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Local and global anthropogenic pressures due to climate change and to local uses and activities are exerting significant cumulative impacts to greater extents of the oceans and seas. Coastal ecosystems are particularly threatened by the intensity and coexistence of several marine uses and pressures, including sewage and urban constructions, tourism, ship traffic, fisheries and aquaculture. Assessment of pressures and the identification of mitigation measures are key urgent actions, as already highlighted by the EU Marine Strategy Framework Directive and the United Nations Sustainable Development Goal 14. The aim of this work, developed within the Interreg-Med project SHAREMED, is to systematize existing knowledge on threats and pollution, including those of transboundary origin, for long term strategies and common action marine spatial planning, jointly developed with stakeholders. The quest is to assess coexisting environmental threats, and their propagation in space and time, at proper spatial and temporal scales, according to the type and action of each stressor (i.e. global vs. local). Cumulative pressures are tackled within a dedicated Atlas comprising three sub-basinsins of the Mediterranean Sea: the North Adriatic Sea, the Sicilian Channel and the North-Western region. The Atlas integrates information generated at the best available resolutions by 1) in-situ sampling, 2) remote observations, 3) numerical models, and 4) focusing on target ecosystems and habitat forming species. These sub-basins are subjected to multiple local and larger scale (e.g. climate) pressures that propagate in space and time, and across political boundaries, that need to be addressed through coordinated actions, based on evidence-rooted common understanding., peer-reviewed

International audience

10 Mediterranean Operational Network for the Global Ocean Observing System (MONGOOS) Workshop, 10 Years of Operational Oceanography in the Mediterranean Sea - Towards a Full Ocean Data Integration, 26-27 October 2021, Scientific research priorities and the need for assessing the marine environmental status and appropriately manage natural resources have encouraged the development of multidisciplinary and a wide range of observing capabilities, ranging from discrete in situ sampling to the use of large scale satellite remote sensing. In addition, long-term efforts have been made by the EU as well as by international organisations (EMODnet, Copernicus, OBIS, IODE, Reef Check ¿) to collect, harmonise and make data and information available to different types of end-users. However, due to the complex and rapidly changing dynamics of marine ecosystems, current monitoring procedures in the Mediterranean need to be revised to address current and most urgent environmental threats. The Interreg Med project SHAREMED (Sharing and enhancing capabilities to address environmental threats in the Mediterranean Sea) organized a virtual workshop aimed to share knowledge on the state of the art of observation systems and to identify the main environmental threats in the Mediterranean Sea. Leading representatives of major international projects and initiatives in marine observation systems and relevant to address the main environmental threats the Mediterranean Sea participated in the workshop. Also, a wide range of stakeholders (research institutions, national, regional and local authorities, NGOs) across the Mediterranean region attended the online workshop while others were contributed through a SHAREMED online survey. The information gathered helped to compare data and information available from current observation systems with the needs to address present and future threats, and thus to identify and prioritise gaps that should be addressed in designing a future transnational joint observation system. The outcomes of the SHAREMED stakeholder consultation highlighted the need to improve, upgrade and integrate physical, biological and chemical observations and assessment systems to cover from high-resolution/small-scale to large scale processes. In addition, the results from this poll highlighted the need for more efficient governance, the establishment of cooperation frameworks, increase data sharing among different entities involved in marine monitoring and assessment and between neighbouring countries, as well as ensuring long-term sustainability of the transnational joint observation system

Ocean Sciences Meeting (OSM), 16-21 February 2020, San Diego, CA, USA.- 1 page, 3 figures, The deep sea remains one of the less known environment on Earth and is characterized by high pressure, low availability of organic matter and absence of light. While there are still numerous discoveries concerning the diversity and adaptations of deep-sea organisms to their environement, this ecosystem is under an increasing anthropogenic pressure such as climate-related stressors (warming, acidification and deoxygenation), deep-sea fishing, human pollution (microplastics, POP), oil and gas extraction and could face new threats from emerging industries (e.g. mineral mining). How these changes will affect biodiversity and ecosystem functioning is one question of major importance for the future. In the darkness of the oceans, several organisms have the capability to emit light: called bioluminescence. Recent studies quantified that as much as 75% of pelagic and about 40% of benthic organisms are known to be bioluminescent. In this framework, we present a new deep-sea crawler, BathyBot, to be dedicated to the long-term exploration of deep-sea ecosystems allowing biological and-geochemical surveys. BathyBot will be deployed in 2020 in the Mediterranean Sea, at the MEUST-NUMerEnv/KM3NeT site, to strength the ecological-based monitoring capability of the European Multidisciplinary Seafloor and water column Observatory (EMSO ERIC) network. BathyBot will be able to explore an area of about 15 000 m2 at a depth of 2500m and will be devoted to 1) observe and monitor the dynamics of deep-sea pelagic and benthic organisms, 2) better define the occurrence and functions of bioluminescence in situ (increasing the dataset of bioluminescence records), 3) explore relationships between deep-sea organisms, biogeochemical (carbon content, oxygen concentrations) and environmental variables (temperature, salinity, current) in the context of global changes and their effects on the deep ocean, and 4) investigate benthic biogeochemical processes through the use of oxygen microprofiling in sediment porewaters, This work is funded by UE FEDER NUMerEnv project (number: 1166-39417, 2017), CNRS-INSU Moyens Mi-Lourd 2019 and VICAT-Tangram-MIO project

The dispersion and fate of the Rhone River inputs to the Gulf of Lions (Northwestern Mediterranean Sea) have been studied through the spatial and temporal distributions of plutonium isotopes in continental shelf sediments. Plutonium isotopes (Pu-238 and Pu-239,Pu-240) are appropriate tracers to follow the dispersion of particulate matter due both to their high affinity for particles and their long half-lives. In the Rhone River valley, plutonium isotopes originate from both the weathering of the catchment basin contaminated by global atmospheric fallout, and the liquid effluents released from the Marcoule reprocessing plant since 1961.;This work presents a first detailed study on Pu-238 and Pu-239,Pu-240 distributions in sediments from the Rhone prodelta to the adjacent continental shelf, since the decommissioning of Marcoule in 1997. The vertical distribution of Pu isotopes has been analysed in a 4.75 in long core sampled in 2001 at the Rhone mouth. Despite this length, plutonium is found at the last 10 cm, manifesting the high sedimentation rate of the prodeltaic area and its ability for trapping fine-grained sediments and associated contaminants. The highest Pu-238 and Pu-239,Pu-240 concentrations reached 1.26 and 5.97 Bq kg(-1) respectively and were found within the layer 280-290 cm. The Pu-238/Pu-239,Pu-240 activity ratios (AR) demonstrated an efficient and huge trapping of the Pu isotopes derived from Marcoule. The fresh sediments, located on the top of the core, show lower plutonium activity concentrations and lower Pu-238/Pu-239,Pu-240 ratios. This decrease is in close relation with the shut down of the Marcoule reprocessing plant in 1997.;In 2001, plutonium isotopes were also analysed in 21 surface sediments located offshore and concentrations ranged from 0.03 to 0.17 Bq kg(-1) for Pu-238 and from 0.33 to 1.72 Bq kg(-1) for Pu-239,24(0). The Pu-238/Pu-239,Pu-240 AR ranged from 0.24 close to the river mouth to 0.06 southwards, indicating the decreasing influence of the Marcoule releases (global fallout AR 0.03-0.05 and Marcoule AR 0.30). This is in good agreement with the main direction spread of the Rhone River plume and the bottom current. This dataset has been compared to those obtained in the same area in 1984 and 1990 in order to follow the time trend in Pit concentrations. This comparison highlights the decrease with time in plutonium concentrations close to the Rhone River mouth, but further away this reduction is not so evident. (c) 2007 Elsevier B.V. All rights reserved.

Regions of Restricted Exchange (RREs) are an important feature of the European coastline. They are historically preferred sites for human settlement and aquaculture and their ecosystems, and consequent human use, may be at risk from eutrophication. The OAERRE project (EVK3-CT1999-0002 concerns ‘Oceanographic Applications to Eutrophication in Regions of Restricted Exchange’. It began in July 2000, and studies six sites. Four of these sites are fjords: Kongsfjorden (west coast of Spitzbergen); Gullmaren (Skagerrak coast of Sweden); Himmerfj.arden (Baltic coast of Sweden); and the Firth of Clyde (west coast of Scotland). Two are bays sheltered by sand bars: Golfe de Fos (French Mediterranean); and Ria Formosa (Portuguese Algarve). Together they exemplify a range of hydrographic and enrichment conditions. The project aims to understand the physical, biogeochemical and biological processes, and their interactions, that determine the trophic status of these coastal marine RRE through the development of simple screening models to define, predict and assess eutrophication. This paper introduces the sites and describes the component parts of a basic screening model and its application to each site using historical data. The model forms the starting point for the OAERRE project and views an RRE as a well-mixed box, exchanging with the sea at a daily rate E determined by physical processes, and converting nutrient to phytoplankton chlorophyll at a fixed yield q: It thus uses nutrient levels to estimate maximum biomass; these preliminary results are discussed in relation to objective criteria used to assess trophic status. The influence of factors such as grazing and vertical mixing on key parameters in the screening model are further studied using simulations of a complex‘research’ model for the Firth of Clyde. The future development of screening models in general and within OAERRE in particular is discussed. In addition, the paper looks ahead with a broad discussion of progress in the scientific understanding of eutrophication and the legal and socioeconomic issues that need to be taken into account in managing the trophic status of RREs.

A biogeochemical box model describing the south-west lagoon of New-Caledonia was developed in order to simulate the seasonal cycle of carbon and nitrogen. We used fluxes generated by a 3D hydrodynamic model to simulate horizontal exchanges between boxes and added freshwater influxes as nitrogen sources from the land. Average residence time proved to be less than 11 days for the lagoon as a whole. Standard simulations showed baseline values of chlorophyll a between 0.2 and 0.4 μg*L-1. Influences of freshwater influxes proved to be significant (increases up to 1 μg*L-1) only in shallow areas protected from wind exposure and during short periods of heavy rainfall (tropical depressions). Tropical climatic events have reduced impact in space and time and long-term simulations over decades with increased nutrient inputs did not show any significant process of eutrophication. Hydrodynamics seemed to be one of the major control factors with respect to organic matter cycling in the lagoon.