ALBERT

Description: Nutrient transfer into the sunlit surface ocean by cyclonic eddies is potentially crucial for sustaining primary productivity in the stratified subtropical gyres. However, the nature of productivity enhancements, including the flow of matter to higher trophic levels and its impact on carbon fluxes, remain poorly resolved. Here, we report a detailed assessment of the biogeochemical response to a cyclonic eddy in the subtropical Northwest Pacific via a combination of ship‐based and autonomous platforms. Primary production was enhanced twofold within the eddy core relative to reference sites outside, whereas phytoplankton biomass even decreased. Pico‐phytoplankton (〈 2 μ m) dominated (〉 80%) both phytoplankton biomass and primary production inside and outside the eddy. The stimulated primary production in the eddy core was accompanied by an approximately twofold increase in mesozooplankton abundance, an approximately threefold increase in particle formation in the deep chlorophyll maximum layer, as well as significantly enhanced surface oceanic CO 2 uptake and net community production. We suggest these observations carry important implications for understanding carbon export in the subtropical ocean and highlight the need to include such subtropical eddy features in ocean carbon budget analyses.

Description: The exploitation of marine resources has caused drastic declines of many large predatory fishes. Amongst these, sharks are of major conservation concern due to their high vulnerability to overfishing and their ecological role as top predators. The 2 protected and endangered shark species tope Galeorhinus galeus and smooth hammerhead Sphyrna zygaena use overlapping coastal areas around the globe as essential fish habitats, but data to assess their trophic ecology and niche partitioning are scarce. We provide the first comparative assessment of the trophic ecology, ontogenetic shifts, and niche partitioning of the co-occurring tope and juvenile smooth hammerhead around the Azores Islands, mid-north Atlantic, based on delta 13C, delta 15N, and delta 34S (CNS) stable isotope analysis of muscle tissue of the sharks and their putative prey species. Overall, isotopic niches of both species indicated a reliance on similar resources throughout the sampled sizes (tope: 35-190; smooth hammerhead 54-159 cm total length), with significant ontogenetic shifts. Topes displayed a gradual shift to higher trophic levels and a more generalist diet with increasing size (increasing delta 15N values and isotopic niche volumes, respectively), whereas smooth hammerhead diet shifted towards prey with lower delta 34S at a constant trophic level and a more specialized diet than tope of comparable body size (decreasing delta 34S and constant delta 15N and delta 13C values, respectively). Our results indicate contrasting ontogenetic shifts in delta 13C and delta 34S along with pronounced differences between niche overlap of life stages pointing to intra- and interspecific niche partitioning of habitat and prey.

Description: Promoting effects of aluminum addition on chlorophyll biosynthesis and growth of two cultured iron‐limited marine diatoms Linbin Zhou CAS Key Laboratory of Tropical Marine Bio‐resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China Marine Biogeochemistry Division GEOMAR Helmholtz Centre for Ocean Research Kiel Germany University of Chinese Academy of Sciences Beijing China https://orcid.org/0000-0001-7230-4116 Fengjie Liu Marine Biogeochemistry Division GEOMAR Helmholtz Centre for Ocean Research Kiel Germany Grantham Institute—Climate Change and the Environment, Department of Life Sciences Imperial College London London UK Eric P. Achterberg Marine Biogeochemistry Division GEOMAR Helmholtz Centre for Ocean Research Kiel Germany Anja Engel Marine Biogeochemistry Division GEOMAR Helmholtz Centre for Ocean Research Kiel Germany https://orcid.org/0000-0002-1042-1955 Peter G.C. Campbell Institut National de la Recherche Scientifique Centre Eau Terre Environnement Quebec Canada https://orcid.org/0000-0001-7160-4571 Claude Fortin Institut National de la Recherche Scientifique Centre Eau Terre Environnement Quebec Canada https://orcid.org/0000-0002-2479-1869 Liangmin Huang CAS Key Laboratory of Tropical Marine Bio‐resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China University of Chinese Academy of Sciences Beijing China Yehui Tan CAS Key Laboratory of Tropical Marine Bio‐resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China University of Chinese Academy of Sciences Beijing China Abstract Aluminum (Al) may play a role in the ocean's capacity for absorbing atmospheric CO 2 via influencing carbon fixation, export, and sequestration. Aluminum fertilization, especially in iron (Fe)‐limited high‐nutrient, low‐chlorophyll ocean regions, has been proposed as a potential CO 2 removal strategy to mitigate global warming. However, how Al addition would influence the solubility and bioavailability of Fe as well as the physiology of Fe‐limited phytoplankton has not yet been examined. Here, we show that Al addition (20 and 100 nM) had little influence on the Fe solubility in surface seawater and decreased the Fe bio‐uptake by 11–22% in Fe‐limited diatom Thalassiosira weissflogii in Fe‐buffered media. On the other hand, the Al addition significantly increased the rate of chlorophyll biosynthesis by 45–60% for Fe‐limited T. weissflogii and 81–102% for Fe‐limited Thalassiosira pseudonana , as well as their cell size, cellular chlorophyll content, photosynthetic quantum efficiency ( F v / F m ) and growth rate. Under Fe‐sufficient conditions, the Al addition still led to an increased growth rate, though the beneficial effects of Al addition on chlorophyll biosynthesis were no longer apparent. These results suggest that Al may facilitate chlorophyll biosynthesis and benefit the photosynthetic efficiency and growth of Fe‐limited diatoms. We speculate that Al addition may enhance intracellular Fe use efficiency for chlorophyll biosynthesis by facilitating the superoxide‐mediated intracellular reduction of Fe(III) to Fe(II). Our study provides new evidence and support for the iron–aluminum hypothesis.

Description: Scientific Significance Statement Millions of predator–prey interactions between deep-diving toothed whales and cephalopods occur daily in the dark deep sea. While predatory whales developed traits to detect and hunt their prey, cephalopods had to expand their anti-predatory strategies specialized for visual predators, to counteract acoustic predators. Since toothed whale-cephalopod interactions have never been directly observed in the deep sea, it remains unknown what selective pressures and traits evolved from this arms race. Combining current knowledge, we formalize four hypotheses and associated research approaches that will guide future investigation on oceanic predator–prey systems. We identify whale echolocation as an unprecedented armament to hunt distant prey and propose that deep-sea squids avoid acoustic predators by (1) reducing their acoustic cross-section through body shape and posture, (2) deep-sea migration, and (3) not schooling. Toothed whale predation emerges as a potential driver of the cephalopod live-fast-die-young strategy—which may now leave cephalopods at competitive advantage under global change.

Description: The simulation of deep-sea conditions in laboratories is technically challenging but necessary for experiments that aim at a deeper understanding of physiological mechanisms or host-symbiont interactions of deep-sea organisms. In a proof-of-concept study, we designed a recirculating system for long-term culture (〉2 yr) of deep-sea mussels Gigantidas childressi (previously Bathymodiolus childressi). Mussels were automatically (and safely) supplied with a maximum stable level of ~60 μmol L−1 methane in seawater using a novel methane–air mixing system. Experimental animals also received daily doses of live microalgae. Condition indices of cultured G. childressi remained high over the years, and low shell growth rates could be detected, too, which is indicative of positive energy budgets. Using stable isotope data, we demonstrate that G. childressi in our culture system gained energy, both, from the digestion of methane-oxidizing endosymbionts and from digesting particulate food (microalgae). Limitations of the system, as well as opportunities for future experimental approaches involving deep-sea mussels, are discussed.

Description: Spatiotemporal observations are data rich and offer insights into links between ecological patterns and underlying processes. We present fine-scale autonomous observations from repeated ferry transects in the Strait of Georgia (British Columbia, Canada) during the 2020 spring bloom period using a FerryBox system (temperature, salinity, chlorophyll a fluorescence) and a digital inline holographic microscope. Despite instrument cleaning interruptions related to COVID-19 restrictions, 3 periods from late winter (February) to springtime (March and April) contained 14 days of high-quality holograms (〉70 000) capturing 〉10 500 identifiable micro- to mesoplankton using automatic object detection. The ferry set-up provided automatic data storage through Ocean Networks Canada, which also automatized data flagging and guaranteed remote access. The highest-quality holograms repeatedly covered the central and eastern Strait and showed aspects of bloom succession. Fast-growing diatoms (Skeletonema sp.) emerged first, followed by a diverse assemblage including Chaetoceros spp., Ditylum spp., and Eucampia spp., and by April, larger centric cells prevailed. The combined approach captured local suppression of chlorophyll a fluorescence and diatom concentrations in Fraser River plume waters during the freshet, suggesting fine-scale spatial patterns in seasonal planktonic community composition. This work is among the first of its kind to autonomously generate in situ imaging and physicochemical data with spatiotemporal resolution.

Description: A sense of kuleana (personal responsibility) in caring for the land and sea. An appreciation for laulima (many hands cooperating). An understanding of aloha 'āina (love of the land). The University of Hawai'i at Manoa hosted the 2023 Ecological Dissertations in Aquatic Sciences (Eco-DAS) program, which fostered each of these intentions by bringing together a team of early career aquatic ecologists for a week of networking and collaborative, interdisciplinary project development

Description: Implementation of pH sensor on Eulerian observations in the Mediterranean Sea (DYFAMED site)

Description: Design of numerical experiments assimilating in situ physical and BGC observations to assess and enhance their impact in CMEMS ocean monitoring and forecasting systems.

Description: Investigations and preparation of glider observations to be assimilated in MED-MFC and WMOP systems.

Description: Derive the user-relevant indicators defined in Milestone MS7 from the ensemble of ECMWF and CMCC seasonal forecasts systems contributing to C3S

Description: Framework of the envisioned time-series synthesis product used to indicate the consistency of biogeochemical time-series data (in-)between different ship-based sites.

Description: This document describes the numerical modelling work done in task 5.2 needed to implement OSPAC

Description: This document describes the numerical modelling work for waves done in wp5.2. needed to implement OSPAC

Description: This report includes the description and the manuals (both at User and Administrator level) for the OSPAC service and its applications

Description: Assess the seasonal forecast skill of selected ocean variables - SST, OHC300m, and SSH - from the ensemble of ECMWF and CMCC seasonal forecasts systems contributing to C3S

Description: Report on ASV-Network structure and roadmap Revised edition

Description: Identification of local and regional impacts of oxygen, heat and pH related “Extreme Marine Events”: Ocean model data products are overlaid with existing marine biological datasets to identify sensitive areas and organism vulnerabilities.

Description: This report includes recommendations for the planification of in situ experiments aimed to reconstruct fine-scale ocean currents (~20 km), such as those that will be conducted to validate SWOT satellite observations.

Description: This deliverable is intended to give an overview of the EuroSea actions at the interface between science and policy, ensuring the EuroSea results are useful for policy and decision-makers both at the EU, regional, and national levels.

Description: This report provides a description of the different tools developed for tackling key issues of the High Frequency Radar (HFR) community: advanced delayed time QC of HFR historical data, implementation of Best Practices, enhancing the application of HFR observations in NRT modelling assessment and Ocean State indicators

Description: The purpose of this deliverable is to describe and highlight specificities of the observing networks involved in Eurosea and to display a list of main data management points done at European level in comparison to what exists at international level.

Description: Euro-Argo strategy in the context of the OneArgo new international design

Description: This report provides recommendations to foster collaboration and cooperation between technologies and disciplines and for implementing truly integrated ocean observing systems. Based on an intensive literature review and a careful examination of different examples of integration in different fields, this work identifies the issues and barriers that must be addressed, and proposes a vision for a real implementation of this ocean integration ambition. This work is a contribution to the implementation of EOOS, a much-needed step forward in Europe, following the international guidance of GOOS.

Description: Several legal frameworks exist that are important for states conducting ocean observing activities or for which it would be relevant to include the necessity of ocean observing activities and development of ocean information products. Existing hard and soft law frameworks and mechanisms will be analysed to enable adequate adaptation of ocean observing system design at a regional and global level, with a focus on supporting sustained ocean observing and fit-for-purpose ocean information products.

Description: EuroSea brought together key European actors of ocean observation and forecasting with key end users of the ocean observations’ products and services to better integrate existing ocean observation systems and tools, and to bring the coordination to a higher level. The EuroSea WP1 “Governance and coordination of ocean observing and forecasting systems”, in particular, aimed to strengthen the interactions between regional, national, and international observing systems and support the development of a European coordinated system through the Framework of the European Ocean Observing System (EOOS). During the project, the challenges and gaps in the design and coordination of the European ocean observing and forecasting system were identified and mapped. Many gaps and challenges related to the observations of physical, chemical and biological Essential Ocean Variables were identified. Some of these gaps are related to technological advancements, while others are caused by insufficient funding, coordination, management, and cooperation between different entities, as well as limitations in foresight activities, policies and decisions. To enhance the sustainability of European ocean observations, several recommendations were compiled for networks, frameworks, initiatives, Member States, and the European Commission.

Description: The European Ocean Observing and Forecasting System (EOOFS) plays a pivotal role in understanding, monitoring, forecasting, and managing the complex dynamics and resources of Europe's Seas. It serves as a critical interdisciplinary system for addressing a myriad of challenges, from climate change impacts to marine resources management. However, to ensure its continued effectiveness, it is essential to identify and address the gaps within this system and provide actionable recommendations for improvements at short- and long-term. Therefore, this document serves as a baseline that can guide the funders and supporters of the EOOFS, as well as the various stakeholders directly or indirectly related to the EOOFS, towards the gaps that hinder better monitoring and prediction of various ocean phenomena, along the ocean observing value chain. The main identified gaps are related to spatial and temporal coverage of data and products of the EOOFS, the data integration and accessibility by various types of users, the uncertainties of projections, the technological challenges, as well as to the engagement of various actors and the communication of results and services to them. The main recommendations to be taken into consideration for addressing all highlighted gaps are detailed in the report for every phenomenon and component of the ocean value chain. These recommendations are not provided just to satisfy the academic interest of the EOOFS community, however, they may have profound implications for multiple sectors and the society as a whole, if taken into consideration. This is due to the fact that the EOOFS is essential for climate change mitigation and adaptation measures, in improving the efficiency of the marine resources’ management, in enhancing the resilience of marine and coastal ecosystems as well as coastal cities and infrastructures against disasters and extreme events, for shipping and navigation safety, and for the scientific advancements and innovations of Europe in the field of marine science that serves the society. We propose a scoring approach that can evaluate the EOOFS readiness level (RL) in monitoring ocean phenomena, on a regular basis and in a systematic way. We have demonstrated the usefulness of this approach by implementing it based on our assessment and the feedback of the EOOFS community. The main results clearly show that the EOOFS has “Fitness for Purpose” readiness levels (RL 7) in the three main pillars of the value chain (Input, Process, and Output) only for one ocean phenomenon, while 83% of ocean phenomena have RLs varying from 1 (Idea) to 4 (Trial). A deeper analysis of the scoring results reflects that the EOOFS major gaps are predominantly concentrated in two of its three pillars: the coordination and observational elements (Process) and data management and information products (Output) (Figure 1). In a changing world that is affecting all aspects of European lives, it is crucial to significantly invest and support the EOOFS to better monitor and accurately predict the European Seas, and provide sustained services that can help businesses and improve the resilience of communities and resources.

Description: This report “Real-time data to central server with display to stakeholders” describes the deployment of two monitoring stations at the aquaculture facilities at Deenish Island (Ireland) and El Campello (Spain), and how the real-time data is distributed to the different stakeholders in the aquaculture industry and the scientific community. The document is structured as follows. First, the background information is presented in the ‘Introduction’. Then, the equipment deployed at Deenish Island and El Campello is described in the ‘Ocean Demonstrator Deployments’ section. Finally, the different ways in which the real-time data is delivered to the stakeholders are presented in the last section ‘Data Delivery to Server’.

Description: The EuroSea project was constructed around the ocean observing value chain. Just as intended, the value chain concept is a useful prism for designing the ocean observing and forecasting system, or, indeed, a project like EuroSea that set out to improve just this system. Indeed, several projects in the past have successfully used the value chain for this purpose, for example the AtlantOS EU-funded project or the TPOS 2020 project. In this report we summarize some of the main take home messages from EuroSea on the technical innovation and data management needs for the European Ocean Observing and Forecasting System. This report does not set out to summarize EuroSea outputs or impacts, but rather look forward on what we still have to accomplish. We do so, using the prism of the ocean observing value chain, and articulate needs in the areas of governance and coordination, design, network integration and, finally, data integration, assimilation and forecasting. This report is not a detailed list of immediate needs and next steps, but rather a compilation of the broader technical needs for the observing and forecasting system and is meant as a broad guide to the community and possibly to funders of a possible path forward.

Description: This report focuses on encouraging usage of Copernicus Marine Service products by fisheries users and scientists, and consists of a number of key studies where numerous EuroSea activities support the uptakes of Copernicus Marine Service data products, focusing on Atlantic mackerel, European hake and Atlantic tuna. The report also contains an intercomparison study focused on oceanographic equipment (CTD) to determine the most suitable sensor for a fisheries observing system. A number of recommendations are provided on how to support the use of Copernicus Marine Service products in fisheries science, such as the production of new Best Practices, stronger partnerships (fisheries scientists and oceanographers) and co-development of ocean indicators.

Description: The EuroSea project has been running for 4 years by the writing of this report, and this report covers months 33-48 of the action at a time when most tasks are completed and deliverables submitted. However, a few items still need to be finalized as we have experienced delays for a few items, mostly due to COVID, or Brexit, but we expect all of those to be solved before the end of the project by the end of 2023. The progress of the WPs is summarized below, and is described in more detail in the main part of this report. As an innovation action, EuroSea is keeping a close eye on creating impact and on creating services and products that will last past the lifetime of the project. Therefore, we would like to emphasis the registry of impacts that is published on the EuroSea website1. These about 100 areas illustrate the impact that EuroSea has had on improving the European ocean observing and forecasting system. EuroSea has produced a number of targeted services and products for ocean health, operational services and climate, that are tested and used by the stakeholders.

Description: This deliverable outlines the sustainability and business plan of the Key Exploitable Result (KER) identified in WP6 with the most potential for commercialisation. The report includes a summary of the KER Solution for marine sensors to measure and forecast oxygen, heat and pH related Extreme Marine Events onsite for aquaculture – monitoring system for extreme marine events at aquaculture sites (WP6), a market analysis in terms of the market size and value, target market, competition, market needs that are being addressed as a result of the co-development process. Information is provided on agreements arranged to continue the service in the demonstrator post project with the creation of MOUs between industry partners and a service level agreement with the cloud provider EGI foundation. The report reviews the size of the markets for the KER, the viable commercial plan and the investment sources to be pursued to further develop the results.

Description: The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort that provides high-quality, quality-controlled ocean biogeochemical bottle data with annual-updates, playing a crucial role in advancing our understanding of the Earth's oceans and their complex biogeochemical processes. This deliverable covers the GLODAP annual updates under the EuroSea funding, as well as the automatization of the quality control process of the data. Under the EuroSea funding, GLODAP has received three updates (GLODAPv2.2020, GLODAPv2.2021 and GLODAPv2.2022) with a total number of 245 cruises added, and in addition, a new version release (GLODAPv3) is planned. These updates were possible as a result of the large degree of automatization of the quality control process that ensures the accuracy of the data. The core of the quality control process is the crossover analysis that is currently performed via the 2nd QC Matlab toolbox from Lauvset and Tanhua (2015). However, following Eurosea’s vision of a user-focused, truly interdisciplinary, and responsive European ocean observing and forecasting system, this deliverable aims to migrate from the Matlab toolbox to an online web application based on the open-source software Django and Python. This will allow the user to simply upload the data file to be quality controlled and the web application performs the secondary quality control through the deep water crossover analysis just as in Matlab, and offers similar graphics for visualization. Because the crossover analysis is partially automated on this online tool, the users do not need to possess any programming knowledge in order to quality control their data. In addition, this online tool can be part of a fully automated GLODAP quality control process, without need for manual intervention.

Description: The aim of the WP3 “Network Integration and Improvements” is to coordinate and enhance key aspects of integration of European observing technology (and related data flows) for its use in the context of international ocean monitoring activities. One of the dimensions of the integrations is the constitution of thematic networks, that is, networks whose aim is to address specific observational challenges and thus to favor innovation, innovation that will ultimately support the Blue economy. In this context, the specific aim of Task 3.8 is to accelerate the adoption of molecular methods such as genomic, transcriptomic (and related “omics”) approaches, currently used as monitoring tools in human health, to the assessment of the state and change of marine ecosystems. It was designed to favor the increase the capacity to evaluate biological diversity and the organismal metabolic states in different environmental conditions by the development of “augmented observatories”, utilizing state-of-art methodologies in genomic-enabled research at multidisciplinary observatories at well-established marine LTERs, with main focus on a mature oceanographic observatory in Naples, NEREA. In addition, an effort is dedicated to connecting existing observatories that intend to augment their observations with molecular tools. Molecular approaches come with many different options for the protocols (size fractioning, sample collection and storage, sequencing etc). One main challenge in systematically implementing those approaches is thus their standardization across observatories. Based on a survey of existing methods and on a 3-year experience in collecting, sequencing and analyzing molecular data, this deliverable is thus dedicated to present the SOPs implemented and tested at NEREA. The SOPs consider a size fractioning of the biological material to avoid biases toward more abundant, smaller organisms such as bacteria. They cover both the highly stable DNA and the less stable RNA and they are essentially an evolution of the ones developed for the highly successful Tara Oceans Expedition and recently updated for the Expedition Mission Microbiomes, an All-Atlantic expedition organised and executed by the EU AtlantECO project. Importantly, they have only slight variations with respect the ones adopted by the network of genomic observatories EMOBON. Discussions are ongoing with EMOBON to perfectly align the protocols. The SOPs are being disseminated via the main national and international networks.

Description: The purpose of this report is to provide a compilation of the communication and dissemination activities in EuroSea. It also proposes, as a guide, some guidelines and considerations to be included in the Communication and Dissemination Strategy in European projects. Dissemination and communication activities are essential for the success of the European Union’s Horizon 2020 research and innovation Programme, and the EuroSea project is no exception. The project has focused on improving ocean observing and forecasting for a sustainable ocean, and effective communication has been a crucial element in bringing together the interest groups, ensuring all stakeholders are to work towards the common goal of sustainable, science-based ocean management, as well as promoting and fostering public understanding of the importance and value of the ocean and its crucial role in climate change. This document offers a summary of the consortium's activities carried out during the whole life of the project (November 2019 - October 2023) related to all EuroSea communication and dissemination tools (official website, social media, newsletter, press release), as well as materials generated for the project (visual identity, printed and audiovisual materials) and the events-based dissemination. Key considerations in planning and strategy include defining project objectives, identifying target audiences, crafting effective messages, and selecting appropriate communication channels and tools. Evaluation and adjustment are also vital to measure the effectiveness of communication and dissemination activities. Overall, this guide could serve as a resource for any team involved in communication and dissemination activities in projects from Horizon 2020. This information will be instrumental in enhancing future efforts, maximizing the impact of the activities and ensuring the success of the project.

Description: Analysis of global numerical experiments with physical and BGC forecasting model to estimate the impact of new observing system design.

Description: While originally developed for weather forecasting, the Extreme Forecast index (EFI) concept has found utility in diverse fields. This study marks the inaugural application of EFI principles to numerical ocean forecasting. EFI offers a metric to gauge the forecast's deviation from historical norms specific to the location and time of year. A heightened EFI value signifies that the forecast falls beyond the usual range of variability, signifying a higher probability of extreme conditions. This novel use of EFI stands to benefit oceanographers by identifying significant oceanic events, aiding decision-making, and supporting early warning systems, particularly for extreme marine conditions. It enhances comprehension of forecast uncertainties and facilitates clearer communication of potential risks to the public and stakeholders. Such insights are invaluable for preparedness, coastal management, and mitigating the impact of marine extremes on communities and ecosystems. EFI indices for the Mediterranean Sea are computed using a first implementation of a forecast ensemble system that is being developed for the Mediterranean Sea Monitoring and Forecasting Center of the Copernicus Marine Environment Service. This deliverable report presents the first-ever application of the EFI approach to the Mediterranean Sea. After presenting the EFI definition adopted in this study, we discuss its application to sea surface temperature (SST) and sea surface height (SSH) extremes. A case studies using ensemble forecasts for the year 2021 are presented and discussed.

Description: The report analyses the interactions between the public and private organisations involved in the project activities as members of the project consortium, internal advisory boards and stakeholders. This strong, collaborative and interdisciplinary collaboration between public and private sectors is essential to improve ocean observing and forecasting systems with innovative technological solutions also in support of the implementation process of important global strategies related to the ocean.

Description: This report provides an overview of EuroSea's initiatives focused on engaging the next generation of ocean observing and forecasting stakeholders. Many activities took place, including delivering workshops, presenting the EuroSea itinerant exhibition, collaborating with the WASCAL Floating University and the SEA-EU inter-university initiative, supporting the international Ocean Observers Initiative, and much more. Engaging the next generation of stakeholders in meaningful discussions and innovative projects is essential to ensure future-oriented intergenerational collaboration. Yet, this is often an overlooked aspect of public engagement within the Horizon 2020 landscape as it requires engagement techniques specifically tailored to reach the young generation. Within the framework of Horizon 2020, the European Union's research and innovation funding program, public engagement traditionally targets a diverse range of stakeholders, including researchers, policymakers, industry representatives, civil society organizations, NGOs, and citizens. While these efforts are crucial for fostering inclusive and transparent dialogue, targeted initiatives directed towards the younger generation and early-career ocean professionals need to be expanded. It is important to recognize the concerns, unique perspectives, and aspirations of young individuals who will inherit the outcomes of today's research and innovation. Dedicating resources to engage with the next generation is vital to ensure their active involvement in shaping their future and addressing global challenges such as the sustainability of ocean observing, monitoring, and forecasting. EuroSea has recognized the importance of fostering a deeper understanding of ocean observing and forecasting among the younger generation. This deliverable and the many activities feeding into it are a testament to EuroSea's commitment to this cause. This report focuses on the lessons learnt from a diverse array of activities engaging the next generation of ocean observing and forecasting stakeholders, demonstrating the extensive range of possibilities for involving the younger generation. It underscores the importance of tailoring approaches to different age groups, from school children to university graduates and adapting engagement strategies to their varying interests and life stages. Every experience—even the ones that did not turn out as expected—has shown to be beneficial, and it is important to share lessons learnt and identify best practices while expanding these kinds of initiatives. EuroSea's dedication to engaging the next generation of stakeholders is a significant step in fostering inter-generational dialogue and promoting blue skills and knowledge sharing. Valuable lessons have been learnt from the EuroSea engagement activities and provide guidance for future initiatives aimed at fostering a deeper understanding of our ocean among the younger generation and engaging them in conversations that impact their future on this planet.

Description: EuroSea is a holistic large-scale project encompassing the full value chain of marine knowledge, from observations to modelling and forecasting and to user-focused services. This report summarizes the legacy of EuroSea as planned and measured through a dedicated impact monitoring protocol, a holistic assessment of the project's successes in advancing and integrating European ocean observing and forecasting systems. Since its start, EuroSea has been analysing how well the project progresses towards the identified areas of impact. Impact assessment is not performance evaluation. These terms overlap but are distinct: performance relates to the efficient use of resources; impact relates to the transformative effect on the users. The EuroSea legacy report is presented through an aggregation and analysis of the EuroSea work towards achieving its impacts. Overall, over 100 impacts have been identified and presented on the website and in a stand-alone impact report. The legacy report sheds light on 32 most powerful impacts (four impacts in each of the eight EuroSea impact areas). EuroSea Impact Areas: 1. Strengthen the European Ocean Observing System (EOOS), support the Global Ocean Observing System (GOOS) and the GOOS Regional Alliances; 2. Increase ocean data sharing and integration; 3. Deliver improved climate change predictions; 4. Build capacity, internally in EuroSea and externally with EuroSea users, in a range of key areas; 5. Develop innovations, including exploitation of novel ideas or concepts; shorten the time span between research and innovation and foster economic value in the blue economy; 6. Facilitate methodologies, best practices, and knowledge transfer in ocean observing and forecasting; 7. Contribute to policy making in research, innovation, and technology; 8. Raise awareness of the need for a fit for purpose, sustained, observing and forecasting system in Europe. Ocean observing and forecasting is a complex activity brining about a variety of technologies, human expertise, in water and remote sensing measurements, high-volume computing and artificial intelligence, and a high degree of governance and coordination. Determining an impact on a user type or an area, therefore, requires a holistic assessment and a clear strategic overview. The EuroSea impact monitoring protocol has been the first known such attempt in a European ocean observing and forecasting project. The project’s progress has been followed according to the identified impact areas, through consortium workshops, stakeholder webinars, tracking, and reporting. At the end of EuroSea, we are able to demonstrate how well we have responded to the European policy drivers set out in the funding call and the grant agreement of our project, signed between the European Commission and 53 organizations, members of the EuroSea consortium. The project's impact is diverse, spanning areas from strengthening ocean observing governance to contributing to policymaking or boosting ocean research, innovation, and technology. Each impact area underscores EuroSea's commitment to a sustainable and informed approach to ocean observing and forecasting for enhanced marine knowledge and science-based sustainable blue economy and policies.

Description: Communities and their functioning are jointly shaped by ecological and evolutionary processes that manifest in diversity shifts of their component species and genotypes. How both processes contribute to community functional change over time is rarely studied. We here repeatedly quantified eco-evolutionary contributions to CO2-driven total abundance and mean cell size changes after short-, mid-, and longer-term (80, 168, and 〉 168 d, respectively) in experimental phytoplankton communities. While the CO2-driven changes in total abundance and mean size in the short- and mid-term could be predominantly attributed to ecological shifts, the relative contribution of evolution increased. Over the longer-term, the CO2-effect and underlying eco-evolutionary changes disappeared, while total abundance increased, and mean size decreased significantly independently of CO2. The latter could be presumably attributed to CO2-independent genotype selection which fed back to species composition. In conclusion, ecological changes largely dominated the regulation of environmentally driven phytoplankton functional shifts at first. However, evolutionary changes gained importance with time, and can ultimately feedback on species composition, and thus must be considered when predicting phytoplankton change.

Description: Eutrophication-driven harmful algal blooms (HABs) can have secondary effects on larval fishes that rely on estuaries as nurseries. However, few studies worldwide have quantified these effects despite the global rise in eutrophication. This study presents a novel approach using biochemical body condition analyses to evaluate the impact of HABs on the growth and body condition of the larvae of an estuarine resident fish. Recurrent phytoplankton blooms of Heterosigma akashiwo occur in the warm-temperate Sundays Estuary on the southeast coast of South Africa. The response in body condition and assemblage structure on larval estuarine roundherring (Gilchristella aestuaria) was measured in conjunction with bloom conditions, water quality and zooplanktonic prey and predators. Larvae and early juveniles were sampled during varying intensity levels, duration and frequency of hypereutrophic blooms. This study demonstrated that extensive HABs could significantly impact larval roundherring, G. aestuaria, by decreasing larval nutritional condition and limiting their growth, resulting in poor grow-out into the juvenile phase. Poor condition and growth may likely affect recruitment success to adult populations, and since G. aestuaria is an important forage fish and zooplanktivore, poor recruitment will hold consequences for estuarine food webs.

Description: Methane (CH4) is a climate-relevant trace gas that is emitted from the open and coastal oceans in considerable amounts. However, its distribution in remote oceanic areas is largely unknown. To fill this knowledge gap, dissolved CH4 was measured at nine stations at 75°S in the Ross Sea during austral summer in January 2020. CH4 undersaturation (mean: 82 ± 20%) was found throughout the water column. In subsurface waters, the distribution of CH4 mainly resulted from mixing of water masses and in situ consumption, whereas the CH4 concentrations in the surface mixed layer were mainly driven by air–sea exchange and diapycnal diffusion between the surface and subsurface layers, as well as consumption of CH4. With a mean air–sea CH4 flux density of −0.44 ± 0.34 μmol m−2 d−1, the Ross Sea was a substantial sink for atmospheric CH4 during austral summer, which is in contrast with most oceanic regions, which are known sources.

Description: Abundance, biomass and respiration rates of dominant medium- to larger-sized copepod species (ML class) from the upwelling system off Peru (8.5-16°S) were determined along with their carbon ingestion and egestion rates. Small copepods (S class) were included for comparisons of community rates. Overall, abundance/biomass was highest in the upper 50 m and decreased with depth and thus also community ingestion and egestion. Ingestion of the ML class (0-50 m) in shelf regions (14-515 mg C m -2 d -1 ) was lower in the south compared to the north and central study areas, while their offshore ingestion (11-502 mg C m -2 d -1 ) was comparable across regions (8.5-16°S). Ingestion rates (0-50 m) of the S class were in a range similar to those of the ML class in shelf regions (100-417 mg C m -2 d -1 ) but were higher offshore (177-932 mg C m -2 d -1 ). Calanus chilensis and the S class contributed most to total ingestion in the north, while in the south, Centropages brachiatus had the highest community ingestion aside from the S class. Egestion varied from 3-155 mg C m -2 d -1 for the ML class and 30-280 mg C m -2 d -1 for the S class. The high community rates highlight the crucial role of both size classes for carbon budgets in the northern Humboldt Current System off Peru and indicate that the ML class may enhance passive vertical carbon flux, whereas the S class may support carbon remineralization rates in surface waters.

Description: Water column imaging multibeam echo sounder systems (MBESs) are a promising technology for quantitative estimates of the gas bubble volume flow within large gas seepage areas. Considerable progress has been made in recent years toward applicable calibration methods for MBESs as well as developing inversion models to convert acoustically measured backscattering cross sections to gas bubble volume flow. However, MBESs are still not commonly used for quantitative gas flow assessments. A reason for this is the absence of published processing methods that demonstrate how MBES data can be processed to quantitatively represent bubble streams. Here, we present a novel method (echo grid integration) that allows for assessing the aggregated backscattering cross section of targets within horizontal water layers. This derived value enables quantifying bubble stream gas flow rates using existing acoustic inversion methods. The presented method is based on averaging geo-referenced volume backscattering coefficients onto a high-resolution 3D voxel-grid. The results are multiplied with the voxel volume to represent measurements of the total backscattering cross-section within each voxel cell. Individual gridded values cannot be trusted because the beam pattern effects cause the values of individual targets to “smear” over multiple grid-cells. The true aggregated backscattering cross-section is thus estimated as the integral over the grid-cells affected by this smearing. Numerical simulation of MBES data acquisition over known targets assesses the method's validity and quantify it's uncertainty for different, realistic scenarios. The found low measurement bias (〈 1%), and dispersion (〈 5%) are promising for application in gas flow quantification methods.

Description: Narcomedusae play a key role as top-down regulators in the midwater, the largest and most understudied biome on Earth. Here, we used ecological niche modeling in three-dimensions (3D), ecomorphology, and phylogeny, to answer evolutionary and ecological questions about the widespread narcomedusan genus Solmissus. Our phylogenetic analyses confirmed that Solmissus incisa represents a complex of several cryptic species. Both the different genetic clades and tentacle morphotypes were widespread and often overlapped geographically- the main difference in their distribution and ecological niche being depth. This demonstrated the importance of including the third dimension when modeling the distribution of pelagic species. Contrary to our hypothesis, we found the modeled distribution of the Solmissus genus (n = 1444) and both tentacle morphotypes to be mostly driven by low dissolved oxygen values and a salinity of 34, and slightly by depth and temperature. Solmissus spp. were reproducing all year round, with specimens reproducing in slightly warmer waters (up to 1.25 & DEG;C warmer). Our results suggest that Solmissus spp. will likely come out as climate change winners by expanding their distribution when facing ocean deoxygenation and by increasing their reproduction due to global warming. However, because most available midwater data comes from the northern Pacific, this sampling bias was undoubtedly reflected in the output of our ecological niche models, which should be assessed carefully. Our study illustrated the value of online databases including imagery and videography records, for studying midwater organisms and treating midwater biogeographic regions as 3D spaces.

Description: Microbes in the dark ocean are exposed to hydrostatic pressure increasing with depth. Activity rate measurements and biomass production of dark ocean microbes are, however, almost exclusively performed under atmospheric pressure conditions due to technical constraints of sampling equipment maintaining in situ pressure conditions. To evaluate the microbial activity under in situ hydrostatic pressure, we designed and thoroughly tested an in situ microbial incubator (ISMI). The ISMI allows autonomously collecting and incubating seawater at depth, injection of substrate and fixation of the samples after a preprogramed incubation time. The performance of the ISMI was tested in a high-pressure tank and in several field campaigns under ambient hydrostatic pressure by measuring prokaryotic bulk H-3-leucine incorporation rates. Overall, prokaryotic leucine incorporation rates were lower at in situ pressure conditions than under to depressurized conditions reaching only about 50% of the heterotrophic microbial activity measured under depressurized conditions in bathypelagic waters in the North Atlantic Ocean off the northwestern Iberian Peninsula. Our results show that the ISMI is a valuable tool to reliably determine the metabolic activity of deep-sea microbes at in situ hydrostatic pressure conditions. Hence, we advocate that deep-sea biogeochemical and microbial rate measurements should be performed under in situ pressure conditions to obtain a more realistic view on deep-sea biotic processes.

Description: Global warming, bioinvasions, and parasitism affect single-species performances and species interactions, substantially impacting the structure and stability of marine ecosystems. In light of accelerated global change, the information derived from studies focusing on single species and single drivers is insufficient, calling for a multi-stressor approach under near-natural conditions. We investigated the effects of warming (+3°C) on the performance of a benthic community composed of native and invasive macroalgae, consumers and a trematode parasite in a mesocosm setting. We also assessed the effects of warming and parasitism on the survival and growth of gastropods and mussels and the thermal dependency of trematode performance. Our findings show that warming and grazing by infected gastropods had a large detrimental effect on the invasive macroalga growth. Furthermore, the single and interactive effects of parasitism and warming were detrimental to intermediate host survival and growth, especially to large mussels. Finally, cercarial emergence positively correlated to the natural peaks of summer temperatures, while infection intensity in mussels was higher in larger individuals. Our findings suggest that grazing and warming will be detrimental to the invasive macroalga, favoring the native alga. Moreover, parasitism will enhance grazing, especially in summer, when higher temperatures trigger parasite development. However, parasite-enhanced grazing may be buffered by higher mortality or a shift in the size of infected intermediate hosts under warming. Our findings demonstrate how complex effects of ocean warming can be on food webs and how they can be mediated by parasitism and, as a result, influence native and invasive macroalgae differently.

Description: Estuaries regulate carbon cycling along the land-ocean continuum and thus influence carbon export to the ocean, and global carbon budgets. The Elbe Estuary in Germany has been altered by large anthropogenic perturbations, such as widespread heavy metal pollution, minimally treated wastewater before the 1980s, establishment of wastewater treatment plants after the 1990s, and an overall nutrient and pollutant load reduction in the last three decades. Based on an extensive evaluation of key ecosystem variables, and an analysis of the available inorganic and organic carbon records, this study has identified three ecosystem states in recent history: the polluted (1985–1990), transitional (1991–1996), and recovery (1997–2018) states. The polluted state was characterized by very high dissolved inorganic carbon (DIC) and ammonium concentrations, toxic heavy metal levels, dissolved oxygen undersaturation, and low pH. During the transitional state, heavy metal pollution decreased by 〉 50%, and primary production re-established in spring to summer, with weak seasonality in DIC. Since 1997, during the recovery state, DIC seasonality was driven by primary production, and DIC significantly increased by 〉 23 μmol L−1 yr−1 in the mid to lower estuary, indicating that, along with the improvement in water quality the ecosystem state is still changing. Large anthropogenic perturbations can therefore alter estuarine ecosystems (on the order of decades), as well as induce large and complex biogeochemical shifts and significant changes to carbon cycling.

Description: Tide gauge metadata catalogue V1.0 (EU-TGN or European and adjacent areas Tide Gauge Network Inventory); accuracy and precision review of the EuroGOOS Tide Gauge Task Team (TGTT) database of permanent monitoring nodes for European and adjacent coastlines. A metadata catalogue of all permanent, managed tide level monitoring stations across Europe and adjacent coastlines, including North Africa.

Description: The WP5 Coastal Resilience and Operational Services demonstrator aims to design and deploy innovative sea level monitoring systems, integrating their observations with downscaled model forecasts into an alert-based monitoring and forecasting tool (OSPAC) that is design for use by ports and local authorities. As part of this data integration process, sea level observations must be quality-controlled in near real-time, to minimise the risk of false alarms. This has historically been achieved using an established open-source software package (SELENE). Recent progress using automatic quality control (QC) in delayed mode has led to the development of additional functionality that could enhance the SELENE software. At the same time, the delivery of new sea level time series from Global Navigation Satellite Systems (GNSS), provides an additional means of data validation. WP5 aims to enhance the SELENE software by incorporating these enhancements and new data feeds, thereby improving the quality of the OSPAC tool. A delay in the installation of the sea level monitoring systems has led to a corresponding delay in the provision of data inputs to SELENE and subsequently to OSPAC. Some development work has been possible using alternative test time series, but a key implementer in presently taking parental leave, which will delay further development work until October 2023. This deliverable report will be updated thereafter.

Description: This report presents steps for the design and implementation of a marine observatory providing current and forecasted oceanic conditions relevant to the aquaculture sector, with particular focus on “Extreme Marine Events”. Examples of successful implementation of these guidelines in the framework of the EuroSea project are presented for two aquaculture sites: Deenish Island in Ireland and El Campello in Spain. The process starts with stakeholder interaction to understand their main needs and concerns and is followed by the design of the software architecture that carries out the data acquisition, post-processing and visualisation in an open-access web platform. User feedback is of paramount importance during the whole process to ensure the services offered match the needs of the aquaculture sector.

Description: The overall goal of this report is to analyse the EuroSea itinerant exhibition as a case study of public engagement activity. Aimed at the general public, this modular and itinerant exhibition raises awareness about the EuroSea project while also promoting ocean literacy and highlighting the importance of ocean observing and forecasting. Public engagement plays a crucial role in Horizon 2020, the EU's research and innovation funding program. It aims to bridge the gap between researchers and society, ensuring that their work is aligned with societal needs and values. This involves bringing together various stakeholders, including researchers, policymakers, industry representatives, civil society organizations, NGOs, and citizens, to foster inclusive and transparent dialogue. The benefits of public engagement are evident in the research and innovation process. It stimulates creativity and innovation, brings ocean science to a broader audience, builds trust and credibility and promotes ocean literacy and empowerment among citizens. Within Horizon 2020, the EuroSea Communication Work Package 8 focuses on public engagement activities related to ocean observing and forecasting, among other activities. To raise awareness about the EuroSea project and ocean observation, the EuroSea itinerant exhibition was created. This exhibition features printed panels, audiovisuals, and a photobooth that could be adapted and translated for different locations. The exhibition has been presented at 8 events and locations across Europe, aiming to engage the general public, promote ocean literacy, and emphasize the importance of ocean observation and forecasting. This report specifically focuses on three events targeted to the general public where the EuroSea exhibition was showcased: 1) 2022 European Researcher’s Night. 2022, September 30th in Palma (Mallorca, Spain); 2) 25th Galway Science & Technology Festival. 2022, November 13th in Galway (Ireland); and 3) 10th ‘Science for all’. 2023, May 11-13th in Palma (Mallorca, Spain). To evaluate the impact of the EuroSea exhibition, an online survey was conducted. The survey assessed visitor satisfaction, knowledge acquisition, interest in the topic, prior knowledge of EuroSea and ocean observation, and preferences for future engagement activities. A total of 41 people participated in the survey. The main results obtained from the analysis of the data demonstrate an overall positive satisfaction with the exhibition and a high level of interest in the topic. Participants reported acquiring new knowledge and expressed a desire for future engagement activities. Additionally, the survey provided valuable demographic insights into the participants, including their age, gender, employment status, educational background, and frequency of engagement in ocean science outreach activities. The findings from the survey will contribute to the improvement of future public engagement activities by better understanding the needs and interests of the public regarding ocean observation and forecasting. This document emphasizes the significance of public engagement in research and innovation, specifically within the EuroSea project. The EuroSea itinerant exhibition was developed to raise awareness and promote ocean literacy, while the survey conducted during the exhibition provided valuable insights into participant satisfaction and preferences. This information will be instrumental in enhancing future engagement efforts.

Description: The EuroSea project is improving the coordination of the European ocean observing and forecasting system to strengthen its capability of tacking the societal challenges related to ocean health, climate change, mitigation of ocean-related natural hazards, and the sustainable exploitation of marine ecosystem services in the Blue Economy. The scientific excellence of the project is based on its better integration, assimilation, coordination and governance of methods, practices, and instruments to collect fit-for-purpose ocean data and the development of innovative tools and solutions to manage some natural coastal risks and support more efficiently fisheries and aquaculture. The societal impact of the research and innovation activities carried out by the EuroSea consortium is enabled through the responsible research and innovation (RRI) policy concept implemented throughout the project progress development and, in particular, in the demonstrators work packages and in those activities focused on communication, dissemination, exploitation and legacy. This report summarizes how the six articulations of the RRI approach were applied so far in the EuroSea project. It also offers some recommendations to boost the societal benefits provided by inclusivity, equality, ethics, transparency and collaborative co-design and co-creation in the research and innovation process applied to ocean observing. Now, and even more in the future, it is necessary to multiply the opportunities to share knowledge and expertise among all transdisciplinary actors to be engaged in improving the European and global ocean observing and forecasting. Moreover, the emerging critical problems affecting the ocean require an increased public involvement through open access to ocean information, effective communication and dissemination of research findings, more diffuse ocean literacy and collective mobilisation. Only these factors seem to be able to establish the global common responsibility necessary to enhance the ocean sustainability, as advocated by the UN Decade for Ocean Science for Sustainable Development supporting the achievement of the SDG 14 in the UN Agenda 2030.

Description: This report presents the results of task 7.3 on “Quantification of improvements in carbon flux data for the tropical Atlantic based on the multi-platform and neural network approach”. To better constrain changes in the ocean’s capture and sequestration of CO2 emitted by human activities, in situ measurements are needed. Tropical regions are considered to be mostly sources of CO2 to the atmosphere due to specific circulation features, with large interannual variability mainly controlled by physical drivers (Padin et al., 2010). The tropical Atlantic is the second largest source, after the tropical Pacific, of CO2 to the atmosphere (Landschützer et al., 2014). However, it is not a homogeneous zone, as it is affected by many physical and biogeochemical processes that vary on many time scales and affect surrounding areas (Foltz et al., 2019). The Tropical Atlantic Observing System (TAOS) has progressed substantially over the past two decades. Still, many challenges and uncertainties remain to require further studies into the area’s role in terms of carbon fluxes (Foltz et al., 2019). Monitoring and sustained observations of surface oceanic CO2 are critical for understanding the fate of CO2 as it penetrates the ocean and during its sequestration at depth. This deliverable relies on different observing platforms deployed specifically as part of the EuroSea project (a Saildrone, and 5 pH-equipped BGC-Argo floats) as well as on the platforms as part of the TAOS (CO2-equipped moorings, cruises, models, and data products). It also builds on the work done in D7.1 and D7.2 on the deployment and quality control of pH-equipped BGC-Argo floats and Saildrone data. Indeed, high-quality homogeneously calibrated carbonate variable measurements are mandatory to be able to compute air-sea CO2 fluxes at a basin scale from multiple observing platforms.

Description: This report summarises demonstrated benefit from integrating BOOS and HELCOM observations with CMEMS observations, including i) improved observation data accessibility by BOOS, CMEMS INSTAC and EMODnet, ii) improved quality of frequently updated CMEMS reanalysis, and iii) improved quality and update frequency of eutrophication assessment in the Baltic Sea based on the reanalysis. Also, feasibility for extending this approach to other regional seas, other indicators, and fishery advice applications is analysed and recommendations from the workshop on “Full value chain integration for monitoring and assessment” are provided.

Description: Currently, the ocean carbon sink annually removes about a third of anthropogenic fossil fuel and industrial CO2 emissions, reducing therefore climate change damages and CO2 abatement costs. While the land sinks have entered climate policies, the ocean sink has not—for good reasons since the former stores carbon within the boundaries of a state while the ocean removes carbon from the atmosphere rather in its property as a global common. However, the question remains what is the value of the ocean carbon sink and should it be differently attributed when comparing a coastal state with a large exclusive economic zone (EEZ) compared to landlocked state. Here, we demonstrate different approaches to value the ocean sink, comparing a climate-change damage-based approach with an abatement, market-based approach. We use a high-resolution carbon flux dataset (0.25x0.25 degree) to estimate the ocean carbon sink and source in coastal areas. We assign a net sink of 1.72 GtC proportional to countries with negative carbon fluxes in their EEZ. In our calculation the annual value of the global ocean sink ranges from 61.19 B USD (Std 31.80), equivalent to the 2021 GDP of Slovenia, to 1433 B USD (Std 94.30), equivalent to the 2021 GDP of Spain (World Bank data) for the abatement cost-based assessment approach (assuming full emission trading and low ambition levels in the national determined contribution) and for the climate-change damage-based assessment approach relying on an upper value of the social cost of carbon in our investigation. By breaking down the carbon sink by nations EEZ we estimate which countries are the largest donors of ocean carbon wealth and which countries would be affected the most if a weakening of the ocean sink would need to be compensated by higher emission reduction levels.

Description: WP5’s Coastal Resilience and Operational Services demonstrator aimed to deliver capacity-building work in a developing country (Colombia) to enable local stakeholders to install a state-of-the-art sea level monitoring system independently. In practice, the WP5 team met this objective and has additionally delivered capacity-building work in tide gauge installation in 2 other countries (Spain and Italy), in order to support the longevity of the EuroSea tide gauge systems. As planned, training material was delivered in relation to the maintenance of these systems in all 3 locations. All installation procedures were fully-documented to support the tide gauge operators in case the systems are to be relocated, refurbished or decommissioned at a future data (for example, in the event of port redevelopment works). Training in the use of quality control software and the OSPAC (Operational Services at the Service of Ports and Cities) tool is planned (but pending) and this deliverable will be updated once that work is complete.

Description: The present deliverable is a continuation of deliverable D4.21, in which we presented the first steps in the design and preparation of different reanalysis simulations assimilating glider data. We here show the assessment and intercomparison of CMCC MedFS and SOCIB WMOP systems experiments. We have performed, for each system, three different experiments, running a one-year simulation during 2017. We compare a free-run simulation without data assimilation (FREE) and two reanalyses including assimilation: one considering only the generic data sources included in each operational system (NOGLID) and another one adding glider observations to the previous dataset (GLIDER). The models are assessed and inter compared to each other, focusing on the performance to represent the observed 3D structure of the ocean and on their capacity to recreate physical processes, as an anticyclonic eddy structure present in the Balearic sea. Results show how in both systems the use of glider observations can help to further improve the results obtained when using data assimilation, helping to an enhancement of the forecasting capabilities.

Description: The accuracy of the Copernicus Marine Environment and Monitoring Service (CMEMS) ocean analysis and forecasts highly depend on the availability and quality of observations to be assimilated. In situ observations are complementary to satellite observations that are restricted to the ocean surface. Higher resolution model forecasts are required by users of the CMEMS global and regional ocean analysis and forecasts. To support this with an efficient observational constrain of the model forecast via data assimilation, an increase observation coverage is needed, associated with an improved usage of the available ocean observations. This work exploits the capabilities of operational systems to provide comprehensive information for the evolution of the GOOS. In this report, we analyse the use and the efficiency of the in-situ observations to constrain regional and global Mercator Ocean systems. Physical and biogeochemical variables are considered. The in-situ observations are used either to estimate physical ocean state at global and regional scale via data assimilation or to estimate BGC model parameters. The impact of the physical in situ observations assimilated in open ocean and coastal areas is assessed with numerical data assimilation experiments. The experiments are conducted with the regional 1/36° resolution and global 1/12° resolution systems operated by Mercator Ocean for the Copernicus Marine Service. For the global physical ocean, the focus is on the tropical ocean to better understand how the tropical mooring observations constrain the intraseasonal to daily variability and the complementarity with satellite observations and the deep ocean. The tropical moorings provide unique high frequency observations at different depth, but they are far away from each other, so part of the signal in the observation are decorrelated from one mooring to the others. It is only via an integrated approach, as data assimilation into a dynamical model and complementarity with other observing networks that those observations can efficiently constrain the different scales of variability of the tropical ocean circulation. As the satellite observations brings higher spatial resolution between the tropical moorings but for the ocean surface, we show that the tropical mooring and Argo profile data assimilation constrain the larger scale ocean thermohaline vertical structure (EuroSea D2.2; Gasparin et al., 2023). The representation of the high frequency signals observed at mooring location is also significantly improved in the model analysis compared to a non-assimilative simulation. The ocean below 2000 m depth is still largely under constrained as very few observations exist. Some deep ocean basins, as the Antarctic deep ocean, shows significant trend over the past decade but they are still not accurately monitored. Based on the spread of four deep ocean reanalysis estimates, large uncertainties were estimated in representing local heat and freshwater content in the deep ocean. Additionally, temperature and salinity field comparison with deep Argo observations demonstrates that reanalysis errors in the deep ocean are of the same size as or even stronger than the observed deep ocean signal. OSSE already suggested that the deployment of a global deep Argo array will significantly constrain the deep ocean in reanalysis to be closer to the observations (Gasparin et al., 2020). At regional and coastal scales, the physical ocean circulation is dominated by higher frequency, smaller scale processes than the open ocean which requires different observation strategy to be well monitor. The impact of assimilating high frequency and high-resolution observations provided by gliders on European shelves is analysed with the regional Iberic Biscay and Irish (IBI) system. It was found that repetitive glider sections can efficiently help to constrain the transport of water masses flowing across those sections. BGC ocean models are less mature than physical ocean models and some variable dependencies are still based on empirical functions. In this task, Argo BGC profile observations were used to optimize the parameters of the global CMEMS biogeochemical model, PISCES. A particle filter algorithm was chosen to optimize a 1D configuration of PISCES in the North Atlantic. The optimization of the PISCES 1D model significantly improves the model's ability to reproduce the North Atlantic bloom Recommendations on the in-situ network extensions for real time ocean monitoring are given based on those results, and the one also obtained in the WP2, Task 2.2 where data assimilation experiments but with simulated observations where conducted. Argo extension and the complementarity with satellite altimetry was also extensively studied.

Description: This document presents the results of simulations that include glider profiles assimilation. Simulations are performed with the Marine Copernicus operational biogeochemical model system of the Mediterranean Sea. The deliverable shows that the assimilation of BGC-glider is feasible in the contest of biogeochemical operational systems and that it is built upon the experience of BGC-Argo float data assimilation. Different configuration of the assimilation of glider data have been tested to assess the impact of the physical and biogeochemical glider observations. The deliverable also describes the pre-processing activities of the BGC-glider data to provide qualified observations for the data assimilation and the cross validation of chlorophyll glider data with other sensors (ocean colour and BGC-Argo floats). Results of the simulations show that BGC-glider data assimilation, as already shown for BGC-Argo floats, provides complementary information with respect to Ocean Colour data (which is the only or the most commonly assimilated data in biogeochemical operational systems). Beside their relatively limited horizontal spatial impact, the assimilation of BGC profiles can constrain model simulations for relevant biogeochemical processes in specific periods (summer and transition periods) and layers (surface and subsurface). Results also highlight the importance of the assimilation modelling systems that can efficiently resolve the inconsistencies between chlorophyll observations of different sensors.

Description: This D3.17 “Data Integration” deliverable has been written in complementarity of the deliverables D3.13 “Data handbook” and D3.7 “Networks harmonisation recommendations”. It has been primarily written with the aim to be useful for users, looking for in situ data or datasets, in their choice of data infrastructures (CMEMS - Copernicus Marine Environment Monitoring Service – EMODnet – European Marine Observation and Data network - and SeaDataNet) best suited to their needs. To start, this deliverable provides a description of these three major European data integrators and explains how to access to the data and what type of data it is possible to find. The cooperation between these three data infrastructures is also presented. A recommendation about what type of metadata should be attached to the measurement is also included in this deliverable. Its objective is to encourage data infrastructures to harmonize their metadata, which would allow data marine users to switch more easily from one infrastructure to another one and thus extend access to more data. This deliverable also presents two case studies, in which we put ourselves in the place of a in situ marine data user.

Description: This deliverable presents the Final Assessment of the observation and thematic networks as those represented in work package 3 of EuroSea, taking as a reference the information on Deliverable 3.2 Observing Network Initial Assessment. Following the same approach with D3.2 the original questionnaire was modified accordingly in order to depict the progress made on the same Network Attributes, Commitments and Benefits following the GOOS, OCG guidelines. The unforeseen COVID-19 pandemic had significant effects upon WP3 activities since the main mechanism foreseen to advance progress within the different networks was the organization of in person workshops. Moreover, adequate funds were allocated towards this in order to promote inclusivity and participation. Adapting to the new situation the first series of workshops had to be changed into online only events which despite the inherent difficulty, proved to have significant advantages as well. In particular they gave the opportunity for a significant number of people to join from all around the globe and participate in the events (for example the Sea Level WS). Another challenge proved to be the variability within some networks with sub-components or sub-groups having significantly different characteristics. In particular Eulerian platforms comprise a wide range of platforms - fixed moorings, surface buoys, cable bottom platforms - with some of them being part of mature and well-developed networks (OceanSITES, EMSO etc) while other are loose partners of on-going programs and projects (JERICO RI, coastal buoys). EuroSea activities had a significant positive impact on all the observing and thematic networks, actively promoting synergies and collaboration, with most of them successfully reaching Framework Processes Readiness Criteria Level 7 and above. Although progress at many different aspects must continue beyond EuroSea, it is important that the framework has been set. It is thus suggested that an annual evaluation/assessment process for each network/task team is adopted within EuroGOOS. By going through this exercise annually, each EuroGOOS Task Team (observing network) will be able to describe its current state, assess progress and most importantly to define next targets and priorities.

Description: Sea-level change is geographically non-uniform, with regional departures that can reach several times the global average rate of change. Characterizing this spatial variability and understanding its causes is crucial to the design of adaptation strategies for sea-level rise. This, as it turns out, is no easy feat, primarily due to the sparseness of the observational sea-level record in time and space. Long tide gauge records are restricted to a few locations along the coast. Satellite altimetry offers a better spatial coverage but only since 1992. In the Mediterranean Sea, the tide gauge network is heavily biased towards the European shorelines, with only one record with at least 35 years of data on the African coasts. Past studies have attempted to address the difficulties related to this data sparseness in the Mediterranean Sea by combining the available tide gauge records with satellite altimetry observations. The vast majority of such studies represent sea level through a combination of altimetry-derived empirical orthogonal functions whose temporal amplitudes are then inferred from the tide gauge data. Such methods, however, have tremendous difficulty in separating trends and variability, make no distinction between relative and geocentric sea level, and tell us nothing about the causes of sea level changes. Here, we combine observational data from tide gauges and altimetry with sea-level fingerprints of land-mass changes using a Bayesian hierarchical model (BHM) to quantify the sources of sea-level changes since 1960 in the Mediterranean Sea. The Bayesian estimates are provided on 1/4o x 1/4o regular grid. We find that Mediterranean Sea level rose at a relatively low rate from 1960 to 1990, at which point it started rising significantly faster with comparable contributions from sterodynamic sea level (ocean dynamics and thermal expansion) and land-mass changes.

Description: Tide gauges can capture sea level variability on multiple timescales, from high frequency events like waves, tides and tsunamis, to seasonal and interannual changes and the longer-term trends associated with Climate Change. However, financial constraints dictate that they are often maintained to lower standards than the stringent accuracy requirements demanded by the IOC-UNESCO’s Global Sea Level Observing System (GLOSS) for monitoring sea level rise. In addition, a sparsity of Global Navigation Satellite System (GNSS) receivers at the coast means that there are large uncertainties in rates of land motion at tide gauges, which also hampers the estimation of long-term sea level trends. Task 5.1.1 has devised prototype low maintenance tide gauge systems, powered by renewable energy and which monitor both land motion and sea level using novel techniques such as ground-based GNSS Interferometric Reflectometry (GNSS-IR). These systems eliminate the need for costly ongoing levelling exercises and also incorporate customisations to local monitoring needs, such as sensors for lightning detection and wave height. Despite a number of unforeseen setbacks, these prototype systems are now operating at 2 locations in the Mediterranean Sea and a third system is in transit to Colombia for installation by local stakeholders who have been trained in the installation methodology by the WP5 team. It is hoped that there is potential to advance these technological solutions as a global standard, via the GLOSS community.

Description: The Humboldt Upwelling System (HUS) supports high levels of primary production and has the largest single-stock fishery worldwide. The high fish production is suggested to be related to high trophic transfer efficiency in the HUS. Mucous-mesh grazers (pelagic tunicates and gastropods) are mostly of low nutritious value and might reduce trophic transfer efficiency when they are locally abundant. Unfortunately, little is known about the spatial dynamics of mucous-mesh grazers from Peruvian waters, limiting our understanding of their potential ecological role(s). We provide a spatial assessment of mucous-mesh grazer abundance from the Peruvian shelf in austral summer 2018/2019 along six cross-shelf transects spanning from 8.5 to 16° S latitude. The community was dominated by appendicularians and doliolids. Salps occurred in high abundance but infrequently and pelagic gastropods were mostly restricted to the North. At low latitudes, the abundance of mucous-mesh grazers was higher than some key species of crustacean mesozooplankton. Transects in this region had stronger Ekman-transport, higher temperature, lower surface turbidity and a broader oxygenated upper water layer compared to higher-latitude transects. Small-scale lateral intrusions of upwelled water were potentially associated with high abundances of doliolids at specific stations. The high abundance and estimated ingestion rates of mucous-mesh grazers in the northern HUS suggest that a large flux of carbon from lower trophic levels is shunted to tunicates in recently upwelled water masses. The data provide important information on the ecology of mucous mesh grazers and stress the relevance to increase research effort on investigating their functioning in upwelling systems.

Description: The Observing Air–Sea Interactions Strategy (OASIS) is a new United Nations Decade of Ocean Science for Sustainable Development programme working to develop a practical, integrated approach for observing air–sea interactions globally for improved Earth system (including ecosystem) forecasts, CO2 uptake assessments called for by the Paris Agreement, and invaluable surface ocean information for decision makers. Our “Theory of Change” relies upon leveraged multi-disciplinary activities, partnerships, and capacity strengthening. Recommendations from 〉40 OceanObs’19 community papers and a series of workshops have been consolidated into three interlinked Grand Ideas for creating #1: a globally distributed network of mobile air–sea observing platforms built around an expanded array of long-term time-series stations; #2: a satellite network, with high spatial and temporal resolution, optimized for measuring air–sea fluxes; and #3: improved representation of air–sea coupling in a hierarchy of Earth system models. OASIS activities are organized across five Theme Teams: (1) Observing Network Design & Model Improvement; (2) Partnership & Capacity Strengthening; (3) UN Decade OASIS Actions; (4) Best Practices & Interoperability Experiments; and (5) Findable–Accessible–Interoperable–Reusable (FAIR) models, data, and OASIS products. Stakeholders, including researchers, are actively recruited to participate in Theme Teams to help promote a predicted, safe, clean, healthy, resilient, and productive ocean.

Description: Plankton is a massive and phylogenetically diverse group of thousands of prokaryotes, protists (unicellular eukaryotic organisms), and metazoans (multicellular eukaryotic organisms; Fig. 1). Plankton functional diversity is at the core of various ecological processes, including productivity, carbon cycling and sequestration, nutrient cycling (Falkowski 2012), interspecies interactions, and food web dynamics and structure (D'Alelio et al. 2016). Through these functions, plankton play a critical role in the health of the coastal and open ocean and provide essential ecosystem services. Yet, at present, our understanding of plankton dynamics is insufficient to project how climate change and other human-driven impacts affect the functional diversity of plankton. That limits our ability to predict how critical ecosystem services will change in the future and develop strategies to adapt to these changes.

Description: The 4th Evolving and Sustaining Ocean Best Practices Workshop was held online during the period 17-30 September 2020, addressing community needs for advanced method development and implementation in ocean observations, data management and application. The proceedings for the subject workshop are provided in 2 volumes. Volume 1 addresses the meeting overview, and Volume 2 - Annexes includes the complete Working Group reports.

Description: Report on European glider network coordination (Best Practices, OceanGliders, metadata and data management

Description: Best practices for eulerian observatories

Description: Harmonisation data management procedures and implementing FAIR principles with the target to serve the data infrastructures: Copernicus Marine Service and EMODnet (first stage) as well as SeaDataNet and historical National Oceanographic Data Centres (later stage)

Description: This deliverable reports on the achievements of the EuroSea project in developing targeted indicators co-designed with demonstrators (WPs 5–7) and forecasts (WP4). For this, the indicators implemented are expressed in term of Essential Ocean/Climate Variables (EOVs/ECVs) together with their requirements. The co-development undertaken address ocean indicators for all range of scales: from the large, basin scale to the regional and local scales. Such approach as well as the proposed solution to focus, at regional/local scales, on EEZs, represent one of the innovative results of EuroSea that will help to rationalize risks assessments and guide environmental management approaches in European Seas.

Description: This deliverable is intended to give an overview of the EuroSea actions at the interface between science and policy, ensuring the EuroSea results are useful for policy and decision-makers both at the EU, regional, and national levels.

Description: Phytoplankton stand at the base of the marine food-web, and play a major role in global carbon cycling. Rising CO2 levels and temperatures are expected to enhance growth and alter carbon:nutrient stoichiometry of marine phytoplankton, with possible consequences for the functioning of marine food-webs and the oceanic carbon pump. To date, however, the consistency of phytoplankton stoichiometric responses remains unclear. We therefore performed a meta-analysis on data from experimental studies on stoichiometric responses of marine phytoplankton to elevated pCO2 and 3–5° warming under nutrient replete and limited conditions. Our results demonstrate that elevated pCO2 increased overall phytoplankton C:N (by 4%) and C:P (by 9%) molar ratios under nutrient replete conditions, as well as phytoplankton growth rates (by 6%). Nutrient limitation amplified the CO2 effect on C:N and C:P ratios, with increases to 27% and 17%, respectively. In contrast to elevated pCO2, warming did not consistently alter phytoplankton elemental composition. This could be attributed to species- and study-specific increases and decreases in stoichiometry in response to warming. While our observed moderate CO2-driven changes in stoichiometry are not likely to drive marked changes in food web functioning, they are in the same order of magnitude as current and projected estimations of oceanic carbon export. Therefore, our results may indicate a stoichiometric compensation mechanism for reduced oceanic carbon export due to declining primary production in the near future

Description: Understanding how marine microbial food webs and their ecosystem functions are changing is crucial for projections of the future ocean. Often, simplified food web models are employed and their solutions are only evaluated against available observations of plankton biomass. With such an approach, it remains unclear how different underlying trophic interactions affect interpretations of plankton dynamics and functioning. Here, we quantitatively compare four hypothetical food webs to data from an existing mesocosm experiment using a refined version of the Minimum Microbial Food Web model. Food web representations range from separated food chains to complex food webs featuring additional trophic links including intraguild predation (IGP). Optimization against observations and taking into account model complexity ensures a fair comparison of the different food webs. Although the different optimized model food webs capture the observations similarly well, projected ecosystem functions differ depending on the underlying food web structure and the presence or absence of IGP. Mesh-like food webs dominated by the microbial loop yield higher recycling and net primary production (NPP) than models dominated by the classical diatom-copepod food chain. A high degree of microzooplankton IGP increases NPP and organic matter recycling, but decreases trophic transfer efficiency (TTE) to copepods. Copepod production, the trophic role of copepods, and TTE are more sensitive to initial biomass changes in chain-like than in complex food webs. Measurements resolving trophic interactions, in particular those quantifying IGP, remain essential to reduce model uncertainty and allow sound conclusions for ecosystem functioning in plankton ecosystems.

Description: The blue mussel (Mytilus species complex) is an important ecosystem engineer, and salinity can be a major abiotic driver of mussel functioning in coastal ecosystems. However, little is known about the interactive effects of abiotic drivers and trematode infection. This study investigated the combined effects of salinity and Himasthla elongata and Renicola roscovita metacercarial infections on the filtration capacity, growth, and condition of M. edulis from the Baltic Sea. In a laboratory experiment, groups of infected and uninfected mussels were exposed to a wide range of salinities (6−30, in steps of 3) for 1 mo. Shell growth was found to be positively correlated with salinity and optimal at 18−24 at the end of the experiment, imposed by constraints in shell calcification under lower salinities. Mussel shell growth was not affected by H. elongata infection. While salinity had only a minor effect on tissue dry weight, infected mussels had a significantly lower tissue dry weight than uninfected mussels. Most interestingly, the combination of salinity and trematode infections negatively affected the mussels’ condition indices at lower salinity levels (6 and 9), suggesting that trematode infections are more detrimental to mussels when combined with freshening. A significant positive effect of salinity on mussel filtration was found, with an initial optimum at salinity 18 shifting to 18−24 by the end of the experiment. These findings indicate that salinity and parasite infections act as synergistic stressors for mussels, and enhance the understanding of potential future ecosystem shifts under climate change-induced freshening in coastal waters.

Description: In the deep sea, benthic communities largely depend on organic material from the overlying water column for food. The remains of organisms on the seafloor (food falls) create areas of organic enrichment that attract scavengers. The scavenging rates and communities of food falls of medium-sized squid, fish and jellyfish (1-100 cm) are poorly known. To test our hypothesis that scavenging responses are specific for different food falls, we deployed camera landers baited with squid, jellyfish and fish for 9 to 25 h at 1360 to 1440 m in the southern Norwegian Sea. Image analysis of 8 deployments showed rapid food fall consumption (20.3 +/- 1.4 [SD] to 31.6 +/- 3.7 g h(-1)) by an amphipod-dominated scavenging community that was significantly different between the food fall types. Fish and squid carcasses were mostly attended by amphipods of the genus Eurythenes. Smaller unidentified amphipods dominated the jellyfish experiments together with brittle stars (cf. Ophiocten gracilis) and decapod shrimps (cf. Bythocaris spp.); the latter only occurred on jellyfish carcasses. The removal time for jellyfish (similar to 17 h) was almost twice as long as that for squid and fish (9-10 h). The maximum scavenger abundance was significantly higher on fish carcasses than on jellyfish and squid. The times at which abundances peaked were similar for jellyfish and fish (after 8-9 h) but significantly sooner for squid (3.00 +/- 0.35 h). Our results, although based on a small number of experiments, demonstrate differences in scavenging responses between food fall species, suggesting tight coupling between the diversity and ecology of benthic scavenging communities in the Norwegian Sea.

Description: In this study, we provide a method to quantify the uncertainty associated with sampling particle size distributions (PSD), using a global compilation of Underwater Vision Profiler observations (UVP, version 5). The UVP provides abundant in situ data of the marine PSD on global scales and has been used for a diversity of applications, but the uncertainty associated with its measurements has not been quantified, including how this uncertainty propagates into derived products of interest. We model UVP sampling uncertainty using Bayesian Poisson statistics and provide formulae for the uncertainty associated with a given sampling volume and observed particle count. We also model PSD observations using a truncated power law to better match the low concentration associated with rare large particles as seen by the UVP. We use the two shape parameters from this statistical model to describe changes in the PSD shape across latitude band, season, and depth. The UVP sampling uncertainty propagates into an uncertainty for modeled carbon flux exceeding 50%. The statistical model is used to extend the size interval used in a PSD-derived carbon flux model, revealing a high sensitivity of the PSD-derived flux model to the inclusion of small particles (80–128 μm). We provide avenues to address additional uncertainties associated with UVP-derived carbon flux calculations.

Description: In this work, we focused on the functional characterization of unicellular eukaryotic assemblages that had previously been taxonomically characterized by 18S rRNA gene amplicon sequencing in a eutrophic coastal site with marked plankton blooms. Biological traits of different functional groups were assigned to the retrieved operational taxonomic units (OTUs). The traits included size, trophic strategy, the presence of spines, mucilage production, colony formation, motility, spore formation, and potential harmfulness. Functional diversity indices were calculated and compared to analogous taxonomic diversity indices, indicating a strong positive coupling of richness and dominance and a negative coupling of evenness, even at a low taxonomic resolution (at the family/genus/species level). Biological trait trade-offs and co-occurrences of specific traits were evident during the succession of plankton blooms. The trophic strategy dominating in the assemblages frequently alternated between autotrophy, mixotrophy, and a few recorded cases of parasitism. Given that there was no indication of nutrient limitation, we suggest that biotic pressures force marine eukaryotes to exploit narrow niches by adopting specific strategies/traits that favour their survival. These traits act by increasing resource acquisition potential and via predator avoidance. This leads to a unique succession of blooms in the system, characterized by adaptations of the bloom taxa that are a direct response to the preceding assemblage.

Description: Recent advancements in telemetry have redefined our ability to quantify the fine-scale movements of aquatic animals and derive a mechanistic understanding of movement behaviours. The VEMCO Positioning System (VPS) is a fine-scale commercial positioning system used to generate highly accurate semi-continuous animal tracks. To date, VPS has been used to study 86 species, spanning 25 taxonomic orders. It has provided fine-scale movement data for critical life stages, from tracking day-old turtle hatchlings on their first foray into the sea to adult fish returning to natal rivers to spawn. These high-resolution tracking data have improved our understanding of the movements of species across environmental gradients within rivers, estuaries and oceans, including species of conservation concern and commercial value. Existing VPS applications range from quantifying spatio-temporal aspects of animal space use and key aspects of ecology, such as rate of movement and resource use, to higher-order processes such as interactions among individuals and species. Analytical approaches have seen a move towards techniques that incorporate error frameworks such as autocorrelated kernel density estimators for home range calculations. VPS technology has the potential to bridge gaps in our fundamental understanding of fine-scale ecological and physiological processes for single and multi-species studies under natural conditions. Through a systematic review of the VPS literature, we focus on 4 principle topics: the diversity of species studied, current ecological and ecophysiological applications and data analysis techniques, and we highlight future frontiers of exploration.

Description: Physiological sensitivity of cold-water corals to ocean change is far less understood than of tropical corals and very little is known about the impacts of ocean acidification and warming on degradative processes of dead coral framework. In a 13-month laboratory experiment, we examined the interactive effects of gradually increasing temperature and pCO2 levels on survival, growth, and respiration of two prominent color morphotypes (colormorphs) of the framework-forming cold-water coral Lophelia pertusa, as well as bioerosion and dissolution of dead framework. Calcification rates tended to increase with warming, showing temperature optima at ~ 14°C (white colormorph) and 10–12°C (orange colormorph) and decreased with increasing pCO2. Net dissolution occurred at aragonite undersaturation (ΩAr 〈 1) at ~ 1000 μatm pCO2. Under combined warming and acidification, the negative effects of acidification on growth were initially mitigated, but at ~ 1600 μatm dissolution prevailed. Respiration rates increased with warming, more strongly in orange corals, while acidification slightly suppressed respiration. Calcification and respiration rates as well as polyp mortality were consistently higher in orange corals. Mortality increased considerably at 14–15°C in both colormorphs. Bioerosion/dissolution of dead framework was not affected by warming alone but was significantly enhanced by acidification. While live corals may cope with intermediate levels of elevated pCO2 and temperature, long-term impacts beyond levels projected for the end of this century will likely lead to skeletal dissolution and increased mortality. Our findings further suggest that acidification causes accelerated degradation of dead framework even at aragonite saturated conditions, which will eventually compromise the structural integrity of cold-water coral reefs.

Description: Strong anisotropy of seismic velocity in the Earth’scrust poses serious challenges for seismic imaging. Where in situ seismic properties are not available the anisotropy can be determined from velocity analysis of surface and borehole seismic profiles. This is well established for dense, long-offset reflection seismic data. However, it is unknown how applicable this approach is for sparse seismic reflection data with low fold and short offsets in anisotropic metamorphic rocks. Here we show that anisotropy parameters can be determined from a sparse 3D data set at the COSC-1 borehole site in the Swedish Caledonides and that the results agree well with the seismic anisotropy parameters determined from seismic laboratory measurements on core samples. Applying these anisotropy parameters during 3D seismic imaging improves the seismic image of the high amplitude reflections especially in the vicinity of the lower part of the borehole. Strong reflections in the resulting seismic data show good correlation with the borehole-derived lithology. Our results aid the interpretation and extrapolation of the seismic stratigraphy of the Lower Seve Nappe in Jämtland and other parts in the Caledonides.

Description: Nutrients limiting phytoplankton growth in the ocean are a critical control on ocean productivity and can underpin predicted responses to climate change. The extensive western subtropical North Pacific is assumed to be under strong nitrogen limitation, but this is not well supported by experimental evidence. Here, we report the results of 14 factorial nitrogen–phosphorus–iron addition experiments through the Philippine Sea, which demonstrate a gradient from nitrogen limitation in the north to nitrogen–iron co-limitation in the south. While nitrogen limited sites responded weakly to nutrient supply, co-limited sites bloomed with up to ~60-fold increases in chlorophyll a biomass that was dominated by initially undetectable diatoms. The transition in limiting nutrients and phytoplankton growth capacity was driven by a gradient in deep water nutrient supply, which was undetectable in surface concentration fields. We hypothesize that this large-scale phytoplankton response gradient is both climate sensitive and potentially important for regulating the distribution of predatory fish.

Description: Juvenile sea turtles can disperse thousands of kilometers from nesting beaches to oceanic development habitats, aided by ocean currents. In the North Atlantic, turtles dispersing from American beaches risk being advected out of warm nursery grounds in the North Atlantic Gyre into lethally cold Northern European waters (e.g. around the United Kingdom). We used an ocean model simulation to compare simulated numbers of turtles that were advected to cold waters around the UK with observed numbers of turtles reported in the same area over ~5 decades. Rates of virtual turtles predicted to encounter lethal temperatures (≤10 and 15°C, mean 19% ± 2.7) and reach the UK were consistently low (median 0.83%, lower quartile 0.67%, upper quartile 1.02%), whereas there was high inter-annual variability in the numbers of dead or critically ill turtles reported in the UK. Generalized additive models suggest inter-annual variability in the North Atlantic Oscillation (NAO) index to be a good indicator of annual numbers of turtle strandings reported in the UK. We demonstrate that NAO variability drives variability in the dispersion scenarios of juvenile turtles from key nesting regions into the North Atlantic. Coastal effects, such as the number of storms and mean sea surface temperatures in the UK were significant but weak predictors, with a weak effect on turtle strandings. Further understanding how changing environmental conditions such as NAO variability and storms affect the fate of juvenile turtles is vital for understanding the distribution and population dynamics of sea turtles.

Description: The benthic boundary layer plays a crucial role in the exchange of trace metals between surface sediments and the water column. So far it has been difficult to study dissolved–particulate interactions of trace metals in this highly reactive interface layer due to the lack of suitable sampling methods. We developed a new device, called Benthic Trace Profiler (BTP), which enables simultaneous sampling of near-bottom water and suspended particles in high depth resolution within the first 3 m above the seafloor. The device was tested successfully in the Baltic Sea. The concentrations of several trace metals (Co, Ni, Cu, Zn, and Cd) in the collected bottom waters overlapped with concentrations in water column samples above collected with conventional methods. This observation indicates that the sampling device and method is trace metal clean. The trace metals Fe and Mn showed concentration gradients within the benthic boundary layer indicating an upward diffusive flux. This observation is consistent with a diffusive benthic flux of these trace metals across the sediment–water interface, which was independently verified using pore-water profiles. Suspended particles can be used to study precipitation processes and to determine the carrier phases of trace metals. The BTP fulfilled all the intended requirements as it allowed a simultaneous, uncontaminating and oxygen-free sampling of seawater and suspended particles to gather high-resolution profiles of dissolved and particulate trace metal concentrations above the seafloor. The device closes the gap between water column and sediment sampling and helps researchers to better understand trace metal exchange processes across the ocean's lower boundary.

Description: The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2022 is an update of the previous version, GLODAPv2.2021 (Lauvset et al., 2021). The major changes are as follows: data from 96 new cruises were added, data coverage was extended until 2021, and for the first time we performed secondary quality control on all sulphur hexafluoride (SF6) data. In addition, a number of changes were made to data included in GLODAPv2.2021. These changes affect specifically the SF6 data, which are now subjected to secondary quality control, and carbon data measured onboard the RV Knorr in the Indian Ocean in 1994–1995 which are now adjusted using CRM measurements made at the time. GLODAPv2.2022 includes measurements from almost 1.4 million water samples from the global oceans collected on 1085 cruises. The data for the now 13 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, CCl4, and SF6) have undergone extensive quality control with a focus on systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but converted to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For the present annual update, adjustments for the 96 new cruises were derived by comparing those data with the data from the 989 quality controlled cruises in the GLODAPv2.2021 data product using crossover analysis. SF6 data from all cruises were evaluated by comparison with CFC-12 data measured on the same cruises. For nutrients and ocean carbon dioxide (CO2) chemistry comparisons to estimates based on empirical algorithms provided additional context for adjustment decisions. The adjustments that we applied are intended to remove potential biases from errors related to measurement, calibration, and data handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 μmol kg-1 in dissolved inorganic carbon, 4 μmol kg-1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5 % in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments.

Description: In recent decades, the increase in terrestrial inputs to freshwater and coastal ecosystems, especially occurring at northern latitudes, has led to a process of water color darkening known as “brownification.” To assess how brownification affects plankton community composition and functioning in northern coastal areas, an in situ mesocosm experiment using a highly colored humic substance to simulate a brownification event was performed in a North Atlantic bay (Hopavågen, Norway) in August 2019. Manual sampling for analyses of nutrient concentrations, phytoplankton pigments and zooplankton abundances was combined with high-frequency (every 15 min) monitoring of key environmental variables to investigate the response of the plankton community in terms of oxygen metabolism and community composition. In response to brownification, the oxygen gross primary production (GPP) and community respiration (R) slowed down significantly, by almost one-third. However, GPP and R both decreased to the same extent; thus, the oxygen metabolic balance was not affected. Moreover, the chlorophyll-a concentration significantly decreased under brownification, by 9% on average, and the chemotaxonomic pigment composition of the phytoplankton changed, indicating their acclimation to the reduced light availability. In addition, brownification seemed to favor appendicularians, the dominant mesozooplankton group in the mesocosms, which potentially contributed to lowering the phytoplankton biomass. In conclusion, the results of this in situ mesocosm experiment suggest that brownification could induce significant changes in phytoplankton and zooplankton community composition and significantly alter the overall oxygen metabolism of plankton communities in a northern Atlantic bay.

Description: Mothers impact the survival and performance of their offspring through the resources they provision, and the degree of maternal investment in an individual offspring can be broadly estimated by egg size for organisms that lack parental care. Animals may also actively maintain symbiotic partnerships with microorganisms through the germ line, but whether microbes are a fundamental component of maternal provisioning is an untested hypothesis in evolutionary symbiosis. We present a preliminary test of this by comparing the egg-associated microbiota of ten sea urchin species with ecological factors known to influence egg size. We found that the microbiota associated with sea urchin eggs had a phylogenetic signal in both composition and richness, which varied between years but not between individuals or within a clutch. Moreover, we found a negative correlation between microbiome richness and taxonomic dominance, and that community diversity covaried with egg size and energetic content but not with pelagic larval duration or latitude. These data suggest that there are multiple parallels between the ecological factors that govern changes in egg size and microbiome composition and diversity, implying that microbial symbionts may be another constituent potentially provided by the mother.

Description: The southern boundary of the Cayman Trough in the Caribbean is marked by the Swan Islands transform fault (SITF), which also represents the ocean-continent transition of the Honduras continental margin. This is one of the few places globally where a transform continental margin is currently active. The CAYSEIS experiment acquired an ∼165-km-long seismic refraction and gravity profile (P01) running across this transform margin, and along the ridge-axis of the Mid-Cayman Spreading Centre (MCSC) to the north. This profile reveals not only the crustal structure of an actively evolving transform continental margin, that juxtaposes Mesozoic-age continental crust to the south against zero-age ultraslow spread oceanic crust to the north, but also the nature of the crust and uppermost mantle beneath the ridge-transform intersection (RTI). The traveltimes of arrivals recorded by ocean-bottom seismographs (OBSs) deployed along-profile have been inverse and forward modelled, in combination with gravity modelling, to reveal an ∼25-km-thick continental crust that has been continuously thinned over a distance of ∼65 km to ∼10 km adjacent to the SITF, where it is juxtaposed against ∼3-4-km-thick oceanic crust. This thinning is primarily accommodated within the lower crust. Since Moho reflections are only sparsely observed, and, even then, only by a few OBSs located on the continental margin, the 7.5 km s-1 velocity contour is used as a proxy to locate the crust-mantle boundary along-profile. Along the MCSC, the crust-mantle boundary appears to be a transition zone, at least at the seismic wavelengths used for CAYSEIS data acquisition. Although the traveltime inversion only directly constrains the upper crust at the SITF, gravity modelling suggests that it is underlain by a higher density (〉3000 kg m-3) region spanning the width (∼15 km) of its bathymetric expression, that may reflect a broad region of metasomatism, mantle hydration or melt-depleted lithospheric mantle. At the MCSC ridge-axis to the north, the oceanic crust appears to be forming in zones, where each zone is defined by the volume of its magma supply. The ridge tip adjacent to the SITF is currently in a magma rich phase of accretion. However, there is no evidence for melt leakage into the transform zone. The width and crustal structure of the SITF suggests its motion is currently predominantly orthogonal to spreading. Comparison to CAYSEIS Profile P04, located to the west and running across-margin and through 10 Ma MCSC oceanic crust, suggests that, at about this time, motion along the SITF had a left-lateral transtensional component, that accounts for its apparently broad seabed appearance westwards.

Description: This report presents the results of Task 7.3 on “Development of BGC-Argo data quality validation based on an integrative multiplatform approach”. Observing changes in ocean conditions on the spatiotemporal scales necessary to constrain carbon uptake is a challenge. Defined as an Essential Ocean Variable (EOV) by the Global Ocean Observing System (GOOS, e.g., Tanhua et al., 2019), pH is relevant to assess numerous crucial questions regarding the oceanic evolution in response to the current global changes. However, the large spatiotemporal variability of this carbonate system parameter requires sustained observations to decipher trends and punctual events. Within this scope, numerous pH sensors suitable for deployments both on autonomous observing tools and fixed stations have been developed. Nevertheless, as interpreting changes relies on accurate data, and because offsets or drifts in pH data might appear in response to changes in the sensor k0 constant, a consistent and rigorous correction procedure to quality-control and process the data has been implemented. This report presents the application of this method to pH data acquired by BGC-Argo floats launched in the Tropical Atlantic area.

Description: This deliverable provides an overview of EuroSea outcomes related to interior ocean carbon variability in deep convection areas in order to assess the linkage of these processes for the use in national climate action (NCA) plans delivered in the framework of the Paris Agreement. In summary, large-scale connectivity in the ocean does not allow clear delineation of patterns of regional carbon uptake across national boundaries, limiting an assessment of the Exclusive Economic Zones (EEZ) in light of NCA plans. This problem becomes already clear by a simple scale estimation: considering sluggish, open ocean (away from continental boundaries) advection speeds of 2 cm/s result in a “relocation” of any water parcel by roughly 630 km per year (or 3150 km in 5 years Paris Agreement carbon auditing period) and crossing national borders easily. Knowing changes in the global ocean carbon uptake is of great importance for the preparation of NCA plans. This is because the NCA plans are motivated by the globally averaged atmospheric CO2 concentration, which is the sum of all sources and sinks and including the ocean sink. In case of decrease in the oceanic sink (e.g., IPCC, 2021), more CO2 will remain in the atmosphere and consequently nations will need to formulate their NCA plans with increased ambition in order to meet the CO2 target defined in the Paris Agreement. In this deliverable key approaches for the assessment of the global ocean carbon uptake have been applied to ocean areas. The observational requirements for applying statistical approaches (i.e., artificial neural networks, Fourrier et al., 2020) to reconstruct dissolved inorganic carbon (DIC) from oxygen, nutrient and hydrographic data are analysed. It is shown that even small changes in the DIC content determined in this way can be linked to anthropogenic increases in atmospheric carbon (Cant). Furthermore, it has been shown that multilinear regression techniques can be used to produce maps of ocean surface carbon fluxes at very high spatial resolution, which in turn can provide a much more accurate estimate of regional CO2 uptake (or release). Finally, a quantification of the redistribution of dissolved gases in boundary current systems could be investigated by following recommendations for observational methods stemming from this deliverable. This deliverable recommends improvement of carbon sampling in all nations EEZ regions and following global standards. Because the objective targets a global assessment, the data must be disseminated rapidly and in a FAIR fashion to enable further global integration (e.g., global carbon budget). A need for defining responsibilities for such global integration and the resourcing is required. It is recommended to make use of statistical methods to create surface and interior carbon parameter distributions via multiparameter approaches with a sufficient amount of reference data (e.g., co-located DIC, oxygen, nutrients, chlorophyll-a, hydrography). In the light of the ongoing crisis related to global availability of the Certified Reference Materials (CRMs) for carbonate system measurements, provision of European-produced material becomes critical to enable traceability of future measurements. Nations should be encouraged to provide appropriate resources by means of corresponding European directives. Example for such national commitments is the collection of reference data in the framework of the Common Fisheries Policy.

Description: The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with annual updates. SOCAT aims to provide data with the highest possible quality for carbon data – consistent quality control (QC) is essential in achieving this primary goal of SOCAT. Currently there are various steps of quality control, and within this task of EuroSea we aimed to develop an operational implementation of QC as a showcase for data within SOCAT from the European Research Infrastructure Integrated Carbon Observing System. The aim within EuroSea is to increase the Technology Readiness Level (TRL) from 5 (Technology validated in relevant environment) to 7 (system prototype demonstration in operational environment) for relevant ICOS data for direct submission to SOCAT. This was achieved by creating automated quality control into the ICOS state-of-art-software QuinCe, a web-based tool for processing and quality control of data from in situ sensors and underway instruments that is used for first and second level quality control for operational ICOS stations. One important aspect of SOCAT is the assessment of data quality, to ensure that all published data is fit for purpose and manual eyes-on QC is currently essential to lower uncertainties. Currently, this assessment consists of evaluating the metadata of each dataset to ensure that the correct Standard Operational Procedures (SOPs) have been followed during data collection, that the system setup is correct, instruments are calibrated and in addition examining data to ensure they are of good quality. SOCAT consists of three steps of QC: 1.) QC while data is being ingested; 2.) Eyes-on QC by regional experts and 3.) QC for the entire dataset defining the uncertainty based upon the submitted metadata and within this task it has been shown that certain parts of this QC process can be automated while other levels bear challenges if a higher level of TRL is aimed for.

Description: This document describes the numerical modelling work done in task 5.2 needed to implement OSPAC

Description: Diatoms often dominate phytoplankton in temperate, polar and upwelling regions. Decreases in silicate availability or silicon to nitrogen (Si:N) ratios may induce silicon limitation in diatoms and lower their proportion within phytoplankton communities. The effects of such changes on the nutritional quality of phytoplankton are not well understood. To examine how changing Si:N ratios affect plankton nutritional value, we applied a range of Si:N ratios on a natural plankton community and manipulated grazing pressure to assess top-down effects of copepod selective grazing. Diatom proportion in phytoplankton increased with increasing Si:N ratios and so did phytoplankton nutritional quality in terms of major fatty acid concentrations, such as polyunsaturated fatty acids, docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids. However, stoichiometric quality (carbon to nitrogen and carbon to phosphorus ratios), DHA:EPA and omega 3:6 (omega 3:omega 6) ratios declined with increasing Si:N ratios, suggesting that proportions between essential compounds in copepod diet may be more favorable in lowered Si:N ratios. Copepods had a negative effect on DHA contents, DHA:EPA and omega 3:omega 6 ratios, indicating possible selective grazing on more nutritious plankton. Our findings show that declining silicate concentrations can affect stoichiometric and biochemical quality of phytoplankton, which copepods can also moderate by selective grazing.