From In Situ to satellite observations of pelagic Sargassum distribution and aggregation in the Tropical North Atlantic Ocean

International audienceThe present study reports on observations carried out in the Tropical North Atlantic in summer and autumn 2017, documenting Sargassum aggregations using both ship-deck observations and satellite sensor observations at three resolutions (MSI-10 m, OLCI-300 m, VIIRS-750 m and MODIS-1 km). Both datasets reported that in summer, Sargassum aggre-gations were mainly observed off Brazil and near the Caribbean Islands, while they accumulated near the African coast in autumn. Based on in situ observations, we propose a five-class typology allowing standardisation of the description of in situ Sargassum raft shapes and sizes. The most commonly observed Sargassum raft type was windrows, but large rafts composed of a quasi-circular patch hundreds of meters wide were also observed. Satellite imagery showed that these rafts formed larger Sargassum aggregations over a wide range of scales, with smaller aggregations (of tens of m 2 area) nested within larger ones (of hundreds of km 2). Match-ups between different satellite sensors and in situ observations were limited for this dataset, mainly because of high cloud cover during the periods of observation. Nevertheless, comparisons between the two datasets showed that satellite sensors successfully detected Sargassum abundance and aggregation patterns consistent with in situ observations. MODIS and VIIRS sensors were better suited to describing the Sargas-sum aggregation distribution and dynamics at Atlantic scale, while the new sensors, OLCI and MSI, proved their ability to detect Sargassum aggregations and to describe their (sub-) mesoscale nested structure. The high variability in raft shape, size, thickness, depth and biomass density observed in situ means that caution is called for when using satellite maps of Sargassum distribution and biomass estimation. Improvements would require additional in situ and airborne observations or very high-resolution satellite imagery

Ocean weather, biological rates, and unexplained global ecological patterns.

As on land, oceans exhibit high temporal and spatial temperature variation. This ocean weather contributes to the physiological and ecological processes that ultimately determine the patterns of species distribution and abundance, yet is often unrecognized, especially in tropical oceans. Here, we tested the paradigm of temperature stability in shallow waters (<12.5 m) across different zones of latitude. We collated hundreds of in situ, high temporal-frequency ocean temperature time series globally to produce an intuitive measure of temperature variability, ranging in scale from quarter-diurnal to annual time spans. To estimate organismal sensitivity of ectotherms (i.e. microbes, algae, and animals whose body temperatures depend upon ocean temperature), we computed the corresponding range of biological rates (such as metabolic rate or photosynthesis) for each time span, assuming an exponential relationship. We found that subtropical regions had the broadest temperature ranges at time spans equal to or shorter than a month, while temperate and tropical systems both exhibited narrow (i.e. stable) short-term temperature range estimates. However, temperature-dependent biological rates in tropical regions displayed greater ranges than in temperate systems. Hence, our results suggest that tropical ectotherms may be relatively more sensitive to short-term thermal variability. We also highlight previously unexplained macroecological patterns that may be underpinned by short-term temperature variability

Mise à jour de l’inventaire des Zones Naturelles d’Intérêt Ecologique Faunistique et Floristique Mer de la région Provence-Alpes-Côte d’Azur, perspectives d’améliorations

National audienceDébuté en 1982, l’inventaire des Zones Naturelles d’Intérêt Ecologique Faunistique et Floristique (ZNIEFF) a pour objectif d’identifier et de localiser des espaces considérés comme « exceptionnels » en termes de biodiversité. En PACA, cet outil majeur de la politique de protection de la nature a été publié pour la première fois en 1988. Les inventaires des ZNIEFF-Mer, étaient basés en grande partie sur des éléments bibliographiques. Les dernières révisions et actualisations bibliographiques et prospection de terrain ont eu lieu entre 1999 et 2004. Plus de 10 ans après, une mise à jour est nécessaire. Établie sur des éléments bibliographiques récents, elle a permis la correction des descriptifs et a été complétée, pour évaluer concrètement les moyens nécessaires à leur actualisation, par la prospection en plongée de quelques sites bien connus et suivis dans le cadre de programmes de recherche. Cette mise à jour a consisté principalement en l’ajout de connaissances à l’intérieur des zones existantes

The Effect of Thermal Stress on the Physiology and Bacterial Communities of Two Key Mediterranean Gorgonians

International audienceIn the Mediterranean Sea, the tree-shaped gorgonian corals form large forests that provide a place to live for many species. Because of this important ecological role, it is crucial to understand how common habitat-forming gorgonians, like Eunicella cavolini and Paramuricea clavata , are affected by high seawater temperatures that are expected in the future due to climate change

Understanding ecological functionning of ecological habitats, and building New Indicators based on Genetic Tools to assess their GES (Good Environmental Status).

International audienceThe coralligenous is a typical Mediterranean marine habitat and hosts the highest concentration of biodiversity of this sea. Paradoxically, unlike Posidonia meadows, it is poorly studied. Like the famous tropical coral reefs, it is a complex biogenic habitat, based on encrusting red algae (numerous metazoan phyla also participate to bio-construction)(Ballesteros 2006). Concerning societal interest coralligenous habitats are known to be very attractive diving spots and but the importance of this ecosystems for fisheries The societal interest relies on the setup of innovative, cost-effective and accurate methods for biodiversity characterization and monitoring, based on genetic tools rigorously inter-calibrated with traditional taxonomy and photo-quadrate approaches. The aim of this project is to improve our understanding of its functioning and resilience capacity, and establish biodiversity and connectivity patterns among localities and ecological profiles, providing information for rationalizing the design of Marine Protected Area networks and monitoring methods. To reach this goal, synergy of interdisciplinarity will be used, combining population genetics, community ecology, microbial ecology and physical oceanography. This requests four tasks, partly using the same data, but different analysis methods. 1- Establishment of the taxonomic composition of the engineer corallinale algae. Several cryptic species in red algae were revealed by genetic markers (cf. B-4). Molecular tools (IMBE) and classical taxonomy (Dr Marc Verlaque, MIO) will be used 2- Establishment of the species composition for numerous small quadrates of coralligenous using meta-barcoding in different ecological profiles 3- Population structure and phylogeography of two selected taxa: a red alga Lithophyllum spp. and a bryozoan Myriapora truncata, on the CIGESMED sampling network, contextualized by ecological factors (cf above). 4- Synthesis and Comparisons: Propose new GES (good environmental status) indicators for the coralligenous and biodiversity management rules

Understanding ecological functionning of ecological habitats, and building New Indicators based on Genetic Tools to assess their GES (Good Environmental Status).

International audienceThe coralligenous is a typical Mediterranean marine habitat and hosts the highest concentration of biodiversity of this sea. Paradoxically, unlike Posidonia meadows, it is poorly studied. Like the famous tropical coral reefs, it is a complex biogenic habitat, based on encrusting red algae (numerous metazoan phyla also participate to bio-construction)(Ballesteros 2006). Concerning societal interest coralligenous habitats are known to be very attractive diving spots and but the importance of this ecosystems for fisheries The societal interest relies on the setup of innovative, cost-effective and accurate methods for biodiversity characterization and monitoring, based on genetic tools rigorously inter-calibrated with traditional taxonomy and photo-quadrate approaches. The aim of this project is to improve our understanding of its functioning and resilience capacity, and establish biodiversity and connectivity patterns among localities and ecological profiles, providing information for rationalizing the design of Marine Protected Area networks and monitoring methods. To reach this goal, synergy of interdisciplinarity will be used, combining population genetics, community ecology, microbial ecology and physical oceanography. This requests four tasks, partly using the same data, but different analysis methods. 1- Establishment of the taxonomic composition of the engineer corallinale algae. Several cryptic species in red algae were revealed by genetic markers (cf. B-4). Molecular tools (IMBE) and classical taxonomy (Dr Marc Verlaque, MIO) will be used 2- Establishment of the species composition for numerous small quadrates of coralligenous using meta-barcoding in different ecological profiles 3- Population structure and phylogeography of two selected taxa: a red alga Lithophyllum spp. and a bryozoan Myriapora truncata, on the CIGESMED sampling network, contextualized by ecological factors (cf above). 4- Synthesis and Comparisons: Propose new GES (good environmental status) indicators for the coralligenous and biodiversity management rules

Community ecology of coralligenous assemblages using a metabarcoding approach

Proceedings accessible at : http://www.rac-spa.org/sites/default/files/symposium/proceedings_mscc_2019_final.pdfInternational audienceCoralligenous habitats are bioconstructed, emblematic habitats of the Mediterranean Sea, which display a remarkably complex tridimensional structure and are considered as one of the most important biodiversity hotspots of the Mediterranean Sea. In order to assess the specific diversity of these habitats we sampled small surfaces (10 cm 2) of these habitats using a suction sampler in different environmental conditions on 19 sites in the Marseilles area (France). These samples were crushed and total DNA was extracted. A small portion of the COI gene was amplified using universal primers targeting metazoans. A total of 3029 Molecular Operationnal Taxonomic Units (mOTUs) were found among all samples. Most of the mOTUs belong to three taxonomic groups: Rhodophyta, Arthropoda and Annelida but many other phyla were detected. Environmental factors such as depth, slope and locality influence the community composition of coralligenous habitats. This first assessment of the specific diversity of these habitats using a metabarcoding approach confirms the status of biodiversity hotspot of these habitats and underlines the importance of abiotic variables to structure the community. Methodological developments can be used to design new monitoring protocols of these habitats