Rapidly accumulating environmental sequencing data have revealed that eukaryotic microbes are far more diverse and complex than previously thought. However, meta-barcoding and meta-genomics surveys are severely limited by the fact that the majority of environmental sequences do not match a sequence with associated phenotypic/taxonomic information in reference databases. Phytoplankton, a polyphyletic group of single-celled photosynthetic organisms that play key roles in aquatic food webs and global biogeochemical cycles, comprise an important part of this undescribed diversity. PHENOMAP will address this major “phenotype gap” for marine phytoplankton by undertaking targeted phenotypic description of key cryptic lineages. The work plan integrates a suite of state of the art methods that will be applied to two outstanding existing resources: the Roscoff Culture Collection, which is the largest and most diverse service collection of living microalgal strains in the world, and the Tara protist sample collection that contains over 15,000 fixed plankton samples from the worldwide Tara Oceans expeditions (2009-2018). Additional targeted sampling at 3 French marine stations will complement these resources. Phenotypic analyses will include light, fluorescence and electron microscopy for both live and fixed samples, as well as photosynthetic pigment analysis for cultures. For fixed samples, fluorescent in-situ hybridisation will be used to target cells belonging to the most abundant cryptic environmental lineages. Genetic barcoding of morphologically identified single cells isolated from fixed and live samples will complete the experimental strategy. We aim to formally describe at least 100 new taxa (including many high taxonomic rank lineages) and link genotypic to phenotypic information for hundreds of additional existing species, adding significant value to integrated community databases (PR2, UniEuk, Ecotaxa) that are increasingly central to studies on phytoplankton biology, ecology and evolution. Widespread dissemination of scientific outputs and development of innovative educational and outreach resources is integral to the PHENOMAP approach.

The ongoing global change is predicted to have numerous consequences on ocean physico-chemical properties, and notably on ‘ocean color’, a signal used by modelers to assess chlorophyll a biomass at global scales. For phytoplankton cells, changes in ocean color are perceived as a modification of their underwater light niches that can trigger competition between species potentially resulting in dramatic changes in community composition. To tackle the question of the respective fitness of phytoplankton species to survive in environments with altered spectral properties, we will focus on the picocyanobacterium Synechococcus, the second most abundant phytoplanktonic organism of the ocean, and the most diversified one with regard to its pigmentation, with at least seven pigment types displaying distinct genetic signatures, making it possible to differentiate them based on three gene markers. We recently showed that chromatic acclimaters (CA4), i.e. cells capable to change their pigment content to match the dominant light color (blue or green) were the most abundant Synechococcus pigment type in the ocean, with about equal abundances of two genetically different types, CA4-A and CA4-B, which exhibit very complementary ecological niches in the field. During the ANR project EFFICACY, we will study the ecological importance and fitness advantage conferred by the CA4 process using a cross-scale approach. We will: i) characterize the function of key genes of the CA4-B genomic island in order to unveil molecular differences between CA4-B and the well-characterized CA4-A process to better understand how and why natural selection has favored these two distinct forms of chromatic acclimation; ii) make competition experiments between CA4 strains and other Synechococcus strains with fixed pigmentation to determine which ones are best fitted in blue or green light and at different irradiances in order to help interpret the spatial and temporal variations of these pigment types; iii) study the seasonal variations of the relative proportions of the different Synechococcus pigment types at two oceanographically distinct sites, the long-term time series stations BOUSSOLE (Mediterranean Sea) and ASTAN (English Channel), using a metagenomic approach, and iv) integrate data derived from the two latter tasks and previous work from the coordinating partner into a powerful global ocean model (Darwin) that will simulate the present global spatial and temporal distribution of Synechococcus pigment types and predict the effect of global change on this population structure over the forthcoming decades. By using cutting-edge technologies and a powerful, state-of-the-art ocean model to study the pigment diversity of an ecologically relevant microorganism at all scales of organization from the genes to the global ocean, including seasonal variations, this ambitious interdisciplinary project should bring unprecedented insights into the field of environmental microbiology and pave the way to refined forecasting of the evolution of phytoplankton communities at large, in the context of global change.

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.

Lack of sexual attraction can directly cause reproductive isolation between individuals from different populations. Divergence of sexual processes between populations is therefore considered one of the most powerful drivers of speciation. However, we do not know exactly how these mechanisms of sexual isolation evolve. One plausible hypothesis is that divergent sexual selection driving sexual signals and preferences in different directions may be at the origin of sexual isolation. Here we propose to test this hypothesis in a complex of marine isopods (Jaera albifrons) in which sexual isolation results from female mate choice based on tactile courtship by males. First, we will simultaneously investigate intraspecific and interspecific sexual processes, asking if competition over mates within species drives selection on the same sexual signals that are involved in sexual isolation between species. Second, we will study the genomic patterns associated with sexual isolation, focusing particularly on the role of sex chromosomes and chromosomal rearrangements. Specifically, we will test if these genomic regions affect reproductive isolation through hybrid fitness effects of recombination arrest. We expect this project to tell us if and how sexual isolation evolves from divergent sexual selection, and improve our understanding of the specific role of sex and rearranged chromosomes in speciation.

In the remote Southern Ocean (SO) considered as a nutrient “hub” between the Atlantic, Pacific and Indian Oceans, the sources, sinks and processes controlling vital nutrient distribution remain a black-box to date. In this context, SWINGS is a multidisciplinary 4-year project dedicated to elucidate trace element sources, transformations and sinks along a section crossing key areas of the SO. Major French contribution to the international GEOTRACES program (www.geotraces.org), SWINGS involves 78 scientists (19 international laboratories, 6 countries). A 63-day oceanographic cruise in the South Indian Ocean (47 participants on board), process-oriented field studies and integrative modeling experiments will be carried out early 2021 to tackle the following objectives: 1) establish the relative importance of sedimentary, atmospheric and hydrothermal sources of TEIs in the Indian sector of the SO, 2) investigate the drivers of the internal trace element cycles: biogenic uptake, remineralization, particle fate, and export, and 3) quantify TEI transport by the Antarctic Circumpolar Current and the numerous fronts at the confluence between Indian and Atlantic Oceans. SWINGS strategy relies on the strong coupling between physical oceanography, biogeochemistry and modeling. A major and original focus will be put on the characterization of the physical and chemical particle speciation in suspended and sinking particles that will be collected during SWINGS. Together with a high resolution sampling of the dissolved phases, the resulting SWINGS harvest of data will allow a major step forward in the understanding and quantification of dissolved-particle exchanges, a major recognized bolt for the element cycle modelling. Dedicated tracers (e.g. Th and Pa isotopes) will help to characterize the particle dynamics. Ra isotopes will support the quantification of land-ocean transfers while Nd ones will trace the origin of the dissolved and particulate matter. Specific attention will be paid to the ocean interfaces: atmospheric and land contacts, and a segment of the South West Indian Ridge suspected to be the home of active hydrothermal sites. State of the art in situ mass spectrometer will be deployed for this exploration. The cruise track –at the Atlantic-Indian boundary- will cross up to 6 currents or fronts. These jets are major pathways of the general circulation, critical for chemical specie transport: they will be thoroughly documented. New model experiments will be designed and take place after first data acquisition, in order to evaluate the sensitivity in TEI distributions to the representation of sources and transports and explore the importance of “the island effect” on the TEI distribution around naturally fertilized islands. SWINGS is structured in 4 tasks: 1) Management of the project, design and management of the cruise, physical parameter measurements and data management; 2) Thorough sampling of particulate and dissolved phases of TEIs all along the track; 3) Characterization of the biological uptake and remineralization mechanisms; 4) Original modelling development, coupling tracer distributions with refine simulations of the circulation to quantify TEI transport and transformation. The first year (2020) will be fully dedicated to the cruise preparation. The cruise is planned for early 2021 on the R/V Marion-Dufresne. Analyses, data validation, interpretation will start in boreal spring 2021. Post-cruise meetings, communications and peer-reviewed publications will happen until 2024 and likely beyond. SWINGS being a GEOTRACES section (#GS02) will follow the mandatory sampling resolution, intercalibration procedure and data validation: all the acquired data will be granted open access following a rigorous Data Management Plan.