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This Collective article reports 17 introduced species and 22 new locations for these species in the Mediterranean Sea. The reports are from three different Marine Strategy Framework Directive (MSFD) subregions (Aegean-Levantine Sea, Adriatic Sea and Western Mediterranean Sea) and the Sea of Marmara and cover ten different countries. The goal of consistent and detailed reporting of introduced species is to complement the existing species inventories and serve as a basis for establishing monitoring strategies and other conservation measures. Some of the reports from this article are the first species records for the Mediterranean Sea, namely the green alga Udotea flabellum from the Aegean Sea (Turkey) and the deepbody boarfish Antigonia capros from the Balearic Sea (Spain). In addition, new records of introduced species are included for different seas, namely the moon crab Matuta victor for the Aegean Sea (Greece), the whale shark Rhincodon typus and the lionfish Pterois miles for the Alboran Sea (Spain), the almaco jack Seriola rivoliana for the Tyrrhenian Sea (Italy), and the hound needlefish Tylosurus crocodilus for the Adriatic Sea (Italy). Furthermore, reports on first country records are included: the red alga Colaconema codicola from Slovenia, the nudibranch Melibe viridis from Bosnia and Herzegovina, the lionfish Pterois miles from Montenegro, and the goldstripe sardinella Sardinella gibbosa from Syria, which also represents a second record for the Mediterranean Sea. Furthermore, the occurrence of the scleractinian coral Oculina patagonica was noted in Gulf of Lion (France). Four polychaete species, namely Leodice antennata, Timarete punctata and Branchiomma bairdi, are reported from the vermetid reef habitat and two of them (L. antennata and B. bairdi) are also recorded for the first time in Lebanon. Evidence for established populations of the Asian date mussel Arcuatula senhousia in the Sea of Marmara (Turkey) and the rayed pearl oyster Pinctada radiata arou

Climate change poses a significant threat to coastal areas, marked by the increasing intensity and frequency of marine heat waves observed in various ecosystems around the world. Over the last 25 years, a vast number of Mediterranean populations of the red gorgonian Paramuricea clavata have been impacted by marine heatwaves. The last mass mortality occurred during the summer of 2022 in the Western Mediterranean Sea, affecting mostly shallow populations (down to 30 m depth). Here we provide an assessment of the health status of mesophotic P. clavata populations down to 90 m depth to investigate a depth refuge hypothesis. Results show that the impact of marine heat waves decreases with depth, with a significant drop in mortality below 40 m depth. These observations support the hypothesis of a depth refuge from marine heat waves that may allow, at least temporarily, the maintenance of P. clavata in the Western Mediterranean Sea. The present study strongly advocates for further investigations and monitoring of the mesophotic zone to chart potential areas that could serve as deep refuge for gorgonians.

Climate change is causing an increase in the frequency and intensity of marine heatwaves (MHWs) and mass mortality events (MMEs) of marine organisms are one of their main ecological impacts. Here, we show that during the 2015–2019 period, the Mediterranean Sea has experienced exceptional thermal conditions resulting in the onset of five consecutive years of widespread MMEs across the basin. These MMEs affected thousands of kilometers of coastline from the surface to 45 m, across a range of marine habitats and taxa (50 taxa across 8 phyla). Significant relationships were found between the incidence of MMEs and the heat exposure associated with MHWs observed both at the surface and across depths. Our findings reveal that the Mediterranean Sea is experiencing an acceleration of the ecological impacts of MHWs which poses an unprecedented threat to its ecosystems' health and functioning. Overall, we show that increasing the resolution of empirical observation is critical to enhancing our ability to more effectively understand and manage the consequences of climate change.

Climate change is causing an increase in the frequency and intensity of marine heatwaves (MHWs) and mass mortality events (MMEs) of marine organisms are one of their main ecological impacts. Here, we show that during the 2015–2019 period, the Mediterranean Sea has experienced exceptional thermal conditions resulting in the onset of five consecutive years of widespread MMEs across the basin. These MMEs affected thousands of kilometers of coastline from the surface to 45 m, across a range of marine habitats and taxa (50 taxa across 8 phyla). Significant relationships were found between the incidence of MMEs and the heat exposure associated with MHWs observed both at the surface and across depths. Our findings reveal that the Mediterranean Sea is experiencing an acceleration of the ecological impacts of MHWs which poses an unprecedented threat to its ecosystems' health and functioning. Overall, we show that increasing the resolution of empirical observation is critical to enhancing our ability to more effectively understand and manage the consequences of climate change.

Potential for, and limits to, adaptation to environmental changes are critical for resilience and risk mitigation. The Mediterranean basin is a mosaic of biodiversity-rich ecosystems long affected by human influence, whose resilience is now questioned by climate change. After reviewing the different components of biological adaptation, we present the main characteristics of marine and terrestrial biodiversity in the Mediterranean basin and of the pressures they face. Taking climatic trends into consideration, we discuss the adaptive potential of a range of ecosystems dominated by species without active dispersal. We argue that the high heterogeneity of Mediterranean landscapes and seascapes constitutes a laboratory for the study of adaptation when environmental conditions change rapidly and may provide opportunities for adaptation and adaptability of species and ecosystems. Adaptive management in the Mediterranean can and should harness the nature-based solutions offered by both ecological and evolutionary processes for increasing the resilience of ecosystems to climate change.

This report presents the results obtained from the data collected during the Circareef and Circatax projects on the circalittoral habitats of interest in the N2000 zone "rocky Basque coast and offshore extension". These results show a remarkable ecological and biogeographical interest of the prospected sites with habitats sheltering an unknown original biodiversity. The analysis of the samples taken and the identification of the taxa collected confirm these observations. In parallel, calculations of an index based on an Ecosystem-Based Quality Index (EBQI) ecosystem approach are presented. From this report, orientations are determined to improve the knowledge of these remarkable habitats in the context of European directives of conservation., Ce rapport présente un bilan des résultats obtenus à partir des données récoltées au cours des projets Circareef et Circatax sur les habitats circalittoraux d’intérêt de la zone N2000 « côte basque rocheuse et extension au large ». Ces résultats montrent un intérêt écologique et biogéographique remarquable des sites prospectés avec des habitats abritant une biodiversité originale non connue. L’analyse des prélèvements réalisés et l’identification des taxons présents confortent ces observations. En parallèle, les résultats d’un indice basé sur une approche écosystémique Ecosystem-Based Quality Index (EBQI) sont présentés. à partir de ce bilan, des orientations sont déterminées pour approfondir la connaissance de ces habitats remarquables dans le contexte des directives européennes de conservation.

Dispersal is a central process that affects population growth, gene flow, and ultimately species persistence. Here we investigate the extent to which gene flow occurs between fragmented populations of the deep-water brown algae Ericaria zosteroides (Turner) Greville (Sargassaceae, Fucales). These investigations were performed at different spatial scales from the bay of Marseille (western Provence) to Corsica. As dispersal of zygotes is shown to be limited over distances beyond a few meters, we used a multidisciplinary approach, based on Lagrangian modeling and population genomics to test the hypothesis that drifting of fertile parts of thallus (eggs on fertile branches), mediated by ocean currents, enable occasional gene flow between populations. Therefore we assessed the respective contribution of oceanographic connectivity, geographical isolation, and seawater temperatures to the genetic structure of this species. The genetic structure was assessed using 10,755 neutral SNPs and 12 outlier SNPs genotyped by dd-RAD sequencing in 261 individuals of E. zosteroides. We find that oceanographic connectivity is the best predictor of genetic structure, while differentiation in outlier SNPs can be explained by the depth of populations, as emphasized by the minimum seawater temperature predictor. However, further investigations will be necessary for clarifying how depth drives adaptive genetic differentiation in E. zosteroides. Our analyses revealed that local hydrodynamic conditions are correlated with the very high divergence of one population in the Bay of Marseille. Overall, the levels of gene flow mediated by drifting were certainly not sufficient to counteract differentiation by local genetic drift, but enough to allow colonization several kilometers away. This study stresses the need to consider secondary dispersal mechanisms of presumed low dispersal marine species to improve inference of population connectivity.

This paper aims at collating and reviewing all data collected using the ESCA (Ecological Status of Coralligenous Assemblages) index from 2009 to 2018 during different local applications, in order to evaluate at large spatial scale its effectiveness and temporal variability. To this scope, the large-scale response of ESCA to anthropogenic disturbance was tested comparing ESCA values calculated at 42 sites of the Western Mediterranean Sea with the anthropization index. Moreover, the sensitivity of ESCA to punctual human disturbance and the robustness of the index across the natural space and time variability were evaluated. The large spatial scale study showed significant correlation between ESCA and the anthropization index, while very low correlation was detected when descriptors of ESCA (i.e., sensitivity levels, α-diversity, and β-diversity) were considered separately. The three impact evaluation studies highlighted significantly lower values of the ESCA index in disturbed conditions than in the control ones. The coastal monitoring study confirmed the robustness of the index which showed a high ecological quality of coralligenous reefs in reference conditions compared to more anthropized sites, and this pattern was maintained throughout the ten years study period. Application of the ESCA index to different situations tested positively its sensibility to different levels and type of human disturbance and its stability with respect to regional spatio-temporal variability. This confirm the reliability of the ESCA index already tested on the local and annual scale, thus broadening its range of application and validating it on a wider space–time scale.

Ce rapport présente les fiches descriptives des 32 unités d’habitats de niveau 3 (biocénose) et 119 unités de niveau 4 (faciès et associations) de la typologie des biocénoses benthiques de Méditerranée version 2, pour servir d’outil d’aide à l’identification et la conservation des habitats. Les habitats ont été décrits sur la base des descriptions existantes dans d’autres typologies complétées par les connaissances disponibles. Ce travail a également permis de mettre à jour la typologie pour suivre les évolutions taxonomiques des espèces caractéristiques, clarifier des libellés d’unité et supprimer un faciès. Toutes les fiches descriptives sont également disponibles en ligne sur les pages habitats de l’INPN.

Les missions d’inventaire de biodiversité comme les Grandes Expéditions du MNHN permettent de prospecter un grand nombre de stations en plongée, pouvant ainsi servir de stations de référence pour la gestion locale (notamment des aires marines protégées), à condition de proposer une approche adaptée aux problématiques de gestion et conservation. Dans le cadre du programme La Planète Revisitée en Corse et l’exploration du Parc Naturel Marin du Cap Corse et de l’Agriate, la prospection en plongée a permis le développement d’une approche complémentaire à l’inventaire de la biodiversité marine, tout en s’intégrant aux contraintes des opérations d’inventaire en plongée. Cette approche combine la photographie sous-marine et un protocole opérationnel d’Inventaire Visuel en Temps Limité (IVTL-MED) pour renseigner l’état écologique des habitats rocheux subtidaux. L’IVTL-MED a été adapté ici pour les biocénoses de l’infralittoral rocheux de Méditerranée (entre 15 - 35 m) et a permis une évaluation semi-quantitative in-situ, standardisée et relativement rapide des communautés sessiles épigées. Ce rapport préliminaire présente le développement de cette approche et les premiers résultats pour le Parc Naturel Marin du Cap Corse et de l’Agriate. La valorisation de l’ensemble des données acquises lors de la campagne La Planète Revisitée Corse 2019 – 2022 fera l’objet d’un rapport complet.

The coralligenous ecosystem is one of the biodiversity hotspots in the Mediterranean Sea. This study aims at determining (i) the organic matter (OM) sources at the base of the food web in a coralligenous ecosystem near Marseille (Cap Caveau, Frioul Island) and (ii) the global functional structure of its community. For that purpose, C and N stable isotope analyses were performed on 78 compartments or species collected in this habitat between 30 and 40 m depth. Results suggested that the pelagic particulate organic matter (POM), mainly composed of phytoplankton, was the main OM source fuelling coralligenous food webs, followed by sedimented organic matter (SOM) and some macrophytes. At least three level of consumers were identified from plankton-feeding invertebrates to piscivorous teleosts. Coralligenous food webs seemed to be characterized by a high abundance and trophic diversity of plankton and filter feeders. Among them numerous sessile invertebrates, such as cnidarians, bryozoans and ascidians, were poorly directly consumed, but played an important role in POM transfer. Further studies on spatial and temporal variations of coralligenous communities would be necessary for providing a general trophic functioning model of this highly diversified ecosystem.

Anthropogenic climate change, and global warming in particular, has strong and increasing impacts on marine ecosystems (Poloczanska et al., 2013; Halpern et al., 2015; Smale et al., 2019). The Mediterranean Sea is considered a marine biodiversity hot-spot contributing to more than 7% of world's marine biodiversity including a high percentage of endemic species (Coll et al., 2010). The Mediterranean region is a climate change hotspot, where the respective impacts of warming are very pronounced and relatively well documented (Cramer et al., 2018). One of the major impacts of sea surface temperature rise in the marine coastal ecosystems is the occurrence of mass mortality events (MMEs). The first evidences of this phenomenon dated from the first half of'80 years affecting the Western Mediterranean and the Aegean Sea (Harmelin, 1984; Bavestrello and Boero, 1986; Gaino and Pronzato, 1989; Voultsiadou et al., 2011). The most impressive phenomenon happened in 1999 when an unprecedented large scale MME impacted populations of more than 30 species from different phyla along the French and Italian coasts (Cerrano et al., 2000; Perez et al., 2000). Following this event, several other large scale MMEs have been reported, along with numerous other minor ones, which are usually more restricted in geographic extend and/or number of affected species (Garrabou et al., 2009; Rivetti et al., 2014; Marbà et al., 2015; Rubio-Portillo et al., 2016, authors' personal observations). These events have generally been associated with strong and recurrent marine heat waves (Crisci et al., 2011; Kersting et al., 2013; Turicchia et al., 2018; Bensoussan et al., 2019) which are becoming more frequent globally (Smale et al., 2019). Both field observations and future projections using Regional Coupled Models (Adloff et al., 2015; Darmaraki et al., 2019) show the increase in Mediterranean sea surface temperature, with more frequent occurrence of extreme ocean warming events. As a result, new MMEs ar

This report presents the assessment of French Mediterranean benthic habitats’ sensitivity to physical anthropogenic pressures, based on best available knowledge, and in collaboration with scientific experts. It summarises the methodological framework and limitations, and provides assessment matrices for each habitat. Each matrix displays, for each pressure, a resistance score, a resilience score and a combined sensitivity score, with associated confidence indices, and a description of the evidence base and type. The generic sensitivity assessments produced by this project aim to serve as a tool in helping the monitoring and management of the marine environment, notably in assessing the risks posed by human activities to benthic habitats.

Le Ministère de l’Ecologie, de l’Energie et de la Mer a confié au Service du Patrimoine Naturel (Muséum National d’Histoire Naturelle), en lien étroit avec les acteurs de la recherche scientifique, la coordination d’un projet sur l’évaluation de la sensibilité des habitats benthiques aux pressions d’origine anthropique. L’objectif de ce travail est de qualifier la sensibilité générique des habitats présents en France métropolitaine pour aider à l’orientation et à la priorisation de mesures de gestion (pour des activités actuelles ou futures), adaptées aux enjeux de conservation, afin de respecter les objectifs d’atteinte ou de maintien d’un ECF (DCSMM) ou BEE (DHFF). Ce travail permet également de mettre en évidence les habitats et/ou les pressions pour lesquels les données et connaissances sont limitées, pour mieux orienter les futurs projets d’acquisition de connaissances. Les livrables de ce projet ont pour vocation à servir d’outil d’aide à la gestion des activités anthropiques. Les évaluations de sensibilité ont été réalisées selon la méthodologie décrite précédemment (La Rivière et al., 2015) par un groupe d’experts spécialistes des habitats benthiques, co-auteurs de ce rapport, lors de deux ateliers travail qui se sont déroulés à Marseille en octobre 2015. Elles se basent sur les meilleures connaissances disponibles à ce jour et ont été complétées par l’avis de ces experts. Il a été choisi de réaliser les évaluations de sensibilité à travers des ateliers de travail thématiques afin de (i) minimiser le biais d’interprétation de chaque expert en clarifiant le contexte d’application des évaluations, (ii) mutualiser les connaissances (en particulier sur des habitats peu connus), et ainsi (iii) maximiser la robustesse des évaluations. Les évaluations ont été réparties en deux ateliers de travail (un atelier par type de substrat – habitats de substrats durs ou de substrats meubles) animés par le SPN et réunissant onze experts benthologues. Des experts externes, cit

A rapid visual assessment (RVA) approach for the characterization and assessment of the integrity of coralligenous reefs was applied in 21 stations subjected to different levels of anthropogenic pressure, along the French Mediterranean coasts. The reefs were characterized from both the geomorphologic and bionomic (biotic cover, conspicuous species richness, canopy-forming species, etc.) points of view, and their health status was estimated through the COARSE (COralligenous Assessment by ReefScape Estimate) index. The sensitivity of the COARSE index and the robustness of the RVA approach to observer biases were analyzed. Results showed that most coralligenous reefs were characterized by (sub) vertical cliffs or platforms with variable slope, usually dominated by biotic facies with Paramuricea clavata and/or Eunicella cavolini in healthy stations, or by algal associations or facies of impoverishment in the most impacted situations. The overall quality scores of the COARSE index generally reflected the putative level of stress of the sampling stations; differences due to observer biases resulted negligible. Coupling the RVA approach with the COARSE index proved an effective protocol for both the characterization and the evaluation of coralligenous reefs: the former is achieved by the analysis of the whole complexity of this habitat, the latter provides for the first time an indication of sea-floor integrity, differently from previous indices that aim at estimating water quality.

Suite à l’acquisition de nouvelles informations sur les habitats marins méditerranéens, une mise à jour du référentiel national était nécessaire pour qu’il soit le reflet des connaissances actuelles. Ces nouvelles informations proviennent principalement de deux campagnes d’exploration des roches profondes et des canyons méditerranéens appelées MEDSEACAN et CORSEACAN, de CARTHAM (Cartographie des Habitats Marins) – deux programmes pilotés par l’Agence des Aires Marines Protégées – ainsi que de propositions émanant directement de la communauté scientifique. En collaboration avec les experts scientifiques benthologues, ces nouvelles observations ont été confrontées à la typologie (Michez et al., 2011) et des modifications et compléments ont été décidés. Ce rapport présente la version actualisée de la partie « Méditerranée » du référentiel français des habitats marins benthiques. Il explique en détail les choix opérés ainsi que les points à appronfondir.

A new genus of soft coral from the Republic of Congo is described, Complexum gen. n. Nine West African octocoral species previously described in the genus Alcyonium by Tixier-Durivault (1955) are referred to this new genus, and a new species is described and figured, C. pusillum sp. n. The new species is characterized by having encrusting growth form and abundant spiny clubs in the surface of the polyparium. It colonizes shallow calcareous rocky banks (5 to 20 m depth) existing in coastal water of the region of Pointe-Noire. Based on molecular phylogeny this new genus is well separated from Alcyonium species.

Gorgonians are important organisms in the Mediterranean Sea, where they form rocky benthic communities. Four main species (3 Holaxonia and 1 Scleraxonia) are predominant in infra- and circalittoral communities of the northwestern Mediterranean basin. Other species, such as Eunicella verrucosa (Pallas, 1766), are more rarely encountered. The expansion to unusually shallow bathymetric levels has been noted in the region of Marseilles (France) (between 20 and 40 m depth). A ten-year monitoring of colonies was used to assess the growth rate according to age (size): from 3.33 cm year(-1) (height <15 cm) to 0.62 cm year(-1) (height >40 cm).

Document rassemblant les fiches de métadonnées nécessaires à la saisie en base de données (Quadrige²) pour un archivage pérenne. Ces fiches concernent les posidonies en Méditerranée. Les données sont essentiellement acquises dans le cadre de la DCE (Directive cadre sur l'Eau). Le programme est nommé POSIDONIES.

The Mediterranean benthic network proposes an integrated approach in term of scientific research and monitoring networks dealing with benthic biocenosis in the Mediterranean Sea (French part) ; it gives a state of the art as well as future needs, regarding regulatory aspects and data storage., L’avant projet sommaire du REBENT Méditerranée propose une approche intégrée des recherches et surveillances portant sur les biocénoses benthiques en Méditerranée ; il dresse un état de l’art des connaissances en la matière ainsi que des besoins futurs, en ciblant sur l’écoute de la demande sociétale et des cadres de gestion, ainsi que la bancarisation des données