To manage and protect marine ecosystems, we first need a spatialised knowledge of the seascape-scale processes surrounding them. However, we lack spatially explicit understanding of how regional processes influence biological patterns in many marine systems. This is especially true of remote marine ecosystems, such as those in the deep sea. Here, we conceptualise potential seascape-scale environmental influences on deep-sea hydrothermal vent ecosystems, guided by experts and literature. We propose environmental characteristics that may shape local biodiversity patterns, such as community structure, habitat availability, and temporal stability. Next, we develop pipelines from data extraction to analysis to improve spatial data accessibility and investigate which variables can be used to draw similarities among vent fields. Finally, we group vents from different regions according to shared environmental characteristics. We show that vents that are spatially isolated and have different species pools can share similar environmental characteristics across ocean basins, including geological, oceanographic, and biological dynamics. We thus illustrate how large-scale environmental data can be used to compare seascape attributes across remote, island-like vent ecosystems. We suggest that looking beyond local scales to consider how seascapes both influence and distinguish different vent systems within a global setting is important for conservation and macroecological contexts.

Hydrothermal vent fields harbour a heterogeneous seascape owing to complex topography and vent fluid emissions, including in peripheral areas beyond active venting. At the Lucky Strike hydrothermal vent field, a remotely operated vehicle was used to acquire two hectares of seabed imagery to evaluate the role of environmental conditions on the structure and distribution of benthic communities. Our analyses revealed that large and mature edifices are potential keystone structures supporting hotspots of vent specialists (e.g., Bathymodiolus azoricus) and associated fauna (e.g., Zoanthidae). Higher densities of mobile bathyal shrimps were found in slabs adjacent to active venting areas. Communities occupying areas with lower hydrothermal exposure displayed significantly higher diversity than areas located closer (≤ 40 m) to vent emissions. Between 40 and 120 m from active sites, community diversity was greatest on hard substrata dominated by sessile organisms—such as octocorals, Cladorhizid and Hexactinellid sponges—in greater densities when these substrates were composed of basalt with complex topography. While the gradient in hydrothermal exposure creates a spatial zonation of benthic communities, abundance and diversity patterns remain locally conditioned by seabed topography and substratum hardness. This interplay fosters a patchwork of faunal communities at the decametre scale. These results underscore the complexity of designing surveys encompassing the diversity of habitat conditions within the deep hydrothermal seascape. Although historically overlooked, the diversity of distinct benthic communities beyond venting zones emphasises the ecological significance and vulnerability of areas that could be targeted by mining.

Deep-sea hydrothermal vents are highly dynamic ecosystems characterized by extreme physicochemical conditions and spatially patchy, transient habitats. Vent-associated organisms must therefore maintain population persistence through flexible life-history and reproductive strategies. This study examined the population structure and reproductive biology of the hydrothermal vent limpet Lepetodrilus atlanticus from the Menez Gwen vent field on the Mid-Atlantic Ridge (37° 50′ 30″ N, 31° 31′ 30″ W; 814 m depth), based on samples collected in July 2023 and May 2025. Population structure was analysed using size–frequency distributions, sex ratios, and non-parametric comparisons between years and sexes, while reproductive biology was assessed through histological analyses of gonadal development, oocyte size-frequency distributions, and fecundity. Length–frequency distributions were unimodal and positively skewed, indicative of continuous recruitment. Significant interannual differences in curvilinear shell length were detected, reflecting a shift toward smaller individuals in 2025, whereas differences between sexes were minimal. Oocyte size distributions exhibited a stable bimodal pattern in both years, with pre-vitellogenic oocytes dominating the oocyte pool and consistent with asynchronous gametogenesis and continuous reproductive activity. Mean fecundity did not differ significantly between years but increased strongly with female body size. Together, these findings indicate that L. atlanticus maintains population persistence through continuous recruitment, asynchronous gametogenesis, and size-dependent reproductive investment, with females reaching reproductive maturity earlier than males. These traits are well suited to the highly variable and unstable environmental conditions characteristic of hydrothermal vent ecosystems.

Deep-sea hydrothermal vents form small, unique, and fragile ecosystems that are widely recognized as sites in need of protection. Deep-seabed mining (DSM) is a future threat to hydrothermal ecosystem integrity. In most areas within, and in all areas beyond national jurisdiction, currently proposed protection measures from DSM are unlikely to be sufficient, as only the known active venting sites on the seafloor are intended to be protected from DSM impacts. To ensure effective protection, we propose protecting not only the active vent sites but the entire hydrothermal ecosystems and their transition zones, embracing the seafloor, subseafloor and overlying water column. We discuss how ecological knowledge supports the proposed three-dimensional (3-D) protection. We suggest no DSM extraction or indirect impacts on the seafloor and entire subseafloor within a minimum 50 km diameter (25 km radius) around visible active vents. This will ensure the maintenance of subseafloor connections that are key for ecosystem integrity, as changes in vent fluid conditions can alter all ecosystem functions and services linked to venting activity. In the water column, protection from pollution from the seafloor to surface is suggested to protect vent larvae. This extent spans the entire length of ridges or back-arc basins, with a crossaxial extent of 80 km. We further discuss how international law can contribute to the effective protection of vent ecosystems and transition zones in international waters, and provide guidance for coastal States to safeguard these ecosystems and transition zones within their own maritime areas.

Crypthelia Milne-Edwards Haime, 1849 is the most diverse genus of lace corals inhabiting the Azores. During the 2012 DEEPFUN cruise, the first coral garden structured by this genus was recorded in the Menez Gwen Marine Protected Area (MPA). Identification of the species was based on morphology of specimens collected in situ and characterized using scanning electron microscopy (SEM). Imagery acquired by the remotely operated vehicle (ROV) Victor 6000 was used to document the species density as well as seabed geomorphology. The stylasterid Crypthelia vascomarquesi Zibrowius Cairns, 1992 is described for the first time based on entire specimens, including female representatives. To date, this is the only Crypthelia species with female efferent pores located on dactylostomes, adding a new category to the feminine ampullar formula developed for the genus. The dense coral garden formed by C. vascomarquesi was recorded between 832 and 856 m depth at 37°48.896′N; 31°33.774′W. This vulnerable marine ecosystem (VME) represents a rare record of fragile and highly endemic corals that reinforces the value of natural heritage protected within a mid-Atlantic ridge MPA. We suggest that the C. vascomarquesi coral garden is included at level 5 of the deep-sea section of the European habitat classification system (EUNIS), as a means to emphasize its conservation value and the monitoring of MPAs.

While vast and often remote, the deep ocean is connected to people, communities, and societies through its role in Earth systems, cultural and social attachments, and distribution of benefits and burdens from resource exploitation. The deep ocean is also a unique space and part of the planet, in many ways fundamentally different from shallow seas. This article explores these differences from the perspective of the social sciences and humanities and argues that the deep ocean presents unique research questions for these disciplines, in the same way that deep-ocean ecosystems require natural-science approaches profoundly different from those employed in shallow seas. To date, the deep ocean has been seen as beyond social influence and importance, with some sector-specific exceptions. With impacts from human activities expanding, there is a growing need to understand relationships between deep-sea environments and people and societies. In this light, we examine the relevance and potential of the deep ocean as a category for social sciences and humanities research. The study makes the case for establishing more fine-grained perspectives within the broader domain of marine social sciences and humanities that account for the unique characteristics of the deep ocean and the distinct human relations to this vast environment.

The mesopelagic zone increasingly attracts the interest of commercial fisheries due to its large fish abundance and the growing worldwide demand for food. Many mesopelagic species serve as an important food source for many top predators but the extent to which these predators rely on mesopelagic prey remain poorly understood, especially in oligotrophic open ocean ecosystems. The Azores archipelago is surrounded by numerous seamounts and is subject to a dynamic oceanography, creating particularly attractive conditions for many top predators, including cetaceans. Using stable isotope mixing models (MixSIAR), we estimated diet proportions of seven species of cetaceans belonging to various trophic guilds. Overall, mesopelagic prey are key contributors to the diet of cetaceans. We find that Balaenoptera borealis, B. musculus and B. physalus consume mostly (> 70%) mesopelagic zooplankton (including copepods and krill). Mesopelagic fish and cephalopods contribute 20–35% to the diet of Delphinus delphis, Stenella frontalis and Tursiops truncatus, along with epipelagic and demersal fish. The diet of Physeter macrocephalus almost exclusively consists of mesopelagic cephalopods (> 94%). This study identifies mesopelagic fauna as a critical food resource for cetaceans in tropical and sub-tropical oceanic ecosystems, emphasizing the need for a precautionary approach and strict governance measures before developing commercial fisheries in the mesopelagic zone.

Aim: Identifying highly vulnerable regions to climate change is increasingly incorporated in marine management planning given the expected redistribution of species with latitude, longitude, and depth following temperature changes. Here, we developed a spatially explicit vulnerability framework incorporating sensitivity, exposure, and adaptive capacity of species living in one of the largest networks of Marine Protected Areas (MPAs) within the EU. Location: Azores Marine Park, North Atlantic. Methods: We quantified benthic, benthopelagic, and pelagic species sensitivity to temperature changes based on adult thermal affinity and georeferenced their distribution with quality-controlled records from various data compilators. To assess their exposure, we extracted historical (1995-2020) temperatures across latitudes, longitudes, and depths and calculated mean interannual change (i.e., increase or decrease) and variability. We estimated the adaptive capacity of species with traits related to relocation ability during adult and early life stages (i.e., "Motility" and "Developmental Mechanism") using the FUN Azores trait database. To map the results, we pooled the species into 3D-regions of 0.25 degrees x 0.25 degrees resolution and 50 and 500 m depth bands at shallow and deep areas, respectively. We assigned a sensitivity, exposure, and adaptive capacity score to each region based on species scores and combined them into a final vulnerability class (i.e., "Highly Vulnerable" (HV), "Advisable Monitoring" (AM), "Expected Relocation" (ER), and "Least Concern" (LC)). Results: HV and AM regions exist only in the benthic environment across various MPAs and depths. Increased mobility of species explains the absence of the most vulnerable categories in the benthopelagic and pelagic environments. Main Conclusions: We advise strong conservation measures in HV areas and to maintain connectivity with climate refugia and monitoring of environmental variables and populations in areas classified as AM and ER, respectively. Our results suggest that the Azores deep-sea benthos is the most vulnerable environment to both warming and temperature variations.

Abyssal seascapes represent over 50 % of the Planet's surface, but the life history traits of fauna present in these ecosystems remain poorly understood. Ophiuroidea constitute about one third of the invertebrate megabenthos assemblage between 3800 m and 4800 m water depth in the Clarion-Clipperton Fracture Zone (CCZ); Asteroidea are present in lower densities. We hypothesize that (1) Ophiuroidea, Xenophyophoroidea, and Hexactinellida have a predator-prey relationship, where Ophiuroidea feed on foraminifera- and sponge-derived organic matter (OM). (2) Ophiuroidea have a reduced dependency on fresh phytodetritus. (3) Brisingida (order of Asteroidea), often cling to stalks to have easier access to particulate OM sinking to the seafloor. To test these three hypotheses, we combined bulk and compound-specific stable isotope analyses of fauna (Ophiuroidea, Asteroidea) and sediments with analyses of seafloor images from the eastern CCZ. All investigated Echinodermata species had a high trophic level. Phospholipid-derived fatty acids (PLFAs) used as biomarkers suggest that Silax daleus consumes sedimentary detritus that is processed by its gut microbiome. Ophiacantha cosmica is likely a top consumer or scavenger, Ophiosphalma glabrum is an opportunistic omnivore ingesting phytodetritus, bacteria, Crustacea, and Foraminifera, while Ophiuroglypha cf. polyacantha (sp. 6) is a more selective omnivore. Freyella benthophila sits mostly on stalks of Hexactinellida and uses this elevated position to catch phytodetritus and zooplankton. Freyastera cf. tuberculata, in comparison, sits mostly on polymetallic nodules from where it preys upon Crustacea moving on the sediment surface. We confirmed that Ophiuroidea are less dependent on phytodetritus, and they consume foraminifera- and sponge derived OM.

The North Atlantic is an ocean basin with a diversity of deep-sea ecosystems. Here we provide a summary of the topography and oceanography of the North Atlantic including the Gulf of Mexico and Caribbean Sea, provide a brief overview of the history of scientific research therein, and review the current status of knowledge of each of 18 pelagic and benthic deep-sea ecosystems, with a particular focus on knowledge gaps. We analyse biodiversity data records across the North Atlantic and highlight spatial data gaps that could provide important foci for future expeditions. We note particular data gaps in EEZs of nations within and bordering the Caribbean Sea. Our data provide a baseline against which progress can be tracked into the future. We review human impacts caused by fishing, shipping, mineral extraction, introduction of substances, and climate change, and provide an overview of international, regional and national measures to protect ecosystems. We recommend that scientific research in the deep sea should focus on increasing knowledge of the distribution and the connectivity of key species and habitats, and increasing our understanding of the processes leading to the delivery of ecosystem services. These three pillars - distribution, connectivity, ecosystem function - will provide the knowledge required to implement conservation and management measures to ensure that any deep-sea development in the future is sustainable. Infrastructure and capacity are unevenly distributed and implementation of strategies that will lead to more equitable deep-sea science is required to ensure that essential science can be delivered.

Hydrothermal vents are “oases” of biological productivity and endemicity on the seafloor. Chemosynthetic communities at deep-sea hydrothermal vents are characterized by high abundance and endemism. The distribution of species among these isolated habitats supports regional biodiversity and stability, so understanding the fundamental processes is a key target of conservation. Larval dispersal resulting from deep-ocean circulations is one of the major factors influencing the diversity and distributions of vent animals. By combining a biophysical model with biological larvae traits, we quantify potential larval dispersal of vent species via ocean circulation in the Azores Triple Junction. Here we present results from a biophysical model of larval dispersal run for the hydrothermal vent benthic mussel Bathymodiolus azoricus. Several scenarios were implemented, based on similar data sets, although changing values for one or two parameters, such as swimming behaviour and planktonic larvae duration. Results showed that larvae retention is the most common pattern from the Azores Triple Junction vent fields mussel. The Rainbow vent field is rather isolated, being the sink population of the Menez Gwen and Lucky Strike but with a very low number of larvae exchange. Results are discussed in the framework of spatial management to maintain the populations after an impact by natural or human disturbance.

Abyssal seascapes between 3,000 and 6000 m water depth represent over 50% of the Planet’s surface, but the species, functions, and particularly the life history traits that these ecosystems harbour remain poorly understood. Brittle stars (Ophiuroidea) contribute about one third to the invertebrate megabenthos assemblage between 3,800 m and 4,800 m water depth in the Clarion-Clipperton Fracture Zone (CCZ, Northeast Pacific). Starfishes (Asteroidea) are present in lower densities. In the CCZ, Ophiuroidea are often seen near Xenophyophoroidea and attached to glass sponge (Hexactinellida) stalks. We hypothesize that (1) the observed relationship between Ophiuroidea, Xenophyophoroidea, and Hexactinellida is a predator-prey relationship, where Ophiuroidea feed on foraminifera- and sponge-derived organic matter. (2) Ophiuroidea have a reduced dependency on fresh phytodetritus. (3) Brisingida (order of Asteroidea), often clings to stalks to have easier access to particulate organic matter sinking to the seafloor. To test these three hypotheses, we combined bulk and compound-specific stable isotope analyses of fauna (Ophiuroidea, Asteroidea) and sediments with the analyses of seafloor images from the eastern CCZ. Faunal specimens and sediments were collected during three research expeditions between 2019 and 2022, and previously collected seabed images were re-analysed to quantify the major behaviours in which Ophiuroidea and Asteroidea engage. All investigated Echinodermata species had a high trophic level. Phospholipid-derived fatty acids (PLFAs) used as biomarkers suggest that Silax daleus consumes sedimentary detritus that is processed by its gut microbiome. Ophiacantha cosmica is likely a top consumer or scavenger, Ophiosphalma glabrum is an opportunistic omnivore ingesting phytodetritus, bacteria, Crustacea, and Foraminifera, while Ophiuroglypha cf. polyacantha is a more selective omnivore. Freyella benthophila sits mostly on stalks of Hexactinellida and uses this elevated position to catch phytodetritus and zooplankton. Freyastera cf. tuberculata , in comparison, sits mostly on polymetallic nodules from where it preys upon Crustacea moving on the sediment surface. This study confirmed the hypothesis that Ophiuroidea in the CCZ are less dependent on phytodetritus than Holothuroidea in the Peru Basin. It was confirmed that Ophiuroidea consume foraminifera- and sponge-derived organic matter, but Brisingida cling to stalks of Hexactinellida to prey upon Crustacea living in the benthic boundary layer. ### Competing Interest Statement The authors have declared no competing interest. Dutch Research Council, https://ror.org/04jsz6e67, 856.18.003, 019.182EN.012, VI.Veni.212.211, OCENW.XS24.2.193 Agencia Estatal de Investigación, RyC2023-043275-I, MCIN/AEI/10.13039/501100011033 BiodivERsA, 101003777 Federal Ministry of Education and Research, https://ror.org/04pz7b180, 03LW0173 Foundation for Science and Technology, UIDB/05634/2025, UIDP/05634/2025, CEECIND/00101/2021

Due to the consistent lack of Environmental Risk Assessment (ERA) for deep-sea mining scenarios, the potential impacts of this industry on marine ecosystems remain largely unknown. In order to fill this gap, a Dynamic Energy Budget (DEB) model was developed to study the consequences of toxic sediment plumes derived from deep-sea mining on the energy budget of the Atlantic deep-sea mussel, Bathymodiolus azoricus. Model calibration was based on environmental conditions observed at the Menez Gwen (MG) vent field (Mid-Atlantic Ridge- MAR), assuming a B. azoricus lifespan of 10 years and a maximum shell length of 119 mm. Scenario simulations were conducted to mimic the effects of increased concentrations of toxic sediment plumes on mussel filtration rates, the absorption of reduced substrates by their endosymbionts, and the energetic costs associated with metal toxicity. Data were sourced from B. azoricus and, when necessary, from proxy species. One disturbance scenario (EF1) incorporated measured rates and realistic parameters, while the other (EF2) was intentionally designed to encompass cumulative effects and uncertainties, representing a potential worst-case scenario. Both disturbance scenarios were initiated at three different timings (0, 1200 and 2400 days) to accommodate the mining effects at different stages of the mussels' life cycle. Results indicate that B. azoricus is significantly impacted by toxic sediment plumes, particularly during earlier life stages, potentially leading to severe growth impairment and mortality. These results were integrated into a food web model of the MG vent field, revealing that disruptions to the energetic balance of the vent mussel have widespread consequences for the entire ecosystem. Overall, we argue that this numerical framework offers a valuable tool for conducting ERA and Environmental Impact Assessments (EIA) in the context of industrial deep-sea mining.

Molecular similarities between embryonic and malignant cells can be exploited to target tumors through specific signatures absent in healthy adult tissues. One such embryonic signature tumors express is oncofetal chondroitin sulfate (ofCS), which supports disease progression and dissemination in cancer. Here, we report the identification and characterization of phage display-derived antibody fragments recognizing two distinct ofCS epitopes. These antibody fragments show binding affinity to ofCS in the low nanomolar range across a broad selection of solid tumor types in vitro and in vivo with minimal binding to normal, inflamed, or benign tumor tissues. Anti-ofCS antibody drug conjugates and bispecific immune cell engagers based on these targeting moieties disrupt tumor progression in animal models of human and murine cancers. Thus, anti-ofCS antibody fragments hold promise for the development of broadly effective therapeutic and diagnostic applications targeting human malignancies.

The Bay of Biscay is a structurally complex region, exhibiting high biodiversity and productivity and hosting a wide variety of benthic habitats. Unfortunately, current scientific knowledge of deep-sea ecosystems is limited. Our investigation provides an updated vision of the existing knowledge on key aspects of the deep-sea ecosystem and identifies research priorities for the definition of a research roadmap in support of sustainable management, including the protection and conservation of deep-sea ecosystem of the Bay of Biscay. To achieve this, firstly a revision of projects, surveys and studies conducted in the region, was carried out resulting in the identification of 62 publicly available scientific documents. Secondly, an online survey was carried out, receiving 51 responses from 24 research institutions in 9 countries. Finally, a workshop was attended by 39 scientists to identify and discuss ways forward on deep-sea research in the Bay of Biscay. Results indicate that knowledge of benthic habitats, and vulnerable and sensitive habitats/species is good or very good for 45% of the respondents, while limited knowledge was reported for deep pelagic habitats. Almost 75% of the scientists agreed that deep-sea processes affect shallower areas. Funding (71%) and research vessel availability (57%) were considered the most constraining aspects limiting deep-sea research. More than 50% of the scientists perceived a short- or medium-term threat from human activities and pressures, while over than 40% of the respondents considered that there are no, or limited, data available to assess the environmental status. Regarding climate change, 55% of scientists partially or fully agreed with the existence of evidence of climate change effects, but 47% of them totally or partially considered that climate change monitoring is insufficient to assess eventual changes and effects. Most respondents (63%) considered that deep-sea ecosystems are not properly represented in the current Marine Protected Areas network. In terms of future needs, the development of monitoring strategies to reduce costs and guarantee an optimal design, data sharing and an increase in transnational collaboration are most cited. Finally, a proposal for a roadmap to fill in knowledge gaps for a better understating of the ecosystem processes of the deep sea of the Bay of Biscay is delivered.

Impaired sleep is a common aspect of aging and often precedes the onset of Alzheimer’s disease. Here, we compare the effects of sleep deprivation in young wild-type mice and their APP/PS1 littermates, a murine model of Alzheimer’s disease. After 7 h of sleep deprivation, both genotypes exhibit an increase in EEG slow-wave activity. However, only the wild-type mice demonstrate an increase in the power of infraslow norepinephrine oscillations, which are characteristic of healthy non-rapid eye movement sleep. Notably, the APP/PS1 mice fail to enhance norepinephrine oscillations 24 h after sleep deprivation, coinciding with an accumulation of cerebral amyloid-β protein. Proteome analysis of cerebrospinal fluid and extracellular fluid further supports these findings by showing altered protein clearance in APP/PS1 mice. We propose that the suppression of infraslow norepinephrine oscillations following sleep deprivation contributes to increased vulnerability to sleep loss and heightens the risk of developing amyloid pathology in early stages of Alzheimer’s disease.

IntroductionThe oceanic waters around the Azores host a high diversity of cetaceans, with 28 species of toothed and baleen whales present year-round or seasonally. This high cetacean biodiversity likely plays an important role in the structure, functioning and productivity of the ecosystem, and may increase trophic redundancy, thus contributing to food web resilience to disturbances.MethodsHere we used stable isotope (δ13C and δ15N) analysis to characterize trophic niches, assess niche overlap, describe the trophic structure and discuss potential redundancy in the cetacean community. Using 407 samples from 12 species, we estimated Standard Ellipse Areas and overlaps between species and used a hierarchical clustering analysis to identify trophic guilds.Results and discussionδ13C and δ15N values ranged from -20.53 to -15.46‰ and from 7.78 to 14.41‰ respectively, suggesting the use of diverse habitats and resources among cetacean species. Clustering analysis revealed that species were grouped into four trophic guilds, segregated mainly by trophic position (TP): a low-TP guild with three zooplanktivore baleen whales, a mid-TP guild with micronektivores, a high-TP guild with micronekton and nekton consumers, and a cluster with only Pseudorca crassidens. There was significant isotopic niche overlap between one pair of species within each guild, indicating some potential for trophic redundancy in the community. Yet, these pairs also showed some form of spatial or temporal partitioning, suggesting that mechanisms promoting species coexistence could play a key role in structuring the cetacean community in the region and in its ecological role.

The study of larval dispersal and connectivity between deep-sea populations is essential for the effective conservation and management of deep-sea environments and the design and implementation of Marine Protected Areas. Dense sponge aggregations, known as “sponge grounds”, are a key component of marine benthic ecosystems, by increasing the structural complexity of the sea floor and providing structure and habitat for many other species. These aggregations are characteristic of the Azores deep-sea environment. These sessile organisms rely primarily on larval dispersal for their reproduction. Connectivity between specific Pheronema carpenteri sponge aggregations in the Azores was studied using a 3-D biophysical dispersal model. Different biological trait scenarios were analyzed, considering spawning seasonality and pelagic larval duration. Model results indicate that regional circulation patterns drive larval dispersion, shaping population connectivity of P. carpenteri sponge aggregations in the Azores, particularly among aggregations in the Central Group of Azorean islands. Some areas present high retention rates, receiving larvae from several sponge aggregations while also being important larval source aggregations. In contrast, aggregations from the Eastern Group may be isolated from the others. Larval dispersal and connectivity patterns were analyzed concerning the current configuration of Marine Protected Areas (MPAs) in the Azores. The results underscored the importance of maintaining protection efforts in existing MPAs and identified stepping-stone locations and specific sites where additional measures could enhance species connectivity in the Azores.

The trait-based approach provides a powerful perspective for analyzing fisheries and their potential impact on marine ecological processes, offering crucial insights into sustainability and ecosystem functioning. This approach was applied to investigate trends in fish assemblages landed by both local and coastal fishing fleets in the Azores archipelago over the past four decades (1980s, 1990s, 2000s, and 2010s). A matrix of ten traits was built to assess functional redundancy (Fred), functional over-redundancy (FOve), and functional vulnerability (FVul) for the fish assemblages caught by every fishing fleet in each decade. The susceptibility of the Azorean fishery to negative impacts on ecosystem functioning was evidenced by low FRed ( <1.5 species per functional entity) and high FVul (exceeding 70 %). However, there is reason for optimism, as temporal trends in the 2000s and 2010s showed an increase in FRed and FOve along with a significant decrease in FVul. These trends indicate the adaptation of the fishery to new target species and, notably, the effectiveness of local fish regulations in mitigating the impacts of targeting functionally important species, such as Elasmobranchii, over the past two decades. These regulations have played a pivotal role in preserving ecological functions within the ecosystem, as well as in managing the removal of high biomass of key important species (e.g., Trachurus picturatus , Pagellus bogaraveo , and Katsuwonus pelamis ) from the ecosystem. This study contributes to understanding the delicate balance between fishing pressure, ecological resilience, and sustainable resource management in Azorean waters. It also highlights the importance of continued monitoring, adaptive management, and the enforcement of local fishing regulations to ensure the long-term health and sustainability of the fishery and the broader marine ecosystem.