DIETARY STRATEGIES TO MITIGATE THERMAL AND HYPOXIC STRESS IN RAINBOW TROUT

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.

Work environment, missions and activities

Global aquaculture heavily depends on the ambient environment, which makes it inherently vulnerable to the effects of climate change¹. Two important abiotic factors threatened by climate change are temperature and dissolved oxygen concentration². These two factors are closely linked, as water temperatures rise, dissolved oxygen levels decrease due to their inverse relationship. For instance, climate change has already caused water temperatures in lakes and rivers across Europe, North America, and Asia to rise by 0.2 to 2°C³, and climate models predict a gradual increase in surface temperatures ranging from 1 to 4°C by the year 2100⁴. These changes are expected to alter freshwater fish communities, with both direct and indirect consequences for aquaculture productivity⁵.

In open or large-scale aquaculture systems (e.g., lakes, ponds, lagoons, or offshore cages), direct control of water temperature is often not feasible. Therefore, alternative strategies are urgently needed to improve fish resilience during extreme temperature and hypoxia events. Among these, nutritional interventions represent a promising approach, with the potential to meet increasing energetic and nutritional demands associated with mitigating the effects of these abiotic climate change stressors¹.

In this context, the present PhD project aims to deepen our understanding of the metabolic impairments caused by thermal and hypoxic stress in the digestive system of rainbow trout. This knowledge is key to developing functional diets that effectively mitigate the adverse effects of these environmental stressors and enhance the resilience of aquaculture species, such as rainbow trout. This project will focus on cellular mechanisms that are key to enduring environmental stress, including cellular stress response, antioxidant defenses⁶, cellular damage and autophagy⁷, and macromolecule metabolism (anabolism and catabolism). Furthermore, the present project will include the formulation of new diets including different supplements such as: 1) antioxidants and mineral supplements that serve to prevent oxidative damage and maintain homeostasis. 2) functional lipids, to stabilize membrane structure, 3) essential amino acids to improve metabolic flexibility and tissue repair under stress, 4) phytogenics, to mitigate oxidative stress and inflammation, and to improve antioxidant capacity, 5) yeast-derived bioactive compounds to improve hepatic and intestinal transcriptomic responses and cellular integrity⁸.

 

References

1. Reid et al. Climate change and aquaculture: considering adaptation potential. Aquacult Environ Interact. 2019, 11:603-624.
2. Stiller et al. The effect of diet, temperature and intermittent low oxygen on the metabolism of rainbow trout. British Journal of Nutrition 2017, 117(6),784-795.
3. FAO, Climate change implications for fisheries and aquaculture. FAO, Rome. 2009, 530.
4. IPCC. Climate change: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2014, Geneva, Switzerland.
5. Ficke et al. Potential impacts of global climate change on freshwater fisheries. Rev Fish Biol Fisheries. 2007, 17 :581–613.
6. Martinez-Alarcon et al. Transcriptomic and biochemical analysis of Procambarus clarkii upon exposure to pesticides: Population-specific responses as a sign of pollutant resistance? Env. Res. 2025, 270 : 120963.
7. Schnebert et al. Chaperone-Mediated Autophagy in Fish: A Key Function Amid a Changing Environments. Autophagy Reports. 2024, 3(1).
8. Frohn et al. Gut physiology of rainbow trout (Oncorhynchus mykiss) is influenced more by short-term fasting followed by refeeding than by feeding fishmeal-free diets. Fish Physiol Biochem. 2024, 50:1281-1303.

Training and skills

INRAE's life quality

By joining our teams, you benefit from (depending on the type of contract and its duration):

- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.

How to apply

I send my CV and my motivation letter