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).

LuckyScales aims to acquire, process and model time-series data to better understand ecosystem dynamics at mid-ocean ridge hydrothermal vents. Fluid fluxes that feed these ecosystems are controlled both by km-scale hydrothermal systems powered by magmatic heat, and by smaller-scale near-surface fluid circulations and mixing between seawater and hydrothermal fluids. Currents in the water column near the seafloor also affect these fluxes. Our plan is to apply a multidisciplinary approach (from geophysics and physical oceanography to ecology and microbiology) to better understand these abiotic factors, and how they interact to control the biodiversity of deep sea vents. This fundamental knowledge is a prerequisite to assess faunal response to other potential sources of perturbation (e.g. deep sea mining activities). We propose to base our study on data from an innovative instrumental array that will complement the existing near real time Lucky Strike Mid-Atlantic Ridge observatory (a node of the European Multidisciplinary Subsea and water column Observatory–EMSO). This will be a prototype for multidisciplinary environmental monitoring in the deep seafloor, allowing us to test approaches that may be transferred to implement management strategies for Marine Protected Areas, for prospective or actual deep-sea mining, or for oil and gas exploitation projects. An important component of the project will be to work on data validation and dissemination procedures adapted to this prototype: identify those data that best qualify environmental changes and faunal response at deep sea hydrothermal vents, validate these data, define the type of metadata that is required for each user (other researchers, schools and universities, interested governmental agencies and industrial partners), the conditions of data accessibility (open or conditionnal, immediate or delayed), and appropriate data visualisation tools. These products will be delivered to the EMSO portal and used for the visibility of the project for the media and general public. The project will last for four years with yearly workshops and participation to the observatory maintenance cruises. We will have six workpackages: WPs 1 to 4 are scientific WPs, targeted at specific components of the hydrothermal ecosystem (focused end-member fluids, small scale sub-seafloor circulations, water column dynamics, and faunal and microbial response). WP5 is tasked with engineering the new seafloor instruments, defining procedures for their deployment at sea, and for the management of their data. WP6 is tasked with workshop organisation and will coordinate the valorisation of the project’s results. The team is comprised of 19 permanent staff from the 4 partner institutes (IPGP, Ifremer, GET and LPO), 19 collaborators from 15 institutions in Europe, Switzerland, Canada and the USA, six (possibly seven) already funded PhD students, and one post-doc also funded by another source. We request funding for three additional participants: two post-doctoral fellows and one engineer.