Search

To enrich spatio-temporal information on the distribution of alien, cryptogenic, and neonative species in the Mediterranean and the Black Sea, a collective effort by 173 marine scientists was made to provide unpublished records and make them open access to the scientific community. Through this effort, we collected and harmonized a dataset of 12, 649 records. It includes 247 taxa, of which 217 are Animalia, 25 Plantae and 5 Chromista, from 23 countries surrounding the Mediterranean and the Black Sea. Chordata was the most abundant taxonomic group, followed by Arthropoda, Mollusca, and Annelida. In terms of species records, Siganus luridus, Siganus rivulatus, Saurida lessepsianus, Pterois miles, Upeneus moluccensis, Charybdis (Archias) longicollis, and Caulerpa cylindracea were the most numerous. The temporal distribution of the records ranges from 1973 to 2022, with 44% of the records in 2020–2021. Lethrinus borbonicus is reported for the first time in the Mediterranean Sea, while Pomatoschistus quagga, Caulerpa cylindracea, Grateloupia turuturu, and Misophria pallida are first records for the Black Sea ; Kapraunia schneideri is recorded for the second time in the Mediterranean and for the first time in Israel ; Prionospio depauperata and Pseudonereis anomala are reported for the first time from the Sea of Marmara. Many first country records are also included, namely: Amathia verticillata (Montenegro), Ampithoe valida (Italy), Antithamnion amphigeneum (Greece), Clavelina oblonga (Tunisia and Slovenia), Dendostrea cf. folium (Syria), Epinephelus fasciatus (Tunisia), Ganonema farinosum (Montenegro), Macrorhynchia philippina (Tunisia), Marenzelleria neglecta (Romania), Paratapes textilis (Tunisia), and Botrylloides diegensis (Tunisia).

Este artículo contiene 18 páginas, 4 figuras., 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., This paper was supported by Euromarine. Joaquim Garrabou acknowledges the funding by the “Severo Ochoa Centre of Excellence” (CEX2019-000928-S), the MCIU/AEI/FEDER [HEATMED; RTI2018-095346-B-I00], Interreg-Med Programme MPA-Engage (1MED15_3.2_M2_337), the European Union Horizon 2020 research and innovation programme (Futuremares SEP-210597628). Nuria Teixido acknowledges the French National Research Agency (4Oceans-MOPGA grant, ANR-17-MPGA-0001) and internal funds from the Stazione Zoologica Anton Dohrn. Gil Rilov was supported by the Israel Ministry of Environmental Protection. Hocein Bazairi, Free Spinosa, and Vasilis Gerovasileiou acknowledge the funding by the MAVA Fondation (MedKeyHabitats I Project) and the European Commission (Ecap-MED II Project; projects implemented by UNEP/MAP-RAC/SPA). Alfonso Ramos was supported the CIESM “Tropical Signals,” Stelios Katsanevakis and Maria Sini were supported by the Project “Coastal Environment Observatory and Risk Management in Island Regions AEGIS+” (MIS 5047038), implemented within the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014–2020), co-financed by the Hellenic Government (Ministry of Development and Investments) and the European Union (European Regional Development Fund, Cohesion Fund), Stelios Katsanevakis, Maria Sini and Vasilis Gerovasileiou acknowledge the support of the MARISCA Project, co-funded by 85% by the EEA GRANTS, 2009–2014, and 15% by the Public Investments Programme (PIP) of the Hellenic Republic. Ivan Guala and Daniele Grech thanks thank the support of the project “Pinna nobilis—ricerca per la sopravvivenza: un'iniziativa di Citizen Science per tracciare la mortalità di massa di Pinna nobilis in Sardegna” project and the L/7 grant (CUP 87G17000070002) funded by the Regione Autonoma Sardegna. Jean-Baptiste Ledoux was funded by an assistant researcher contract framework of the RD Unit—UID/Multi/04423/2019—Interdisciplinary Centre of Marine and Environmental Research—financed by the European Regional Development Fund (ERDF) through COMPETE2020—Operational Program for Competitiveness and Internationalization (POCI) and national funds through FCT/MCTES (PIDDAC). This research was supported by the Strategic Funding UIDB/04423/2020 and UIDP/04423/2020 through national funds provided by the FCT—Foundation for Science and Technology and European Regional Development Fund (ERDF), in the framework of the program PT2020. Bernat Hereu and Cristina Linares acknowledge the support of the long-term monitoring programme of the catalan Natural Parks, funded by the Departament de Territori i Sostenibilitat of the Generalitat de Catalunya. Cristina Linares acknowledges the support of the ICREA Academia programme. David Díaz acknowledges the support the research grant CTM2016-77027-R of the Programa Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad and Program of Marines Strategies of Spain funded by MITERD. Jamila Ben Soussi was partially funded by the Fondation Albert 2 Monaco (MIMOSA Project) and the Tropical Signals Program of CIESM. Giovanni Chimienti was supported by the Italian Ministry of Education, University and Research (PON 2014–2020, AIM 1807508–1, Linea 1), by the Ente Parco Nazionale del Gargano (Research agreement with CoNISMa N. 21/2018), and by the National Geographic Society (Grant EC-176R-18). Nathaniel Bensoussan acknowledges financial support from the European Commission through the programme “Caroline Herschell” in the context of the action “Developing Downstream applications and services on BIO-PHYsical characterization of the seascape for COASTal management” (BIOPHYCOAST). Monica Montefalcone and Annalissa Azzola collected some of their data on MMEs in the frame of the project “Mare Caldo” funded by Greenpeace Italy. Núria Marbà acknowledges financial support from the Spanish Ministries of Economy and Competitiveness (CTM2012-32603, CGL2015-71809-P) and Ministerio de Ciencia, Innovación y Universidades (RTI2018-095441-B-C21). Diego K. Kersting acknowledges support by the postdoctoral fellowship programme Beatriu de Pinós funded by the Secretary of Universities and Research (Government of Catalonia) and the Horizon 2020 programme of research and innovation of the European Union under the Marie Sklodowska-Curie grant agreement No 801370.

Detailed knowledge about the distribution of species in need of protection is required for the management of Marine Protected Areas, a major tool to reduce marine biodiversity loss. Such knowledge is deficient for most marine invertebrates. Axinella polypoides is a marine sponge included on the list of protected species by the Barcelona Convention (1976) and the Bern Convention (1987). This large and erect species has an important ecological role in habitat forming and benthic–pelagic coupling. Bathymetrical, geographical and ecological data over the last 60 years were collated from publications and reports, together with new surveys to assess the distribution and protection status in Liguria of A. polypoides. It identified a more widespread distribution than previously thought, which points at a general need for dedicated investigations on the occurrence of species that require protection. Bathymetrical distribution was trimodal, with peaks corresponding to different geomorphological settings: coastal cliff bases (around 38 m depth), inner shelf shoals (52 m) and rocks amidst coarse sediment on the outer shelf (79 m). Density was significantly greater at the shallowest depths. The species was mostly found in the coralligenous biocoenosis, in association with other characteristic species or forming a monospecific facies. On (sub)vertical cliffs, A. polypoides often exhibited an unusual cane shape, rather than the typical bushy morphology, thus causing confusion with the congeneric A. cannabina, a more southern species. Records of the latter in the Ligurian Sea therefore need confirmation. Only a minority (22.6%) of A. polypoides records were in Marine Protected Areas, the remainder being located in areas with no current environmental protection plans in place. While the occurrence of this species in MPAs remained stable over the decades, the only quantitative historical data available indicated that populations in non‐protected areas were declining owing to anthropogenic impacts (fishing and anchoring).

Climate change is affecting rocky reef ecosystems in a multitude of ways at global scale. During summer 2018, the rocky reef communities of Portofino Marine Protected Area (MPA) (NW Mediterranean) were affected by thermal anomalies, a mucilaginous event, and the seasonal expansion of Caulerpa cylindracea. Moreover, a severe storm occurred on 29 October. The effects of these pressures on the rocky reef communities were analysed at different depths (10 m, 20 m, 30 m, and 40 m) and at three times (June, October, December) to evaluate change at short temporal scale. Portofino MPA’s communities have significantly changed: thermal anomalies mostly affected the biota living above the summer thermocline (ca 20 m depth); mucilaginoius aggregates first impacted the communities in shallow waters and only later those in deep waters, where they typically fall in late summer; the greatest impact by Caulerpa cylindracea was detected at 20 m depth; the storm directly impacted communities in shallow and intermediate waters by uprooting algal species, while it had indirect effects at greater depths through sediment redistribution. Disentangling the effects of multiple pressures on coastal ecosystems is one of the most pressing goals in marine ecology and biodiversity conservation. This study represents an attempt in this direction as applied to the short-term dynamics of rocky reef communities under a climate change scenario.

Este artículo contiene 11 páginas, 2 figuras, 2 tablas., Local, regional and global targets have been set to halt marine biodiversity loss. Europe has set its own policy targets to achieve Good Environmental Status (GES) of marine ecosystems by implementing the Marine Strategy Framework Directive (MSFD) across member states. We combined an extensive dataset across five Mediterranean ecoregions including 26 Marine Protected Areas (MPAs), their reference unprotected areas, and a no-trawl case study. Our aim was to assess if MPAs reach GES, if their effects are local or can be detected at ecoregion level or up to a Mediterranean scale, and which are the ecosystem components driving GES achievement. This was undertaken by using the analytical tool NEAT (Nested Environmental status Assessment Tool), which allows an integrated assessment of the status of marine systems. We adopted an ecosystem approach by integrating data from several ecosystem components: the seagrass Posidonia oceanica, macroalgae, sea urchins and fish. Thresholds to define the GES were set by dedicated workshops and literature review. In the Western Mediterranean, most MPAs are in good/high status, with P. oceanica and fish driving this result within MPAs. However, GES is achieved only at a local level, and the Mediterranean Sea, as a whole, results in a moderate environmental status. Macroalgal forests are overall in bad condition, confirming their status at risk. The results are significantly affected by the assumption that discrete observations over small spatial scales are representative of the total extension investigated. This calls for large-scale, dedicated assessments to realistically detect environmental status changes under different conditions. Understanding MPAs effectiveness in reaching GES is crucial to assess their role as sentinel observatories of marine systems. MPAs and trawling bans can locally contribute to the attainment of GES and to the fulfillment of the MSFD objectives. Building confidence in setting thresholds between GES and non-GES, investing in long-term monitoring, increasing the spatial extent of sampling areas, rethinking and broadening the scope of complementary tools of protection (e.g., Natura 2000 Sites), are indicated as solutions to ameliorate the status of the basin., This article was undertaken within the COST Action 15121 MarCons (http://www.marcons-cost.eu, European Cooperation in Science and Technology), the Interreg MED AMAre Plus (Ref: 8022) and the project PO FEAMP 2014-2020 Innovazione, sviluppo e sostenibilita ` nel settore della pesca e dell’acquacoltura per la Regione Campania (ISSPA 2.51). M.C.U., A.B. have been funded by the project MEDREGION (European Commission DG ENV/MSFD, 2018 call, Grant Agreement 110661/ 2018/794286/SUB/ENV.C2). Aegean Sea data were retrieved from the project PROTOMEDEA (www.protomedea.eu), funded by DG for Marine Affairs and Fisheries of the EC, under Grant Agreement SI2.721917. JB acknowledges support from the Spanish Ministry of Science and Innovation (Juan de la Cierva fellowship FJC 2018-035566-I)., With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S).

Marine ecosystems are subject to global and local impacts, both contributing to dramatic changes in coastal communities. Assessing such changes requires time series or the revisitation of sites first surveyed in the past. In both cases, data are not necessarily collected by the same observers, which could lead to a bias in the results. In the Marine Protected Area (MPA) of Capo Carbonara (Sardinia, Italy), established in 1998, rocky reef communities were first assessed in 2000 by two diving scientists. Twenty years later, the same rocky reefs were resurveyed using the same method by two other diving scientists. In both surveys, semi-quantitative data on conspicuous species were collected at five sites in four depth zones, providing the possibility of assessing change over time. To explore the influence of climate and local pressures, existing data on sea surface temperature, resident population, tourism and diving activities were analysed. The reef communities of the Capo Carbonara MPA have distinctly changed over time, mostly under the effect of seawater warming, as highlighted by the occurrence of thermophilic species and by other climate-related indicators. On the other side, species vulnerable to local human pressures have increased over time, demonstrating the effectiveness of the protection measures undertaken by the MPA. Comparing data collected by four different observers in the two periods demonstrated that change over time was significantly greater than variability between the observers.

Marine coastal ecosystems are facing structural and functional changes due to the increasing human footprint worldwide, and the assessment of their long-term changes becomes particularly challenging. Measures of change can be done by comparing the observed ecosystem status to a purposely defined reference condition. In this paper, a geospatial modelling approach based on 2D mapping and morphodynamic data was used to predict the natural position of the upper limit (i.e., the landward continuous front) of Posidonia oceanica seagrass meadows settled on soft bottom. This predictive model, formerly developed at the regional spatial scale, was here applied for the first time at the Mediterranean spatial scale in eight coastal areas of Spain, France, Italy, and Greece showing different coastal morphologies and hydrodynamic characteristics, and affected by a number of natural and/or human local disturbances. The model was effective in measuring the regression (i.e., seaward withdrawal) of the meadow upper limit. In all the meadows investigated the upper limit was regressed, laying deeper than the reference condition, with the proportion of regression ranging from 17.7% to 98.9%. The highest values of regression were found in Spain and in France, and were consistent with the highest levels of fragmentation detected with map analysis and of coastal pressures. This geospatial modelling approach represents an effective tool to define the reference conditions when proper pristine areas or historical data are not available, thus allowing the assessment of long-time changes experienced by seagrass ecosystems due to human impacts.

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.

The Mediterranean Sea supports high levels of biodiversity and complexity but is facing increasing human pressures, so that strategies to protect and recover its ecosystems must be a priority in environmental policies. Benthic cartography represents the first step of marine spatial planning for the proper management and protection of our sea. Univocal habitat classification systems are thus needed to map, monitor, and inventory marine habitats, and to guarantee common and shared frames for a harmonized interpretation of the Mediterranean habitat types. In this paper we reviewed the existing classification systems of marine benthic habitats, to discuss the process of revision and updating of one of the first system developed under the Barcelona Convention (BC) in 1998 and adopted by all the Mediterranean countries. The BC classification was revised including the new habitats discovered in the last 30 years, and consistently with the criteria used to revise the EUropean Nature Information System (EUNIS), which is a comprehensive pan-European system for habitat identification. The updated BC classification is hierarchical with 5 levels, which allows representing the most suitable habitat level with respect to the restitution scale of the map. Each habitat is univocally identified by an alpha-numeric code, name and general description following the bionomic approach traditionally adopted in the Mediterranean benthic cartography since the late nineteen century. The new BC classification lists 128 main habitats up to the level 4, which may also contain sub-habitats at the level 5, i.e. associations and facies, totalising 394 habitat types (54% of new habitats with respect to the first BC classification). The updated BC classification system has been used for the selection of reference marine habitats that support two fundamental processes of environmental management: i) identification of Specially Marine Protected Areas according to the SPA/BD Protocol of Barcelona Convention; ii) selection of habitats to be monitored, as requested by the Integrated Monitoring and Assessment Programme and the European Directives (e.g., Water Framework and Marine Strategy). The new list of reference habitats, selected because of their high ecological and conservation value, contains 267 habitats, corresponding to 68% of the total habitats listed in the updated BC classification.

Biotic indices are major tools recommended by the European Directives for assessing the ecological status of marine coastal ecosystems such as Posidonia oceanica meadows. Nevertheless, the multitude of available metrics commonly adopted in the P. oceanica monitoring often provide diverging responses about the health status of the habitat. In this study, we investigated the effectiveness and consistency of a set of 11 indices and descriptors working at different level of ecological complexity of P. oceanica ecosystem (individual, population, community, and seascape), applying them on 13 seagrass meadows of the Ligurian Sea (NW Mediterranean). A new approach, named RESQUE (RESilience and QUality of seagrass Ecosystem), is here proposed and aims to provide a single and comprehensive measure of the ecological status of seagrass meadows. RESQUE is a graphical approach that involves the calculation of both the Relative Area Index (RAI) and the Relative Circularity Index (RCI) starting from a radar chart where all the different values of indices and descriptors are reported after being normalized. The RAI represents a measure of the overall environmental quality, while the RCI constitutes a measure of the consistency among indices and it is assumed as a good proxy of meadow resilience. RESQUE turned out to be an effective method to incorporate all the different indices responses, and allowed integration of relevant information into an overall expression of meadow health. Beyond the ability of merely defining the quality of the Ligurian P. oceanica meadows, this approach displayed a great potential being possibly applicable to other habitats and with ideally infinite combinations of metrics., University of Genoa internal funds (FRA2019, Fondi di Ricerca d'Ateneo), Part of this work received an economic support from University of Genoa internal funds (FRA2019, Fondi di Ricerca d'Ateneo).

The ESCA (Ecological Status of Coralligenous Assemblages) index was developed to assess the ecological quality of coralligenous habitat using macroalgae as a biological indicator. The aim of this study was to evaluate the response to human-induced pressures of macroalgae and sessile macro-invertebrates shaping the coralligenous habitat and to integrate their sensitivity into the ESCA index. Coralligenous assemblages were sampled at 15 locations of the NW Mediterranean Sea classified into three groups: i) marine protected areas; ii) low urbanized locations; and iii) highly urbanized locations. A sensitivity level value was assigned to each taxon/group on the basis of its abundance in each environmental condition, the data available in the literature and the results of an expert judgement survey. The index that includes the totality of the assemblages (named ESCA-TA), calculated using both macroalgae and sessile macro-invertebrates, detected the levels of human pressure more precisely than the index calculated with only macroalgae or with only invertebrates. The potential for assessing the ecological quality of marine coastal areas was thus increased with the ESCA-TA index thanks to the use of a higher variety of descriptors., El índice ESCA (Estado Ecológico de las Comunidades Coralígenas) ha sido desarrollado para determinar el estado ecológico de los hábitats coralígenos utilizando macro-algas como indicador biológico. El objetivo de este estudio fue evaluar la respuesta, ante presiones antropogénicas, de macro-algas y macro-invertebrados sésiles moldeadores de la comunidad coralígena y su sensibilidad al índice ESCA. Se muestrearon comunidades coralígenas en 15 localizaciones del Mediterráneo Nord-Occidental clasificadas en 3 grupos: i) áreas marinas protegidas; ii) poco urbanizadas; iii) muy urbanizadas. Un valor de Nivel de Sensibilidad fue asignado a cada taxón/grupo en base a su abundancia en cada condición medioambiental, a información bibliográfica disponible y a los resultados de juicios por parte de expertos. El índice que integra la totalidad de las comunidades (llamado ESCA-TA), calculado usando tanto macro-algas como macro-invertebrados sésiles, detectó los diferentes niveles de presión humana de manera más precisa que el índice calculado solo con macro-algas o solo con invertebrados. El potencial para determinar el estado ecológico de las áreas marinas protegidas se incrementó con el índice ESCA-TA gracias al uso de una mayor variedad de descriptores.

Este artículo contiene 18 páginas, 4 figuras., Good datasets of geo-referenced records of alien species are a prerequisite for assessing the spatio-temporal dynamics of biological invasions, their invasive potential, and the magnitude of their impacts. However, with the exception of first records on a country level or wider regions, observations of species presence tend to remain unpublished, buried in scattered repositories or in the personal databases of experts. Through an initiative to collect, harmonize and make such unpublished data for marine alien and cryptogenic species in the Mediterranean Sea available, a large dataset comprising 5376 records was created. It includes records of 239 alien or cryptogenic taxa (192 Animalia, 24 Plantae, 23 Chromista) from 19 countries surrounding the Mediterranean Sea. In terms of records, the most reported Phyla in descending order were Chordata, Mollusca, Chlorophyta, Arthropoda, and Rhodophyta. The most recorded species was Caulerpa cylindracea, followed by Siganus luridus, Magallana sp. (cf. gigas or angulata) and Pterois miles. The dataset includes records from 1972 to 2020, with the highest number of records observed in 2018. Among the records of the dataset, Dictyota acutiloba is a first record for the Mediterranean Sea. Nine first country records are also included: the alga Caulerpa taxifolia var. distichophylla, the cube boxfish Ostracion cubicus, and the cleaner shrimp Urocaridella pulchella from Israel; the sponge Paraleucilla magna from Libya and Slovenia; the lumpfish Cyclopterus lumpus from Cyprus; the bryozoan Celleporaria vermiformis and the polychaetes Prionospio depauperata and Notomastus aberans from Malta., The publication of this article is supported by the Open Access Publishing Fund of the International Association for Open Knowledge on Invasive Alien Species (INVASIVESNET; www.invasivesnet.org). Stelios Katsanevakis, Maria Sini and Konstantinos Tsirintanis were supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project Number: HFRI-FM17-1597). Enalia Physis acknowledges Pantelis Patsalou for his support with field-logistics and links with fishers. Fiona Tomas would like to acknowledge funding from FECYT FCT- 14-9319 (¡OJO A LAS INVASORAS! BIODIVERSIDAD Y ESPECIES INVASORAS DEL MEDITERRÁNEO BALEAR). Vasilis Gerovasileiou, Thanos Dailianis and Maria Sini acknowledge the support by the MARISCA project (www.marisca.eu), co-funded (85%) by EEA GRANTS, 2009–2014, and the Public Investments Program (PIP) of the Hellenic Republic (15%). Razy Hoffman acknowledges funding by Yad-Hanadiv foundation, through the Israel Society of Ecology and Environmental Sciences and Israel Nature and Parks Authority (An integrated program for establishing biological baselines and monitoring protocols for marine reserves in the Israeli Mediterranean Sea). Argyro Zenetos and Paraskevi K. Karachle would like to thank the citizenscientists collaborating with the Ellenic Network on Aquatic Invasive Species (ELNAIS – elnais.hcmr.gr). Nikolaos Doumpas, Ioannis Giovos, Periklis Kleirou and Francesco Tiralongo would like to thank all the citizen-scientists that contributed with their shared records and data in the citizen-science project “Is it alien to you? Share it!!!” (https://www.facebook.com/ groups/104915386661854/). Data from Gyaros Island marine reserve were collected under the “GyarosMPA” project, funded by “MAVA Fondation pour la Nature”. Data from Corsica coastline were mainly collected in the framework of the “Corsica Alien Network” initiated by “Office de l’Environnement de la Corse”. Carla Morri and Carlo Nike Bianchi received financial support from FFARB (funds for basic research activities) by the Italian Ministry of Education, University and Research. Ergün Taşkın has been supported by TÜBİTAK, Ankara, Turkey (Project Number: 114Y238). The Slovenian authors would like to acknowledge their financial support from the Slovenian Research Agency (research core funding No. P1-0237) and the Ministry of Agriculture, Forestry and Food of the Republic of Slovenia. Mehmet Fatih Huseyinoglu thanks University of Kyrenia’s Scientific Research Project numbered GRN-20191-004. Fabio Crocetta was funded by the COST (European Cooperation in Science and Technology) Action TD1209 Alien Challenge project. The FRI (HAO DEMETER) team is very grateful to the Marine Strategy Project for financial support. Records of NIS in Jbel Moussa, the National Park of Al Hoceima and Cap des Trois Fourches sites from Morocco were obtained during surveys conducted within the framework of the MedKeyHabitats and the MedMPAnet Projects implemented by UNEP/MAP-RAC/SPA in close collaboration with the Haut Commissariat aux Eaux et Forêts et à la Lutte Contre la Désertification (HCEFLCD) and financially supported by RAC/SPA, Tunisia and the MAVA Foundation, Switzerland (MedKeyHabitats Project) and the European Commission (EC), the Spanish Agency for International Cooperation to Development (AECID), and the French Global Environment Facility (MedMPAnet Project). Jamila Ben Souissi was partially funded by BiodivMex /Chantier MISTRALS. Konstantinos Tsiamis sampling records were retrieved during his post in the Hellenic Centre for Marine Research, which he would like to thank for. Periklis Kleitou and Demetris Kletou were supported by the LIFE financial instrument of the European Union – RELIONMED project [Grant Agreement LIFE16 NAT/ CY/000832]. Some of the data included in the dataset were obtained through the marine citizen science platform Observadores del Mar www.observadoresdelmar.es with the support of FECYT FCT-17-12469, LIFE IP Intemares and Fundació Marilles, and through the citizen science site of the Italian Marine Protected Area of “Regno di Nettuno” (islands of Ischia, Procida and Vivara): www.citizensciencerdn.org. Most data from Lebanon were retrieved from social media dedicated to citizen science (Facebook group: Sea Lebanon https://www.facebook.com/ groups/109615625861815/) or fishers and scuba divers WhatsApp groups). Jamila Rizgalla wishes to thank the administration of Regatta for granting a free pass to conduct field surveys and the security personnel for providing a safe environment. Anna Occhipinti-Ambrogi was supported by European Community’s Seventh Framework Program VECTORS (Vectors of Change in Oceans and Seas Marine Life, Impact on Economic Sectors). The long lasting collaboration with the ICES Working Group on Introductions and Transfer of Marine Organisms (WGITMO) has been a good forum where many information and ideas could be exchanged within some of the authors (Anna Occhipinti-Ambrogi, Argyro Zenetos, Agnese Marchini, and a wider community of scientists working on biological invasions). A. Rosso and R. Sanfilippo received grants from the Catania University Research Plan 2016/2018. Data from Kuriat island were collected under the “Kuriat project”, funded by “MAVA Fondation pour la Nature” executed by SPA/RAC in partnership with the Coastal Protection and Management Agency (APAL) and Notre Grand Bleu (NGB) NGO. The AIS/ERA (Environment and Resources Authority) Maltese data were obtained from the EU funded project EMFF 8.3.1 under the European Maritime and Fisheries Fund 2014–2020 with a total cost of €1.6 million in public eligible EMFF funds (75% EU 25% MT), managed by AIS/ERA (Environment and Resources Authority). The ultimate goals of this European Maritime and Fisheries Fund (EMFF 2014–2020) project are to devise a holistic approach towards marine monitoring and develop a comprehensive database of data collected about the Maltese waters., With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Extreme environmental events can strongly affect coastal marine ecosystems but are typically unpredictable. Reliable data on benthic community conditions before such events are rarely available, making it difficult to measure their effects. At the end of October 2018, a severe storm hit the Ligurian coast (NW Mediterranean) producing damages to coastal infrastructures. Thanks to recent data collected just before the event on two Posidonia oceanica seagrass meadows hit by the storm, it has been possible to assess the impact of the event on one of the most valuable habitats of the Mediterranean Sea. By means of seagrass cover and depth data gathered along four depth transects positioned within the two meadows in areas differently exposed to the storm waves, and by using models (WW3® + SWAN + XBeach 1D) to evaluate wave height and bed shear stress, we showed that meadows experienced erosion and burial phenomena according to exposure. Paradoxically, meadows in good conditions suffered more damage as compared to those already suffering from previous local anthropogenic impacts. Besides the direct effect of waves in terms of plant uprooting, a major loss of P. oceanica was due to sediment burial in the deepest parts of the meadows. Overall, the loss of living P. oceanica cover amounted to about 50%. Considering that previous research showed that the loss of the original surface of P. oceanica meadows in 160 years due to anthropogenic pressures was similarly around 50%, the present study documented that an extreme environmental event can generate in a single day a loss of natural capital equal to that produced gradually by more than a century of human impact.

The study aimed at contributing to the knowledge of alternative stable states by evaluating the differences of mobile and sessile macro-zoobenthic assemblages between sea urchin barrens and macroalgal forests in coastal Mediterranean systems considering a large spatial scale. Six sites (100 s km apart) were selected: Croatia, Montenegro, Sicily (Italy), Sardinia (Italy), Tuscany (Italy), and Balearic Islands (Spain). A total of 531 taxa, 404 mobile and 127 sessile macro-invertebrates were recorded. Overall, 496 and 201 taxa were found in macroalgal forests and in barrens, respectively. The results of this large-scale descriptive study have met the expectation of lower macrofauna complexity and diversity in barrens rather than in macroalgal forests, and have allowed estimating the differences in levels of diversity and the consistency of variability across Mediterranean sites. Some peculiar patterns in barrens, related to both abundance of specific taxa and to high values of beta diversity, have been evidenced.

Biotic homogenization is an expected effect of biological invasions. Invasive alien species typically show great adaptability to a wide range of environmental conditions and may expand into different habitats, thus reducing the dissimilarity among the recipient communities. We tested this assumption by analyzing a comprehensive database (78 species × 229 samples) collected between 2012 and 2017 in the marine protected area of Portofino (NW Italy), where Caulerpa cylindracea, one of the worst invaders in the Mediterranean Sea, exhibits high substratum cover at depths between 1 m and 45 m in 14 different communities (identified according to the European Nature Information System EUNIS for habitat classification). Five samples for each of the eight depth zones (i.e., 5 m, 10 m, 15 m, 20 m, 25 m, 30 m, 35 m, and 40 m) were randomly re-sampled from the comprehensive database to produce a dataset of 67 species × 40 samples. Then, a second dataset of 66 species × 40 samples was simulated by excluding Caulerpa cylindracea. Both re-sampled datasets underwent multivariate analysis. In the presence of C. cylindracea, the overall similarity among samples was higher, thus indicating homogenization of the rocky reef communities of Portofino Marine Protected Area. Continued monitoring activity is needed to understand and assess the pattern and extent of C. cylindracea’s inclusion in the recipient ecosystems.

International audience; The dearth of long-time series hampers the measurement of the ecosystem change that followed the global marine climate shift of the 1980-90s. The sessile communities of Portofino Promontory reefs (Ligurian Sea, NW Mediterranean) have been discontinuously studied since the 1950s. Collating, information from various sources, three periods of investigations have been distinguished: 1) 1950-70s; 2) 1980-90s; 3) 2000-10s. A cooler phase in time I was followed by a rapid warming in time 2, to stabilize at about 0.5 degrees C higher in time 3. Human pressure grew impressively, especially after the establishment of a MPA in 1999. Multivariate analyses evidenced a major change of community composition in time 2. Some species disappeared or got rarer, many found refuge at depth, and among the newcomers there were recently introduced alien species. This study demonstrated the importance of descriptive historical data to understand magnitude and pattern of change in the long term evolution of marine ecosystems. (C) 2016 Elsevier Ltd. All rights reserved.

A new index of ecological status, named Mesophotic Assemblages Ecological Status (MAES) index, was elaborated on the basis of ROV (Remotely Operated Vehicle) photography and video footage in order to assess the status of mesophotic megabenthic assemblages from hard bottom. The index was tested on seven sites located between 50 and 150 m depth in the Ligurian and Tyrrhenian seas (western Mediterranean Sea). The MAES index considers three main parameters: (i) the community structure (number of megabenthic taxa, percent biotic cover in the basal layer, density of erect species); (ii) the condition of the dominant erect species (average height, percent of colonies with epibiosis/necrosis); (iii) the visible human impact (density of marine litter, including lost fishing gears). Two versions of the index have been elaborated, the complete version (MAES) and the quick version ( q -MAES), which showed comparable results, therefore suggesting the possibility of fastening assessment times. The sensitivity of the MAES index was correlated with the putative human pressure acting upon the site (semi-quantitatively assessed considering fishing effort and coastal urbanization). A standard working protocol related to the evaluation of the MAES index is here proposed with the intent to create an effective monitoring tool for the assessment of the ecological status of mesophotic assemblages on a large scale, as required by the EU Marine Strategy Framework Directive. MAES index will enhance the comprehension of the dynamics of mesophotic Mediterranean megabenthic assemblages with respect to human pressures and will also provide marine scientists and managers with a valuable tool specifically designed for the conservation of such vulnerable marine ecosystems.

Temperate mesophotic reefs (circalittoral and offshore circalittoral hard/firm habitats), host complex three-dimensional animal forests and are vulnerable habitats protected by international agreements. In order to evaluate and monitor the environmental status of these ecosystems, the multi-parametric index Mesophotic Assemblages Conservation Status (MACS) was developed, including two independent components, namely Index of Status (Is) and Index of Impact (Ii). The Is includes six metrics, targeting conspicuous species diversity, basal layer and canopy composition, whilst the Ii is composed by six metrics targeting siltation level, canopy condition and marine litter occurrence. Underwater video transects recorded with a Remotely Operated Vehicle (ROV) along the Ligurian and Tyrrhenian Seas offered the chance to test the index on a large geographic scale and various ecological settings, for a total of 14 sites subjected to different human pressures. MACS index showed a high potentiality to distinguish among a wide range of environmental conditions, with local critical situations mainly related to high fishing pressure. With respect to other existing indices, MACS is based on a larger number of parameters, resulting in a higher ability to disentangle natural and anthropogenic factors, hence it leads to a better interpretation of local situations. This tool represents a contribution to the requirements for the monitoring of these marine environments, set by the EU Marine Strategy Framework Directive, the Habitats Directive, and the guidelines of the Integrated Monitoring and Assessment Programme of the Mediterranean Sea and Coast of the Barcelona Convention.

Seawater warming is impacting marine ecosystems, but proper evaluation of change requires the availability of long-term biological data series. Mesco Reef (Ligurian Sea, Italy) offers one of the longest Mediterranean data series on sessile epibenthic communities, based on underwater photographic surveys. Photographs taken in four stations between 20 m and 40 m depth allowed calculating the percent cover of conspicuous species in 1961, 1990, 1996, 2008, and 2017. Multivariate analysis evidenced an abrupt compositional change between 1990 and 1996. A parallel change was observed in Ligurian Sea temperatures. Two invasive macroalgae (Caulerpa cylindracea and Womersleyella setacea) became dominant after 1996. Community diversity was low in 1961 to 1996, rapidly increased between 1996 and 2008, and exhibited distinctly higher values in 2008&ndash, 2017. A novel community emerged from the climate shift of the 1990s, with many once characteristic species lost, reduced complexity, biotic homogenization, greater diversity and domination by aliens. Only continued monitoring will help envisage the possibility for a reversal of the present phase shift or for further transformations driven by global change.

Bazairi, Hocein/0000-0002-1788-0580; Gattuso, Jean-Pierre/0000-0002-4533-4114; Gerovasileiou, Vasilis/0000-0002-9143-7480; Cerrano, Carlo/0000-0001-9580-5546; Turicchia, Eva/0000-0002-8952-9028; Topcu, Nur Eda/0000-0003-2734-2695; Ponti, Massimo/0000-0002-6521-1330; deudero, salud/0000-0001-5584-2801; Ledoux, Jean-Baptiste/0000-0001-8796-6163; Fraschetti, Simonetta/0000-0002-1780-1651; BERTOLINO, Marco/0000-0003-3233-303X; Duarte, Carlos M./0000-0002-1213-1361, WOS: 000499719400001, [No abstract available], postdoctoral contract Juan de la Cierva-Incorporacion [IJCI-2016-29329]; Ministerio de Ciencia, Innovacion y Universidades [PTA2015-10829-I]; Interreg Med Programme [MPA-Adapt 1MED15_3.2_M2_337]; European Regional Development Fund - Foundation Prince Albert II Monaco; European UnionEuropean Union (EU) [689518, FPU15/05457]; Spanish Ministry of EducationSpanish Government [UID/Multi/04423/2013]; FCT - Foundation for Science and TechnologyPortuguese Foundation for Science and Technology; European Regional Development Fund (ERDF)European Union (EU), MV-L was supported by a postdoctoral contract Juan de la Cierva-Incorporacion (IJCI-2016-29329) of Ministerio de Ciencia, Innovacion y Universidades. AI was supported by a Technical staff contract (PTA2015-10829-I) Ayudas Personal Tecnico de Apoyo of Ministerio de Economia y Competitividad (2015). Interreg Med Programme (grant number Project MPA-Adapt 1MED15_3.2_M2_337) 85% cofunded by the European Regional Development Fund, the MIMOSA project funded by the Foundation Prince Albert II Monaco and the European Union's Horizon 2020 research and innovation programme under grant agreement no 689518 (MERCES). DG-G was supported by an FPU grant (FPU15/05457) from the Spanish Ministry of Education. J-BL was partially supported by the Strategic Funding UID/Multi/04423/2013 through national funds provided by FCT - Foundation for Science and Technology and European Regional Development Fund (ERDF), in the framework of the programme PT2020.

International audience; The two alien green algae Caulerpa taxifolia and Caulerpa cylindracea (formerly Caulerpa racemosa var. cylindracea) are among the most notorious and threatening invasive species in the Mediterranean Sea. From the beginning of their introduction, C. taxifolia aroused a great concern due to its initial exponential spread and impacts on native ecosystems, whilst C. cylindracea received lower attention. In this paper, the distribution of the two aliens over the last 30 years in the Italian side of the Ligurian Sea (NW Mediterranean Sea) is reviewed and the kinetics of their spreading is compared. We combined available data on habitat occupancy with data on substratum cover obtained during underwater surveys to compute the average annual spreading rates for both aliens. C. taxifolia had an impressive expansion phase from 1984 to 2000 but then, its dispersal rate showed lower than that predicted and the species did not persist in areas formerly colonized. Today, abundance of this species is strongly declined as it disappeared from most of the attained areas. On the contrary, C. cylindracea exhibited an impressive and constant expansion from the beginning of its first appearance in the Ligurian Sea and, today, it is still increasing its range and habitat occupancy. Its abundance results 1.5-times greater than that reached by C. taxifolia during the period of its maximum expansion. The divergent kinetics of spreading of the two aliens prevents any possibility of generalization of the future behaviour of invasive species in the Mediterranean Sea: continuous and periodic surveys are thus mandatory to understand the kinetics of expansion and to define species-specific models.

Seagrass communities are considered one of the most productive and complex marine ecosystems. Seagrasses belong to a small group of 66 species that can form extensive meadows in all coastal areas of our planet. Posidonia oceanica beds are the most characteristic ecosystem of the Mediterranean Sea, and should be constantly monitored, preserved and maintained, as specified by EU Habitats Directive for priority habitats. Underwater 3D imaging by means of still or video cameras can allow a detailed analysis of the temporal evolution of these meadows, but also of the seafloor morphology and integrity. Video-photographic devices and open source software for acquiring and managing 3D optical data rapidly became more and more effective and economically viable, making underwater 3D mapping an easier task to carry out. 3D reconstruction of the underwater scene can be obtained with photogrammetric techniques that require just one or more digital cameras, also in stereo configuration. In this work we present the preliminary results of a pilot 3D mapping project applied to the P. oceanica meadow in the Marine Protected Area of Capo Rizzuto (KR, Calabria Region – Italy).

In the Mediterranean Sea, Cystoseira species are the most important canopy-forming algae in shallow rocky bottoms, hosting high biodiverse sessile and mobile communities. A large-scale study has been carried out to investigate the structure of the Cystoseira-dominated assemblages at different spatial scales and to test the hypotheses that alpha and beta diversity of the assemblages, the abundance and the structure of epiphytic macroalgae, epilithic macroalgae, sessile macroinvertebrates and mobile macroinvertebrates associated to Cystoseira beds changed among scales. A hierarchical sampling design in a total of five sites across the Mediterranean Sea (Croatia, Montenegro, Sardinia, Tuscany and Balearic Islands) was used. A total of 597 taxa associated to Cystoseira beds were identified with a mean number per sample ranging between 141.1 ± 6.6 (Tuscany) and 173.9 ± 8.5(Sardinia). A high variability at small (among samples) and large (among sites) scale was generally highlighted, but the studied assemblages showed different patterns of spatial variability. The relative importance of the different scales of spatial variability should be considered to optimize sampling designs and propose monitoring plans of this habitat.

International audience; Connectivity studies in the marine realm are of great importance to understand the evolutionary potential of populations in a context of growing pressures on the marine environment. Here, we investigated the effect of the local, regional, and depth spatial scale on the population genetic structure of the yellow gorgonian Eunicella cavolini, one of the most common octocoral species of the Mediterranean hard-bottom communities. This species, along with other sessile metazoans typical of coralligenous ecosystems, plays an important role in supporting biodiversity, but is also impacted by direct and indirect consequences of human activities, such as physical destruction or mortality events due to thermal anomalies. Samples were taken from 15 sites located in the Ligurian Sea (NW Mediterranean) in two adjacent regions 100 kilometres apart, i.e. from the areas of Marseille (France) and Portofino (Genoa, Italy), and were analysed using six microsatellite loci. A pattern of isolation by distance was observed at the regional as well as the local scales. Although E. cavolini showed less genetic structure than other Mediterranean octocorallian species, we observed a significant genetic differentiation between populations a few kilometres apart. A low genetic differentiation was also observed between shallow and deep populations. The occurrence of genetically differentiated populations of E. cavolini at the scale of kilometres has important consequences for the management of this species and of the associated communities.

Marine caves are unique and vulnerable habitats exhibiting high biodiversity and heterogeneity, but threatened by multiple global and local disturbances. Marine caves, although widely distributed along the Mediterranean coast, suffer for the lack of quantitative data on their structure and function, which hinder their conservation status assessment. Thanks to the availability of a nearly 30-year-long series of data (1986-2013), we evaluated ecosystem change in the Bergeggi marine cave (Ligurian Sea, NW Mediterranean), a cave with a complex shape and high habitat heterogeneity. Non-taxonomic descriptors were adopted, namely growth forms (GF) and trophic guilds (TG), which are informative about ecosystem structure and functioning, respectively. The cave experienced a general trend of change during the last three decades, mainly due to the decline in the cover of sessile organisms (especially 3-dimensional forms) matched by an increase of turf and sediment, thus causing the structural and functional homogenization of the cave community. While change before 2004 had been attributed to climatic factors (especially to the summer heat waves of 1999 and 2003), the most important rate of change was observed between 2009 and 2013, coinciding with recent major beach nourishments and the extension of the neighbouring Vado Ligure harbour, thus providing evidences on the importance of local disturbances deriving from coastal interventions. Monitoring the status of cave ecosystems is urgently needed, and the use of effective indicators, such as the specific traits here adopted (morphology and feeding strategy), could provide effective tools to assist marine cave conservation.

Ferrari, M.; Cabella, R.; Berriolo, G., and Montefalcone, M., 2014. Gravel sediment bypass between contiguous littoral cells in the NW Mediterranean Sea. The efficiency of a rocky headland in delimiting littoral cells and preventing sediment bypass was investigated in a coastal area of Liguria (Italy, NW Mediterranean). This area harbours two contiguous pocket beaches separated by a headland that can be considered as a geomorphic and hydrodynamic limit of two littoral cells. Surveys using a single-beam echo sounder were carried out in order to update historical data on the morphology and hydrodynamics of the area. Sediment samples were collected from the foreshore and the nearshore in two pocket beaches, and sediment (including gravel) transport patterns around the headland were described. Distribution and state of health of the endemic seagrass Posidonia oceanica were assessed in order to explore potential links among sediment transport, hydrodynamics, and meadow development. A rip current trans...

Making nature's value visible to humans is a key issue for the XXI century and it is crucial to identify and measure natural capital to incorporate benefits or costs of changes in ecosystem services into policy. Emergy analysis, a method able to analyze the overall functioning of a system, was applied to reckon the value of main ecosystem services provided by Posidonia oceanica, a fragile and precious Mediterranean seagrass ecosystem. Estimates, based on calculation of resources employed by nature, resulted in a value of 172 € m(-2)a(-1). Sediment retained by meadow is most relevant input, composing almost the whole P. oceanica value. Remarks about economic losses arising from meadow regression have been made through a time-comparison of meadow maps. Suggested procedure represents an operative tool to provide a synthetic monetary measure of ecosystem services to be employed when comparing natural capital to human and financial capitals in a substitutability perspective.

Mapping marine coastal habitats provides an important aid to the long-term sustainability of urban development and the conservation of marine biodiversity. Historical maps, when available, may represent effective tools to evaluate quali-quantitative changes over time and to fix reference conditions. Scientific mapping of marine habitats is relatively recent, but the existence of fishery maps could compensate, after a critical evaluation, for the lack of more rigorous historical data. Coralligenous reefs are among the most important marine coastal habitats in the Mediterranean Sea, whose conservation requires, as a first step suggested by the recent European Directives, updated and detailed cartographies. This paper compares the recent cartographies (i.e. 2006 and 2009) on coralligenous reefs distribution in Liguria (NW Mediterranean Sea) with two historical fishery maps (i.e. dating back to the second half of the last century), on a GIS platform. Application of the Reliability Index (RI) showed that both historical sources can be trusted, with some caution. Fishery maps report few quantitative data (e.g. extent in hectares of coralligenous reefs) that are in little agreement with recent cartographies, mainly due to errors in positioning. In contrast, qualitative data (i.e. presence/absence in a specific site) represent the main information found in these maps and agree much more with the recent ones. It is more than likely that many of the rocky bottoms reported only in the fishery maps may host coralligenous reefs, which are apparently unknown in the recent cartographies. Latent information provided by this kind of historical maps may thus be useful for planning new surveys to sea-truthing on sites where no recent information is available and to promote the ecological studies required for their conservation.

Side Scan Sonar (SSS) is a common method for mapping seagrass meadows that allows to define meadow extent and typology. Should sonogram interpretation be efficient, repeated mapping would allow evaluation of spatial meadow dynamics through time. Here, maps of Posidonia oceanica (L.) Delile meadows from western Liguria (NW Mediterranean Sea) produced in 1990, 1991 and 2006 through SSS surveys, were processed with GIS (Geographical Information System) and compared by means of diachronic analysis to establish concordances and discordances. While any difference between maps of 1990 and 2006 might provide information about change in seagrass cover with time, the availability of maps taken at only one year of distance (1991 vs 1990) offered the unique opportunity to evaluate the efficiency of SSS mapping, as the slow dynamics of P. oceanica makes significant change over such a short time scale unrealistic in absence of any large-scale environmental catastrophe. Results showed obvious differences in P. oceanica meadow distribution among the three periods in most of the areas. The largest differences were found between the maps of 1990 and 1991. This discrepancy was probably due to erroneous interpretation of small, fragmented shallow-water meadows on sonograms. Errors in sonogram interpretation combine with inefficient positioning in old cartographies to blur the evaluation of change over large time scales (i.e. between 1990 and 2006). Extensive sea-truthing based on a rigorous design is mandatory for efficient acoustic mapping of seagrass meadows.

Marine coastal ecosystems are affected by a vast array of human-induced disturbances and stresses, which are often capable of overwhelming the effects of natural changes. Despite the conceptual and practical difficulty in differentiating between disturbance and stress, which are often used interchangeably, the two terms bear different ecological meanings. Both are external agents, but the former causes mortality or physical damage (subtraction of biomass), whereas the latter causes physiological alteration (reduction in productivity). Sensitivity of marine organisms may thus have a dual connotation, being influenced in different ways by disturbance and by stress following major environmental change. Coralligenous assemblages, which shape unique biogenic formations in the Mediterranean Sea, are considered highly sensitive to change. In this paper, we propose a method to differentiate between disturbance and stress to assess the ecological status of the coralligenous assemblages. Disturbance sensitivity level (DSL) and stress sensitivity level (SSL) of the sessile organisms thriving in the coralligenous assemblages were combined into the integrated sensitivity level of coralligenous assemblages (ISLA) index. Changes in the coralligenous status were assessed in space, along a gradient of stress (human-induced pressures) at several sites of the western Mediterranean, and in time, from a long-term series (1961-2008) at Mesco Reef (Ligurian Sea) that encompasses a mass mortality event in the 1990s. The quality of the coralligenous assemblages was lower in highly urbanised sites than that in sites in both marine protected areas and areas with low levels of urbanisation; moreover, the quality of the assemblages at Mesco Reef decreased during the last 50years. Reduction in quality was mainly due to the increase in stress-tolerant and/or opportunist species (e.g. algal turfs, hydroids and encrusting sponges), the disappearance of the most sensitive macroalgae (e.g. Udoteaceae and erect Rhodophyta) and macro-invertebrates (e.g. Savalia savaglia, Alcyonium coralloides and Smittina cervicornis), and the appearance of invasive alien algal species. Although the specific indices of SSL or DSL well illustrated the changes in the spatial or temporal datasets, respectively, their integration in the ISLA index was more effective in measuring the change experienced by the coralligenous assemblages in both space and time.

Meiofauna in sediments colonized by Posidonia oceanica in the Ligurian Sea (NW Mediterranean) was investigated to evaluate its use as an early warning indicator of environmental disturbance. Descriptors commonly used in seagrass health assessment are mainly related to the plant (e.g., phenological parameters) and/or to the meadow (e.g., structural parameters) and are subjected to long-term response times. Conversely, meiofauna is considered a good bioindicator with a rapid response to environmental variations, due to its main features (e.g., short life cycle, scarce mobility, presence/absence of tolerant/sensitive species). Meiofaunal community, sediment characteristics and organic matter descriptors in three meadows located in urbanized coastal areas were contrasted with those observed in three meadows located within Marine Protected Areas. Samplings were carried out in two distinct periods, at the beginning and at the end of the summer season, in order to individuate early changes in the meiofaunal assemblages. The meiofauna and, particularly, the nematode assemblage composition and diversity, highlighted differences among meadows at the end of the summer not detectable by organic matter descriptors and structural parameters of the meadow (e.g. shoot density). Nematodes are, thus, proposed as appropriate biological quality elements (BQEs) able to show early responses to environmental disturbance.

Posidonia oceanica, the most important and abundant seagrass in the Mediterranean Sea, forms large meadows from the sea surface down to 40 m. The depth of the lower limit of the meadows marks the boundary between the infralittoral and the circalittoral zone, and is said to be normally set by light attenuation underwater, while the role of water movement has been little explored. In this paper, the position (i.e. distance from the shoreline and depth) of P. oceanica meadow lower limits along the whole Ligurian coastline (about 350 km) was related to the annual storm wave base. This depth represents the limit of interaction between waves and seafloor and corresponds to L0/2, where L0 is the annual offshore wave length. In all meadows, the lower limit has never been found deeper than the annual storm wave base, and its depth (Zc) showed related to L0 according to the equation Zc = 0.32∙L0 + 5.62. In the coastal tracts affected by the least intense waves, the reduction of water movement with depth represents the most important constraint to the seaward development of the meadow, whereas light availability plays a major role in meadows affected by the most intense waves. The present study represents the first attempt at understanding the role of hydrodynamic factors in setting the depth limit of seagrass meadows. If corroborated by future research at other sites, this will have important implications for both basic and applied science, as it would imply rethinking about the relative importance of water movement and light in seagrass depth distribution, and could allow for a better estimate of the extent of meadow regression in anthropized areas.

article i nfo Quantification and comparisons of the structure of subtidal marine communities are essential for answering a suite of basic and applied ecological questions. However, time constraint associated with sampling underwater by scuba diving is a major obstacle to achieve adequate sampling effort. We tested a technique for rapid-assessment of hard substrate epibenthic communities, based on counts of the frequency of different taxa within sampling units (quadrats). This technique was compared to a broadly used technique, based on visual estimation of percent cover of taxa, to determine whether a significant amount of information is lost when using the rapid assessment technique. We applied both techniques in three case studies from the Ligurian Sea, in the NW Mediterranean. Field measurements showed that the same communities can be surveyed twice as fast with the frequency-count compared to the cover-estimation. Structural variables of communities as species richness and diversity yield almost identical values with the two techniques while dominance showed underestimated by frequency-count when compared to the cover-estimation. Multi- variate analyses indicated that the two techniques yield similar results, highlighting similar patterns of variation in all three case studies, particularly when data are transformed (square-root or fourth-root transformation). Our findings suggest that applying the frequency-count technique to the assessment of benthic communities is an effective strategy for increasing sampling effort when working underwater at depth.

The recognized ecological importance of Posidonia oceanica, the most important seagrass of the Mediterranean Sea, makes it crucial to assess the state of health of its meadows, discriminating natural from anthropogenic impacts. In this paper, the hydrodynamic conditions at the upper limit of P. oceanica meadows along the Ligurian coast (NW Mediterranean Sea) were investigated. A relationship between the distance of the upper limit of the meadow from the shoreline and the morphodynamic domain of the beach (i.e. distinctive types of beach produced by the topography, wave climate and sediment composition) was found. A zonation of the state of the shallow portions of the meadows down the submerged beach profile was identified. Zone a, from the shoreline to the breaking limit, is naturally critical for the development of the meadow. Zone b, from the breaking limit to the closure depth, is subjected to natural and human impacts. Zone c, below the closure depth, is little influenced by coastal dynamics. This study quantifies for the first time how much the status of the shallow portions of P. oceanica meadows is dependent on coastal dynamics, which is important for their proper management.

The epiphyte community structure of the Posidonia oceanica leaves in three impacted meadows occurring in urbanised coastal areas was contrasted with that observed in three meadows located within Marine Protected Areas in the Ligurian Sea. Samplings were carried out in two distinct periods, at the beginning and at the end of the summer season, in order to individuate early changes in the epiphyte community structure. Differently from the descriptors commonly adopted for evaluating the health status of P. oceanica ecosystem, the epiphyte community structure was able to detect alterations in the water quality already after 4 months. The impacted meadows showed an immature epiphyte community characterised by large development of brown algae. Leaf P. oceanica epiphytes are, thus, proposed as appropriate biological quality elements (BQEs) able to show early responses to environmental alterations and they should be included in the monitoring programs for the conservation and the management of coastal areas.

Thermal anomalies up to 4 °C above the climatological mean caused dramatic mass mortalities in benthic ecosystems of the NW Mediterranean during the summer heat waves of 1999 and 2003. Information on the sessile communities of the submarine cave of Bergeggi (Ligurian Sea) was taken in 1986 and 2004, i.e. before and after the two thermal events, using wire-frame photography in four sectors of the cave ecosystem with different morphologies and environmental features. Percent cover data of growth forms (as descriptors of the structural aspects of cave ecosystem) and feeding guilds (functional aspects) were analysed by multivariate and univariate techniques. Differences in trophic organisation and total biotic cover in the four sectors were significant and consistent in the two years. Thus, food web constraints (such as water confinement and trophic depletion), that are mostly dependent on topography, underwent no major change following the thermal events. On the contrary, structural aspects changed across time, 3-dimensional growth forms being replaced by 2-dimensional ones, leading to a general homogenisation of the cave communities. Positive thermal anomalies are thought to have selectively killed erect and massive organisms, their replacement by encrusting organisms possibly representing a phase in cave recolonisation. Submarine caves are poorly resilient ecosystems, and understanding their capacity of recovery after major disturbances is mandatory for their management and conservation.

The endemic Mediterranean seagrass Posidonia oceanica is a key species in coastal waters and it is widely employed as an ideal biological indicator for assessing the quality of water bodies, in accordance to the Water Framework Directive (WFD), as well as for assessing the health status of coastal ecosystems. In this contribution the current situation of the P. oceanica monitoring programs in the Mediterranean Sea is reviewed focusing on those descriptors adopted commonly by researchers and local administrators. The application of recently introduced approaches based on a set of synthetic ecological indices, namely the Conservation Index (CI), the Substitution Index (SI) and the Phase Shift Index (PSI), is also reviewed discussing their effectiveness in the context of ecosystem health assessment and of the requirements of the WFD. The CI, the SI and the PSI go beyond the quality of the water and, thus, the WFD, as they provide additional indications on past events of disturbance that affected a meadow, on potentiality of a meadow to recover, on quality of sediments, on biological pollutants. An integrated approach based on the descriptors of the water quality together with the three ecological indices of the ecosystem health (CI, SI, and PSI) is thus recommended in order to discriminate the main components affecting the status of coastal ecosystems. Application of the CI, the SI and the PSI should be experienced in different areas of the Mediterranean Sea for selecting appropriate reference sites and for formulating more generalized classifications that shift the requirements of the WFD toward the perspective of the ecosystem health evaluation.

The key species Posidonia oceanica is the dominant endemic seagrass in the Mediterranean Sea and its meadows are considered as one of the most important and productive ecosystems in coastal waters. Covering the seabed from the surface down to about 40 m, meadows of P. oceanica are often affected by mechanical direct damages caused by boat anchoring and mooring activities. Negative effects of these activities have been shown to be recorded by P. oceanica at two different levels: the individual level (phenology of the plant) and the population level (structure of the meadow). We investigated the effect of an anchoring chain system on the P. oceanica meadow of Prelo cove (NW Mediterranean Sea) at two different depths (shallow, deep) and at three different situations of P. oceanica bottom cover (high, medium, low). Several standardized descriptors of the meadow health, working either at the individual or at the population level, were analysed in order to quantify the impact of the deployment of the chain system. A symmetrical BACI design was adopted to detect the impact, where multiple disturbed sites were contrasted with multiple controls in two distinct times, i.e. right few days after the chain settling (early) and 4 months later the disturbance (late). The anchoring chain system has been shown to strongly affect the meadow in terms of shoot density decline and rhizome baring, especially in the deep portions and where the cover of the meadow was low. All descriptors working at the population level proved effective in detecting the impact of the anchoring system. In contrast, descriptors working at the individual level did not show a consistent response to the impact. Our results pointed out the imperative necessity to proper regulate the boat anchoring and mooring activities on the P. oceanica meadows and the adoption of seagrass friendly mooring technology is thus recommended.

A review and update of the existing knowledge on the coralligenous assemblages of Liguria (NW Italy) was conducted as an essential step towards management measures for their conservation according to the EU Marine Strategy Framework Directive. By combining a literature review, acoustic mapping and in situ observations on a geographic information systems platform, we were able to assess the distribution and heterogeneity of coralligenous assemblages and the main pressures affecting them. The reliability of the literature was previously estimated using a dependability index. The coralligenous assemblages cover an area of 130.9 ha and range from 10 to 113 m depth. Twelve different biological facies (five of them not included in the EUNIS list) were identified and four main geomorphotypes (plungingcliffs, paleocliffs, rockfalls and shoals) were recognized. Incident light values influenced the distribution of four facies in Portofino promontory. Pressures were found on 33% of the coralligenous assemblages investigated, mainly due to fishing activities, mass mortality events, invasive species and occasional mucilaginous events. Our results showed a high spatial, geomorphological and biological heterogeneity of coralligenous assemblages in Liguria. Una revisión y actualización del conocimiento existente sobre las formaciones coralígenas en Liguria (NO de Italia) ha sido implementado como paso esencial con vistas a las medidas de gestión para su conservación de acuerdo con la Directiva Marco sobre la Estrategia Marina. Combinando en plataforma SIG revisión bibliográfica, mapas acústicos y observaciones in situ hemos sido capaces de determinar la distribución de las formaciones coralígenas, su heterogeneidad y sus principales presiones. La fiabilidad de la bibliografía fue estimada a través del índice de confianza (DI). Las formaciones coralígenas cubren un área de 130.9 ha en un rango de profundidad que va desde los 10 m a los 113 m. 12 facies biológicas diferentes (5 de ellas no incluidas en la lista EUNIS) fueron identificadas y 4 geomorfotipos principales (acantilado actual, paleoacantilado, cúmulo de rocas y bajos) fueron reconocidos. Los valores de luz incidente influenciaron la distribución de 4 facies en el promontorio de Portofino. Fueron encontradas presiones en el 33% de las formaciones coralígenas inves-tigadas, principalmente debidas a actividades de pesca, episodios de muerte masiva, especies invasoras y proliferación de algas mucilaginosas. Nuestros resultados mostraron una elevada heterogeneidad espacial, geomorfológica y biológica de las formaciones coralígenas en Liguria.

We investigated the conservation status and ecosystem substitution in six Posidonia oceanica (L.) Delile meadows in 2002 along 300 km of the Ligurian coast (NW Mediterranean Sea). We studied the meadows by scuba transects and we compared the meadows state of health through in situ shoot density counts and computing the Conservation Index (CI), the latter measuring the proportional amount of dead matte relative to live P. oceanica . Both measures evidenced a generalised state of regression for most of the six meadows. We also reported the occurrence, within the meadows, of the other common Mediterranean seagrass Cymodocea nodosa , the Mediterranean green alga Caulerpa prolifera , and the invasive green algae Caulerpa taxifolia and Caulerpa racemosa . We measured the replacement of P. oceanica by these species using the Substitution Index (SI), related to the proportional cover of each substitutes. These were ranked in order of their colonisation potential with respect to P. oceanica . We identified and measured a community “phase shift” occurring within the Mediterranean seagrass meadows using a combined index, the Phase-Shift Index (PSI). The analysis of the three environmental indices (CI, SI and PSI) at regional scale allowed to introduce three “regional” ordinal scales to classify the conservation status, the degree of substitution and the level of phase shift in P. oceanica meadows.

The effects of global change are particularly serious in areas where range shifts of species are physically constrained such as the Ligurian Sea, which is one of the coldest sectors of the Mediterranean. In this basin, historical information on water temperature (from the sea surface down to 75 m depth) dates back to the 1950s. Early studies also recorded warm-water species occurrence. Thanks to these data we provide the first detailed characterization of water temperature variation from 1958 up to 2010 in the layer 0–75 m depth. We coupled this analysis with the available information on rocky reef epibenthic communities (literature review from 1955 to 1964 and field data from 1980 to 2010). The analysis of water temperature revealed several patterns of variation: a cooling phase from 1958 to 1980, a phase of rapid warming from 1980 to 1990 and a phase of slower warming from 1990 to 2010. Inter-annual variation in temperature increased over the entire period for the water layer down to 20 m. Warm-water native and alien species richness increased during the warming phases. Literature estimates suggest a decrease in warm-water native species richness during the cooling phase. The analysis of quantitative data collected in the early 1990s and late 2000s indicated a decrease in the cover of warm-water native species on shallow rocky reefs and an increase in deeper waters. We argue that increased inter-annual variation in water temperature may disadvantage native warm-water species in shallow waters. Our results indicate that the effect of temperature rises in cold, constrained basins may be more complex than the simple prediction of species changing their geographical range according to their thermal limits.