The severe increase in environmental plastic pollution is at the very heart of the society current concerns. If so far its impact on environment and human health remains not well known, the vast majority of scientics agrees on the fact that it may represent a major environmental issue with dramatic consequences on the whole ecosystem. Participatory research is at the core of various plastic waste monitoring programs. As plastic pollution is directly related to nowaday lifestyles and consumption modes, involving civil society apears crucial in order to raise awareness and involve citizens in the decision-making process to contain plastic pollution. Microplastics (plastic particles from 1 nm to 5 mm) are responsible for an hardly discernible pollution that have penetrated almost all marine and terrestrial ecosystems. An increasing number of studies is working on the understanding of their origine and impacts. For 3 years, Expedition MED NGO have been conducting a participatory research program by receiving and training citizens on its vessel for the sampling of surface water microplastics in Mediterranean sea. Samples are partially analyzed onboard, and then sent to public research institutions for deeper analysis. Microplastics analysis aims to identify their concentration, their morphological characteristics (size, shape, color), their concentration in contaminants such as heavy metals or endrocrine disrupters and to study the microorganisms that colonize plastics (bacteria, virus, fungi, etc.). Historically, participatory research protocols are designed by scientists for study scale-up and diversification of the sampling localizations. Citizens are mainly involved in the samping step, and their participation to the analysis step remains quite limited. Considering microplastics contamination studies, this is explained by a number of reasons. Due to their high concentraitons and small sizes, microplastics analysis is particularly difficult and time consuming. Timelines between the sampling step and the analysis step are significantly important, even for specialized academic actors. Furthermore, analysis methods require high-tech equipments that are not accessible for civil structures actors. The ambition of this project is therefore to develop microplastics analysis protocols that can be implemented during field participatory research programs. The goal is to involve citizens not only during the sampling step but also during the analysis step, in order to train them during the whole scientific study process. It should strengthen the implication and understanding concerning microplastics pollution, its impacts and origins, while supporting a stronger collaboration between academic and civil societies in order to highlight suitable solutions for plastic pollution reduction.

Delineating the evolution of the Earth’s dynamics and the interactions between the different silicate reservoirs (crust, mantle) is key to understanding planetary differentiation and the conditions of surface habitability. Today, plate tectonic processes play a major role in creating and destroying the Earth’s crust. For this reason, the Earth is unique in the solar system because such global dynamics are absent on other planets. Reconstructing the long-term evolution of the Earth is, however, extremely difficult since the Hadean record is essentially missing and most Archean rocks have experienced reworking and overprinting of their original signatures. AMNESIA proposes a new way to interrogate rock records by linking petro-geochemical signatures to the Earth’s dynamic processes through geological time. Precious information are enclosed in several tiny accessory minerals found in a large variety of rock and these are particularly resistant to post-magmatic disturbance. The proposed approach is built on recent advances made by the PI on the geochemical characteristics (trace elements and O isotopes) of these phases and their inclusions, and is based on unique sets of samples collected on the different continents. The main objectives are to: 1) use accessory minerals to discriminate the different tectonic settings in which magmas can be generated during the different Earth periods and 2) recover geodynamic information on early Earth (subduction vs intraplate crust production) and the timing of the onset of plate tectonics. AMNESIA will combine cutting edge geochemical measurements and petrology on natural samples to define new proxys for the study of crustal evolution, identify and determine the nature of the first continents.

The objective of the MUSIC is to analyze 3 years of continuous and low-frequency acoustic data (0-120 Hz) recorded by a widespread network of autonomous hydrophones in the southern Indian Ocean (24S-56S; 55E-81E). The network was deployed in 2020, maintained in 2022 and recovered in 2023 during cruises of RV Marion Dufresne from the TGIR French Oceanographic Fleet, for monitoring: • The dynamics of the three Indian spreading ridges with contrasted spreading rates (14 to 70 mm/yr), from the low-level seismic activity they generate; • The presence and migration pattern of 6 species of baleen whales from their vocal activity (fin, Antarctic blue, 3 populations of pygmy blue and Minke whales); • The ambient soundscape, which includes cryogenic sounds from icebergs and anthropogenic noises. This dataset will be analyzed in light of previous works in the same area to assess the long-term evolution of all these components of the Southern Indian Ocean soundscape. The project is divided in 4 Tasks: Task 1 is devoted to bioacoustic analyses to exhaustively identify all whale species present in this area, and to establish their migratory routes and seasonality. Their geographical and temporal distribution, linked to the environment and presence of prey, will be examined against the evolution of environmental variables near the hydrophones (bathymetry, SST, Chlorophyll-A). Catalogs of calls, established with detection tools suited to stereotyped (blue whales) or pulse-like (fin and Minke) calls, will be compared with a set of metrics between the different species and sites. These observations will be placed in their environment to try to link them. Task 2 will focus on the low-level seismic and volcanic activity generated by the three Indian spreading ridges to study their dynamics. By trilateration of arrival times of earthquake-generated acoustic waves, sources can be located within few km and their level measured. As in Task 1, catalogs of events will be established, yielding the temporal and geographical distribution of the seismo-volcanic activity. Event clusters will be analyzed to determine their tectonic or volcanic origin, which reflects the thermal and mechanical state of the ridge. Is this state stable in time and space and only dependent on spreading rates? A new type of events, short and highly energetic, resulting from hot lava-seawater interactions on the seafloor, would be indicative of active magmatic eruptions. How are they distributed? Task 3 will investigate the long-term evolution and components of the Indian Ocean soundscape. In 2012, the main seasonal variations in the soundscape were due to natural sources such as baleen whale calls and cryogenic events from drifting icebergs, with a limited anthropogenic contribution. Have these components evolved since then, with global warming, or increase in ship traffic as in other oceans? Task 4 is methodological. Such large amount of data to process and variety of sounds to detect require new deep-learning techniques to automatically detect and classify acoustic events. Cross-feeding between Tasks 1, 2 and 4 will be crucial, since algorithms need to be trained on annotated catalogs. Source mechanisms of impulsive events (bubble implosion or cracks due to lava quenching) and the role of earthquake moment tensor in the radiation pattern of acoustic waves are still debated and require further modelling. Partners of MUSIC are Geo-Ocean, providing the data and expertise in geosciences, and Lab-STICC with a solid experience in signal-processing, computer science and bioacoustics. This multidisciplinarity for analyzing this large acoustic database is a strength of the project. All participants are supportive of Open Science and will make their results available through data repository and collaborative platforms. The general public being very receptive to the sounds of sea, we will continue to participate to public manifestations and outreach.

Earth’s most ancient sedimentary rocks preserve abundant physical, chemical, and isotopic evidence of a thriving and evolving microbial biosphere that reigned on Earth for billions of years. In the first billion years or so, this primitive biosphere gave rise to the major metabolic pathways that define our living planet today: the diverse forms of photosynthesis, chemotrophy, and respiration that underpin modern global biogeochemical cycling and the biospheric regulation of Earth’s climate. Lessons from this early history constitute some of humanity’s most profound origin stories and strongly inform the search for life on other planets. Yet many of the details of the earliest history of microbial life on Earth – when exactly in deep geological time particular metabolisms were operational, in which environments, and under which local chemical or environmental conditions – remain poorly understood. The EARLY-ECO project aims to significantly advance our knowledge of Earth’s earliest microbial ecosystems via the careful sedimentological, geochemical, and isotopic examination of the best-preserved traces of life spanning a variety of sites dating from 3.48 billion years to 2.6 billion years ago. From the scale of individual microfossils and microbial mat lamina to the chemostratigraphy of entire geological formations, the EARLY-ECO project will push the analytical frontier to provide new constraints on life’s carbon, nitrogen, and energy acquisition strategies across multiple environments of the Archean Earth, including shallow water stromatolitic ecosystems, offshore pelagic ecosystems, and the first emerged terrestrial habitats. The ultimate goal of the EARLY-ECO project is a paradigm shift towards a paleoecological understanding of Earth’s earliest ecosystems – an integrated view of the who, how, where, and when – in order to better understand Life’s first steps on Earth and how it might develop elsewhere in the universe. This current ANR ERC-Tremplin CoG submission aims to boost the chances of success of the EARLY-ECO project, which was favorably evaluated in 2022 but not retained for funding. ANR support will significantly enhance the chances of success in 2023 for the EARLY-ECO project by enabling (1) proof-of-concept technological development and instrument testing in relation to the novel analytical instrumentation to be developed through the EARLY-ECO project, (2) the generation of additional supporting isotopic data from ancient sedimentary records in support the EARLY-ECO project, and (3) publication, conference participation, and scientific exchange to bolster the impact of EARLY-ECO supporting data amongst the wider community.