Description: This report reviews the current situation as regards to the Marine Strategy Framework Directive (MSFD) Descriptor 1 (Biodiversity) for pelagic habitats and serves as a basis for a workshop with Member States experts and scientists that will be held on March 9-10 2021. Recommendations are in the concluding section. Pelagic habitats cover the 71% of Earth’s surface and play an essential role in regulating temperature on land, producing oxygen and food. They are also a management challenge where the alterations of their physical, chemical and biological characteristics negatively impact their ecosystem functioning and services (e.g. provisioning services). To address these challenges, the MSFD has required the assessment of pelagic habitats against environmental targets to reach Good Environmental Status (GES). A key step in the pelagic habitat assessment is a thorough understanding of its physical, chemical and biological processes and the drivers that underlie the spatiotemporal variability in its ecologically relevant ecosystem components. However, pelagic assessments to date have not sufficiently addressed the functional and structural characteristics of pelagic habitats processes, which is limiting our ability to inform on their environmental status and to disentangle the anthropogenic drivers. This report evaluates previously published work on pelagic habitats assessments considering the actions and targets to meet the MSFD requirements. To do this, the report (i) summarises the main drivers of variation in pelagic habitat characterization; (ii) reviews the common empirical approaches used to assess pelagic habitats, the advantages, and challenges; and finally (iii) exposes a set of recommendations for characterising pelagic habitats in EU waters. Since the pelagic habitats are made of a highly dynamic fluid, appropriate spatiotemporal scales regarding data and methods must be considered to assess their GES. This applies in particular to the selected indicators to propose the effective and quantifiable GES targets that need to be reached.

Description: Host-microbe interactions play crucial roles in marine ecosystems. However, we still have very little understanding of the mechanisms that govern these relationships, the evolutionary processes that shape them, and their ecological consequences. The holobiont concept is a renewed paradigm in biology that can help to describe and understand these complex systems. It posits that a host and its associated microbiota with which it interacts, form a holobiont, and have to be studied together as a coherent biological and functional unit to understand its biology, ecology, and evolution. Here we discuss critical concepts and opportunities in marine holobiont research and identify key challenges in the field. We highlight the potential economic, sociological, and environmental impacts of the holobiont concept in marine biological, evolutionary, and environmental sciences. Given the connectivity and the unexplored biodiversity specific to marine ecosystems, a deeper understanding of such complex systems requires further technological and conceptual advances, e.g., the development of controlled experimental model systems for holobionts from all major lineages and the modeling of (info)chemical-mediated interactions between organisms. Here we propose that one significant challenge is to bridge cross-disciplinary research on tractable model systems in order to address key ecological and evolutionary questions. This first step is crucial to decipher the main drivers of the dynamics and evolution of holobionts and to account for the holobiont concept in applied areas, such as the conservation, management, and exploitation of marine ecosystems and resources, where practical solutions to predict and mitigate the impact of human activities are more important than ever.

Description: Biological invasions are a major component of anthropogenic environmental change, incurring substantial economic costs across all sectors of society and ecosystems. There have been recent syntheses of costs for a number of countries using the newly compiled InvaCost database, but New Zealand—a country renowned for its approach to invasive species management—has so far not been examined. Here we analyse reported economic damage and management costs incurred by biological invasions in New Zealand from 1968 to 2020. In total, US$69 billion (NZ$97 billion) is currently reported over this ∼50-year period, with approximately US$9 billion of this considered highly reliable, observed (c.f. projected) costs. Most (82%) of these observed economic costs are associated with damage, with comparatively little invested in management (18%). Reported costs are increasing over time, with damage averaging US$120 million per year and exceeding management expenditure in all decades. Where specified, most reported costs are from terrestrial plants and animals, with damages principally borne by primary industries such as agriculture and forestry. Management costs are more often associated with interventions by authorities and stakeholders. Relative to other countries present in the InvaCost database, New Zealand was found to spend considerably more than expected from its Gross Domestic Product on pre- and post-invasion management costs. However, some known ecologically (c.f. economically) impactful invasive species are notably absent from estimated damage costs, and management costs are not reported for a number of game animals and agricultural pathogens. Given these gaps for known and potentially damaging invaders, we urge improved cost reporting at the national scale, including improving public accessibility through increased access and digitisation of records, particularly in overlooked socioeconomic sectors and habitats. This also further highlights the importance of investment in management to curtail future damages across all sectors.

Description: The Ægir Ridge System (ARS) is an ancient extinct spreading axis in the Nordic seas extending from the upper slope east of Iceland (∼550 m depth), as part of its Exclusive Economic Zone (EEZ), to a depth of ∼3,800 m in the Norwegian basin. Geomorphologically a rift valley, the ARS has a canyon-like structure that may promote increased diversity and faunal density. The main objective of this study was to characterize benthic habitats and related macro- and megabenthic communities along the ARS, and the influence of water mass variables and depth on them. During the IceAGE3 expedition (Icelandic marine Animals: Genetics and Ecology) on RV Sonne in June 2020, benthic communities of the ARS were surveyed by means of a remotely-operated vehicle (ROV) and epibenthic sledge (EBS). For this purpose, two working areas were selected, including abyssal stations in the northeast and bathyal stations in the southwest of the ARS. Video and still images of the seabed were usedtoqualitatively describebenthic habitats based on the presence of habitat-forming taxa and the physical environment. Patterns of diversity and community composition of the soft-sediment macrofauna, retrieved from the EBS, were analyzed in a semiquantitative manner. These biological data were complemented by producing high-resolution bathymetric maps using the vessel’s multi-beam echosounder system. As suspected, we were able to identify differences in species composition and number of macro- and megafaunal communities associated with a depth gradient. A biological canyon effect became evident in dense aggregates of megafaunal filter feeders and elevated macrofaunal densities. Analysis of videos and still images from the ROV transects also led to the discovery of a number ofVulnerable Marine Ecosystems (VMEs) dominated by sponges and soft corals characteristic of the Arctic region. Directions for future research encompass a more detailed, quantitative study of the megafauna and more coherent sampling over the entire depth range in order to fully capture the diversity of the habitats and biota of the region. The presence of sensitive biogenic habitats, alongside seemingly high biodiversity and naturalness are supportive of ongoing considerations of designating part of the ARS as an “Ecologically and Biologically Significant Area” (EBSA).

Description: Forward looking analyses are needed in order to anticipate which policy/management options can deliver the very ambitious objectives of the Zero Pollution (ZP) action plan. Integrated and sophisticated numerical modelling tools are useful to generate future scenarios and ‘what if’ analysis as they allow the virtual manipulation of the anthropogenic pressures on ecological systems. JRC has been developing an integrated modelling framework covering the inland and marine waters of the EU, the Marine Modelling Framework (MMF) that follows the principle of the Digital Twins (DT) and that allow to test the impacts of diverse management strategies on the status of freshwater and marine ecosystems through the EU. In the present report, the JRC-DT for water and marine ecosystems is used to test how different policy options can help achieve some of the ZP objectives. From the six top ambitions of the ZP action plan, two are particularly relevant for the water/marine environments. First, the ZP action plan states that it aims at ‘improving water quality by reducing waste’ and in particular, it mentions the (reduction of) ‘plastic litter at sea (by 50%)’. The second relevant ambition refers to ‘improving soil quality by reducing nutrient losses and chemical pesticides’ use by 50%’, which does not only impact soil quality but also the receiving waters (rivers, lakes and seas).

Description: Climate, which sets broad limits for migrating species, is considered a key filter to species migration between contrasting marine environments. The Southeast Mediterranean Sea (SEMS) is one of the regions where ocean temperatures are rising the fastest under recent climate change. Also, it is the most vulnerable marine region to species introductions. Here, we explore the factors which enabled the colonization of the endemic Red Sea octocoral Melithaea erythraea (Ehrenberg, 1834) along the SEMS coast, using sclerite oxygen and carbon stable isotope composition (delta O-18(SC) and delta C-13(SC)), morphology, and crystallography. The unique conditions presented by the SEMS include a greater temperature range (similar to 15 degrees C) and ultra-oligotrophy, and these are reflected by the lower delta C-13(SC) values. This is indicative of a larger metabolic carbon intake during calcification, as well as an increase in crystal size, a decrease of octocoral wart density and thickness of the migrating octocoral sclerites compared to the Red Sea samples. This suggests increased stress conditions, affecting sclerite deposition of the SEMS migrating octocoral. The delta(OSC)-O-18 range of the migrating M. erythraea indicates a preference for warm water sclerite deposition, similar to the native depositional temperature range of 21-28 degrees C. These findings are associated with the observed increase of minimum temperatures in winter for this region, at a rate of 0.35 +/- 0.27 degrees C decade(-1) over the last 30 years, and thus the region is becoming more hospitable to the IndoPacific M. erythraea. This study shows a clear case study of "tropicalization" of the Mediterranean Sea due to recent warming.

Description: The purpose of this report is to examine the current situation, risks and responses to the recreational use of nitrous oxide in Europe. To support this, the report also provides a state-of-the-art review of the chemistry, pharmacology and toxicology of the gas. It is intended for policymakers and practitioners.

Description: This study reviews the status of Marine Biodiversity Monitoring in the European Commission tendered the study “Marine Biodiversity Modelling” [RTD/2021/MV/10] to pursue the identification and characterization of a subset of candidate biodiversity models that could contribute to the implementation of the European Digital Twin of the Ocean (EU DTO). The EU DTO will be an operational infrastructure for digital ocean services that aims to support decision-making capabilities by authorities to implement EU policies like the Marine Strategy Framework Directive (MSFD) but also by citizens and businesses operating at sea. Specific objectives of the project were: 1. Conduct a horizon scan to identify and map available modelling approaches used to hindcast, nowcast; 2. Develop a comprehensive catalogue to classify available modelling approaches according to their characteristics; 3. Propose a subset of the most meaningful models among major model typologies; 4. Assess whether these models can be used in the implementation of the Digital Twin Ocean and can improve the decision-making capacity under the MFSD.

Description: This is the fourth collection of reports of EFSA’s EU-FORA Fellowship Programme. EU-FORA started in 2016 as part of EFSA’s efforts to support the development of next generations of Europe’s food risk assessors. Five years later, it continues to empower food safety professionals, ensuring an interconnected community of experts, while stimulating the involvement of Member States in risk assessment work and building a common EU risk assessment culture.