One internship position focusing on the vulnerability of freshwater species to climate change in relation to their trophic position is available at the RECOVER laboratory in Aix-en-Provence (France). The student will work under the supervision of Marine SAVARIS, Martin DAUFRESNE and Arnaud SENTIS.
Topic:
Climate change and extreme climatic events such as heat waves are expected to profoundly affect the structure and functioning of freshwater ecosystems. Although many studies have investigated species’ thermal tolerance, we still lack a clear understanding of how vulnerability to heat waves relates to thermal tolerance within ecological communities. In particular, it remains uncertain whether thermal tolerance is a reliable proxy for predicting species vulnerability to heat stress in complex food webs.
Objective:
The aim of this internship is to evaluate whether species’ thermal tolerance (CTmax) is a good ecological indicator of vulnerability to heat waves in multispecies communities that include several trophic levels (e.g. phytoplankton, zooplankton, macroinvertebrates, fish).
Tasks:
The intern will:
• Measure the upper thermal limits (CTmax) of several species representing different trophic levels (fish, macroinvertebrates, zooplankton, phytoplankton).
• Conduct a mesocosm experiment including species for which CTmax has been measured, and apply a controlled heat wave treatment.
• Sample the mesocosms to assess changes in the relative abundance and composition of species before, during, and after the heat wave.
• Analyze the resulting data and interpret species and community-level responses.
• Write a scientific report summarizing the findings.
Candidate competences:
We are seeking a motivated student with a strong interest in experimental ecology, climate change biology, and ecophysiology. Experience or coursework in laboratory or mesocosm experiments, aquatic ectotherm biology, ecological data analysis, statistics (R), and/or food web ecology would be an asset.
Practical information:
Starting date (flexible): February 2026
Duration: 6 months
Location: INRAE, RECOVER laboratory, 3275 route Cézanne, 13182 Aix-en-Provence, France
Main advisors: Marine Savaris, Martin Daufresne and Arnaud Sentis
Application:
Deadline for applications: November 8, 2025.
Please send your CV and a motivation letter (1 page maximum, in French or English) to:
marine.savaris@inrae.fr, Martin.daufresne@inrae.fr, arnaud.sentis@inrae.fr
Informal enquiries are welcome – please contact us by email in French or English.
Key-words:
climate change, heatwaves, thermal tolerance, food webs, trophic ecology, freshwater lakes
References:
Peralta-Maraver, I. & Rezende, E.L. (2021). Heat tolerance in ectotherms scales predictably with body size. Nat. Clim. Change, 11, 58-63.
Dahlke, F.T., Wohlrab, S., Butzin, M. & Pörtner, H.-O. (2020). Thermal bottlenecks in the life cycle define climate vulnerability of fish. Science, 369, 65-70.
Desforges, J.E., Birnie‐Gauvin, K., Jutfelt, F., Gilmour, K.M., Eliason, E.J., Dressler, T.L. et al. (2023). The ecological relevance of critical thermal maxima methodology for fishes. J. Fish Biol., 102, 1000-1016.
Jørgensen, L.B., Ørsted, M., Malte, H., Wang, T. & Overgaard, J. (2022). Extreme escalation of heat failure rates in ectotherms with global warming. Nature, 611, 93-98.
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