During the geological history of the Earth, evolutionary competition for dissolved silicon in the ocean directly influenced changes in the global cycles of silicon, carbon, and other nutrients that regulate ocean productivity and ultimately the Earth’s climate. Radiolarians are key players of this evolution and, as such, have provided rich palaeontological records for a multitude of palaeoceanographic studies. These marine micro-organisms, which can produce intricate skeletons of silica, are very sensitive to changes in environmental conditions. The resistant silica-based skeletons of radiolarians are particularly useful in regions of importance for studying climate change where carbonate-based archives are poorly preserved (e.g. Southern Ocean) and offer a biogeochemical window into the mid-depth section (i.e. 30-500 m) of the marine environment. The mid-depth zone in the marine environment is currently inaccessible for Si cycle palaeo-reconstructions and its characterization is pivotal to the detection of glacial–interglacial changes in water column stratification, which plays a critical role during periods of abrupt climate change. Fortunately, radiolarians are common plankton found in this mid-depth zone. However, in contrast to other silicifying organisms found in the palaeo-record, such as deep-water sponges and surface dwelling diatoms (unicellular silicifying micro-algae), the use of radiolarian geochemistry to describe palaeoceanographic variation in dissolved Si (DSi) is very much in its infancy largely due to the challenges associated with their growth under laboratory-controlled conditions and limited knowledge on the factors that govern their contemporary biogeographic distribution. The RadiCal project offers to develop Radiolarians as a novel palaeo-proxy for marine silicon cycling by Calibrating the silicon stable isotope composition (d30Si) of these organisms to their modern environment. This objective will be achieved by applying an innovative multidisciplinary approach evaluating the influence of the modern environment and taxonomy on the variability of radiolarian silicon isotope fractionation (1) in situ, (2) under laboratory-controlled conditions, and (3) from a core-top calibration study from a variety of different oceanographic basins within the Southern Ocean. RadiCal fosters the innovative and inter-disciplinary approach of the P.I., which aims to combine non-traditional stable isotope biogeochemistry with in situ observations, in vitro experimental culture experiments, and sediment core samples in order to answer questions regarding the role of marine silicifiers (e.g. radiolarians) on the global cycling of Si. The RadiCal project will also develop collaborations between French and foreign scientists, strengthen the link between internationally recognized laboratories, and aggregate a community of researchers with diverse expertise on silicifying organisms (e.g. radiolarians) while developing potential for further collaboration and development of larger scale projects (e.g. ERC). In addition, the project RadiCal will permit the training of a new generation of oceanographers using an innovative and multi-disciplinary approach.

The Pacific oyster (Crassostreae gigas) has been introduced from Asia to numerous countries throughout the world (Canada, USA, Australia, New-Zealand, Chile, Mexico, Argentina, South Africa, Namibia and in numerous European countries including France) during the 20th century. C. gigas is currently the main oyster species farmed in the world and represents more than 95% of world production. For decades, C. gigas has been suffering mortalities but the severity of these outbreaks has dramatically increased since 2008. They mainly affect juvenile stages, decimating up to 100% of young oysters in French farms. In recent years, this mortality syndrome, designated Pacific oyster mortality syndrome (POMS), has become panzootic and represents a threat for the oyster industry worldwide. Recently, the consortium of the DECICOMP project overcame a major step towards understanding POMS using a holistic molecular approach developed in mesocosm. We showed that the infection by the Ostreid herpesvirus (OsHV-1 µVar) was the initial step of the infectious process leading to an immune-compromised state, which evolved towards subsequent bacteraemia by opportunistic bacterial pathogens. Nevertheless, by elucidating the mechanisms of the pathogenesis, only a part of the POMS complexity was deciphered. Indeed, this multifactorial disease is tightly controlled by a series of host and environmental factors (temperature, oyster age and diet). However, we still ignore the mechanisms by which these key factors control disease expression. This knowledge is urgently needed to elucidate the whole complexity of the disease and ultimately assess the epidemiological risk. In this context, the first objective of the DECICOMP project is to determine how temperature, oyster age and diet control POMS expression. The second objective is to weight and evaluate the interactions between all the factors controlling POMS in real farming conditions. Finally, our third objective is to model the epidemiological risk of POMS in oyster farms by using the sum of data generated in the project. To address the objectives of the DECICOMP project, we will combine laboratory/field experiments and theoretical approaches. Our multidisciplinary approach (mesoscosm and rationalized infections, integrative omics including epigenomics and metatranscriptomics, physiological/histological/functional validation approaches, modelling) is unique, ambitious and, as we believe, highly original. To reach our objectives, we have put together a consortium of researchers with highly complementary expertises that makes possible the implementation of a multiscale approach for deciphering the functioning of such a complex pathosystem from the finest molecular level to farmed populations. We believe DECICOMP will not only open prospects for substantial scientific knowledge advancement on a complex multifactorial disease but will also help decision-making thanks to tools and applied innovations for a sustainable and integrated management of oyster aquaculture. Indeed, by modelling the epidemiological risk under the influence of the different factors influencing POMS, we will be able to quantify the benefits of different measures that could be conducted by oyster farmers to play on these factors and consequently provide some action-levers to reduce the impact of the disease in farms.

The GEOPRAS consortium comprises seven partners that have been involved for several years in coastal archaeology. Our programme studies the coastal societies of recent Prehistory (Mesolithic and Neolithic) on the French Atlantic shores in order to understand their social and economic organization and the role they play in broader historical dynamics such as neolithization. Characteristics such as the accumulation of goods through storage, specialised modes of production, and the emergence of a social hierarchy or a sedentary lifestyle are often attributed to these coastal populations, on the basis of ethnographic documents from the last two centuries. However, each of these social manifestations must be described according to regional environmental variables, without evolutionary preconceptions. Our research hypothesis is that environmental dynamics have greatly facilitated certain forms of historical evolution. This encourages us to determine with greater precision the nature of these environmental transformations, then to analyse human networks at the continent-ocean interface. The first task will be to restore the environmental benchmarks. During the Mesolithic and Neolithic periods, most coastal landscapes were radically transformed by the sea-level rise and the associated processes of erosion and sedimentation. The coastal environments of the past will be reproduced through a three-level approach combining a large scale (region) with an intermediate scale (nearby landscape) and a local scale (archaeological site). Our consortium proposes a combination of methods suited to different geographical conditions (dunes, rocky coasts, marshlands) around the Bay of Biscay, testing the limits of several of them. To gain the best possible understanding of an "archaeological signal", the GEOPRAS project will focus on developing rapid intervention and rescue methods for archaeology and geoarchaeology. We intend to apply these methods to sites currently being excavated or whose exploration is planned as part of the project, such as foreshore and marshland sites and shell middens. Optimal integrated methods and procedures will be developed for the recording of archaeological remains, which are often ephemeral on foreshores, as well as for sampling, particularly in shell middens. These procedures include geophysical surveys, archaeozoology, micromorphology, geochemistry, taphonomy, metagenomic approaches, and OSL datings. The second task is to study how human societies have managed the land-sea interface. Shell middens have become the emblematic nodes of these coastal Holocene settlements because they contain an abundance of bio-archaeological data. They will be analysed to judge biodiversity as well as food practices. The third task is to understand the specific features of technical systems in a maritime context, especially seafaring. This technical field is at the heart of all the questions raised about the relationships between coastal areas, as well as the decisive features of the various technical systems developed in these areas. To overcome the lack of knowledge of prehistoric watercraft, we suggest an approach, based on three disciplinary poles in permanent interaction: 1) ethnographic and historical references, 2) technological and use-wear analyses of lithic and bone tools, 3) experimentation. In addition to proposing methodological developments, we aim to lay down the conceptual, methodological and technical foundations of a maritime prehistory with procedures adapted to coastal heritage. The results will be included in a handbook of maritime prehistory, to be published in French and English. The involvement of amateur archaeologists, observers, tourists and other citizens in scientific tasks will be anticipated and coordinated by inviting them to take part in the main scientific meetings and, of course, in field operations such as surveys, excavations and experiments.

APERO proposes a mechanistic approach of the biological carbon pump (export of surface production of biogenic carbon and fate in the water column -200/2000m). APERO aims at reducing the gap between the quantity of organic carbon produced by photosynthesis transferred to the deep ocean and the carbon demand in the water column. The three major contributions of APERO are the study of the role of small-scale dynamics (~1-10km) using autonomous platforms, imaging and innovative instrumentation, the simultaneous observation of all the processes regulating the attenuation of carbon flux in the water column and the quantification of the fluxes associated with these processes. Based on a substantial international collaboration and an ambitious observation strategy, complemented by molecular biology and modeling approaches, the field study, planned for 2022, will contribute to a significant reduction in the uncertainties of carbon storage by the ocean.

Transported by currents, plastics strand on the coastal areas, important places of artisanal fisheries. Plastics can harbor pathogens that are involved in human epidemics. It is thus legitimate to ask whether these pathogens and their virulence & resistance genes (PVR) can be transferred to marine animals that ingest plastics, and potentially to human who consumes them. Plastics would thus play a role of vector. VectoPlastic implements a multidisciplinary approach to evaluate this role in a socio-ecosystem dependent on artisanal fisheries (Tule´ar, Madagascar). The objectives are to evaluate the transfer of PRV to 2 commercial species, their persistence from capture to sale on stalls, the perception of populations of the health risk related to plastics and their pathogens, and an integrated risk assessment; in order to define sensitization and management actions adapted to the socio-cultural context.