T4-2 | Environmental, social and economic impacts arising from deep-ocean activities

T4-2

Environmental, social and economic impacts arising from deep-ocean activities

Orals

| Wed, 04 Jun, 16:00–17:30 (CEST)|Room 6

Posters on site

Posters virtual

Further information on the theme is available at: https://one-ocean-science-2025.org/programme/themes.html#T4

Orals: Wed, 4 Jun | Room 6

Chairperson: Diva Amon

16:00–16:10

OOS2025-699

ECOP

How Much Worth is the Deep-Sea ? Insights from a Meta-Analysis

Benjamin Blanc, Alexandre Mathieu, Vincent Geronimi, Laurence Goury, and Stéphane Goutte

Context

The deep sea, covering vast areas below the 200-meter depth mark, represents a critical and complex frontier for sustainable development, encapsulating both immense economic potential (Folkersen & al., 2018) and vital ecosystem services (Thurber & al., 2014). Within the framework of the blue economy - formalized at the 2012 United Nations Conference on Sustainable Development, this largely uncharted region challenges conventional views of resource utilization and ecological preservation. Once perceived as inaccessible, the deep sea currently emerges as an essential area for balancing economic growth with environmental responsibility (Mejjad & Rovere, 2021).

Despite increasing awareness of the need for sustainable management, the valuation of deep-sea resources often remains fragmented, particularly regarding non-market ecosystem services but also the incorporation of emerging sectors such as deep-sea mining (Sharma, 2017), ocean-based renewable energy or even marine biotechnology (Saide et al., 2021). This fragmented approach hinders the development of coherent policy frameworks and international cooperation, impeding a comprehensive understanding of the deep sea's true economic and ecological value. A robust monetary evaluation is essential to quantify these contributions effectively.

The proposed contribution focuses on the results of a meta-analysis processed in the context of a collective scientific assessment on deep sea knowledge and governance issues, commissioned by the French government.

Methodology and Analysis

Thus, this paper aims to conduct a comprehensive meta-analysis to consolidate and synthesize existing research, grounded by the article of Folkersen et al. (2018), extending their work by addressing methodological gaps and proposing a unified framework for deep-sea resource valuation. This extended framework will not only refine the methodological approach but also provide an updated monetary valuation of deep-sea resources.

We will employ a Systematic Literature Review (SLR) approach, utilizing the PRISMA protocol (Moher et al. 2009) for selecting relevant research articles. The SLR methodology provides a structured, replicable approach to identify literature on deep-sea resource valuation. By following it, we ensure an original approach not yet explored to this extent in the literature.

The methodology will facilitate a deeper examination of how various valuation approaches have treated both market and non-market contributions, revealing inconsistencies and omissions in the current literature. By aggregating diverse findings and cross-comparing methodologies, this analysis should provide a holistic view that accounts for the regulatory, ecological and socio-economic dimensions critical for sustainable deep-sea resource management.

For the One Ocean Science Congress

Our research aligns with the One Ocean Science Congress 2025 theme 4. By conducting a meta-analysis that bridges fragmented valuation approaches and proposes a comprehensive framework, this work directly addresses the multifaceted value of the deep-sea. This is vital for shaping policies that seek a more resilient and inclusive model that prioritizes long-term ecological health over short-term exploitation (Spalding, 2016). This integrated approach reinforces the notion of the ocean as a common heritage of mankind (Bourrel et al., 2018) - emphasizing not just its direct profitability potential but also its role in supporting biodiversity (Paulus, 2021), climate regulation (Hilmi & al., 2023) and socio-cultural significance (Bennett et al., 2022; Barianaki et al., 2024).

How to cite: Blanc, B., Mathieu, A., Geronimi, V., Goury, L., and Goutte, S.: How Much Worth is the Deep-Sea ? Insights from a Meta-Analysis, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-699, https://doi.org/10.5194/oos2025-699, 2025.

16:10–16:20

OOS2025-1095

ECOP

Deep-sea mining as an emerging threat to deep sea ecosystems

Marlene Pinheiro, Nélson Alves, Joana Raimundo, Miguel Caetano, Joana Xavier, Teresa Neuparth, and Miguel M. Santos

The deep sea is the biggest ecosystem on Earth, representing around 90% of the marine environment. Despite its remoteness and inaccessibility, the deep sea is under constant threat from anthropogenic activities. Among them is deep-sea mining, that is quickly rising as an appealing alternative to land-based mining. Deep-sea mining refers to the extraction of mineral resources from the seabed, an activity that can potentially, among other consequences, release large plumes of sediments and ore across the water column affecting vast areas of the ocean. The present work aimed at assessing the effects of suspended sediments and ore on several benthic species (Mytilus galloprovincialis, Spisula solida and Adreus fascicularis) under hyperbaric conditions through the assessment of functional, biochemical and molecular endpoints to improve our understanding of how these stressors impact exposed organisms and the marine environment. Sediments and ore were used in different size ranges and concentrations to better represent a realistic scenario of resuspension as a byproduct of mining activities. Experiments lasted for 96h at different pressures (up to 50 Bar) in a hyperbaric chamber. After each exposure experiment, several endpoints were evaluated for each species (i.e. respiratory and filtration rates, oxidative stress biomarkers such as catalase, lipid peroxidation and glutathione s-transferase and transcriptomic profiles). Overall, suspended sediments and ore caused significant harmful effects in all three species, ranging from filtration/respiratory ability decrease to alterations in oxidative stress response and gene expression profiles. These findings highlight the need to establish guidelines and regulatory frameworks before deep-sea mining starts at the commercial level to mitigate potential negative effects, especially for benthic communities in the deep sea.

Acknowledgments: This work was developed under the project DEEPRISK [reference PTDC/CTA-AMB/7948/2020].

How to cite: Pinheiro, M., Alves, N., Raimundo, J., Caetano, M., Xavier, J., Neuparth, T., and Santos, M. M.: Deep-sea mining as an emerging threat to deep sea ecosystems, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1095, https://doi.org/10.5194/oos2025-1095, 2025.

16:20–16:30

OOS2025-982

Short-term impacts of polymetallic nodule mining on sediment remineralization activity: in situ observations of benthic oxygen fluxes after a nodule collector prototype trial in the Clarion Clipperton Fracture Zone

Felix Janssen, Antje Boetius, Matthias Haeckel, Massimiliano Molari, Duygu Sevgi Sevilgen, and Frank Wenzhöfer

The vertical distribution of oxygen concentrations in sediment porewaters and oxygen fluxes across the sediment-water interface are key variables to assess benthic redox conditions and quantify seafloor community respiration. Oxygen fluxes serve as proxies for benthic activity and organic matter remineralization rates. Measurements of the distribution of oxygen in the sediment and sediment community oxygen consumption are also recommended by the International Seabed Authority (ISA) to establish ecological baselines and to identify effects of mining-related impacts (e.g., ISBA/25/LTC/6/Rev.2 and ISBA/27/C/11). This presentation addresses short-term impacts on benthic oxygen distribution and remineralization activity in response to primary (i.e., nodule removal and sediment reworking) and secondary impacts of nodule mining (i.e., blanketing of neighboring areas with resettling sediment plumes). Distribution of oxygen concentrations in porewaters and interfacial oxygen fluxes were investigated before and after trials of the pre-prototype nodule collector ‘PATANIA II’ carried out in 2019 by the Belgian Company DEME-GSR. Measurements were performed in situ in two exploration contract areas with microsensor profilers deployed by a Remotely Operated Vehicle (ROV). Additional measurements were obtained with benthic chamber systems. 1.5 years after the collector trial, diffusive oxygen fluxes were clearly reduced in ‘collector impact sites’ where nodules have been removed and surface sediments were redistributed and partly transported away. The opposite was found in neighboring ‘plume impact’ sites where sediments got covered by blanketing layers of different thickness. Here, fluxes were higher as compared to reference and undisturbed sites. The presentation will discuss possible explanations of the observed patterns including the redistribution of organic matter with resuspended sediments and possible effects of physical disturbances on metabolic activity of benthic communities. The study was carried out in the framework of the collaborative European project MiningImpact under the Joint Programming Initiative Healthy and Productive Seas and Oceans (JPI Oceans).

How to cite: Janssen, F., Boetius, A., Haeckel, M., Molari, M., Sevilgen, D. S., and Wenzhöfer, F.: Short-term impacts of polymetallic nodule mining on sediment remineralization activity: in situ observations of benthic oxygen fluxes after a nodule collector prototype trial in the Clarion Clipperton Fracture Zone, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-982, https://doi.org/10.5194/oos2025-982, 2025.

16:30–16:40

OOS2025-805

Environmental impacts of deep-sea mining - from scientific research to policy recommendations

Matthias Haeckel and the MiningImpact project

The abyssal seabed harbours minerals, i.e. polymetallic nodules, massive sulphides, and cobalt-rich ferromanganese crusts, which are rich in metals that are critical for the technologies of our energy and mobility transition and digitalization. As a consequence, interest in deep-seabed mining has been growing over the last decade, and regulations for the exploitation of these resources are being developed on international and national level. While extracting metals from deep-sea ores may contribute to the desired overall reduction of our CO₂ emissions, it will certainly introduce a new environmental threat to our oceans that calls for effective protection and the precautionary approach defined in UNCLOS.

The research of the JPI Oceans project MiningImpact (miningimpact.geomar.de) has demonstrated that abyssal ecosystems show unrivalled high biodiversity in combination with high spatial and temporal variability of faunal populations and environmental variables. Our results indicate that environmental impacts from future deep-sea mining operations will be severe and will last for centuries to millennia. Our independent scientific monitoring of a recent industrial test of mining technology in the Clarion-Clipperton-Zone of the Eastern Equatorial Pacific shows that polymetallic nodule mining will not only remove the metal ore, which forms a specific habitat for a rich benthic fauna, but the entire biologically active surface layer of the seafloor, which forms the basis of the abyssal food web. In addition, the produced suspended particle plume will also blanket the benthic ecosystem outside the mined areas. Larger-scale consequences are still uncertain due to the largely unknown species connectivity and our limited understanding of ecosystem structure and functions. Hence, at the anticipated scale of impact of several hundreds of square kilometres per year for each nodule mining operation, careful and adaptive spatial planning of mining operations on regional and even global scale is required. Conservation areas must be set aside that closely match ecosystem characteristics in mined areas, and effective ecological indicators and threshold values indicative of harmful effects to the marine environment need to be defined. Transparent monitoring of mining operations is needed to ensure compliance with high environmental standards to protect the marine environment from serious harm.

This presentation will summarize the observed immediate and expected long-term consequences of deep-sea mining operations and will discuss how independent scientific studies can inform regulatory processes, such as the development of the Mining Code of the International Seabed Authority.

How to cite: Haeckel, M. and the MiningImpact project: Environmental impacts of deep-sea mining - from scientific research to policy recommendations, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-805, https://doi.org/10.5194/oos2025-805, 2025.

16:40–16:50

OOS2025-590

Aligning the social sciences with the deep ocean: developments and definitions for a new research agenda

Susanna Lidström and Neil Craik

The deep ocean is connected to people, communities and societies in fundamental and intricate ways, including through regulation of Earth system processes such as the climate but also through direct impacts on economies and wellbeing through resource extraction, distribution of benefits, research practices and governance regimes. While a dedicated community of natural scientists study the nature and particularities of the deep ocean, corresponding deep-sea social sciences are yet to be developed – or named as such. Economists, historians, anthropologists, law scholars and other social scientists have so far worked with different categorisations of the marine realm, focusing on political and legal classifications, such as territorial or coastal waters, exclusive economic zones, and the high seas. However, this horizontal approach to ocean zones reflects a lack of appreciation of the importance of the verticality and three-dimensionality of the ocean space, where the deeper parts of the ocean are fundamentally different from the shallower parts, regardless of whether they are in national or international territories.

This paper aims to challenge and revise the traditional horizontal conceptualisation of maritime zones in the social sciences by approaching the deep ocean as a relevant category for studies of human-ocean relationships and investigating the unique social science-dimensions of deep-sea environments. Our intention is to provide a fundamental perspective of how the social sciences may interact with deep-sea definitions developed in the natural sciences over the past couple of decades. Establishing this base, we contend, will provide a sound starting point for identification and investigations of more particular social science concerns and areas of study, such as social, economic and equity impacts from specific deep-sea activities including seabed mining, marine carbon dioxide removal and storage, bioprospecting, pollution, and corresponding governance responses.

Our paper draws on a collaboration between social scientists and deep-sea natural scientists, and is an attempt to bridge these fields. The collaborative effort to identify the scientific foundations for treating the deep ocean as a distinct unit of analysis includes a 2024 workshop organised by the Deep Ocean Stewardship Initiative at Scripps Institution of Oceanography, followed by continued efforts to combine diverse perspectives in multiple papers. The study presented here is the main attempt within this broader framework to align social science issues and areas of relevance to the key bio-geo-physical processes, ecosystems and ecological conditions, and challenges and threats that justify the distinct scientific treatment of the deep ocean across disciplines.

How to cite: Lidström, S. and Craik, N.: Aligning the social sciences with the deep ocean: developments and definitions for a new research agenda, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-590, https://doi.org/10.5194/oos2025-590, 2025.

Discussion Post a comment

16:50–17:00

OOS2025-1142

ECOP

Sleeping data awakened: Exploring 20+ years of socio-ecological dynamics in NW Mediterranean fisheries

Juliana Quevedo, Nixon Bahamon, Jacopo Aguzzi, Marco Francescangeli, and Joan B. Company

In the framework of the recently awarded EU Project Digital Twin-sustained 4D ecological monitoring of restoration in fishery depleted areas (DIGI4ECO), we are investigating the socio-ecological dynamics of demersal fisheries in the Northwestern Mediterranean Sea over the past 20+ years. This research draws on an extensive collection of "sleeping data" from over 30 oceanographic cruises, meaning data that’s not digitalized, standardized and therefore not used. Our goal is uncovering the impacts of anthropogenic pressures, regulatory policies, and economic factors on deep-sea demersal populations, providing an historical perspective on the sustainability of Mediterranean fisheries. This “sleeping data” allows to evaluate how demersal species biomass and abundance have shifted over time from earlier, less impacted conditions, and to explore the connections between these changes, fishing practices, and economic outcomes for local fisheries. To capture the complexity of these dynamics, we will employ a variety of statistical and quantitative methods. Generalized Additive Models (GAMs) will allow for the exploration of nonlinear trends in species populations and community structures over time. Multivariate ordination techniques, including Principal Component Analysis (PCA) and Cluster Analysis (Bray-Curtis), will distinct ecological patterns across different periods and locations. Additionally, fishery metrics such as landings, catch per unit effort (CPUE), income, and revenue will be examined to provide insights into the economic viability and impacts of fishing activities on local livelihoods. This approach addresses a critical research gap, as no study has yet comprehensively assessed these combined factors over time. Our work offers actionable insights to policymakers and stakeholders, revealing how historical data can support informed decisions on sustainable fishing practices and economic resilience in the Mediterranean. Ultimately, this research will help develop strategies to ensure that Mediterranean fisheries can thrive sustainably, balancing ecological integrity with socio-economic needs.

How to cite: Quevedo, J., Bahamon, N., Aguzzi, J., Francescangeli, M., and Company, J. B.: Sleeping data awakened: Exploring 20+ years of socio-ecological dynamics in NW Mediterranean fisheries, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1142, https://doi.org/10.5194/oos2025-1142, 2025.

17:00–17:10

OOS2025-1396

Beyond the status quo: defining and enabling a sustainable deep-ocean blue economy

Diva Amon and the Deep-Sea Blue-Economy Team

17:10–17:30

Discussion

Posters on site | Poster area "La Baleine"

Display time: Tue, 3 Jun, 17:00–Thu, 5 Jun, 20:00

P380

OOS2025-113

Deep-sea tailing practices: contamination and societal perspectives. Lessons learnt from the French success story of the Gardanne plant discharge in reducing environmental footprint.

Stéphanie Jacquet, Brigitte Juanals, Déborah Mille, and Pierre Boissery

What is the impact of discharging mining waste residues into the sea, both in terms of marine environment contamination and its societal dimension? This question is at the heart of the INTERFACES project, an interdisciplinary study focusing more specifically on the discharges from the Gardanne alumina production plant (southern France) into the Mediterranean Sea. The case of the Gardanne plant embodies the contemporary challenges of managing waste generated by its activity. It illustrates the modern conflict between industrial and environmental concerns. It also serves as an example of how marine contamination levels can be improved when adequate human, technological, and financial resources are properly mobilized. However, these advances have taken place within a significant context of environmental controversy spanning several decades. The Gardanne plant has been active since the late 19th century. It took nearly 55 years of contentious public debate and challenges before the sea discharges, initiated in the 1960s, met the requirements of the Barcelona Convention (1976) and its protocols. The period from 2012 to 2022 marks a pivotal decade in addressing this discharge issue, distinguished by significant advancements both scientifically and technologically as well as administratively and socio-politically, leading to compliance and a medium-term perspective of zero sea discharge. We examine the modalities of production, dissemination, and circulation of scientific information over this decisive decade, shedding light on the interactions between institutional actors and stakeholders of the Gardanne plant involved in the committees for evaluation and monitoring of discharges, including civil society. Our presentation focuses on the lessons learned from this complex interaction between mobilized resources, environmental improvement in terms of chemical contamination, and scientific communication around these processes. Based on a situated analysis of the risks and measures under debate in the case of the Gardanne plant, our study aims to explore methodological avenues for designing action strategies and information and exchange interfaces. These are centered on open access to information and stakeholder participation, as well as the public visibility and involvement of researchers engaged in scientific work. These strategies and interfaces will be configured and tested in case studies presenting similar contexts of environmental conflict. The Gardanne case serves as a reference element in terms of method, results, and governance, ensuring transparency in decision-making and stakeholder involvement for the management and monitoring of this type of Installation Classified for the Protection of the Environment.

How to cite: Jacquet, S., Juanals, B., Mille, D., and Boissery, P.: Deep-sea tailing practices: contamination and societal perspectives. Lessons learnt from the French success story of the Gardanne plant discharge in reducing environmental footprint., One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-113, https://doi.org/10.5194/oos2025-113, 2025.

P382

OOS2025-806

ECOP

Environmental Constraints on European Hake (Merluccius merluccius) Recruitment and Trawling Fisheries Management in Algeria

Yousra Zaoui, Mohamed Kacher, and Billal Meradef

European hake (Merluccius merluccius) landings in Algeria remain low and unstable, despite multiple increases in trawling efforts since 1990. Comparative analysis of landings in Algeria with those observed in other northern Mediterranean countries (Italy, Spain, and France) indicates that when Algeria achieves higher catches, landings in other countries decline, and vice versa. To explain this situation, an analysis was conducted using data collected during monitoring surveys named ALDEM (2013, 2014, and 2015) in Algeria. This analysis considered that Algerian waters extend from the Alboran Sea in the west to the Algerian Basin in the east.

The results of this analysis on hake sampled during the three surveys suggest that environmental parameters do not meet the optimal conditions necessary for effective juvenile recruitment, making the existence of nursery grounds unlikely in these waters. Finally, it appears that recruitment in Algeria mainly depends on juvenile hake originating from nursery areas located further north, specifically in the northern Algerian Basin and the northeastern Atlantic near the Mediterranean for the Alboran Sea. In the absence of local nursery areas and with a reliance on these externally sourced recruits, sustainable management of hake stocks in Algeria is complex and reliant on inputs from adjacent regions, potentially impacting the socio-economic stability of Algeria’s trawling fishery.

How to cite: Zaoui, Y., Kacher, M., and Meradef, B.: Environmental Constraints on European Hake (Merluccius merluccius) Recruitment and Trawling Fisheries Management in Algeria, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-806, https://doi.org/10.5194/oos2025-806, 2025.

P383

OOS2025-1239

Deep sea mineral resources: a true Eldorado? Geological, biological and economic cross-perspectives

Julien Collot, Vincent Geronimi, Walter Roest, Sarah Samadi, Stephane Goutte, Karine Olu, Valelia Muni Toke, Anouk Barberousse, and Pierre-Yves Lemeur

Deep sea minerals (DSM) may be on the verge of a turning point, from the status of a geological resource to that of an economic reserve (according both to the SEC regulation and the ni 43-101 Canadian norm, see http://ccmr-ocrmc.ca/wp-content/uploads/43-101_ni_fr.pdf). Today, this transition notably concerns the potential exploitation of polymetallic nodules in the Clarion-Clipperton Zone.

With a view to a possible exploitation of these nodules, the next step, from an economic and financial point of view, has to be based on the realisation of a pre-feasibility study, announced but not carried out to date. The figure of a profitability of 27% is, however, already announced in several documents provided by The Metals Company (TMC) concerning the NORI Area D Mineral Resource project (Technical Report Summary. Initial Assessment of the NORI Property, Clarion-Clipperton Zone, Deep Green Metals Inc., 17 mars 2021).

However, the move towards industrial exploitation of deepsea minerals has long been announced, but never been enacted, and it is fraught with various forms of uncertainty. These uncertainties concern the elements of geological, biological and economic knowledge, as well as question the desirability / feasability of this exploitation. Uncertainties also includes the status of the entities and actors involved in the DSM arena. For instance, the categorization of corporations like TMC as junior (speculative) or major (industrial) companies remains an open question, as does the relationship between sponsoring states and partner corporations at ISA.

The impacts of the exploitation of DSM on the environment are surely underestimated. The caracterization of the biological components of the ecosystems, including the biological identification and the heterogeneity of the benthic communities and abiotic factors, where the mineral resources are found, but also their relationships with other compartments of the ocean, are very poorly known. Acquiring this knowledge requires further scientific studies, despite international research efforts and APEI (Areas of Particular Environmental Interest) establishments in the CCZ. For example, TMC collected data to study the sedimentary plume generated by a small size pilot nodule collector and concluded that the vertical and lateral extents of this plume are negligible. However, local impacts might still be considerable. In addition, the data that led to this conclusion are not available to the science community for independant validation. Moreover, the impact of the midwater sedimentary plume generated by the ore process (from the surface vessel) is only fewly documented

Because the geographical distribution of potential deepsea mineral occurences is so large (several tens of thousands of square kms per exploration area) and the available data are so sparse, it is very difficult to assess the lateral extent, continuity and density of nodule fields and Fe-Mn crusts. The spatial heterogeneity is, therefore, likely underestimated and consequently the exploited surface area will be greater than expected and hence the associated impact too.

Here, we present the elements gathered within the framework of the IRD collective assessment on the deep-sea knowledge and governance, and question the representation of the deep seabed as a mineral resource Eldorado.

How to cite: Collot, J., Geronimi, V., Roest, W., Samadi, S., Goutte, S., Olu, K., Muni Toke, V., Barberousse, A., and Lemeur, P.-Y.: Deep sea mineral resources: a true Eldorado? Geological, biological and economic cross-perspectives, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-1239, https://doi.org/10.5194/oos2025-1239, 2025.

Posters virtual | online

Display time: Tue, 3 Jun, 17:00–Thu, 5 Jun, 20:00

vP91

OOS2025-134

Assessing Significant Adverse Impacts on Deep-Sea Vulnerable Marine Ecosystems in the NAFO Regulatory Area.

Andrew Kenny, Pierre Pepin, Ellen Kenchington, James Bell, Anna Downie, Mariano Koen-Alonso, Camille Lirette, Barbara Neves, Javier Murillo, Mar Sacau, Susanna Fuller, and Daniela Diz

Biodiversity loss due to human activities is a critical ecological challenge, particularly in the High Seas where bottom-contact fishing poses a significant threat to Vulnerable Marine Ecosystems (VMEs). These ecosystems, composed of slow-growing, long-lived benthic organisms like deep-sea corals and sponges, are often found in geomorphological features such as seamounts and canyons. The United Nations General Assembly and the Food and Agriculture Organization (FAO) have developed guidelines to protect these ecosystems from Significant Adverse Impacts (SAI) caused by bottom trawling activities.

This study focuses on the Northwest Atlantic Fisheries Organization (NAFO) area, utilizing fishery-independent surveys and Vessel Monitoring System (VMS) data to map fishing intensity and VME biomass. Seven VME functional types were identified: large-sized sponges, sea pens, sea-squirts, bryozoans, black corals, large and small gorgonian corals. Species data were analysed using Kernel Density Estimation (KDE) to model the spatial distribution of VME biomass and to assess SAI risk.

Of the VMEs assessed, results indicate that large sponge, black coral, and large gorgonian VME are the most sensitive to bottom trawling activities, with significant biomass loss occurring at very low fishing intensities. The study proposes impact thresholds for each VME functional type and argues that modest reductions in fishing effort in sensitive areas could mitigate SAI whilst having little or no impact on fishing opportunities. The findings emphasize the importance of spatial fisheries management measures, such as defining fishing footprints and establishing closed areas, to protect VMEs, to ensure the long-term sustainability of deep-sea ecosystem functions and diversity.

The proposed impact thresholds provide a quantitative basis for assessing SAI and support ecosystem-based fisheries management. The research underscores the need for integrated assessments and data-driven approaches to balance ecosystem and fisheries sustainability objectives.

How to cite: Kenny, A., Pepin, P., Kenchington, E., Bell, J., Downie, A., Koen-Alonso, M., Lirette, C., Neves, B., Murillo, J., Sacau, M., Fuller, S., and Diz, D.: Assessing Significant Adverse Impacts on Deep-Sea Vulnerable Marine Ecosystems in the NAFO Regulatory Area., One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-134, https://doi.org/10.5194/oos2025-134, 2025.

Discussion Post a comment

vP92

OOS2025-237

ECOP

Marine Global Commons Renewable Energy? International Law for a Sustainable Deep Ocean

Violeta Radovich

The presentation aims to study the current regulation and governance of renewable energy platoforms installation on the high seas, and therefore in the Area. The Area is the legal denomination that UNCLOS (United Nations Convention on the Law of the Sea) confers to the deep ocean. The high seas and the Area are marine areas beyond State jurisdiction, or marine global commons. The high seas are mainly those waters outside of the 200 nautical mile Exclusive Economic Zone (EEZ) (UNCLOS, art. 86). The Area includes the seabed and ocean floor and subsoil thereof, beyond the limits of national jurisdiction (UNCLOS, art. 1.1.). Technological advances currently allow that renewable energy platforms, such as wind turbines, be installed on the high seas. If renewable energy platforms are installed on the high seas, they will be attached to the deep ocean floor, or in legal terms, the Area; even if they are mobile or fixed platforms (Herrera Anchustegui & RadovIch, 2022).

This study will contribute to detect regulatory challenges concerning sustainable renewable energy generation in marine global commons. Will the generation of renewable energy in marine global commnos be sustainable and therefore, will it start taking place? Is currently any international autority vested with the power to grant authorizations for the installation of these platforms in marine global commons? The International Seabed Authority (ISA) was established under UNCLOS to administer the mineral resources of the Area. The Area has been declared common heritage of humankind by UNCLOS. However, ISA has no authority to grant permits to install these platforms on the high seas (Herrera Anchustegui & Radovich, 2022).

Is this topic regulated in the recently adopted Agreement on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction (BBNJ Agreement) to UNCLOS? If the BBNJ Agreement enters into force, is it possible that its Conference of the Parties (COP) establishes an authority vested with this power?

The BBNJ Agreement has included for the first time in the history of the law of the sea indigenous peoples and local communities (IPLC’s) knowledge. Neither UNCLOS nor ISA regulations refer to IPLC’s. In what ways does the BBNJ include IPLC's knowledge? May IPLC's knowledge contribute to the regulation of renewable energy generation on marine global commons if the BBNJ enters into force? Does the BBNJ introduce a space of co-creation of knowledge?

How can international law address the environmental, social and economic impacts arising from deep-ocean activities related to the generation of renewable energy? Such as impacts to marine animals and ecosystems (Garthe et al, 2023) and equity in granting these permits.

References:

Garthe S, Schwemmer H, Peschko V, Markones N, Müller S, Schwemmer P, Mercker M. Large-scale effects of offshore wind farms on seabirds of high conservation concern. Sci Rep. 2023 Apr 13;13(1):4779. doi: 10.1038/s41598-

Herrera Anchustegui, I., & Radovich, V. (2022). Wind energy on the High Seas: Regulatory challenges for a science fiction future. Energies 15 (23), 9157.https://doi.org/10.3390/en15239157

How to cite: Radovich, V.: Marine Global Commons Renewable Energy? International Law for a Sustainable Deep Ocean, One Ocean Science Congress 2025, Nice, France, 3–6 Jun 2025, OOS2025-237, https://doi.org/10.5194/oos2025-237, 2025.