Current methods for microplastic (MP) analysis can be divided into low-cost versus more advanced methods. ANDROMEDA recognizes that further development and validation is needed for both approaches. Low-cost methods are needed that can identify a broad range of MP polymers with acceptable accuracy. Advanced methods need further development in order to push the limit of detectability for smaller sizes of MP and nanoplastics (NP) and improve their ability to analyze MP types that are currently difficult to analyze by microspectroscopy. Moreover, to study plastic degradation mechanisms over a reasonable time frame, lab-based accelerated degradation approaches are required that mimic natural fragmentation and additive chemical leaching. Within ANDROMEDA, in situ MP detection, efficient sampling and cost-effective laboratory methods will be developed and optimized to analyze MP. Approaches will be based on hyperspectral imaging, chemical markers and fluorometric detection techniques. Advanced analysis techniques making use of µFTIR, Raman imaging and SEM-EDX (amongst others) will be applied to quantify and characterize MP and NP down to 1 µm, 0.2 µm or lower. Specific tasks will focus on challenging types of MP such as microfibers, tire wear particles (TWPs) and paint flakes. UV, hydrolytic and thermo-oxidative methods to study accelerated plastic degradation at the lab-scale will be developed and used to prepare partially degraded reference materials. Comprehensive degradation studies will be conducted to study in detail the mechanisms of UV and microbial degradation, as well as to investigate the influence of parameters such as temperature, pH and hyperbaric pressure, where attention will be paid to additive chemical leaching. Quality assurance will be a central theme in all aspects of the project. Partners specialized in dissemination, communication and data management will ensure strong stakeholder involvement and efficient outreach of the project results.

The FOAMWAKE project is carried out by a consortium consisting of an academic partner (Laboratoire de Mécanique des Fluides et Acoustique UMR 5509), two institutional partners (IFREMER and ONERA), and a major company (SIREHNA, a subsidiary of Naval Group). The objective of this project is to characterize the two-phase bubbly wake generated behind a cylinder piercing the air-water surface. Specifically, the work of this project contributes to the characterization of the physical phenomena that govern the generation, propagation, and persistence of this two-phase wake. These phenomena are currently underexplored, poorly understood, and even less modelled. A second line of work aims to characterize the perception of this wake by optronic sensors. Indeed, the bubbles generated by the wake have very different optical properties from those of the background seastate, which can lead to the detection and recognition of the semi-immersed craft that generated the wake. The military purpose of this project is the understanding and control of the optical indiscretion generated by the foam wake behind a body piercing the free surface (for example, a submarine mast operating at periscopic immersion) and, reciprocally, the improvement of the detection capabilities of these phenomena by optical sensors. Civil applications include, among others, maritime security or the phenomenon of air entrainment downstream of hydraulic structures, the modelling of which is necessary in hydroelectric applications, but often very empirical. The objective of the project is to understand the physical phenomena that control bubble formation, the size distributions of these bubbles, their propagation in the wake of the body, and their persistence in the form of foam. To achieve this goal, the following tasks will be carried out: 1) Conducting measurements downstream of a fixed cylinder piercing a flow at speeds up to 5 m/s. This experimental facility, which already exists at LMFA, is small in size (length 2.3 m) but extensively available. The test facility will help understand the generation of bubbles and their propagation in the wake near the body, particularly through measurements by optical phase detection probes providing access to bubble size and velocity distributions. The persistence of the wake cannot be studied using this test facility. 2) Conducting tests in seawater in a larger-scale towing tank (IFREMER). These tests will complement the previous ones, in an unconfined environment. In addition to providing information on a scale closer to the application, they will allow the study of the persistence of the foam wake downstream of the mast. This test facility will also provide access to the free-surface shape representative of that generated by a mast in an infinite medium. These tests will validate the numerical models used or developed in task 3, or models developed subsequently. This task will be carried out in collaboration with LMFA, and will also include measurements by optical sensors by ONERA. 3) Conducting numerical simulations by Naval Group replicating the tests carried out in the previous two tasks, with two turbulence modelling approaches (RANS and LES). These simulations will not aim to track the bubbles but to characterize the global flow topology and turbulent structures and thus bridge the gap between the observed bubble propagation in the experiments and turbulence. These simulations will be complemented by direct numerical simulations with Basilisk (LMFA) to focus on a smaller scale and on air entrainment mechanisms, by accurately tracking the interface. The final aim of the experiments and simulations we propose will be to develop an air entrainment model for this configuration, in order to clarify how the smallest air inclusions responsible for the persistence of the wake are generated.

Phytoplankton is an essential component in the functioning of marine ecosystems and in the carbon cycle. It is therefore essential to assess its variability and its main drivers. However, unlike seasonal and interannual variations, fluctuations of phytoplanktonic biomass and communities on decadal to multi-decadal timescales remain hampered by the lack of long-term observations at global scale and the uncertainties related to the complex balance of the processes that control their fate. These processes are imperfectly and diversely parameterized in biogeochemical models, limiting their use to document long-term phytoplankton variability. Yet, it is crucial to detect natural low-frequency cycles in phytoplankton biomass (and thus carbon fluxes) because they can enhance, weaken or even mask climate-related trends. In this context, the inter/transdisciplinary DREAM project proposes to investigate and benchmark different deep learning (DL) frameworks (learned from satellite and in situ observations) to emulate past and future multi-decadal time-series of surface phytoplankton biomass and communities. This approach will allow us to assess the relative contribution of the different processes (e.g. physical, predation, community structures) involved in phytoplankton dynamics over the last decades in response to natural climate low-frequency variability but also to past and future anthropogenic forcing. Ultimately, DREAM will also contribute to characterizing and better constraining the uncertainties in the climate projections of the different Earth System Models gathered in the Coupled Model Intercomparison Project Phase 6 (CMIP6).

The terminal lobes of the Congo deep-sea fan are a unique area in the world ocean. These lobes are fuelled quasi-continuously by turbidites containing a large proportion of labile organic matter delivered by the Congo River (the second largest river in the world by its freshwater discharge) which is linked to its submarine canyon by an incision in the shelf. This connection between the river and the canyon is unique for large rivers on a global scale as all other large rivers (Amazon, Yangtze, Mississippi) are disconnected from their canyons since the increase of sea level linked to interglacial periods. The lobe zone is the receptacle of the organic inputs channelized by the canyon and covers an area of 3000 km2. The sedimentation of labile organic matter in the lobe zone located at 750 km from shore and at 5000 m depth which displays the same features as a river delta (high burial rate, fresh organic matter) allows the development of an exuberant ecosystems which is visualized by large bivalves, bacterial mats, mucus blankets of polychetes, an assemblage which has never been observed out of peculiar regions of active cold seeps. Despite this specificity, the ecosystem from the terminal lobes of the Congo fan have been only poorly observed (preliminary pictures during ROV dives and rare multiple coring). This prevented the investigation of their exact composition, spatial extension and, furthermore, their functioning. The Congolobe project aims at studying the ecosystems from the terminal lobes of the Congo deep-sea fan, which constitutes a hot spot for biology and biogeochemistry in the region. In addition to the biological description of the ecosystem in terms of biodiversity, we will test a hypothesis concerning the functioning of this ecosystem which composition seems to be close to chemosynthesis based ecosystems. Our hypothesis aims at establishing a link between organic imputs from the Congo canyon/channel, their diagenesis in the first meters of the sediment (or deeper), the possible production of reduced fluids bearing sulphide and methane, and the presence of chemo-autotrophic fauna and bacterial mats in the lobe zone. In the heterogeneous context of the lobes, a multidiciplinary approach is needed, gathering geologists specialists of this deep-sea fan, organic geochemists capable of characterizing the origin and reactivity of organic matter, marine geochemists estimating the recycling and burial of biogenic compounds, microbiologists assessing the nature and activity of bacteria and archea of the sediment, and biologists studying biodiversity and functioning of the fauna of all size. The working approach chosen is based on sea expeditions, such as those that IFREMER masters. One preliminary field campaign is already programmed in February 2011 with 5 days in the lobe zone (WACS leg 2) and will be occupied by a biogeochemical and biological survey of the zone. The second expedition which is already accepted by the French cruise committee (CNFE) will use the undersea equipment in order to characterize the diversity and heterogeneity of the ecosystem. Advanced technologies will be used: ROV Victor 6000 of IFREMER will allow the visualization and precise sampling of the biological and geological structures; in situ technologies will be fully employed with 3 landers (movable by the ROV) carrying either standard or polarographic micro-electrodes and benthic chambers.