Although covering only ~0.2% of the ocean’s surface, coral reefs harbour ~25% of ocean biodiversity and provide food to nearly a billion people. Ecological services from coral reefs are essential through fisheries, tourism, coastal protection and are estimated at about 30 billions USD per year. But corals are being stressed and recent estimates indicate that ~20% of reefs have permanently disappeared and about 50% will be threatened by 2050. Coral reefs are often at the forefront of research on climate change, due to bleaching, ocean acidification, and concerns about reef growth processes. Recent genomic developments have demonstrated the complexity of the coral genome that appears as complex as that for vertebrates. Reef corals further add to this complexity through an obligatory photo-endosymbiosis developed with microalgae. The physiological consequences of the presence of these photosynthetic microalgae (called zooxanthellae), which further add to the complexity of the coral hologenome, and the deep physio-genomic impacts resulting from this symbiosis on both partners, have yet to be fully elucidated. Furthermore, corals are hosts of a still largely unknown world of associated bacteria, viruses and other protists, forming a complex symbiocosm that biologists refer to as ‘holobiont’. This project entitled, “Genomic complexity of the coral holobiont across biodiversity gradients in the Pacific” is ambitious and seeks to investigate the complex diversity of the coral holobiont within the context of global change. It will serve as the foundation for the new Tara Pacific expedition (2016-2018). It builds upon the experience of previous Tara-Oceans expeditions and will focus on coral reefs throughout the Pacific Ocean, drawing an east-west transect from Panama to Japan and a south-north transect from New Zealand to Japan, and will sample corals throughout roughly 35 island systems with local replicates. CORALGENE will develop and apply state-of-the-art technologies in very-high-throughput genetic sequencing to reveal the entire microbial diversity (i.e. full biological complexity) present within coral holobionts. CORALGENE brings together a consortium of international experts in marine biology and ecology, cellular and molecular biology, genomics, and bioinformatics. Though this diverse team of global coral reef experts, we will have the expertise needed to build a comprehensive morpho-molecular inventory of the biodiversity of the coral holobiont, from viruses to prokaryotes, unicellular eukaryotes, and metazoans, which will include the biodiversity from both interstitial and surrounding seawaters. This very ambitious project will reveal a massive amount of cryptic and novel biodiversity, will shed light on the complex links between genomes, transcriptomes, metabolomes, organisms, and ecosystem functions in coral reefs, and will provide a reference of the biological state of modern coral reefs for the large research community working on coral adaptation to global and regional stressors.

Over periods of hundreds of millions of years, Earth's surface is recycled via the fragmentation of continents to form new oceans and elsewhere the sinking of oceanic plates into the mantle beneath. The breakup of continents involves progressive stretching and thinning prior to final breakup and the formation of new oceanic crust from molten rock that rises from below, flanked by continental margins comprised of thinned continental crust. There is a range of continental margin types, varying from those where the underlying mantle starts to melt very early in the process and very large volumes are added to the crust, to those "magma-poor" margins where there is little evidence for such melting until the very end of the process. At these magma-poor margins, which are common globally, it has been found that the crust can thin to nothing and mantle rocks can be exposed at the seabed, where they react with seawater in a process called serpentinisation. This serpentinisation plays an important role in exchange of chemicals between the Earth's interior and the ocean, and may be particularly intense around geological faults. While the final stages of thinning of the continental crust have been studied extensively over the past three decades, the transition from exposing mantle at the seabed through to forming new oceanic crust by the eruption of molten rock has been less well studied. Even designing such a study can be challenging because it is often unclear how wide this transition is. Also, because such mantle exposure has also been found in the middle of the oceans, this transition may be more complicated than often assumed. Our project will use a novel combination of geophysical techniques to study this final stage of continental breakup at a magma-poor continental margin southwest of the UK. There, crust that seems from all available data to be "normal" oceanic crust lies within about 150 km of crust confirmed by drilling to be continental. A region of serpentinised mantle, now overlain by up to around 1 km of mud, lies in between. For the first time in such a location, we will use electromagnetic waves, generated from a towed source, to measure the electrical resistivity of the crust and serpentinised mantle. Electromagnetic waves are strongly attenuated by seawater, so the source must be powerful and must be towed close to the seabed. We will use a combination of towed sensors, that are most sensitive to structures just below the seabed, and seabed detectors that can measure tiny fluctuations in electrical and magnetic fields at distances of up to tens of kilometres from our source, and thus allow us to probe deeper. We will also use some of the same seabed receivers to detect sound waves travelling through the crust from a source towed close to the ship, and to detect lower-frequency electromagnetic waves that are generated by natural sources and penetrate deeper into the Earth. The data that we collect will allow us, via the use of powerful computer programmes, to construct models of the variation of both sound speed and electrical resistivity in the crust and in the upper few tens of kilometres of the mantle beneath. These parameters provide a powerful combination because they are sensitive in different ways to the nature of the rocks. The electrical resistivity is particularly sensitive to the presence of water, and also of a mineral called magnetite that can be formed during the process of serpentinisation. The sound velocity is less sensitive to the presence of water but can be more sensitive to variations in the minerals present. From our models, we expect to be able to distinguish the continental crust and mantle, the oceanic crust and mantle, and the nature of the materials in between. We will then link these observations to computer models of the physical and chemical processes occurring as continents break apart. Thus we will find out how the formation of new oceanic crust actually starts.

The main aim of the MODAL project is to carry out hazard and hazard analyses associated to sediment deformations in submarine environments prone to earthquakes, fluid activities and landslides. The study zone -the Nice Slope (France) - is nested in heavily populated areas, highly exposed to geohazards. The major challenging scientific question in this project concerns the coupling between fluids and sediment deformation in submarine environments. Historically, the study area is sadly famous for the 1979 catastrophic submarine landslide which results in several casualties and infrastructural damage. Geotechnical and geophysical investigations carried out in late 2007 to the East of the 1979 landslide scar provide evidence for the possible occurrence of a new important sedimentary collapse and submarine landslide. Geophysical data acquired in the area show the presence of several seafloor morphological steps rooted to shallow sub-surface seismic reflections. Moreover, in situ piezocone measurements demonstrate the presence of several shear zones at the border of the shelf break at different depth below the seafloor. Both geophysical and geotechnical data suggest the start-up of a progressive failure mechanism and reveal the possible occurrence of future submarine landslide. The MODAL project is built according to a typical scheme for hazard and risk analysis going from the understanding of underlying physical processes (causal, predisposition and triggering factors) through the detection of revealing factors (thanks to geophysical mapping and imaging, in situ measurements and monitoring) and hazard assessment (calculation of probability of a given danger to occur during a given time period). More specifically, we propose to monitor the displacement rate field of the sediment and measure the fluid pressure to assess the probability of the slope failure, in response to gravity sliding, earthquake loading or excess pore pressure associated with rainfalls on the Nice region. The study site has been actively studied during the last decade within the framework of national and/or European projects. We have already an important set of geotechnical, geological and geophysical data which facilitate the application and validation of the proposed schemes. The MODAL project will be conducted within the framework of fundamental research, technological developments and practical field applications.