Thesis In Fish Ecophysiology

Deadline for applications: 26/05/2026 Who are we? The Ifremer unit integrated within the UMR MARBEC (Marine Biodiversity, Exploitation and Conservation) conducts research on marine biodiversity, its uses, and its conservation. The Adaptation, Adaptability of Animals and Farming Systems laboratory (L-3AS), which is one of the components of this unit, develops multidisciplinary approaches combining genetics, physiology, ethology, ecology, animal science, and systems engineering. What is the topic of the thesis? Mediterranean coastal ecosystems, already weakened by fishing, pollution, and habitat loss, are facing increasing pressure from recreational activities (diving, spearfishing, boating), particularly in summer. While marine protected areas (MPAs) attract many visitors, tourism can also degrade habitats, promote the transmission of pathogens, introduce exotic species, and cause stress to wildlife. Subtle changes in fish behavior or physiology may reduce their growth, reproduction, and survival, but these effects remain poorly studied in temperate regions. This PhD project, linked to the ANR RECREAFISH project (2026-2030), will analyze the impacts of tourism on the biology and physiology of two model species, Sarpa salpa and Chromis chromis. The research will measure stress (gene expression, cortisol in scales), metabolism (routine rate and responses to disturbances using respirometry), and growth (otolith increments).The results will provide tools for adaptive management that balances tourism and biodiversity conservation. What will your mission and activities be?

• Participation in fieldwork and sampling missions (capture, dissection, biological sampling)
• Conducting analyses on collected biological samples: RNA extraction and quantification of stress-related genes; cortisol quantification
• Carrying out respirometry experiments to measure metabolism
• Processing, analyzing, and presenting results (presentations, scientific articles, reports)
• Participation in project meetings

Key words

• Recreational activities
• Fish physiology
• Stress and metabolism
• Marine protected areas
• Conservation and sustainability

How are your activities organized?

• The study will compare sites with and without tourist pressure in two marine protected areas in southeastern France.
• Sampling will take place before, during, and after the tourist season (June, August, October). Juvenile and adult fish will be captured at each site and period.
• Acute stress will be assessed through gene expression in the brain (hypothalamus), while chronic stress will be measured via cortisol accumulated in the scales.
• The impact of tourism on metabolism and growth will be studied using respirometry in both laboratory and field conditions.

What are your benefits?

• We have a teleworking agreement and our staff have 12 comp time days (after 6 months' seniority) and supra statutory leave.
• We allocate a significant budget to developing skills, through individual or collective training actions.
• We have a CSR policy inspired by the purposes of the institute (sustainable mobility allowance, etc.)

How to apply? Your application file must include in a pdf file :

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

The deadline for applications is 26th May, 2026. Nevertheless, we strongly urge you to let us know as soon as possible of your intention to apply, by contacting the subject supervisor:

• Benjamin Geffroy
• David J. McKenzie

Doctoral students' contracts will start as of October 5th, 2026, 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). What are the next steps?

• Review of your application
• In-person or video conference interview
• Interview before a doctoral school committee, with representatives from the doctoral school and Ifremer
• Approval of your application by the doctoral school council

Who are you? - Master's degree in marine biology, ecology, or a related field, with strong foundations in fish physiology and ecology. You have the following skills, knowledge and experience:

• Experience in field sampling
• Knowledge of laboratory techniques in molecular biology, biochemistry (ELISA), and respirometry is desirable
• Skills in data analysis (R, statistics)

You have the following qualities :

• Rigor and methodical approach
• Strong organizational skills
• Good writing skills
• Initiative and open-mindedness, ability to work collaboratively
• Motivation for interdisciplinary research in the field of conservation