Marine ecosystems are facing unprecedented pressure from escalating human activities – overfishing, pollution, habitat destruction – compounded by the accelerating impacts of climate change. These combined stressors are driving rapid biodiversity loss and ecosystem degradation, creating an urgent need not only to halt further damage but to actively restore and regenerate marine environments. In response, the UN 2030 Agenda has set an ambitious target: to protect at least 30% of the ocean by 2030.
A significant challenge, however, is that many existing Marine Protected Areas (MPAs) do not ensure effective conservation. The urgent need to rethink, improve and develop alternative marine conservation strategies forms the focus of the research carried out by Julián Esteban-Cantillo, BIOcean5D PhD student at the CNRS-Institut Jean Nicod.
“Historically, conservation frameworks were primarily developed in terrestrial environments,” explains Julián. “These strategies were designed to restrict certain activities within geographically defined areas with fixed boundaries to protect flora and fauna.” Although there is broad agreement that conservation should be grounded in ecosystem-specific knowledge, terrestrial models were transferred to marine environments for several reasons: their demonstrated effectiveness on land, perceived similarities between terrestrial and marine ecosystems and their compatibility with geopolitical territorial divisions.
Yet marine ecosystems differ fundamentally from terrestrial ones. “Our analysis of area-based marine conservation strategies within international frameworks revealed that most MPAs are static – both spatially (with fixed geographical boundaries) and temporally (with protection defined by a set number of years rather than according to ecological processes),” explains Julián. “This static paradigm fails to capture the fluid and dynamic nature of the ocean, which is constantly evolving and is characterised by shifting habitats and highly mobile species.”
While some dynamic approaches exist, all are temporally dynamic – adjusting protection during specific periods such as breeding or feeding seasons. Spatially dynamic conservation – where boundaries shift, changing the shape and size of the protected area, in response to ecosystem processes and needs – remains theoretical.
Presentation of the policy brief ‘Dynamic Ocean, Dynamic Solutions: New multi-disciplinary approaches for marine conservation tools’ at the 2024 UNCBD COP16, Cali by Julián Esteban-Cantillo with co-authors Umer Gurchani, André Abreu and Eva Wanek. Credit: Julián Esteban-Cantillo.
BIOcean5D is dedicated to exploring marine life and how it changes across space, time and human impact. “I’ve applied this five-dimensional perspective to propose alternatives that move from area-based to ecosystem-based conservation approaches, aiming to ensure more effective protection of marine ecosystems,” explains Julián.
Together with colleagues, Julián synthesised existing research into ten key recommendations to improve current conservation strategies, addressing issues such as boundaries that fail to align with habitat distribution or protect highly mobile species – a major limitation of many MPAs.
Read more soon in ‘Marine Conservation Strategies: A review of the effectiveness of current approaches alongside drivers of ecosystem and biodiversity loss’, submitted to Biological Reviews
The argument for integrating dynamic approaches into marine conservation was developed – together with six policy recommendations aligned with specific objectives of the CBD’s Kumming-Montreal conservation framework – in the article by Julián and co-authors:
Oscar Julián Esteban-Cantillo, et al., 2025. Six key policy recommendations to advocate for marine conservation that matches the ocean’s dynamism, npj Ocean Sustainability
Recognising the ocean as a dynamic entity also requires a conceptual shift from current frameworks that define marine areas according to their spatial extent at the surface level (Exclusive Economic Zones, EEZ). Julián and co-authors propose instead a volumetric perspective, introducing the concept of Exclusive Economic Volumes (EEV).
Read more soon in ‘Volumetric Analysis of maritime areas under national jurisdiction to introduce Exclusive Economic Volumes’, submitted to Ocean & Coastal Management
Another research strand (highlighted in our article here) explores the often-overlooked economic value and ecosystem services provided by plankton, proposing them as an additional metric to assess the necessity and effectiveness of MPAs.
Read more in Eva Wanek, et al., 2025. Valuing marine plankton: a review of ecosystem services and disservices and an expert assessment of the potential of area-based protection, Frontiers in Marine Science
Presentations of BIOcean5D research by Julián Esteban-Cantillo and Roberto Casati at La Baleine area of the One Ocean Science Congress (OOSC), 3-6 June 2025 in Nice, France. Credit: Julián Esteban-Cantillo.
Marine conservation is inherently complex, requiring multidisciplinary knowledge, understanding and insights from climatology, oceanography, marine ecology, physics, mathematics and chemistry, as well as from the humanities and social sciences, including economics and political science. “Carrying out my PhD within BIOcean5D – which brings together 31 partners across 11 countries – has provided the opportunity to engage with individuals from leading academic and research institutions across Europe,” says Julián. “This collaborative, multidisciplinary environment has enabled meaningful exchanges of complementary expertise, broadened my research perspective and significantly shaped the development of my work.”
According to Julián, this experience has been further enriched by being based at the CNRS-Institut Jean Nicod, where an interdisciplinary environment bridges science and the humanities. “Working in such an environment has transformed my perception of science,” says Julián. “Discussions about ocean-related issues that combine multiple disciplinary angles and the exchange of complementary knowledge and expertise allows for a far more comprehensive understanding and conceptualisation of the ocean, opening up new pathways for research and the development of ideas.”
Professionally, marine conservation is often framed as either generating scientific knowledge to inform decision-makers or applying scientific understanding as a decision-maker to ensure evidence-based policy. “My PhD, carried out in such a multidisciplinary context, has shown me that these roles are not mutually exclusive. It’s possible to be both: a scientist and a decision maker,” explains Julián. “I hope to continue working at this interface, ensuring the best available science informs the design and implementation of MPAs that are socially equitable, environmentally effective, and economically sound.”
Three policy briefs outlining recommendations for ocean governance processes were developed within the framework of BIOcean5D, in collaboration with project partners. The launch and promotion of each brief were strategically aligned with major high-level international events, as described in the BIOcean5D Policy Strategy Plan:
BIOcean5D is now working to actively integrate these newly developed approaches into three key ocean policy frameworks related to marine conservation: the High Seas Treaty (BBNJ), the Kunming-Montreal Global Biodiversity Framework (KMGBF) and the Blue NDC Challenge (UNFCCC). “Providing insights and a strong conceptual foundation for innovation in marine conservation will be crucial for developing tools capable of addressing the scientific and technical challenges involved in protecting the High Seas and the ocean ecosystem as a whole,” resumes André Abreu, Head of International Policy at Tara Ocean Foundation.