Rising global temperatures pose significant risks to marine ecosystems, biodiversity, and fisheries. Recent comprehensive assessments suggest that large-scale mitigation efforts to limit warming are falling short, and all feasible future climate projections, including those that represent optimistic emissions reductions, exceed the Paris Agreement's 1.5°C or 2° warming targets during this century. While avoiding further CO 2 emissions remains the most effective way to prevent environmental destabilization, interest is growing in climate interventions—deliberate, large-scale manipulations of the environment aimed at reducing global warming. These include carbon dioxide removal (CDR) to reduce atmospheric CO 2 concentrations over time, and solar radiation modification (SRM), which reflects sunlight to lower surface temperatures but does not address root CO 2 causes. The effects of these interventions on marine ecosystems, both direct and in combination with ongoing climate change, remain highly uncertain. Given the ocean's central role in regulating Earth's climate and supporting global food security, understanding these potential effects is crucial. This review provides an overview of proposed intervention methodologies for marine CDR and SRM and outlines the potential trade-offs and knowledge gaps associated with their impacts on marine ecosystems. Climate interventions have the potential to reduce warming-driven impacts, but could also alter marine food systems, biodiversity and ecosystem function. Effects will vary by pathway, scale, and regional context. Pathway-specific impact assessments are thus crucial to quantify trade-offs between plausible intervention scenarios as well as to identify their expected impacts on marine ecosystems in order to prioritize scaling efforts for low-risk pathways and avoid high-risk scenarios.

Historical baselines are essential for evaluating the cumulative impacts on modern marine ecosystems, particularly in regions such as the Mediterranean, where human activities have been intensive for millennia, and climate change is accelerating. However, quantitative evidence of historical impacts remains fragmented. In this study, we investigate changes in the presence, abundance and body size (BS) of the Atlantic bluefin tuna (Thunnus thynnus), gilthead sea bream (Sparus aurata), banded-dye murex (Hexaplex trunculus) and turbinate monodont (Phorcus turbinatus) across the Mediterranean Sea from 130 000 years Before Present until the Industrial Revolution (1850 ad), using geological, archaeological, and historical records. Our results reveal significant temporal shifts in the abundance and BS of the banded-dye murex, Atlantic bluefin tuna, and gilthead sea bream. Environmental factors, particularly seawater temperature, were the primary drivers of abundance and size in Atlantic bluefin tuna in the past. Human activities, especially exploitation, influenced the abundance of banded-dye murex and Atlantic bluefin tuna, as well as the BS of gilthead sea bream. These findings underscore the importance of integrating long-term ecological data to understand better the interplay between climate, human pressures, and ecosystem dynamics.

The Western Mediterranean Sea is a region of high biodiversity and cultural heritage that is subject to significant cumulative pressures, such as fishing, shipping, invasive species, coastal development, and climate change. Effective marine management requires comprehensive assessments of cumulative pressures and their effect on environmental status. This study presents the first integrated assessment of the environmental status of the Western Mediterranean Sea using the Nested Environmental status Assessment Tool (NEAT) within the context of the European Union's Marine Strategy Framework Directive (MSFD). Combining an extensive amount of data, modelled and measured, from various sources including open databases and scientific literature, this assessment utilized a comprehensive set of 755 indicator values, covering four MSFD descriptors and 14 ecosystem components. Two distinct assessment methods were employed: a standard NEAT application, and an assessment adapting NEAT to the MSFD's hierarchical criteria structure. The results consistently showed that the Western Mediterranean does not achieve Good Environmental Status (GES) on a basin-wide scale, with non-GES across all sub-regions. The degraded conditions of several ecosystem components, specifically those associated with seafloor integrity and biodiversity, were the primary drivers of this status. While the current assessment is not completely aligned with the MSFD framework, it represents a critical step towards a standardized methodology for evaluating marine environmental status and implementing Ecosystem-Based Management (EBM) in the Western Mediterranean Sea.

Species distribution models (SDMs) are one of the most common statistical methods to assess species occupancy and geographic distribution patterns. With the increasing complexity of ecological data, many methodological approaches have been developed, often accessible through command-line interfaces or graphical user interfaces (GUIs). However, few species distribution modeling tools are designed to be well-documented, user-friendly, flexible, and reproducible. Here we introduce GLOSSA, an open-source R package and Shiny app designed for species distribution modeling using species occurrence and environmental data. GLOSSA's user-friendly interface guides users through steps including data uploading, processing, model fitting, spatial and temporal projections, and interactive visualization of results. The app also calculates variable importance, generates response curves with environmental variables, and performs cross-validation. At its core, GLOSSA modeling approach is based on Bayesian Additive Regression Trees (BART), an innovative machine learning method. We present the functionality and versatility of GLOSSA through three case studies, addressing a range of ecological scenarios at regional and global scales. Along with comprehensive documentation, examples, and tutorials, these case studies illustrate how an intuitive graphical interface can make species distribution modeling accessible to a broad audience. GLOSSA stands out as an easy-to-use tool for species distribution modeling, providing an intuitive interface, detailed documentation, flexible modeling, and interactive result exploration and export options. Additionally, its outputs can be used directly to inform marine ecosystem models (MEMs), enhancing its utility in ecological research and applications.

We investigated ecosystem impacts of marine heatwaves (MHWs) in the Western Mediterranean Sea using a spatially explicit Ecopath with Ecosim (EwE) food web modelling framework. This model is forced with temperature time series, including or excluding MHWs, and simulates biomass dynamics through trophic interactions and energy flows. Our simulations suggest that declining biomass trends observed over the past decades in the Western Mediterranean, driven by long-term ocean warming and fishing pressure, have been exacerbated by the occurrence of MHWs. A north–south dipole in biomass rate of change emerged in response to MHWs: while the northern region displayed positive or neutral responses due to MHWs, the south, particularly the Alboran and Algerian seas, experienced negative impacts. Benthic producers and commercially important species (pelagic and demersal fish and invertebrates) were particularly affected, leading to catch reductions exceeding 10%. We identify previously unreported vulnerable groups and regions, supporting the use of ecosystem models in guiding adaptive management for the future. The increase in intensity and extension of MHWs with time suggests that larger effects may be expected in the future.

The Sahelian upwelling supports highly productive fisheries and is vital for food security in Western Africa. Previous studies have shown an influence of El Niño − Southern Oscillation (ENSO) on the abundance of several species in the region. With recently released Fisheries and Marine Ecosystem Model Intercomparison Project (FishMIP) simulations, a global-scale analysis of climate-driven teleconnections and their cascading effects across the Sahelian trophic web is now possible. In this study, seasonal to multi-annual predictability of Sahelian Upwelling marine ecosystem productivity was assessed applying data-driven methods on different climatic sources. These include an atmospheric reanalysis (NCEP) and oceanic biogeochemical retrospective simulations (GFDL-COBALT and ECE-Recon-ORAS4) for the (available) period 1971–2005, together with a FishMIP global marine ecosystem simulation (EcoOcean v1). Leave-one-out cross-validated hindcasts based on Maximum Covariance Analysis revealed a key role of Atlantic and Pacific Niños/Niñas as predecessors of February to May enhanced marine primary productivity and subsequent pelagic fisheries in the Sahelian Upwelling, where a bottom-up physical-biological mechanism was identified. The observed delay of up to 2-yr between climatic triggers and marine ecosystem responses provides a useful first step for marine ecosystem prediction in the area. These insights could inform sustainable fisheries management practices, ensuring the resilience of local communities dependent on these resources for food security and economic stability.

Human activities exert increasing pressure on the northwestern Mediterranean Sea, a region of high ecological and socio-economic importance. In this context, it is crucial to assess which activities contribute most to ecological risk in order to inform management options within an Ecosystem-Based Management (EBM) framework. This study applies the Spatial Cumulative Assessment of Impact Risk for Management (SCAIRM) method to assess cumulative impact risks arising from multiple activities and pressures to identify priority activities and ecosystem components for maritime management and spatial planning. SCAIRM explicitly links activities, pressures, and ecosystem components while accounting for their spatial distribution. This study provides the first comprehensive quantitative assessment of cumulative ecological risk in the northwestern Mediterranean. The results indicate that fishing is the dominant contributor to cumulative impact risk in the region (51%), with bottom trawling representing the most significant activity, followed by tourism-related maritime traffic and coastal development (18%). At the same time, we quantified their contribution over the main ecosystem components. Demersal communities, circalittoral habitats, and seagrass beds exhibited the highest levels of risk. Findings complete partial existing literature, providing a holistic systematic approach to marine risk assessment supporting the achievement of marine Good Environmental Status in the study region.

Despite the potential of functional traits for mediating ecological responses to environmental perturbations, they are rarely incorporated into Species Distribution Models (SDMs). Furthermore, complex ecological data often exhibit spatial autocorrelation, which, if ignored, can reduce model power and compromise robustness. Here, we present a hierarchical spatiotemporal Bayesian framework that incorporates trait-environmental relationships and explicitly accounts for spatial autocorrelation through the implementation of Integrated Nested Laplace Approximation (INLA) and Stochastic Partial Differential Equations (SPDE). We applied this framework to four case studies to examine how trait-based and, spatially explicit approaches affect single- and multi-species models. In both scenarios, we tested the hypothesis that incorporating functional traits (body size) and accounting for spatial autocorrelation improves model performance using simulations, and we reinforced these findings with empirical analyses of a single species, the European hake (Merluccius merluccius), and a multispecies approach using the Iberian demersal fish assemblages. In all cases, incorporating body size as a functional trait strengthened ecological interpretation of species responses. Moreover, explicit spatial models outperformed non-explicit spatial models, highlighting the importance of accounting for spatial autocorrelation. Results revealed a consistent relationship between body size and thermal sensitivity, with larger-bodied species showing stronger responses in their distributions to temperature gradients. The results underscore the importance of incorporating traits into spatial SDMs to account for both intraspecific and interspecific distribution variations, improve ecological understanding, and boost predictive accuracy. Our trait-based SDM framework provides a scalable, interpretable, and ecologically grounded tool to support population and biodiversity predictions and conservation planning under global change.

ABSTRACT Aim To identify and map Priority Penguin Habitat Areas (PPHAs), defined as marine regions that are environmentally suitable for penguins under present and future climates, in order to inform climate‐smart conservation planning across Southern Hemisphere. Location Marine realms of the Southern Hemisphere. Methods We modelled occurrence data for 12 of the 21 currently recognised penguin species using a Bayesian joint species distribution framework to estimate present and future suitable habitats under two contrasting climate scenarios (SSP1‐2.6, low forcing; SSP5‐8.5, high forcing). We quantified species‐level expansions and contractions in suitable habitat, then integrated these projections into a systematic conservation planning optimisation framework to delineate present and future PPHAs and to assess their spatial overlap with existing (implemented and proposed) Marine Protected Areas (MPAs). Results Most species (King, Southern Rockhopper, Macaroni, Snares, Chinstrap, Gentoo, Yellow‐eyed and Magellanic penguins) are projected to gain environmentally suitable habitat, whereas Emperor, Fiordland, Little and Adélie penguins show marked contractions and, in some scenarios, complete loss of optimal conditions. Consistent with a homogenization of habitat suitability for the expanding species, PPHAs increase in extent and cluster in established sub‐Antarctic and temperate hotspots. Despite this expansion, current MPA coverage of PPHAs is low and is projected to decline further under both climate scenarios. Main Conclusions Climate‐driven shifts in penguin habitats will alter the spatial configuration and protection needs of PPHAs across the Southern Hemisphere. Our approach provides a transferable blueprint to align conservation priorities with expected climate trajectories, enabling proactive MPA design and coordinated transboundary actions to safeguard PPHAs before they are irreversibly lost.

ABSTRACT Aim To quantify temporal (Middle Holocene, historical and future) and spatial changes in habitat suitability for marine species in two South American Large Marine Ecosystems, and to evaluate the ecological consistency of long‐term Species Distribution Model projections using archaeological records as independent evidence of past species occurrences. Location Humboldt Current and Patagonian Shelf Large Marine Ecosystems (LMEs). Time Period Middle Holocene (~8200–4200 years BP), present day (1850–2014), and a projected future warming scenario (2015–2099; SSP5‐8.5). Major Taxa Studied Marine fish, penguins and pinnipeds. Methods SDMs were developed for nine marine species using present‐day occurrence records and contemporary environmental predictors. Models were projected to Middle Holocene climatic conditions and to a future high‐emissions scenario. Archaeological records of fish, penguins and pinnipeds from the Middle Holocene were compiled and used as proxies for past species occurrences to evaluate model projections through time. Results Bathymetry emerged as a key predictor of habitat suitability for most species. Projections revealed pronounced temporal and spatial shifts in suitable habitat. Most fish species showed higher suitability at higher latitudes during the Middle Holocene, followed by contractions in the historical period and future projection. Penguin species exhibited heterogeneous responses, with several showing strong declines in future suitable habitat. Pinniped species displayed mixed patterns of contraction and expansion depending on region and time period. Comparison with archaeological records indicated that seven of the nine SDMs correctly identified suitable habitats consistent with Middle Holocene occurrences. Main Conclusions Zooarchaeological data provide an independent line of evidence to assess the temporal robustness of marine SDMs. Incorporating past climatic periods improves confidence in long‐term biogeographical projections and enhances understanding of species' distributional dynamics under climate change.

Significant declines in biomass, as well as changes in body condition, life-history traits, and diet of key pelagic species (European anchovy, Engraulis encrasicolus, and European sardine, Sardina pilchardus) have been observed over recent decades in the western Mediterranean coast of the Iberian Peninsula. In parallel, population changes have been recorded in one of their main predators, European hake (Merluccius merluccius). These changes, together with the social-economic importance of the area, highlight the need to better understand the food-web dynamics and trophic interactions. Stable isotopes of nitrogen (δ15N) and carbon (δ13C) are commonly used as proxies for trophic interactions in the marine environment. Georeferenced stable isotope data have increasingly been used to generate isoscapes, which provide spatially explicit information on isotopic variability. We assess the spatial variability of stable isotope compositions for anchovy, sardine, and hake across the latitudinal gradient of the western Mediterranean Sea. We analyse their variations in relation to static (depth) and dynamic (chlorophyll-a, and temperature) oceanographic variables. We also test whether latitudinal patterns in stable isotope ratios are consistent among the three species. Our results show a north-to-south gradient in δ15N and δ13C for all three species, as well as a distinct isotopic pattern in the surroundings of the Ebro Delta shelf. The structural similarity index between isoscapes indicates a notable spatial correspondence among the three species, suggesting a shared latitudinal variability in isotope values. Overall, we highlight how isoscapes can provide valuable insights into spatial structuring of food-web dynamics, isotopic baselines, and the environmental factors influencing these processes in the western Mediterranean Sea.

Food webs illustrate the complex interactions among organisms in ecosystems, crucial for understanding energy and material flows. However, building accurate food webs is challenging due to ecological complexity and data demands. FoodwebAI, a user-friendly web application, addresses this by using AI, specifically OpenAI's GPT models via the ellmer R package, to enrich species lists with metadata and generate food webs from taxa lists alone. The application offers three functional modules: an AI-powered Food Web Creation module that generates trophic structure from a species list alone; an Ecopath module that allows users to visualize and augment food webs exported from Ecopath with Ecosim, including AI-generated icons for nodes; and a Manual module for exploratory food web construction. While still experimental, FoodwebAI demonstrates how AI can support ecological research by improving data accessibility and understanding of complex networks. The app is available at https://foodwebai.shinyapps.io/foodweb under a General Public License (GPLv3).

Understanding the trophic ecology of marine megafauna is essential for elucidating their ecological roles and supporting effective conservation strategies. The ocean sunfish (Mola mola) is the second-largest bony fish worldwide and has a broad distribution, including the Mediterranean Sea. Despite its size and widespread occurrence, many aspects of its biology remain poorly understood. Traditionally regarded as an obligate feeder on gelatinous zooplankton, recent evidence instead points to a more generalist feeding strategy. Here, we applied a multi-method approach integrating stomach content analysis, DNA metabarcoding, and stable isotope analysis to investigate the feeding ecology of ocean sunfish in the western Mediterranean Sea. Our results revealed that, indeed, ocean sunfish mainly consume gelatinous zooplankton, particularly siphonophores such as Chelophyes appendiculata. However, substantial arthropod, mollusc and chordate contributions were also detected by molecular or observational methods, suggesting a more generalist diet. Stable isotope analysis showed high δ15N values compared to other sympatric marine predators reported in the literature, while δ13C values showed that ocean sunfish feed extensively in oceanic/pelagic environments. Our results suggest that ocean sunfish in the western Mediterranean Sea occupy an intermediate trophic position but are isotopically segregated from other sympatric marine predators, reflecting a distinct trophic niche. Our integrated approach shows that ocean sunfish play an important role as intermediate predators, facilitating energy transfer from low pelagic trophic levels to higher-level predators, and potentially contributing to the regulation of gelatinous plankton populations.

In response to alarming declines in biodiversity around the globe, policies have been created to support interventions such as Nature-based Solutions (NbS) for marine protection and restoration, and ecosystem-based management to increase the sustainability of fisheries yields. Projections from mechanistic models of marine socio-ecological systems may be of use to demonstrate the potential effectiveness of these interventions and inform decision-makers on effective strategies. As a starting point, we created a set of regionalized scenarios on marine restoration (NbS1), marine protected areas (NbS2), and nature-inclusive harvesting (NiH) of seafood that incorporates the Ecosystem Approach to Fisheries Management within European regional seas. Our scenarios were based on the IPCC Shared Socio-economic Pathways (SSP) narratives developed for global projections of climate change. Those narratives were enriched by defining PESTLE (political, economic, social, technological, legal, environmental) elements associated with each of the three interventions. This matrix of 3 SSPs x 6 PESTLE elements x 3 interventions (NbS & NiH) was downscaled using stakeholder dialog in seven European regional seas or sub-areas. The rationale for using a common PESTLE framework was to enable cross-system comparisons of common narratives. Downscaling to specific regions allowed us to include elements of key interest to environmental managers from each region tasked with implementing NbS and NiH to meet obligations of the EU Biodiversity Strategy for habitat protection, the EU Nature Restoration Regulation or other national environmental policy objectives.

Marine ecosystems are increasingly threatened by multiple anthropogenic pressures, leading to biodiversity loss, habitats degradation and resources deterioration. To address these challenges, international and regional policy frameworks have established conservation targets. Ecologically or Biologically Significant Marine Areas (EBSAs), designated by the Convention on Biological Diversity based on multiple criteria, can guide spatial conservation and play a vital role in maintaining ocean health. In this study, we provide a quantitative, systematic approach to refine existing EBSAs within the Western Mediterranean Sea via spatially explicit proxies for the internationally agreed protection criteria. Spatial prioritization was conducted and included environmental stability to account for ecological resilience under climate change. Our results reveal a pronounced spatial imbalance in the representation of EBSA criteria within internationally agreed protection schemes (Natura2000 sites, Ramsar sites, Specially Protected Areas of Mediterranean Importance and proposed Sites of Community Importance), ranging from 2.2 % to 63.9 %, providing relevant information for the study area. There is a marked bias toward the northern part of the basin, with current EBSAs covering 47 % of the study area, while existing protected spatial features correspond to 19.7 % of the study area. This spatial bias may undermine the effectiveness of marine biodiversity conservation and highlights the need for more equitable and data-driven spatial planning approaches. By redefining existing EBSAs and evaluating their alignment with internationally agreed protection schemes, our work provides a scientific basis to inform future conservation strategies and support the development of ecologically coherent transnational networks of protected areas aligned with global and regional goals.

Marine protected areas (MPAs) are used for biodiversity conservation and Parties to the Convention on Biological Diversity agreed to use them together with other effective area-based conservation measures to protect 30 % of the ocean by 2030. Scientific evidence shows that most positive outcomes are dependent on full protection, where all extractive activities are banned. Yet, most of what is being protected is under partial protection, with often heterogeneous levels of protection. Here, we assess the protection level based on fishing regulations of 27 Spanish Mediterranean nationally and regionally designated MPAs and identify the fishing gears allowed within the partially protected areas. The level of protection from fishing is assigned based on the number of allowed fishing gears within MPA borders and their potential ecological impact. Approximately 0.8 % of the total area of the Spanish Mediterranean Sea is covered by the included MPAs, of which 63 % is incompatible with the conservation of nature and 7 % is fully or highly protected. Our results show that the composition of allowed gears varies across partially protected areas within the same level of protection (i.e. lightly protected areas) and regions. Including the reasoning behind specific gear restrictions on fishing regulations that apply to each MPA could help to understand the context of each MPA, and improve MPA effectiveness. Our study contributes to illustrate the suboptimal current situation of marine protection in the Spanish Mediterranean Sea and the need to increase effective protection efforts to achieve area-based conservation targets.

In the context of nature conservation, a nexus can be defined as the interlinkages of biodiversity in protected and conserved areas with food, water, health, or climate. Evidence of nature conservation expansion scenarios suggest that such interlinkages are ubiquitous across management types, realms, and scales. Ignoring these interlinkages, including synergies, co-benefits, leakages, and trade-offs, can reduce the effectiveness and cross-sectoral benefits of future protected and conserved area expansions. Integrated planning that is inclusive of different value and knowledge systems can help to bridge disciplines and mitigate severe trade-offs impacting effectiveness of these areas. To enable appropriate expansion of protected and conserved areas to 30% of land and sea by 2030, identifying and including such interlinkages in spatial planning is essential.