PhD Thesis on the influence of increasing SALinity on farmed oysters in the THAU lagoon

and their trophic resources under global change (SALTHAU) (M/F)

Reference: PV-2024-1460/1


Duration in months :36

Start date:

Deadline for applications:12/05/2024



General areas of responsibility

This PhD thesis will be carried out at Ifremer and MARBEC in collaboration with LEMAR, LOV, IHPE and DFO (Department of Fisheries and Oceans Canada). The thesis will be supervised by specialists in shellfish farming/environment interactions, with expertise on Pacific oyster (Dr Marion Richard), phytoplankton (Dr Béatrice Bec) and lagoon ecosystem modelling (Dr Annie Fiandrino). The thesis follows on from experiments carried out in mesocosms as part of the 'COCORICO2' project in collaboration with the regional comity of mediterranean shellfish farmers (CRCM). It will form part of the MITIC project (2024-2027), led by Dr Fabrice Pernet, in collaboration with Dr Frédéric Gazeau.




Mediterranean lagoons are under threat from global warming and acidification, coupled with increasing salinity. This raises the question of the long-term sustainability of ecosystem services. This is the case in the Thau lagoon, used for shellfish farming, where salinity is constantly increasing, reaching values of 42.9 in summer. Up to what salinity threshold, coupled with high temperatures, will the Pacific oysters (Crassostrea gigas), their microbiota and their trophic resources survive? Will it still be possible to produce hollow oysters in the lagoon in 2050?

The aim of this thesis is to answer these questions by focusing on the impact of global warming, acidification and high salinity on the survival, growth, metabolism and microbiota of oysters and on two phytoplankton species (Chaetoceros, Skeletonema) corresponding to their trophic resources. It combines laboratory, mesocosm and modelling approaches to better understand and predict the changes brought about by global change on the sustainability of marine cultures in the Thau lagoon.

It is in line with Ifremer's contract of objectives, resources and performance, and with ambitions 2 & 5 of MARBEC, and will go some way towards addressing the concerns of the government and the industry about better management of the shellfish industry in the context of global change. Finally, it will be promoted internationally through a conference and publications.


Key words


Climate change, acidification, salinity, Crassostrea gigas, Chaetoceros, Skeletonema, mesocosms, observation, modelling




Required Knowledge, skills, and characteristics


Master II student motivated to do a PhD on the proposed topic. Good knowledge of marine ecology, oysters, phytoplankton and their microbiota and motivated by the idea of carrying out experiments in mesocosms and in the laboratory. Enthusiastic about metabarcoding and modelling approaches. Solid academic record. Data processing and statistical analysis skills. Ability to write and communicate in English. Rigorous, conscientious, autonomous, team player, mobile and available from 2024-2027.



Specific working conditions


Phd is a real opportunity to work on Ifremer's scientific and technological priority themes. It entitle the holder to a gross monthly salary of 2300 euros gross for a period of 3 years, which cannot be combined with other scholarships. 


Specific arrangements for the thesis:

  • Main work at the Ifremer station in Sète (France) within the LERLR and UMR MARBEC.
  • Weekly trips to Mèze (France) for mesocosm experiments and possible on-call duty (2025-2026)
  • Embarkation on the Thau lagoon for sampling
  • Regular trips to Montpellier and Palavas (MARBEC sites, France) for phytoplankton experiments and associated analyses
  • Planned mission to Plouzané (France) (LEMAR) in 2025 for experiments on oysters and associated analyses
  • Mobility planned to New Brunswick (Canada) in 2026 for the Modelling component

How to apply for this position


Your application file must include:

  • a curriculum vitae 
  • a covering letter
  • a reference letter
  • an academic transcript (Bachelor + Master 1 and first semester Master 2)


Your application must be compiled into 2 PDF files, up to 3 MB for each file.



The deadline for applications is 10th May 2024. However, we strongly urge you to let us know as soon as possible of your intention to apply, by writing to the three thesis supervisors:, and


Doctoral students' contracts will start as of October 1st, 2024, subject to the submission of administrative documents authorizing Ifremer to recruit the doctoral student (certificate of completion of the Master 2 or engineering degree + visa for foreign doctoral students outside the EU).




The Institute and the recruiting departement 

A pioneer in ocean science, IFREMER’s cutting-edge research is grounded in sustainable development and open science. Our vision is to advance science, expertise and innovation to:

- Protect and restore the ocean

- Sustainably use marine resources to benefit society

- Create and share ocean data, information & knowledge.

With more than 1,500 personnel spread along the French coastline in more than 20 sites, the Institute explores the 3 great oceans: the Indian, Atlantic and Pacific oceans. A leader in ocean science, IFREMER is managing the French Oceanographic Fleet and its dedicated scientists create ground-breaking technology to push the boundaries of ocean exploration and knowledge, from the abyss to the atmosphere-ocean interface.

Well-established in the international scientific community, our scientists, engineers and technicians are committed to advance knowledge about our planet’s last unexplored frontiers. They provide the science we need for informed decision-making and public policy and they transfer this knowledge and technology to businesses to fulfill public and private needs. Core to our mission is also to strengthen public awareness about the importance of understanding the ocean and its resources, and empowering future generations of leaders through education and outreach national campaigns.

Founded in 1984, IFREMER is a French public organization and its budget approximates 240 million euros. It is operating under the joint authority of the French Ministry for Higher Education, Research and Innovation, the french Ministry of the Sea, the French Ministry for the Ecological and Solidary Transition, and the French Ministry of Agriculture and Food.


How to apply for this position

Deadline for applications: 12/05/2024

All applications are processed exclusively via our website. Interested candidates can apply by clicking the Apply button. 

Ifremer - French Research Institute for Exploitation of the Sea

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Location: France, Sète
Categories: Data analysis, Ecology, Fisheries Technology, Laboratory analysis, PhD,


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