea Interface Areas</strong><br>Biological diversity (D1)</td><td>Input of NIS (D2)<br><strong>Excessive input of nutrients and organic matter (D5)</strong><br>Contamination (D8)<br><strong>Marine Litter (D10)</strong></td><td>Excessive input of nutrients and organic matter (D5)<br>Contamination (D8)<br><strong>Marine Litter (D10)</strong></td><td>Input of NIS in shellfish culture (D2)<br>Excessive input of nutrients and organic matter (D5)<br><strong>Marine Litter (D10)</strong></td><td><strong>Excessive input of nutrients and organic matter (D5)</strong><br>Contamination (D8)<br><strong>Marine Litter (D10)</strong></td><td>Excessive input of nutrients and organic matter (D5)<br>Contamination (D8)<br><strong>Marine Litter (D10)</strong></td><td><strong>Marine Litter (D10)</strong><br>Marine Litter (D10)</td><td></td></tr><tr><td><strong>Protected species</strong><br>Biological diversity (D1)</td><td>Disturbance, collisions (D1)<br>Input of NIS (D2)<br>Contamination (D8)<br><strong>Marine Litter (D10)</strong><br>Underwater noise disturbances (D11)</td><td><strong>Extraction of species (D1)</strong><br>Disturbance, collisions (D1)<br>Contamination (D8)<br><strong>Marine Litter (D10)</strong><br>Underwater noise disturbances (D11)</td><td><strong>Extraction of species (D1)</strong><br>Marine Litter (D10)<br>Underwater noise disturbances (D11)</td><td>Contamination (D8)<br><strong>Marine Litter (D10)</strong></td><td>Contamination (D8)<br><strong>Marine Litter (D10)</strong></td><td>Disturbance, collisions (D1)<br>Marine Litter (D10)<br><strong>Underwater noise disturbances (D11)</strong></td><td>Disturbance, collisions (D1)<br>Underwater noise disturbances (D11)</td></tr><tr><td><strong>Commercial species</strong><br>Populations (D3)</td><td>Contamination (D9)</td><td><strong>Extraction of species (D3)</strong><br>Contamination (D9)</td><td><strong>Extraction of species (D3)</strong></td><td>Contamination (D9)</td><td>Contamination (D9)</td><td></td><td></td></tr></tbody></table>
the scale of a marine region to provide an attribution to specific activ-
ities. Addressing these issues requires the implementation of roadmaps
at national and international levels (Borja et al., 2016).

4. Implementation of the methodological framework to the Mediterranean marine subregion

In application of the guidelines defined above, an example of a
synthetic IEA is presented on a study area corresponding to a marine
sub-region<fnref n="3" />: the Western Mediterranean.

The guidelines for the synthesis of an IEA proposed in part 3 were established by considering information covering a perimeter encompassing the Mediterranean. Therefore, their implementation will be undertaken without modification. For implementation in a different context, particularly tropical or polar environments, adjustments to these guidelines may be made taking into account the general knowledge and the regulatory and normative corpus specific to the area concerned.

Prior to the summary presentation of the IEA, a presentation of area-
specific data is required, namely (i) a summary presentation of ecolog-
ical components; (ii) a summary presentation of human activities.

4.1. *Environmental components*

The synthesis map (Fig. 5) presents the main ecological character-
istics of species groups and their food webs, habitats and hydrographic
conditions.

OFB (2021, 2024) provides a detailed description of the ecological
components. For the purposes of our study, we will focus on the
following.

The French Mediterranean is particularly representative of sedi-
mentary habitats; they occupy nearly 99 % of the continental shelf and
almost all the abysses. On the continental shelf, muddy and detrital
sediments cover almost the entire circalittoral layer. These sediments
are essential functional zones for many fish species. Some biogenic
habitats of the sedimentary seafloor also present very diversified bio-
cenoses. *Posidonia herbarium*, of the infralittoral layer, is a pivotal
ecosystem of the Mediterranean littoral strip. It occupies nearly 900
km², or 5 % of the continental shelf. It offers many key ecological fea-
tures: sediment stabilization and oxygenation, spawning and nursery
sites, hydrodynamic mitigation, etc. In more sheltered areas (lagoons
and upper baies), beds of *cymodeceae* and eelgrass can develop.

The Gulf of Lion is the main area of concentration of marine avifauna (shearwaters, terns, storm petrels and gulls) in summer and to a lesser extent in winter. The open sea is less frequented except by the storm petrels and little gulls in winter. French waters are a major area on the Mediterranean scale for cetaceans recognized as an Important Marine Mammals Area. Seven species are regularly recorded: deep-diving cetaceans, namely the fin whale and the cachalot, the Cuvier's beaked whale, the striped dolphin, the Risso's dolphin, the bottlenose dolphin and the long-finned pilot whale. Areas of concentration of bottlenose dolphins, mainly coastal species, are at the Gulf of Lion, and north and south of Corsica. The distribution and abundance of beaked whales is poorly understood. Offshore waters are also frequented by loggerhead turtles in the summer.

Lagoons, islands and islets are important nesting areas for marine
birds. This gives the facade an important responsibility for the conser-
vation of eight marine species, namely the storm petrel, the Yelkouan
shearwater, the Scopoli shearwater, the Audouin's gull, the slender-
billed gull, the yellow-legged gull, the gull-billed tern and the Euro-
pean shag, as well as, in the coastal zone, the Kentish plover. The Gulf of
Lion is a major sector in the Mediterranean for feeders and spawning

grounds for pelagic fish (e.g., sprat, anchovy, sardine, horse mackerel, hake, tuna) and demersal fish (e.g., sole, gurnard, red mullet). The surroundings of the slope are of particular interest for hake, horse mackerel and langoustines. In addition, several species of elasmo-branchs, with very unfavorable conservation status at the global level, are present on the facade (e.g., white skate, angelshark and Mediterranean mantis shrimp, leafscale gulper shark, porbeagle shark, basking shark and blue shark). Offshore waters are also frequented by pelagic fish, including the bluefin tuna and the swordfish.

4.2. Maritime and coastal activities

Due to its geographical location, the Mediterranean Sea is an area with high strategic stakes and represents a support of economic activities unequalled worldwide: 25 % of sea freight, 30 % of oil traffic and 31 % of tourism. Located in the western basin, the French Mediterranean is no exception to this dynamic, which translates into a demographic increase and a development of economic activities (MTES, 2019), potentially causing increases in anthropogenic pressures on the marine and coastal environment. Fig. 6 presents these activities in relation to international issues, as well as national issues, including those of the hinterland. The port of Marseille, the first Mediterranean port with 75 million tonnes of traffic in 2021 (Observatoire Régional des Transports Provence - Alpes - Côte d'Azur, 2021) occupies a central place in trade.

4.3. Assessment of the ecological status of the Western Mediterranean

The methodological framework outlined in Part 3 has been applied. In particular, Fig. 4 shows this organization where ecological components are grouped into environmental compartments, while specifying the most relevant DCSMM descriptors for each of these compartments. In addition to the data required for the construction of this framework, specific studies conducted on the territory under consideration were used, namely the references cited above in the summary presentation of ecological components (OFB, 2021, 2024) and human activities (MTES, 2019). Finally, the strategic facade document resulting from the second cycle of application of the MSFD (MTES, 2019) includes in Annex 2 the last IEA relating to the Western Mediterranean.

Using the organization of Table 3, which presents on the basis of
general knowledge the main pressures directly induced by human ac-
tivities on each environmental compartment, Table 4 summarizes, based
on area-specific data (OFB (2021, 2024) and MTES (2019)), the pres-
sures directly induced by human activities on each of the ecological
compartments in the Western Mediterranean. In bold are the pressures
whose origin can clearly be attributed to one or more types of activity.
The other pressures, mentioned in ordinary characters, are observed in
the Western Mediterranean, but their attribution can only be made on
the basis of the general knowledge.

The attribution of pressures to activities can generally only be
considered with a high degree of certainty when pressures occur at the
location of the activity. In Table 4, the strongest impacts directly
attributable to activities are.

* Physical disturbance of benthic habitats by fishing activities using seabed trawling and recreational activities using chain anchoring techniques for mooring. Fine particles and organic matter from the dilution plume of the Rhône can also contribute to the degradation of the seabed.

* For protected species, collisions with fin whales and noise distur-
bances of marine mammals are attributable to various activities
using means of navigation; incidental catches on bottlenose dol-
phins, Blue and White Dolphins and Loggerhead Turtles, as well as
strangulations or entanglements on turtles and seabirds, are the
result of fishing activities excluding seabed trawling.

* On commercial species, the pressure that fishing puts on the pop-
ulations studied is too great. For stocks for which indicators are

<footnote n="3">³ The term “marine sub-region” is adopted here in reference to the definition given in Article 4 of the MSFD.</footnote>
<figure><img src="image_8.png" /><figcaption>Fig. 5. Summary map of ecological components in the Western Mediterranean (MTES, 2019)</figcaption></figure>

available with their reference values (i.e., maximum sustainable yield threshold), the majority have fishing mortality above the threshold, and a number of spawners below the threshold.

In addition to this attribution of impacts to activities, it is necessary to specify the pressures that cannot be attributed to specific activities. For the effects of climate change, the causes are global. For the development of NIS and for pollution by contaminants and marine litter, the attribution of impacts is complex and can only be done according to the types of species, contaminants and waste.

Other developments, such as the abundance of birds and fish (excluding species affected by overfishing), cannot in general be explained by specific activities. However, knowledge of the status of these ecological components should be incorporated into the assessment, regardless of the pressures causing the status change.

### 4.3.1. Climate change effects

The ecological status assessment carried out in Western Mediterranean (MTES, 2019) does not establish direct links between environmental disturbances associated with climate change (including temperature and water acidity increase) and the disturbed functioning of the various ecological compartments. Nevertheless.

* Regarding biogenic habitats, the surface of vegetated coastal ecosystems (seagrass beds and macroalgae fields) has decreased, due in part to more frequent and intense heat waves resulting from climate change (Mongruel et al., 2019);

* regarding food webs: since 2008, episodes of phytoplanktonic bloom, including proliferations of potentially harmful/toxic species, have been highlighted, in connection or not with anthropogenic disturbances (MTES, 2019). These episodes, the origin of which is poorly explained, may have led to a significant fall in small pelagic biomass (OFB, 2021);

* regarding protected and commercial species, climate change will lead to a tropicalization of the Mediterranean (Mongruel et al., 2019). Endemic species of temperate affinity, currently confined to the Gulf of Lion and the Adriatic, are trapped in these areas with no possible retreat to colder waters and are therefore doomed to extinction (Ben Rais Lasram et al., 2010).

### 4.3.2. Development of non indigenous species

394 ENI have been identified in the Western Mediterranean by an inventory and bibliographic synthesis work (MTES, 2019). In particular, over the period 2012–2017: 9 new NISs were observed and 11 new NISs were reported. The NIS observations were mainly made on coastal habitats consisting of rocky seafloors, seagrass beds and coralligenes. Nevertheless, species have also been observed on soft seafloors. This is the case for the invasive algae *Caulerpa taxifolia*.

### 4.3.3. Pollution by contaminants

In the sediment, the results of the assessment for MSR WM showed threshold exceedances for all metals and PCBs assessed, as well as for most PAHs (except naphthalene) and p,p'-DDE, metabolite of DDT (MTES, 2019). These contaminants can be attributed mainly to industry and agriculture, but shipping and other activities using nautical means
<figure><img src="image_9.png" /></figure>

Sources: DIRM MED, Cerema, Shom - Realization: Cerema Normandie Centre - Date: 12/2024

<figure><img src="image_10.png" /><figcaption>Fig. 6. Maritime and coastal activities on the Mediterranean coast [MTES, 2019].</figcaption></figure>

can also be responsible for some of these pollution, by cargo losses, fuel leaks, release into the environment of combustion residues or careening products.

Similarly, for contaminants present in commercial species, of the 11 groups of contaminants studied, relatively large exceedances of the

regulatory limit are highlighted for phycotoxin analyses and for two metal elements, mercury and lead.

#### 4.3.4. Marine litter pollution

Floating waste is mostly small plastic debris. Total waste densities
<table><caption>**Table 4**
Pressures directly induced by human activities on environmental compartments in the Western Mediterranean.</caption><thead><tr><th></th><th>Maritime transport, defence, research, at-sea exploration</th><th>Fishing (seabed trawling)</th><th>Fishing (excluding seabed trawling)</th><th>Agriculture and urbanization</th><th>Industry, coastal housing</th><th>Boating, yachting and bathing activities</th></tr></thead><tbody><tr><td><strong>Pelagic habitats and food webs</strong><br>Biological diversity (D1)<br>Food web (D4)</td><td>Marine Litter (D10)</td><td>Marine Litter (D10)</td><td>Marine Litter (D10)</td><td></td><td>Marine Litter (D10)</td><td>Marine Litter (D10)</td></tr><tr><td><strong>Benthic habitats</strong><br>Biological diversity (D1)<br>Seafloor integrity (D6)</td><td>Input of NIS (D2)<br>Loss and physical damage to the seafloor (D6)<br>Contamination (D8)<br>Marine Litter (D10)</td><td>Physical Disturbance of Circalittoral and Bathyal Habitats (D6)<br>Contamination (D8)<br>Marine Litter (D10)</td><td>Loss and physical damage to the seafloor (D6)<br>Marine Litter (D10)</td><td>In the Rhône dilution plume, degradation of benthic habitats by fine particles and organic matter (D6)<br>Contamination (D8)</td><td>Contamination (D8)<br>Marine Litter (D10)</td><td>Input of NIS (D2)<br>Physical Disturbance of infralittoral Habitats (D6)<br>Marine Litter (D10)</td></tr><tr><td><strong>Land-Sea Interface Areas</strong><br>Biological diversity (D1)</td><td>Input of NIS in ports (D2)<br>Contamination (D8)<br>Marine litter in coastal areas (D10)</td><td>Contamination (D8)<br>Marine litter in coastal areas (D10)</td><td>Input of NIS in aquaculture sectors (D2)<br>Marine litter in coastal areas (D10)</td><td>Excessive input of nutrients and organic matter at the mouth of the Rhône (D5)<br>Contamination (D8)<br>Marine Litter (D10)</td><td>Contamination (D8)<br>Marine litter in coastal areas. On beaches, litter from sanitation (D10)<br>Contamination (D8)<br>Marine Litter (D10)</td><td>Marine litter in coastal areas. On beaches, litter from tourism and leisure (D10)<br>Collisions with fin whales (D1)<br>Marine Litter (D10)</td></tr><tr><td><strong>Protected species</strong><br>Biological diversity (D1)</td><td>Collisions with fin whales (D1)<br>Contamination (D8)<br>Marine Litter (D10)<br>Noise disturbance of marine mammals (D11)</td><td>Fish populations increasing for 23 species and decreasing for 10 (D1)<br>Collisions with fin whales (D1)<br>Contamination (D8)<br>Marine Litter (D10)</td><td>Fish populations increasing for 23 species and decreasing for 10 (D1)<br>Bycatch on bottlenose dolphin, blue and white dolphin and loggerhead turtle (D1)<br>Ingestion of waste and strangulation or entanglement in turtles and seabirds (D10)<br>Contamination (D9)<br>Marine Litter (D10)</td><td></td><td></td><td>Noise disturbance of marine mammals (D11)</td></tr><tr><td><strong>Commercial species</strong><br>Populations (D3)</td><td>Contamination (D9)<br>Marine Litter (D10)</td><td>Out of 8 species, only one (bluefin tuna) increased between 2012 and 2018 (D3)<br>Contamination (D9)<br>Marine Litter (D10)</td><td>Contamination (D9)<br>Marine Litter (D10)</td><td>Contamination (D9)<br>Marine Litter (D10)</td><td>Contamination (D9)<br>Marine Litter (D10)</td><td></td></tr></tbody></table>

observed range from 0 to 1675 units/km.² The analysis of data from long-term associative campaigns and data from aerial observation campaigns made it possible to identify areas of accumulation near major cities and cities with high summer traffic (such as Marseille, Cassis, Toulon, Saint-Tropez and Nice). The Gulf of Lion also appears as an accumulation zone.

Concerning floating micro-waste, densities observed near rivers, ponds, water bodies (e.g., near Montpellier, Marseille and Bonifacio) are high because the abundance of micro-plastics depends strongly on weather conditions, geomorphological and hydrodynamics of the area. Coastal areas that are heavily urbanized or tourist-frequented are also regularly impacted by micro-waste (e.g., in Saint-Tropez, Sanary-sur-Mer, Nice, Antibes, Toulon and Villefranche-sur-Mer). The coasts of the Gulf of Lion often have less important values of density in micro-plastics than those observed on the eastern half of the Western Mediterranean.

The waste from the seabeds collected during the fishing campaigns are mainly plastics. The most frequently encountered categories after plastic are metals and glass. The activities causing the waste are difficult to determine precisely. Densities (i.e., number of wastes collected relative to the sampled surface) show a high spatial variability, particularly on the continental shelf of the Gulf of Lion, with an accumulation zone in the western part generated by marine currents. Accumulation zones are also identified near major cities, port areas, tourist areas and river mouths, especially the Rhone.

### 4.3.5. Evolution of bird and fish populations

Finally, the number of breeding pairs increased for 11 of the 12 species monitored between 1988 and 2016. Only the storm petrel experienced a decline in abundance over this period.

A decrease is observed for the populations of 6 species of coastal fish: the common dentex, the dusky grouper, two species of seahorses *Hip pocampus guttulatus* and *H. hippocampus*, the green wrasse and the brown meagre. The conclusions are identical for the three amphihaline species considered: the twaite shad, the European eel and the sea lamprey.

The reasons for these fluctuations are not known.

## 5. Discussion

The relevance of the methodological framework can be assessed against the following two criteria.

* its contribution to the implementation of the ecosystem approach;

* its transposability outside the European context.

### 5.1. Contribution to the implementation of the ecosystem approach

The ecosystem approach was initially defined by twelve principles enshrined in the Convention on Biological Diversity (CBD, 2000). Of the twelve principles set out in this convention, four principles are particularly important at the assessment stage. The contributions of our methodological framework can be specified in relation to these principles. The other principles concern the management of ecosystems beyond the assessment of its ecological status.

**Principle 5.** Conservation of ecosystem structure and functioning, in order to maintain ecosystem services, should be a priority target of the ecosystem approach.
By this principle, the ecosystem approach goes beyond the notion of sustainable use of each of its resources. For example, the use of species in fishing activities should not only be sustainable at the population or species level: it should not weaken the ecosystem in any way (Vasconcellos and Ünal, 2021). While analytical approaches, by construction, shed light separately on the various components of the ecosystem, the proposed methodological framework contributes to cross-referencing the results of analyses, which can lead to improve the diagnosis.

**Principle 7.** The ecosystem approach should be undertaken at the appropriate spatial and temporal scales.

The proposed methodological framework provides for national or supranational analyses, in particular through bibliographic analyses, followed by other analyses on smaller geographical perimeters. Its application on a concrete case shows that it makes it possible to establish a diagnosis of the state of knowledge and to identify the areas in which knowledge should further progress, specifying the scale at which further investigations should be conducted. It should be noted that the geographical areas on which the criteria and indicators apply should in some cases be redefined to better correspond to biophysical, socio-economic and management conditions (Pınarbaşı et al., 2020; Jarníková et al., 2022). In addition, the spatial extent and complexity of coastal and marine systems remain major challenges despite advances in monitoring techniques (Borja and Elliott, 2013; Rayner et al., 2019). The development of techniques for investigating the marine environment, using genomic tools, remote sensing, acoustic devices and modelling should nevertheless contribute to improving knowledge of all the environmental compartments of the marine environment, including plankton and food web (Borja et al., 2016).

As regards time scales, the proposed methodological framework is intended to be implemented in conjunction with existing evaluation methods, that is, on a regular basis. The transparency and reproducibility of the evaluation is guaranteed by relatively stable typologies on ecological components, pressures and activities, and well-defined criteria and indicators.

**Principle 8.** Recognising the varying temporal scales and lag-effects that characterise ecosystem processes, objectives for ecosystem management should be set for the long term.

The reproducibility of the proposed methodological framework contributes to an overall appreciation of the evolution of the ecosystems over the evaluation cycles, which promotes taking a step back, learning and adaptation. This helps to set long-term management objectives.

As an example, it is remarkable that climate change does not appear in the criteria and methodological standards applicable for the implementation of MSFD (European Commission, 2017b), whereas this directive (European Commission, 2008) specifies in point 34 that: « In view of the dynamic nature of marine ecosystems and their natural variability, and given that the pressures and impacts on them may vary with the evolvement of different patterns of human activity and the impact of climate change, it is essential to recognize that the determination of good environmental status may have to be adapted over time. »

Under these conditions, given the multiple effects of climate change, it is clear that, despite the recommendations for an ecosystem approach to MSFD, a study restricted to the strict application of criteria and methodological standards inevitably drifts towards a mainly analytical approach, in which the effects of climate change are invisibilized. The proposed methodological framework, by regularly drawing attention to the alteration of hydrographic conditions, as shown in Fig. 4, at the level of almost all environmental compartments, forces in the synthesis phase to reintegrate these long-term evolutions.

**Principle 12.** The ecosystem approach should involve all relevant sectors of society and scientific disciplines.

The proposed methodological framework facilitates exchanges with

a wide audience by promoting the production of summary elements in the form of concise texts, tables and maps. In particular, it promotes the appropriation of IEA results by a non-specialist audience, thanks to the choices made on the different typologies. For example, areas at the land-sea interface (i.e., estuaries, extensive aquaculture production areas, coastal lagoons and salt marshes, beaches and associated dunes) are defined based on geographical and geomorphological criteria. Another choice would have been possible but would not have had the same advantages, particularly in terms of cartographic representation. Thus, the typology proposed by the OFB (2021, 2024) classifies the functional areas according to the groups of species: halieutics (for example, spawning grounds and nurseries), amphihalins and elasmobranchs, bottlenose dolphins, seals and porpoises, seabirds, shorebirds and waterbirds. Given the large number of species considered in an IEA, this typology is more suitable for the study of each species than for the production of a synthetic assessment of the state of the marine environment.

## 5.2. Transposability of the methodological framework outside the European context

The proposed methodological framework was developed in the European context, and the example of application remains on the same geographical perimeter. In particular, we have adopted as a reference the European legislative framework defined by the DCSMM and the associated regulatory texts. It is therefore necessary to assess the possibility of transposing this approach to other contexts. Three arguments, relating respectively to its purpose, the underlying concepts and its operational principles, tend to show that this transposition is possible.

* regarding the purpose of the method: maritime areas must meet, to varying degrees, the same challenges linked in particular to the multiple effects of climate change, the intensification of well-established activities and the development of new uses, the massive introduction of contaminants and waste into the marine environment and the rapid urbanization of coastal areas (IPBES et al., 2019). The proposed methodological framework aims to improve the assessment of the consequences of these major developments on the marine environment and to better communicate the results of these assessments to a wide audience including decision-makers. Its purpose is therefore well adapted to the main issues currently appearing in most maritime areas;

* regarding the underlying concepts: legislation at national or regional levels that aims to control the potential adverse impacts of marine activities (e.g., Oceans Act in USA, Australia or Canada, National Water Act in South Africa) recommends the ecosystem approach. The proposed methodological framework, respecting the principles of this approach, promotes conceptual compatibility with the laws of the countries mentioned. As part of the drafting of this article, the investigations have not been extended to other countries, however international conventions also promote the homogeneity of the principles of management of the marine environment;

* From an operational point of view, it should be borne in mind that the proposed methodological framework does not replace existing evaluation methods, but aims to supplement them. For its implementation, it is necessary to rely on general knowledge of the state of the marine environment and the pressures it undergoes. For the definition of the methodological framework and its application in the case of the Mediterranean, reference was made to the French report EFESE (Mongruel et al., 2019). For other case studies, adjustments can be made using other continental assessments (e.g., in Europe, European Environment Agency (2019a; Chapter 6)) and/or worldwide (e.g., Millennium Ecosystem Assessment, 2005; IPBES et al., 2019). In addition to general knowledge, the data used comes from local investigations on the state of the environment and the pressures to which it is exposed. These investigations are mainly aimed at
providing information on the achievement of the good ecological
state, based on criteria and methodological standards defined by
regulation at national or supranational level. This protocol is
implemented in particular for IEAs, which constitute, the dominant
methodological framework of the ecosystem approach (Agardy et al.,
2011; Levin et al., 2014; Borja et al., 2016). The proposed method-
ological framework is therefore likely to be transposed to most cur-
rent regulatory contexts.

6. Conclusion

The legislative and normative frameworks require, in Europe and other regions of the world, assessments of the ecological state of the marine environment. The segmentation of scientific studies often leads to a set of disjointed results, voluminous and little readable by a non-scientific public. The proposed new methodological framework appears relevant to produce integrated ecosystem assessments that go beyond the juxtaposition of sectoral analyses. It aims in particular to alert on the critical situations observed and to identify as far as possible the causes of the damage observed. Assessments, produced in a synthetic form, can contribute to the emergence of transversal proposals that meet the necessarily multiple objectives of public policies. Its regular application, over the cycles of evaluation and implementation of measures and monitoring programs, would lead to comparing general knowledge with observations made in each of the study areas. The application of this new methodological framework may also contribute to a clearer, simpler and more coherent set of criteria and standards. Finally, these new methodological inputs could also strengthen the foundation on which research programmes are built. Improvements may include the organization of investigations at the most relevant spatial and temporal scales, according to a geographical division defined according to the biophysical characteristics of the environment and uses. Conversely, progress in knowledge could enrich the assessments of the ecological state of the marine environment.

CRediT authorship contribution statement

**Marc Igigabel:** Writing – review & editing, Writing – original draft, Validation, Supervision, Resources, Project administration, Methodology, Formal analysis, Conceptualization. **Olivier Laroussinie:** Project administration, Conceptualization. **Alan Quentric:** Writing – review & editing, Investigation. **Neil Alloncle:** Writing – review & editing, Investigation. **Fanny Châles:** Writing – review & editing. **Sophie Rumin:** Writing – review & editing. **Antonin Gimard:** Writing – review & editing, Writing – original draft. **Maxime Jobin:** Writing – review & editing. **Séverine Hallot:** Writing – review & editing.

Funding

This research did not receive any specific grant from funding
agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
the work reported in this paper.

Acknowledgments

The authors would like to thank Céline Jacob and Rémi Mongruel
from the French Research Institute for Exploitation of the Sea (Ifremer)
for their comments on the manuscript.

**Appendix A. Supplementary data**

Supplementary data to this article can be found online at https://doi.org/10.1016/j.jenvman.2025.124953.

Data availability

No data was used for the research described in the article.

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