2 PhD Positions at MIO, Marseille, France

We are seeking to recruit two young scientist for two fully-funded 3-year PhD position to work at the frontiers of 1)microbial oceanography, bioinformatics and biogeochemistry and 2)chemical oceanography, stable isotopes biogeochemistry, and ecology at Mediterranean Institute of Oceanography. The PhD positions are funded via the ANR (Agence Nationale de la Recherche) HOT_Hg project (2022-25) “HydrOThermal Mercury – the natural history of a contaminant” (PI Lars-Eric Heimbürger-Boavida, MIO). 

The UNEP Minamata Convention, aims to reduce human exposure to toxic mercury (Hg). We are primarily exposed via the consumption of fish that bioaccumulate Hg from the ocean. Current estimates of anthropogenic Hg emissions highlight a 3-fold increase in Hg levels in the surface ocean since pre-industrial times. While decades of intense research have led to a good understanding of anthropogenic Hg fluxes (Fig.1), we still lack answers to some of the most fundamental questions concerning the natural Hg sources and transformations in the environment. Hydrothermal vents (HV) represent potentially the single most important natural source of Hg, yet flux estimates range several orders of magnitude (20 to 2,000 t y-1) and are based on HV fluid measurements from only 4 Deep Hydrothermal Vents (DHV; Fig.2). Near-shore Shallow Hydrothermal Vents (SHV; <200 m depth) have been largely ignored, and their contribution to the local and global Hg cycling remains ill-constrained. 

Figure 1. UNEP Global Mercury Assessment 2018 indicates volcanic activity as the single most important natural Hg source (600 t y-1). Hg fluxes from hydrothermal vents are virtually unknown. Both numbers need to be better constrained. 
Figure 2 Known hydrothermal fields along the global ridge-crests. Black numbered circles indicate 5 SHV. Boxes show the selected 3 DHV sites: (A) Mid-Atlantic Ridge, (B) Tonga Arc and (C) South West Indian Ridge. Green triangles present previous DHV Hg studies. 

 The overarching goal of the ANR HOT_Hg research project is to understand and quantify the role of hydrothermal Hg emissions in both local marine ecosystems and in the global Hg cycle. In particular, we will investigate the biogeochemical (WP1), and microbial (WP2) conditions that control Hg discharge and MeHg production at HV, and their impact on the local food web (WP3) controlled by local hydrodynamics and dispersal (WP4). ANR HOT Hg will investigate Hg fluxes, speciation, and transformations at HV to provide better constraints on the global Hg cycle and to study the bioaccumulation on the local ecosystem. To do so, we will conduct multidisciplinary studies at 5 selected SHV (Fig2; 1-5) and 3 DHV (Fig 2; A, B, C) sites, covering complementary geographic, geologic and biogeochemical settings. 

1- Microbial mercury transformation near hydrothermal vents

The PhD project is embedded into WP2 and focuses on the structural composition of the microbial communities. The specific aim is to describe the microbial communities involved in Hg cycling and unravel key microbial metabolic pathways of the Hg cycle. The PhD student will enroll into the Université de Pau et Pays de l’Adour (UPPA, Pau) and closely collaborate with the Mediterranean Institute of Oceanography (MIO, Marseille), and the Institute of Marine Sciences (ICM-CSIC, Barcelona), where s/he will be based for much of the time. The PhD student will be supervised by Marisol Goni (WP2 lead, UPPA), Andrea Bravo (ICM-CSIC), Lea Cabrol (IRD-MIO) and Lars-Eric Heimbürger-Bovida (CNRS-MIO). The ANR HOT_Hg consortium is fully equipped to perform all sampling and laboratory analyses, but some specific approaches dedicated to the complex matrix of HV will have to be developed. The PhD student will be in charge of Hg methylation/demethylation incubation experiments, sample preparation/processing for RT-qPCR, metabarcoding, metagenomics, metatranscriptomics, and bioinformatic analysis. The PhD student will participate to field campaigns, help with the validation and interpretation of all acquired data, assist with the implementation of the data into numerical models and contribute to the publication of the findings. The PhD student is expected to lead at least 2 publications. 

A qualification comparable to a Master’s degree or Diploma in Bioinformatics or Microbial Ecology, Microbiology, Environmental Chemistry, Oceanography or related fields is required. Experience in bioinformatics would be ideal. An essential requirement for selection for the PhD projects is a top-quality MSc or equivalent 4–5 year degree. We also expect good English language skills, and that the candidate is motivated to participate in sea-going expeditions. Most importantly, we are looking for a creative and curious young mind. 

Preferred starting date September 1st 2022. 

Applications including a motivation letter, CV and contact details of 2 referees should be send to marisol.goni@univ-pau.fr, andrea.bravo@icm.csic.es, lea.cabrol@mio.osupytheas.fr and lars-eric.heimburger@mio.osupytheas.fr, as a single pdf file, using as email subject “HOT Hg MICROBIO“. 

2- Mercury bioaccumulation in the trophic network near hydrothermal vents 

The overarching goal of the ANR HOT_Hg research project is to understand and quantify the role of hydrothermal Hg emissions in both local marine ecosystems and in the global Hg cycle. In particular we will investigate the biogeochemical (WP1), and microbial (WP2) conditions that control Hg discharge and net MeHg production at HV, and their impact on the local food web (WP3) controlled by local hydrodynamics and dispersal (WP4). ANR HOT Hg will investigate Hg fluxes, speciation, and transformations at HV to provide better constraints on the global Hg cycle and to study the bioaccumulation on the local ecosystem. To do so, we will conduct multidisciplinary studies at 5 selected SHV (Fig 2; 1-5) and 3 DHV (Fig 2; A, B, C) sites, covering complementary geographic, geologic and biogeochemical settings. 

The PhD project is embedded in WP3 and work on phyto-, zooplankton, suspended particles, and local benthic biota to investigate the bioaccumulation of different Hg species (pHg, pMMHg) in the marine food web. Stable C and N isotope (δ13C, δ15N) analyses will allow identifying food web sources and trophic levels. The PhD student will enroll into the University of Reims Champagne-Ardenne (URCA), and be supervised by Claudia Cosio (WP3 lead, URCA), Anne Lorrain (IRD-LEMAR) and Lars-Eric Heimbürger-Bovida (CNRS-MIO). The ANR HOT_Hg consortium is fully equipped for basic and advanced Hg analysis: cold vapor atomic fluorescence spectrometry (CV-AFS), an automated total Hg analyzer purge & trap CV-AFS, an automated methylHg analyzer purge & trap GC-CV-AFS, an automated combustion atomic absorption spectrometry, and a gas chromatography coupled to an ICPMS for Hg speciation by isotope dilution and incubation experiments. The PhD student will be trained in ultra-trace clean techniques, participate to field campaigns, help with the validation and interpretation of all acquired data, help with the implementation of the data into numerical models and contribute to the publication of the findings. The PhD student is expected to lead at least 2 publications. 

A qualification comparable to a Master’s degree or Diploma in (Marine) Biology, Oceanography, Ecology or related fields is required. Experience in analytical chemistry and / or marine biogeochemistry is desirable. An essential requirement for selection for the PhD projects is a top-quality MSc or equivalent 4–5 year degree. We also expect good English language skills, and that the candidate is motivated to participate in sea-going expeditions. Most importantly, we are looking for a creative and curious young mind. 

Preferred starting date September 1st 2022

Applications including a motivation letter, CV and contact details of 2 referees should be send to claudia.cosio@univ-reims.fr, anne.lorrain@ird.fr and lars-eric.heimburger@mio.osupytheas.fr, as a single pdf file, using as email subject “HOT Hg BIO“. 

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