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WOS: 000449618200117, PubMed ID: 27932909, Background Over the last decade, inventorying and monitoring of marine biodiversity has significantly benefited from the active engagement of volunteers. Although several Citizen Science projects concern tropical reef ecosystems worldwide, none of the existing initiatives has yet specifically focused on their Mediterranean equivalents. Mediterranean coralline reefs, known as "coralligenous", are bioherms primarily built by calcifying rhodophytes on hard substrates under dim-light conditions; they are considered hotspots of biodiversity and are extremely popular among divers due to their complex structure, conspicuous biological wealth and high aesthetic value. Nevertheless, data on their distribution, structure and conservation status is lacking for several Mediterranean areas while they are vulnerable to an increasing number of threats. New information In the framework of CIGESMED SeasEra (ERAnet) project a specialized Citizen Science project was launched, aiming to engage enthusiast divers in the study and monitoring of Mediterranean coralligenous assemblages through the gathering of basic information regarding their spatial occurrence, assemblage structure and associated pressures or threats. For its active implementation, a data collection protocol and a multilingual website were developed, comprising an educational module and a data submission platform. Georeferenced data reporting focuses on: (a) basic topographic and abiotic features for the preliminary description of each site, and the creation of data series for sites receiving multiple visits; (b) presence and relative abundance of typical conspicuous species, as well as (c) existence of pressures and imminent threats, for the characterization and assessment of coralligenous assemblages. A variety of tools is provided to facilitate end users, while divers have the choice to report additional information and are encouraged to upload their photographs. The long-term goal is the development of an active community of amateur observers providing widespread and ecologically significant data on coralligenous assemblages. more...

International audience; Multi-facet diversity indices have been increasingly widely used in conservation ecology but congruence analyses both on horizontal and vertical axes have not yet been explored. We investigated the vertical and horizontal distributions of alpha and beta taxonomic (TD), functional (FD) and phylogenetic diversity (PD) in a three-dimensional structured ecosystem. We focused on the Mediterranean coralligenous assemblages which form complex structures both vertically and horizontally, and are considered as the most diverse and threatened communities of the Mediterranean Sea. Although comparable to tropical reef assemblages in terms of richness, biomass and production, coralligenous assemblages are less known and more rarely studied, in particular because of their location in deep waters. Our study covers the entire range of distribution of coralligenous habitats along the French Mediterranean coasts, representing the most complete database so far developed for this important ecosystem. To our knowledge, this is the first analysis of spatial diversity patterns of marine biodiversity on both horizontal and vertical scales. Our study revealed that taxonomic diversity differed from functional and phylogenetic diversity patterns at the station level, the latter two being strongly structured by depth, with shallower stations generally richer than deeper ones. Considering all stations, phylogenetic diversity was less congruent to taxonomic diversity (Pearson's correlation of r= 0.48) but more congruent to functional diversity (r=0.69) than randomly expected. Similar congruence patterns were revealed for stations deeper than 50 m.(r= 0.44 and r= 0.84, respectively) but no significantly different congruence level than randomly expected was revealed among diversity facets for more shallow stations. Mean functional alpha- and alpha-diversity were lower than phylogenetic diversity and even lower than taxonomic alpha- and beta-diversity for both vertical and horizontal scales. Low FD and PD values at both alpha- and beta-diversity indicated functional and phylogenetic clustering. Community dissimilarities (beta-diversity) increased over depth especially in central and eastern part of the French Mediterranean littoral and in northern Corsica, indicating coralligenous vertical structure within these regions. Overall horizontal beta-diversity was higher within the 50-70 m depth belts. We conclude that taxonomic diversity alone is inadequate as a basis for setting conservation goals for this ecosystem and additional information, at least on phylogenetic diversity, is needed to preserve the ecosystem functioning and coralligenous evolutionary history. Our results highlight the necessity of considering different depth belts as a basis for regional scale conservation efforts. Current conservation approaches, such as the existing marine protected areas, are insufficient in preserving coralligenous habitats. The use of multi-facet indices should be considered, focusing on preserving local diversity patterns and compositional dissimilarities, both vertically and horizontally. (C) 2015 Elsevier Ltd. All rights reserved. more...

International audience; Coralligenous outcrops represent a "hotspot" of Mediterranean marine biodiversity. Algae and sessile invertebrate taxa (mainly sponges, cnidarians, bryozoans and tunicates) structure the associated benthic assemblages and constitute remarkable seascapes. Nevertheless, this fragile habitat is submitted to a wide array of human impacts such as sewage outfalls, eutrophication, physical impacts linked to fishing and diving activities, as well as global warming effects. The current European legislative context (EU WFD, EU Habitat Directive, EU MSFD) imposes to reach or maintain a good environmental status for marine ecosystems. In this context, the MPA stakeholders need to have robust and accessible tools allowing the evaluation of the conservation state of the habitats. Concerning coralligenous bottoms, we propose a new method based on an integrated approach taking into account (i) the ratio between sensitive and tolerant species according to human impacts, (ii) the richness of macrotaxonomic descriptors assessed from direct observation (in situ or from images) and (iii) their structural complexity (basal, intermediate and upper layers present in coralligenous bottoms). These three metrics are combined into a global index called INDEX-COR. Datasets were acquired along the French coasts. In each site, 2 transects 15m long were installed on the bottom. Along each transect, 15 photo quadrats (40 cm x 60 cm) and 1 video were recorded and notes were taken by a SCUBA diver-Observer. This method was applied between 15 and 50 meters depth and can be also performed by a ROV (Remotely Operating Vehicule) or an AUV (Autonomous Underwater Vehicle). INDEX-COR is intended to be applied to other Mediterranean areas using metrics and species lists adapted to the different regional contexts. more...