Ocean Changes Research Articles

A decrease in pH, increase in temperature, and pollution exposure elicit distinct stress responses in a scleractinian coral (Desmophyllum pertusum)

Scleractinian corals create habitat that persists on geological timescales and supports some of the most diverse ecosystems on Earth. Throughout their depth range, these ecosystems are threatened by anthropogenic disturbances, including global ocean change and hydrocarbon extraction. While numerous studies have focused on how shallow-water corals respond to stressors, there is a paucity of research on deep-sea corals. Here, we analyze the gene expression patterns from a reef-forming deep-sea coral, Desmophyllum pertusum (previously Lophelia pertusa), exposed to oil and dispersant mixtures under current and projected future temperature and pH conditions. The overall gene expression patterns varied among coral colonies (genets), but dispersant exposure induced the strongest response. A Weighted-Gene Correlation Network Analysis (WGCNA) identified networks of co-expressed genes in response to different stressors. Gene ontology (GO) enrichment analysis revealed that D. pertusum exhibited the coral cellular stress response (CSR) during exposure to oil, dispersant, and a decrease in pH. Dispersant exposure elicited a response that included up-regulation of apoptosis, immune system, wound healing, and stress-related pathways. Coral nubbins exposed to oil exhibited signs of resource reallocation and a reduction in growth to maintain cellular homeostasis. The decrease in seawater pH resulted in a less severe stress response than dispersant exposure. These results support the idea that there is an underlying environmental stress response (ESR) shared by scleractinians, but that this response varies depending on the type and intensity of the stress with which they are challenged.

Diversity and structure of pelagic microbial community in Kuroshio Extension

Kuroshio Extension (KE) is the most active region of oceanic change in the North Pacific Ocean, which provides an essential place for the survival of marine microorganisms. However, Vertical changes in microbial communities in the Kuroshio Extension and the mechanisms by which environmental factors drive vertical changes in community structure remain unclear. In this work, microbial diversity, abundance, and community structure of 12 water layers (from surface to bottom) at five stations were uncovered by 16S rRNA gene high–throughput sequencing. Microbial diversity and richness decreased with increasing seawater depth. Microorganisms in the euphotic zone can be well separated from other zones based on NMDS analysis. Proteobacteria (65.20%), Bacteroidota (8.48%), Actinobacteriota (5.76%), and Crenarchaeota (4.49%) accounted for a relatively large proportion and their distribution is similar in four zones. Most of microorganisms were significantly (Spearman test, p < 0.05) correlated with salinity, density, pressure, and temperature. This work enhances our understanding of vertical microbial diversity and provides insights into the pelagic microbial community structure.

Climate-driven succession in marine microbiome biodiversity and biogeochemical function.

Seasonal and El Niño-Southern Oscillation (ENSO) warming result in similar ocean changes as predicted with climate change. Climate-driven environmental cycles have strong impacts on microbiome diversity, but impacts on microbiome function are poorly understood. We quantified changes in microbial genomic diversity and functioning over 11 years covering seasonal and ENSO cycles at a coastal site in the southern California Current. We observed seasonal oscillations between large genome lineages during cold, nutrient rich conditions in winter and spring versus small genome lineages, including Prochlorococcus and Pelagibacter , in summer and fall. Parallel interannual changes separated communities depending on ENSO condition. Biodiversity shifts translated into clear oscillations in microbiome functional potential. Ocean warming induced an ecosystem with less iron but more macronutrient stress genes, depressed organic carbon degradation potential and biomass, and elevated carbon-to-nutrient biomass ratios. The consistent microbial response observed across time-scales points towards large climate-driven changes in marine ecosystems and biogeochemical cycles.

The Greenland–Scotland Ridge in a Changing Ocean: Time to Act?

The Greenland–Scotland Ridge in a Changing Ocean: Time to Act?

Novel high-throughput oxygen saturation measurements for quantifying the physiological performance of macroalgal early life stages.

Understanding how macroalgal forests will respond to environmental change is critical for predicting future impacts on coastal ecosystems. Although measures of adult macroalgae physiological responses to environmental stress are advancing, measures of early life-stage physiology are rare, in part due to the methodological difficulties associated with their small size. Here we tested a novel, high-throughput method (rate of oxygen consumption and production; ) via a sensor dish reader microplate system to rapidly measure physiological rates of the early life stages of three habitat-forming macroalgae, the kelp Ecklonia radiata and the fucoids Hormosira banksii and Phyllospora comosa. We measured the rate of O2 consumption (respiration) and O2 production (net primary production) to then calculate gross primary production (GPP) under temperatures representing their natural thermal range. The microplate system was suitable for rapidly measuring physiological rates over a temperature gradient to establish thermal performance curves for all species. The microplate system proved efficient for measures of early life stages of macroalgae ranging in size from approximately 50 μm up to 150 mm. This method has the potential for measuring responses of early life stages across a range of environmental factors, species, populations, and developmental stages, vastly increasing the speed, precision, and efficacy of macroalgal physiological measures under future ocean change scenarios.

High infectivity and waterborne transmission of seagrass wasting disease.

Pathogen transmission pathways are fundamental to understanding the epidemiology of infectious diseases yet are challenging to estimate in nature, particularly in the ocean. Seagrass wasting disease (SWD), caused by Labyrinthula zosterae, impacts seagrass beds worldwide and is thought to be a contributing factor to declines; however, little is known about natural transmission of SWD. In this study, we used field and laboratory experiments to test SWD transmission pathways and temperature sensitivity. To test transmission modes in nature, we conducted three field experiments out-planting sentinel Zostera marina shoots within and adjacent to natural Z. marina beds (20 ± 5 and 110 ± 5 m from bed edge). Infection rates and severity did not differ among outplant locations, implicating waterborne transmission. The infectious dose of L. zosterae through waterborne exposure was assessed in a controlled laboratory experiment. The dose to 50% disease was 6 cells ml-1 and did not differ with the temperatures tested (7.5°C and 15°C). Our results show L. zosterae is transmissible through water without direct contact with infected plants. Understanding the transmission dynamics of this disease in the context of changing ocean conditions will improve Z. marina protection and restoration in critical coastal habitats worldwide.

Prediction of Sea Level Using Double Data Decomposition and Hybrid Deep Learning Model for Northern Territory, Australia

Sea level rise (SLR) attributed to the melting of ice caps and thermal expansion of seawater is of great global significance to vast populations of people residing along the world’s coastlines. The extent of SLR’s impact on physical coastal areas is determined by multiple factors such as geographical location, coastal structure, wetland vegetation and related oceanic changes. For coastal communities at risk of inundation and coastal erosion due to SLR, the modelling and projection of future sea levels can provide the information necessary to prepare and adapt to gradual sea level rise over several years. In the following study, a new model for predicting future sea levels is presented, which focusses on two tide gauge locations (Darwin and Milner Bay) in the Northern Territory (NT), Australia. Historical data from the Australian Bureau of Meteorology (BOM) from 1990 to 2022 are used for data training and prediction using artificial intelligence models and computation of mean sea level (MSL) linear projection. The study employs a new double data decomposition approach using Multivariate Variational Mode Decomposition (MVMD) and Successive Variational Mode Decomposition (SVMD) with dimensionality reduction techniques of Principal Component Analysis (PCA) for data modelling using four artificial intelligence models (Support Vector Regression (SVR), Adaptive Boosting Regressor (AdaBoost), Multilayer Perceptron (MLP), and Convolutional Neural Network–Bidirectional Gated Recurrent Unit (CNN-BiGRU). It proposes a deep learning hybrid CNN-BiGRU model for sea level prediction, which is benchmarked by SVR, AdaBoost, and MLP. MVMD-SVMD-CNN-BiGRU hybrid models achieved the highest performance values of 0.9979 (d), 0.996 (NS), 0.9409 (L); and 0.998 (d), 0.9959 (NS), 0.9413 (L) for Milner Bay and Darwin, respectively. It also attained the lowest error values of 0.1016 (RMSE), 0.0782 (MABE), 2.3699 (RRMSE), and 2.4123 (MAPE) for Darwin and 0.0248 (RMSE), 0.0189 (MABE), 1.9901 (RRMSE), and 1.7486 (MAPE) for Milner Bay. The mean sea level (MSL) trend analysis showed a rise of 6.1 ± 1.1 mm and 5.6 ± 1.5 mm for Darwin and Milner Bay, respectively, from 1990 to 2022.

Contrasted Trends in Chlorophyll‐a Satellite Products

AbstractPhytoplankton sustains marine ecosystems and influences the global carbon cycle. This study analyzes trends in surface chlorophyll‐a concentration (Schl), a proxy for phytoplankton biomass, using six of the most widely used merged satellite products. Significant regional variations are observed, with contrasting trends observed among different products. To assess if these trends can be related to changes in the environment or to bias in radiometric products, a convolutional neural network is used to examine the relationship between physical ocean variables versus Schl. The results suggest that the merging algorithm of Globcolour‐GSM is not reliable for trend detection and that observed changes in Schl after 2012/2016 are not supported by changes of the physical ocean. These results emphasize the need for careful interpretation of satellite‐derived Schl trends and highlight the potential of machine learning in understanding the complex interactions in marine ecosystems.

Role of the Boreal Autumn Antarctic Oscillation in Controlling the Winter Frequency of Severe Pollution Events in the Beijing–Tianjin–Hebei Region, China

AbstractThe Antarctic Oscillation (AAO), which is the main mode of extratropical circulation in the Southern Hemisphere, also has a substantial effect on the Northern Hemisphere climate. We investigated the influence of the early AAO on the frequency of late severe pollution events (SPEF) in the Beijing–Tianjin–Hebei region (SPEFBTH) of China during winter. The results show that the winter (December–January–February) SPEFBTH is negatively correlated with the AAO from the previous autumn (August–September–October). The controlling mechanism can be briefly described as follows: the autumn AAO is positively correlated with the mid‐latitude sea surface temperature (SST) in the South Atlantic Ocean. The SST preserves the autumn anomaly signal into the following winter. This anomalous SST regulates changes in the tropical western Indian Ocean–Intertropical Convergence Zone (IN–ITCZ) via air–sea coupling. Subsequently, as a response to the IN–ITCZ anomalies, anomalous wave trains are excited in the upper troposphere from the tropical western Indian Ocean to East Asia. In addition, the local meridional circulation is modulated; therefore, the circulation field and other meteorological elements favorable for the SPEFBTH appear and exacerbate the SPEFBTH. This study describes a new physical mechanism for the pathway of the AAO influence on subsequent SPEFBTH and finds a predictable source in the Southern Hemisphere air–sea system.

Beyond equilibrium thinking: dynamic area-based management tools in a changing ocean

Area-based management tools (ABMTs), including marine protected areas (MPAs) are often static and fail to reflect the dynamic realities of marine ecosystems. Marine ecosystems are characterized by their embodiment of constant change, which is further amplified by anthropogenic stressors, particularly climate change. ABMTs and MPAs are, however, premised on an implicit assumption of environmental equilibrium as their boundaries and management framework are often fixed and difficult to adjust. This article seeks to lay bare the tension between static conservation strategies and the deeply and inherently dynamic nature of marine ecosystems. It further seeks to advance the notion of dynamic ABMTs, proposing an integrated conceptualization of ABMT governance, one that is more apt to respond to the type of challenges that the dynamism of complex marine ecosystems presents. Dynamism, in this context, is broadly construed as encompassing three dimensions: spatial, with fluid and adjustable conservation measures; normative, denoting a volatile and adaptive management framework that utilizes ecological and management thresholds as an initiator for adaptive, timely, and prospective approaches to enhance management outcomes; and institutional, i.e., sufficiently flexible and dynamic institutional machinery overseeing ABMT implementation. Following a comprehensive conceptualization of dynamic ABMTs, the article addresses the question whether the legal frameworks governing the ocean can sustain such a dynamic mode of ocean governance.

A sustainable blue economy may not be possible in Tanzania without cutting emissions

Balancing blue growth with the conservation of wild species and habitats is a key challenge for global ocean management. This is exacerbated in Global South nations, such as Tanzania, where climate-driven ocean change requires delicate marine spatial planning (MSP) trade-offs to ensure climate resilience of marine resources relied upon by coastal communities. Here, we identified challenges and opportunities that climate change presents to the near-term spatial management of Tanzania's artisanal fishing sector, marine protected areas and seaweed farming. Specifically, spatial meta-analysis of climate modelling for the region was carried out to estimate the natural distribution of climate resilience in the marine resources that support these socially important sectors. We estimated changes within the next 20 and 40 years, using modelling projections forced under global emissions trajectories, as well as a wealth of GIS and habitat suitability data derived from globally distributed programmes. Multi-decadal analyses indicated that long-term climate change trends and extreme weather present important challenges to the activity of these sectors, locally and regionally. Only in few instances did we identify areas exhibiting climate resilience and opportunities for sectoral expansion. Including these climate change refugia and bright spots in effective ocean management strategies may serve as nature-based solutions: promoting adaptive capacity in some of Tanzania's most vulnerable economic sectors; creating wage-gaining opportunities that promote gender parity; and delivering some economic benefits of a thriving ocean where possible. Without curbs in global emissions, however, a bleak future may emerge for globally valuable biodiversity hosted in Tanzania, and for its coastal communities, despite the expansion of protected areas or curbs in other pressures. Growing a sustainable ocean economy in this part of the Global South remains a substantial challenge without global decarbonization.

The adaptive mechanisms of the marine diatom Thalassiosira weissflogii to long-term high CO2 and warming.

While it is known that increased dissolved CO2 concentrations and rising sea surface temperature (ocean warming) can act interactively on marine phytoplankton, the ultimate molecular mechanisms underlying this interaction on a long-term evolutionary scale are relatively unexplored. Here, we performed transcriptomics and quantitative metabolomics analyses, along with a physiological trait analysis, on the marine diatom Thalassiosira weissflogii adapted for approximately 3.5 years to warming and/or high CO2 conditions. We show that long-term warming has more pronounced impacts than elevated CO2 on gene expression, resulting in a greater number of differentially expressed genes (DEGs). The largest number of DEGs was observed in populations adapted to warming + high CO2, indicating a potential synergistic interaction between these factors. We further identified the metabolic pathways in which the DEGs function and the metabolites with significantly changed abundances. We found that ribosome biosynthesis-related pathways were upregulated to meet the increased material and energy demands after warming or warming in combination with high CO2. This resulted in the upregulation of energy metabolism pathways such as glycolysis, photorespiration, the tricarboxylic acid cycle, and the oxidative pentose phosphate pathway, as well as the associated metabolites. These metabolic changes help compensate for reduced photochemical efficiency and photosynthesis. Our study emphasizes that the upregulation of ribosome biosynthesis plays an essential role in facilitating the adaptation of phytoplankton to global ocean changes and elucidates the interactive effects of warming and high CO2 on the adaptation of marine phytoplankton in the context of global change.

Can biochemical tracers reveal ontogenetic trophic shift and individual prey selection in white sharks from Guadalupe Island, Northeast Pacific?

Refining the role of apex predators in marine food webs is a necessary step in predicting the consequences of their global decline under the footprint of fishing activities. White sharks (Carcharodon carcharias) are vulnerable predators, performing large migrations and able to forage on a variety of prey in different habitats. In the Northeast Pacific, juvenile and adult white sharks are found seasonally at the same aggregation sites, such as Guadalupe Island off Mexico. While adults are thought to target local pinniped colonies, very few predator-prey interactions have been documented and the diet of juveniles in this area remains poorly understood. Here we used carbon/nitrogen stable isotopes and fatty acids to characterize the trophic ecology of white sharks at Guadalupe Island. In contrast to the ontogenetic trophic shift paradigm, we detected no influence of size on muscle stable isotope and fatty acid composition, revealing no significant dietary variation between juvenile and adult sharks. Stable isotopes did not allow definitive conclusions to be drawn regarding the diet of white sharks at Guadalupe Island, due to significant variability in the contribution of different potential prey depending on the trophic discrimination factors used. However, most sharks were rich in polyunsaturated fatty acids (such as long-chain omega 3), suggesting a local diet of mainly pelagic prey (potentially large fish or cephalopods). A few individuals appeared to show recent consumption of pinnipeds, with higher proportions of saturated and monounsaturated fatty acids. These individual differences in fatty acid composition could reflect an ecological trade-off between consumption of prey rich in fat (marine mammals) versus prey rich in polyunsaturated fatty acids (pelagic prey), respectively meeting the energetic and physiological needs of white sharks. Although ontogenetic trophic changes were not able to be discerned, our results provide new insights into the physiological drivers of predator-prey interactions, which can benefit the definition of conservation strategies in a changing ocean.

Hidden underlying mechanisms for changes in mesozooplankton communities: Transport and eddy driven changes

Mesozooplankton communities have been used extensively as reliable climate change indicators, mainly because of their rapid growth and sensitivity to environmental changes. This study explored the modifications in the taxonomic composition of the mesozooplankton community and the associated physical changes of transport-driven, eddy-driven, and marine heatwaves in the summers of the last 14 years (2009–2022) within the mixed layer of the Ulleung Basin in the East Sea/Japan Sea, where surface waters have rapidly warmed in recent decades. A slight increase was observed in the abundance of mesozooplankton from 2009 (3709 inds.m−3) to 2022 (4231 inds.m−3), with two notable peaks in 2015 (11,377 inds.m−3) and 2020 (11,184 inds.m−3), which was mainly attributed to the prevalence of Noctiluca scintillans. The first peak in 2015 showed thaliaceans to be the next dominant taxa, in which the southward direction of meandering in East Korea Warm Current (EKWC), presence of the Ulleung warm eddy, lower volume of the Western Channel (V-west) of the Korea Strait, and marine heatwaves (MHWs) did not occur. In contrast to the first peak, the second peak in 2020 showed Pyrocystis pseudonoctiluca to be the next dominant species, which may have been transported and advected by the strong V-west and eastward direction of the EKWC and the occurrence of MHWs that allowed the persistence of the subtropical species P. pseudonoctiluca. Overall, the significant increases in the second dominant mesozooplankton taxa appeared to be affected by physical changes, including transport or eddy-driven changes, along with the occurrence of strong V-west, the direction of the EKWC, and the occurrence of MHWs, which may synergistically influence the increase in the second dominant taxa during summer. This study highlights the complex interplay between notable variations in mesozooplankton communities and environmental factors, highlighting the potential consequences of different physical changes (transport-driven and eddy-driven) in this regional ocean.

Influence of the sea surface temperature of equatorial Pacific Ocean on the tropical cyclones activity

Introduction. Today, the study of climate is one of the most important tasks of modern science. Particular attention is paid to issues of climate variability on different time scales. The El Niño – Southern Oscillation (ENSO) is the leading signal of interannual climate variability that influences the weather and climate of the globe. It has been revealed that during the onset of its different phases, weather and climate anomalies (up to extreme ones) are observed not only over the tropical zone of the Pacific Ocean, but also in extratropical latitudes, which are transmitted through teleconnections in the ocean-atmosphere system. Numerous studies have shown that ENSO modulates tropical cyclone activity in the northwest Pacific Ocean. The purpose of the study is to determine the relationship between sea surface temperature (SST) changes in the equatorial Pacific Ocean and the frequency of tropical cyclones of varying intensity in the northwestern Pacific Ocean under current climatic conditions. Materials and methods of research. The work uses data of the number of cases and intensity of tropical cyclones (TCs) for the period 1991-2020, and series of indices ONI and SOI. Using these data, statistics on the frequency of TCs in the study area were calculated and Pearson correlation coefficients were calculated. The scientific novelty lies in obtaining quantitative characteristics of the relationship between SST and the number of TCs of varying intensity in modern climatic conditions. The practical significance of the work lies in the fact that TCs are associated with the occurrence of severe weather conditions, which, when a TC reaches the densely populated coast of Southeast Asia, can pretend to be significant losses. Therefore, information that can be used in forecasting TCs and their trajectories is very high importance. Research results. Analysis of the frequency of TCs of different intensity in the northwestern Pacific Ocean during the 1991-2020 showed that there was a decrease in the number of tropical depressions and typhoons. However, there has been a slight increase in the occurrence of tropical storms. The results of the analysis of the influence of SST variability in the equatorial Pacific Ocean on the frequency of TCs, showed that there is a statistically significant relationship only with the frequency of typhoons. The establishment of positive SST in the center of the equatorial Pacific Ocean, associated with the El Niño episode, is associated with an increase in typhoons in the northwestern Pacific Ocean.

Drivers of Interannual Salinity Variability in the Arctic Ocean

AbstractAccurate projections and attribution of Arctic Ocean changes in climate models require a good understanding of the mechanisms underlying interannual salinity variability in the region. Although some mechanisms have been extensively studied in idealized setting, in particular for the dynamics of the Beaufort gyre (BG), it remains unclear how applicable they are to more complex systems. This study introduces a new diagnostic based on salinity variance budget to robustly assess the mechanisms of salinity variations. The diagnostic is then applied to the “Estimating the Circulation and Climate of the Ocean” state estimate. Results indicate that the advection of salinity anomaly in the direction of the mean salinity gradient made by velocity anomalies is the primary source of interannual salinity variability. These velocities are primarily attributed to fluctuating winds via Ekman transports. Fluctuating surface freshwater fluxes from the atmosphere and sea ice are the second most important source of variability and cannot be neglected. The two sinks of interannual salinity variance are associated with the erosion of large scale gradients of the mean circulation by eddies and to a lesser extent to the diffusive terms. Over continental shelves, particularly over the East Siberian Shelf (ESS), ocean surface freshwater fluxes and diffusion play a more important role than in the deep basins. We also report a strong intensification of all sources and sinks of interannual salinity variability in the BG and an opposite weakening in the ESS in the second decade of the analysis (2004–2014) with respect to the first (1993–2003).

Emergence of decadal linkage between Western Australian coast and Western–central tropical Pacific

The impact of interbasin linkage on the weather/climate and ecosystems is significantly broader and profounder than that of only appearing in an individual basin. Here, we reveal that a decadal linkage of sea surface temperature (SST) has emerged between western Australian coast and western–central tropical Pacific since 1985, associated with continuous intensification of decadal variabilities (8–16 years). The rapid SST changes in both tropical Indian Ocean and Indo-Pacific warm pool in association to greenhouse gases and volcanoes are emerging factors resulting in enhanced decadal co-variabilities between these two regions since 1985. These SST changes induce enhanced convection variability over the Maritime Continent, leading to stronger easterlies in the western–central tropical Pacific during the warm phase off western Australian coast. The above changes bring about cooling in the western–central tropical Pacific and strengthened Leeuwin Current and anomalous cyclonic wind off western Australian coast, and ultimately resulting in enhanced coupling between these two regions. Our results suggest that enhanced decadal interbasin connections can offer further understanding of decadal changes under future warmer conditions.

When species don't move together: Non-concurrent range shifts in Eastern Pacific kelp forest communities.

Species range shifts due to changing ocean conditions are occurring around the world. As species move, they build new interaction networks as they shift from or into new ecological communities. Typically, species ranges are modeled individually, but biotic interactions have been shown to be important to creating more realistic modeling outputs for species. To understand the importance of consumer interactions in Eastern Pacific kelp forest species distributions, we used a Maxent framework to model a key foundation species, giant kelp (Macrocystis pyrifera), and a dominant herbivore, purple sea urchins (Strongylocentrotus purpuratus). With neither species having previously been modeled in the Eastern Pacific, we found evidence for M. pyrifera expansion in the northern section of its range, with no projected contraction at the southern range edge. Despite its known co-occurrence with M. pyrifera, models of S. purpuratus showed a non-concurrent southern range contraction and a co-occurring northern range expansion. While the co-occurring shifts may lead to increased spatial competition for suitable substrate, this non-concurrent contraction could result in community wide impacts such as herbivore release, tropicalization, or ecosystem restructuring.

Projecting marine fish distributions during early life stages under future climate scenarios

AbstractChanges to Earth's climate affect organisms globally; in marine systems, these impacts are seen through warming water temperatures, ocean acidification, hypoxia and frequent marine heatwaves. These effects may lead to the movement of species to more favourable conditions. While climate‐driven movement is well studied at the adult stage, how the early life stages of marine fish will respond to future variability is less clear. Many fish species are constrained by specific spawning locations or phenology. Spawning in certain locations allows for local retention of offspring, while precise timing can facilitate transport of offspring to nursery locations through seasonal circulation patterns. Our research investigates how changing oceans impact the location and timing of spawning of Bering Sea groundfishes over the next century. We used ROMS SST and SSS model output and NOAA survey data in species distribution models to hindcast and project distributions and centre of gravity for eggs and larvae of six groundfish species. Our analyses found that most of our study species exhibit flexible geography. However, the speed and direction of egg and larval movement did not track the speed and direction of their respective thermal niches. Hence, the projected distributional patterns of adult stages may be limited by their early life stages. This response is likely to be mirrored globally by other species with planktonic eggs and larvae. These results indicate that life history considerations are critical for the management of commercially important species, as effects on early life stages are strongly connected to the success or failure of adult populations.

A roadmap to reduce the risk of overexploiting EU marine living resources in a changing ocean

We provide a balanced overview of how risk assessment and management is being tackled in the European Union (EU) and beyond to address the challenges of overexploiting marine living resources in EU waters. We aim to guide EU fisheries and aquaculture policymakers towards key actions to foster the transition to responsible, sustainable, clean energy, and resilient fisheries and aquaculture sectors, aligning with EU environmental objectives under the European Green Deal and the Common Fisheries Policy. Despite progress in reducing fishing pressure on some stocks in recent years, most of the stated (single-stock) sustainability objectives still need to be met. The risk of overexploiting marine resources remains high, especially when combined with other pressures such as pollution and climate change. Risk is defined as the probability of an adverse event arising from natural or human activities and excessive pressures. Scientists have documented these pressures, proposing regional risk assessments to support adequate risk-based management of human activities impacting marine and coastal regions. As a next step, we recall actionable short- to long-term recommendations to reduce the risks associated with exploiting these natural resources and ensure their sustainability and resilience. This includes actions the EU can take to improve and implement fisheries policy while prioritising less harmful alternatives among current fishing methods and considering the three pillars of sustainability i.e. environmental, economic and social. Such actions include capturing in scientific advice the strong, causal links between pressures induced by human activities, natural disturbances and ecosystem states; such understanding can be used in an uncertain and changing environment, with ocean productivity possibly trending towards new levels. Finally, we restate that conserving by reducing pressures and restoring the integrity of marine ecosystems is crucial for minimising the risk of overexploitation and ensuring future fishing and farming opportunities. This is the aim of an Ecosystem Approach to fisheries and aquaculture – it should safeguard the long-term economic and social capital already invested by the public and private sectors in exploiting marine living resources to continue delivering healthy, low-carbon, low-impact seafood to EU citizens and beyond.