Trace elements and their isotopes (TEIs) play a crucial role in the ocean and can be used as tracers for past and modern oceanic processes. Studying their biogeochemical cycles has direct implications in diverse research areas such as carbon cycling, climate, ocean ecosystems and environmental contamination. In this context, GEOVIDE proposes to undertake an integrated oceanographic transect in the North Atlantic and Labrador Sea. This area is crucial for the Earth climate and the thermohaline circulation as it represents a major overturning area of the so-called Meridional Overturning Circulation (MOC). Moreover, TEI distribution is poorly constrained in this area. GEOVIDE is an international collaborative programme which aims at better constraining the uncertainties on water and heat fluxes across the cruise section, notably by adding information on the deep water mass export and circulation, but also in providing new information on chemical element fluxes. GEOVIDE will allow the quantification of processes that influence the distribution of key TEIs in this area, in particular advective and scavenging processes, biological uptake, exchanges with the margins, and atmospheric deposition. The main scientific objectives of GEOVIDE are to: 1- Better know and quantify the MOC and the carbon cycle in a decadal variability context, adding new key tracers 2- Map the TEI distribution with their physical and chemical speciation along a full-depth high resolution ocean section 3- Characterize the TEI sources and sinks and quantify their fluxes at the ocean boundaries 4- Investigate the link between the TEIs, and the production, export and remineralisation of particulate organic matter 5- Better understand and quantify the paleoproxies 231Pa/230Th, Nd isotopes, and Si isotopes. The project is based on a 44-day oceanographic cruise on the R/V “Pourquoi Pas?” (summer 2014). We will use a series of novel techniques and state-of-the-art instrumentation. The strength of the project resides in its interdisciplinarity: physical oceanography, geochemistry and biogeochemistry will be coupled, merging observation and modelling. GEOVIDE gathers highly qualified scientific teams from five different countries. This project will be the French contribution in the North Atlantic to the Global GEOTRACES TEI survey (official GA01 GEOTRACES section) and will provide essential information, notably for the modelling of the present and past ocean, on TEI distributions in this key area of the thermohaline circulation. GEOVIDE will also actively contribute to other international programmes, such as SOLAS, IMBER, CARBOCHANGE and CLIVAR. GEOVIDE is part of the axis 2 of the LabexMER “A changing Ocean” and is linked to the Equipex NAOS “Novel Argo Ocean observing System”, in particular to the WP5 “Deep oxygen floats in the North Atlantic”. GEOVIDE is also a strong international and original action of the UPEE Pole in the framework of the IDEX UNITI in Toulouse. Finally, GEOVIDE has an educational component at various academic levels and the results of the project will be incorporated into materials for web dissemination and public outreach, as well as through scientific publications and presentations at international conferences. Five young scientists (three research associates and two PhD students) will be trained during this project. The results obtained during this project will be available through various databases (SISMER, LEFE-CYBER, and the GEOTRACES International Data Assembly Centre).

Marine ecosystems play a central role in geochemical cycling and climate regulation. These environments harbour complex and cryptic communities, dominated in terms of abundance and biomass by planktonic microbes including bacteria, archaea, viruses, and eukaryotic organisms (such as protists and fungi). These organisms form numerous and diverse interactions encompassing all kind of exchanges (e.g. predator-prey relationships) and all shades of symbiosis from commensalism to parasitism. However, this equilibrium is threatened by an un-precedent irreversible ecological transformation due to multifactorial anthropogenic changes. This phenomenon is illustrated by a variation in prevalence and severity of disease outbreaks, leading to massive die-offs events. Numerous studies then confirmed these observations and Harvell et al. (2009) in Ecology argued: “a warmer world would be a sicker world”. Perkinsea (Alveolata) is a group of parasites infecting molluscs, dinoflagellates and amphibians. Perkinsus marinus and P. olseni are responsible of the economically important shellfish disease ‘Dermo’, the main cause of mortality of bivalves. Parvilucifera spp. are known to infect dinoflagellates including the toxic ones. Finally Rana Perkinsus has been recently identified as responsible of massive die-off of tadpole populations across the USA. The Perkinsus spp. and the Rana Perkinsus have been recently classified as “emerging disease”. However, these described species represent only three clades over the 30 recently identified by their genetic signatures in the sediment through molecular environmental surveys. Hence, the major challenge of this project is now to elucidate the ecological role of this diverse group of parasites, the Perkinsea. In this context the PARASED project will seek 1) to evaluate global phylogeography and local seasonal genetic diversity and abundance of Perkinsea, 2) to decipher the life cycle and host range of the Perkinsea and finally 3) to describe fundamental biological processes involved during the parasitic association between the Perkinsea and their hosts. The research strategy that we propose here is firstly to conduct a global phylogeography study of the whole Perkinsea lineage, and then to target two French ecosystems (the bays of Arcachon and Brest) to evaluate the ecological role of the Perkinsea parasites. We will firstly focus on the commercially important school model P. olseni, and subsequently translate methodologies and concepts to Perkinsea only detected so far by their genetic signatures. This multi-disciplinary project will encompass classical parasitology methods as well as new state-of-art microscopy, genomic and transcriptomic techniques that lean on the expertise of the different partners of this project. Moreover, this project is innovating and challenging because it focuses on 1) poorly described group of parasites, the Perkinsea (including P. olseni), linked with shellfish mass mortalities and 2) on the benthic compartment in which the protist assemblages and their ecological functions are still totally ignored in trophic networks. The data and outcomes generated will substantially increase the body of knowledge on the functional ecology of P. olseni and others Perkinsea on host population. We will identify their life cycle and evaluate their knock-on effect on host populations that encompass species of economical/ecological interest. Ultimately, we aim to decipher the cellular mechanisms and pathways involved during the infection. Because of the environmental issues tackled in this project, the new data generated might have implications to improve sustainable conservation policies for managing global diversity.

The mechanisms of macroplastics degradation in the environment are well documented. Large plastic debris undergo different processes leading to successive fragmentation steps. Hence, when disposed in the environment, most of them end up in water bodies as small particles. Plastic particles smaller than 5 mm were defined as microplastics (MP). MP are very stable in the environment, thus they have been accumulating in oceans worldwide over the last decades. In addition, recent studies show that: (i) MP contain some toxic additives, adsorb and concentrate persistent organic pollutants (POP) present at their vicinity; (ii) MP act as a new substrate for marine biota and may vehicle harmful microorganisms; (iii) MP can be ingested by several marine organisms leading to consequences on their health. However, no studies have considered the trends in increase of MP abundance alongside with the decrease of their size over time. Indeed, continuous fragmentation of macro and micro plastic debris may potentially lead to high concentrations of nano size fragments. To date, sampling of MP in the water column is almost exclusively achieved with nets of 333-335 µm mesh apertures. Scarce data on the collection of small MP (< 330 µm) were recently published but sizes lower than a few µm have never been studied due to analytical limitations in extraction from environmental samples, their fate in the aquatic environment being consequently totally unknown. Nanoplastics (NP) may have sorption/desorption properties rather different from MP as they offer a much higher surface area to volume ratio. Small MP and NP may also be ingested (depending on their aggregation state) and exhibit toxic effects as they will have the ability to cross biological membranes more easily than MP. To provide a better understanding of their impact on marine ecosystem, NP have to be investigated from a chemical, physical and biological point of view and compared with investigations on MP distribution and impacts. This project presents five main objectives: (i) understand the processes of plastic debris fragmentation in the marine environment; (ii) set-up a methodology for the sampling and full characterization of small MP and NP; (iii) obtain consistent data on their presence in environmental samples (seawater, sediment, marine organisms); (iv) provide knowledge on MP/NP interaction with marine microcosm (chemicals, microbial communities) and evaluate their toxicity to marine life; (v) evaluate MP/NP transfer along the marine food chain and the potential associated health risks to human. At first, we will mimic the mechanisms of production of MP/NP by studying the biotic and abiotic degradations of thin polymer films until fragmentation into MP/NP that will be fully characterized (size, shape, surface properties, chemical composition). POP adsorption/desorption and colonization by marine microorganisms on lab MP/NP will be also studied. In parallel, optimized protocols allowing NP extraction and quantification in environmental samples will be developed based on protocols used for MP and plankton monitoring. This will allow small MP and NP collection and monitoring in three marine areas of interest (Bay of Brest, western Mediterranean Sea and English Channel). Besides quantification and identification, collected particles will also be characterized to determine chemical loads (additives, POP) and microorganisms present at their surface. MP/NP impacts on marine organisms will be investigated in vitro with an innovative approach to study their interaction with biological membranes and cells, and in vivo following an integrative approach from molecular changes to ecophysiology responses in key marine species experimentally exposed to MP/NP loaded or not with chemicals. Finally, health risks linked to a potential accumulation of MP/NP in the food chain will be evaluated. This project will also involve a large outreach program to inform the public about the issue of MP/NP.