Marine Protected Areas (MPAs) management usually involves bringing multiple stakeholders together, to construct policy-relevant research programs and science-based tools for adaptive management. Here, we present the conclusions of a transdisciplinary workshop that aimed at reviewing experiences in the co-design of EBM research in MPAs. We find that MPAs represent powerful instruments for conducting real-world experiments, de facto acting as living labs in support of ocean governance.

The identification of drivers and barriers influencing the initiation of commercial deep-sea mining (DSM) is key to developing research approaches to support the development of adequate DSM management frameworks. This study aims to provide a systems-level understanding of DSM drivers and barriers integrating both academic literature and diverse stakeholder perspectives (industry, NGOs, policy-makers, and academic researchers). To this end, we carry out a political, economic, social, technological, environmental, and legal (PESTEL) analysis combining the results of a literature survey, a participatory workshop, and semi-structured interviews. The results provide a broad overview of scientific knowledge and uncertainties relating to DSM drivers and barriers identified in the literature, alongside a synthesis of emerging perspectives and concerns expressed by stakeholders during the participatory workshop and interviews. The discussion highlights both areas of consensus and divergence across stakeholder groups and the literature, as well as a critical reflection on the relevance and limitations of the PESTEL approach, highlighting research needs to further support holistic decision making around DSM.

The development of an ecosystem accounting system to complete current wealth indicators is a core issue. Biophysical ecosystem accounts of the SEEA EA have been adopted as a statistical standard to bridge this gap. However, challenges remain as the specificities of marine ecosystems are poorly considered in the current standard, and link with policies is weak. This article aims at developing pilot biophysical ecosystem accounts in the European territory of France exclusive economic zone. We use available information from research and marine policy reporting databases to construct the extent and condition accounts. Remaining challenges include temporal and spatial issues of data availability, and several links between biophysical accounts and economic accounts.

Globally, land use change has consistently resulted in greater losses than gains in aboveground biomass (AGB). Forest fragmentation is a primary driver of biodiversity loss and the depletion of natural capital. Measuring landscape characteristics and analyzing changes in forest landscape patterns are essential for accounting for the contributions of forest ecosystems to the economy and human well-being. This study predicts national forest distribution for 2036 and 2054 using a Cellular Automata (CA) system and assesses ecosystem conditions through landscape metrics at the patch, class, and landscape levels. We calculated 130 metrics and applied a Variance Threshold method to remove features with low variance, testing different thresholds. The first filtered-out metrics were further analysed through Principal Component Analysis combined with a Feature Importance technique to select and rank the top 10 indicators: effective mesh size, splitting index, mean radius of gyration, largest patch index, mean core area, core area percentage, Simpson's evenness index, mutual information, Simpson's diversity index, and mean contiguity index. The eleventh selected indicator is the AGB density, a structural measurement for ecosystem condition and a proxy for forest carbon storage and sequestration assessments. From 2000 to 2018, the national AGB forest carbon stock decreased from 131.5 to 91.3 Megatons (Mt) with expected values for 2036 and 2054 being 71.8 and 55.3 Mt., respectively. Landscape measurements quantitatively describe forest dynamics, providing insights into the structure, configuration, and changes characterizing landscape evolution. This research underscores the capability of CA models to map large-scale forest resources and predict future development scenarios, offering useful information for conservation and environmental management decisions. Additionally, it provides measurements to support Ecosystem Accounting by assessing forest extent and indicators of its conditions.

The critical role of inland Green-Blue Ecosystems (GBE) in delivering goods and services underscores the need to understand their relationships. This research investigates the impact of climate variables on GBE stock accounts by estimating Tree Cover Density (TCD) and Water & Wetness Probability Index (WWPI). Using supervised machine learning and factor analysis, we measured GBE extent and condition. Key predictors for Blue Ecosystems were topographic variables, while vegetation indices were crucial for Green Ecosystems. In 2018, 33% of the inland area was covered by forests, freshwater, and wetlands. Key climate-driven factors for forests included precipitation (0.65), aridity index (0.54), and evapotranspiration (0.44). For freshwater and wetlands, precipitation (0.69), aridity index (0.55), and elevation (0.42) were significant. This research enhances our understanding of how climate impacts GBE, influencing biomass density and water availability. It bridges socio-environmental science with engineering by integrating advanced modelling techniques, promoting ecosystem resilience and sustainability.

A significant challenge in the integration of ecosystem services into decision-making processes lies in effectively capturing the dynamics of marine socio-ecological systems, including their evolutionary pathways, equilibrium states, and tipping points. This paper explores the evolutionary trajectories of a vital marine ecosystem endemic to the Mediterranean Sea: the Posidonia oceanica seagrass meadows, in response to various drivers of change. A state-and-transition model is employed to assess the ecosystem services provided by P. oceanica across different states defined by selected transitions, such as overfishing, fragmentation, pollution, and invasion by non-native species. To apply this model, scientific expertise is combined with field data generated using the Ecosystem-Based Quality Index to evaluate the conservation status of P. oceanica. This integrated approach allows for the representation of the ecosystem services offered by the meadows across different states, leveraging ecological data. The findings highlight the disproportionate impact on provisioning services, particularly sea urchins and commercial fish production, which suffer the most under various stressors. Notably, when these services decline to critical levels, the meadows cease to provide significant benefits. Finally, a synthesized representation is presented, merging ecological insights with monitoring data, offering a framework that is more accessible to stakeholders and decision-makers.

In line with international frameworks and following the example of other countries, France conducted a national ecosystem services (ES) assessment in 2012. National assessments are intended to be both comprehensive and useful. In practice, these objectives are conflicting and difficult to reach, leading the experts in charge of the assessment to allocate effort according to their own priorities. In the case of the marine part of the French ES assessment, we consulted stakeholders at the national scale to better connect the assessment to the interest of the end-users. We implemented a participatory approach based on a combination of workshops and online questionnaires. We collected stakeholder's perception of (i) ES bundle; (ii) hierarchization of issues; (iii) specific issues of concern; and (iv) research needs for different types of marine ecosystems and groups of species. The results of the consultation assisted the assessment process in selecting key issues that necessitate in-depth analysis, and identifying discrepancies between stakeholders' perceptions and the scientific knowledge that need to be addressed. Stakeholders' perceptions were also mobilized as an additional source of data to inform decision-makers regarding the state of ecosystems and their ES. In the end, this work underlines the importance of stakeholder's consultation to support ES assessment and provides guidance for its implementation in the future. Our results can also inform research needs to support the conservation of marine ecosystems.

In 2016, the French government adopted a law for biodiversity, setting an objective of protecting 55,000 hectares of mangroves. This objective is particularly important to French Guiana, which shelters almost 60% of French mangrove ecosystems, and where mangroves occupy three quarters of the coastline. The coast of French Guiana is also where issues associated with demographic and economic dynamics concentrate. There is thus a need to plan for an economic development that is compatible with the objective of protecting mangrove ecosystems. Ecosystem services (ES) assessment can support such decision-making, informing on the costs and benefits associated with alternative mangrove conservation strategies. While the many services provided by mangrove ecosystems are well documented worldwide, the extent to which these can be encountered in the specific case of French Guiana is currently only very partially known. Relying on the Fuzzy cognitive mapping (FCM) approach, we collected and compared the perception of multiple and heterogeneous groups of stakeholders, of the functioning of the mangrove social-ecological system at the scale of French Guiana. Results, allow to identify mangroves ES and threats particularly influenced by the high sedimentary dynamism of the shoreline. This generates two distinct components of the mangrove social-ecological system: mud banks where ecosystem services are spatially and temporally unstable, and associated with perceived constraints for key coastal activities, and estuarine mangroves where the ecosystem services usually described in the literature on mangroves can be found. Disservices associated with mangrove ecosystems were also identified as a key interaction. This can inform the research needs that should support sustainable development trajectories, fully accounting for the protection of French Guianese mangrove ecosystems.

Maritime transportation is a major contributor to the world economy, but has significant social and environmental impacts. Each impact calls for different technical or operational solutions. Amongst these solutions, we found that speed reduction measures appear to mitigate several issues: (1) collision with wildlife; (2) collision with non-living objects; (3) underwater noise; (4) invasive species; and (5) gas emission. We do not pretend that speed reduction is the best solution for each individual issue mentioned in this paper, but we argue that it could be a key solution to significantly reduce these threats all together. Further interdisciplinary research is required to balance private economic costs of speed reduction measures with environmental and social benefits emerging from all mitigated issues.

Standard approaches to environmental and natural resource use externalities generally focus on single-sector resources and user groups. Remedies include Pigouvian-style government constraints, small group controls following Elinor Ostrom, or less frequently, bargaining across users as outlined by Ronald Coase. However, many difficult natural resource management problems involve competing uses of the same resource or multiple interdependent resources, across multiple, heterogeneous sectors. Cross-sectoral externalities are generated and impede attainment of conservation objectives. The multiplicity of resources and stakeholders, who may have different property rights, hold different use or non-use values, have different traditions, or fall under different regulatory regimes, increases the likelihood of multi-jurisdictional conflicts. We provide an institutional analysis following Oliver Williamson?s four-levels of institutions (social embeddedness, institutional environment, governance, resource allocation) to illustrate the sources of potential conflict, the costs of addressing them, and the potentials for exchange. In comparing the costs of alternative approaches, we include transaction costs associated property rights; the costs of lobbying, implementing, and enforcing government regulation; and the costs of scaling up from small-group controls when resource problems involve multiple sectors and heterogeneous populations. In our illustrative case examples, instruments that are not formal property rights are exchanged at lower transaction costs. We close by discussing how Coasean, Pareto-improving voluntary exchange agreements may be lower cost, more effective, and more durable solutions than alternative management regimes to mitigate cross-sectoral externalities.

L’epidemie COVID-19 pose de nombreuses questions. Quels sont les liens de cette crise sanitaire avec la faune sauvage, quels sont ses liens avec l’erosion de la biodiversite que le dernier rapport de l’Ipbes a souligne, quels sont ses liens avec certains systemes de production alimentaire et plus generalement avec l’anthropisation de la planete ? Pour les eclairer sur ces sujets, les pouvoirs publics se sont tournes vers la recherche.

The aim of the European program Life Integrated Project Environment (IPE) MarHa (2018-2025) is to restore and sustain the favorable conservation status of marine natural habitats in French Natura 2000 sites. In this context, Ecosystem Service Assessments (ESA) are carried out at various French sites including the Bay of Marseille (Provence, France). First, we applied the TRIAGE methodology: a strategic assessment of the issues with experts of the area (local MPA managers and scientists). TRIAGE raises two main concerns: (i) the intensification of recreational uses (by both residents and visitors), and (ii) the conservation of Posidonia oceanica (Linnaeus) Delile, 1813 seagrass meadows. In order to address both issues, we selected two adapted methodologies based on the strategic assessment: (i) a study oriented toward understanding the demand for ecosystem services (focused on recreational activities), and (ii) a study of the capacity of P. oceanica meadows to deliver ecosystem services using state-and-transition modeling. The objective of this work is to present the ESA process, from the strategic assessment to the analysis results. We focus on the study of the capacity of P. oceanica seagrass meadows to provide ecosystem services. State and transition models consist in defining alternative states of the habitat based on ecological indicators, identifying the bundle of services associated with each state and identifying transition vectors capable of explaining the shifts between each state. State-and-transition models can be very powerful frameworks for integrating multiple functions and services delivered by ecosystems while accounting for their temporal dynamics.

Marine and coastal activities are closely interrelated, and conflicts among different sectors can undermine management and conservation objectives. Governance systems for fisheries, power generation, irrigation, aquaculture, marine biodiversity conservation, and other coastal and maritime activities are typically organized to manage conflicts within sectors, rather than across them. Based on the discussions around eight case studies presented at a workshop held in Brest in June 2019, this paper explores institutional approaches to move beyond managing conflicts within a sector. We primarily focus on cases where the groups and sectors involved are heterogeneous in terms of: the jurisdiction they fall under; their objectives; and the way they value ecosystem services. The paper first presents a synthesis of frameworks for understanding and managing cross-sectoral governance conflicts, drawing from social and natural sciences. We highlight commonalities but also conceptual differences across disciplines to address these issues. We then propose a novel analytical framework which we used to evaluate the eight case studies. Based on the main lessons learned from case studies, we then discuss the feasibility and key determinants of stakeholder collaboration as well as compensation and incentive schemes. The discussion concludes with future research needs to support policy development and inform integrated institutional regimes that consider the diversity of stakeholder interests and the potential benefits of cross-sectoral coordination.