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Individual variation in tolerance of hypoxia and high temperatures in teleost fish: mechanisms and implications

Periodic Reporting for period 1 - INDITOL (Individual variation in tolerance of hypoxia and high temperatures in teleost fish: mechanisms and implications)

Período documentado: 2019-04-15 hasta 2021-04-14

• What is the problem/issue being addressed?
Our oceans are changing. They are losing in their oxygen inventory and becoming more hypoxic. Hypoxia is a condition where the dissolved oxygen levels present in the water is becoming depleted. More than 700 coastal sites have been reported as new hypoxic or worsening in their oxygen conditions. With this recurrent environmental stressor, oceans are also becoming warmer. Hypoxia and acute warming share a common physiological mode of action in fishes, both stressors challenge the animal's capacity to provide sufficient O2 to respiring tissues. This can have severe consequences at the individual level, causing reduced performance and fitness, even threatening survival. Therefore, it is important to study the inter-individual variation in tolerance of these stressors within fish populations. This variation in tolerance will determine the ability of the population to persist, and even thrive, when challenged by these stressors.
Why is it important for society?
Investigations into physiological mechanisms that underlie tolerance of climate change are well-aligned with strategic priorities of the European Union and consist of one of the major societal challenges within the Horizon 2020 objectives. Determining the adaptive responses of fish populations towards two major environmental stressors will help us to predict the future of fisheries stocks and also improve sustainability of aquaculture by identifying robust strains. As fisheries and aquaculture, are both extremely important economic activities based on natural resources; with 1.2 million tonnes produced from EU aquaculture in 2012 of which 69% coming from marine water environment. Sustainable management of fisheries and aquaculture have been identified as an EU research and development priority, in accordance with the Horizon 2020 objectives. Current EU policy is committed to ensure the European fishing and aquaculture industry are sustainable, do not threaten fish population size, productivity and secure food quality and security over the long-term. The EU commission also recognizes that the impacts of climate and environmental changes on the marine environment are not fully understood and strongly encourage long-term scientific research project relevant to aquaculture management. The current project is fundamental research but is nonetheless perfectly in harmony with these EU policies and research objectives. It will provide important insights about how climate change stressors may affect the nature of populations of valuable coastal fishes, in terms of productivity (growth rates) and population dynamics (aging and life span). The proposed work will also inform about how selection for robust individuals in aquaculture may have correlated effects in terms of production and welfare.
• What are the overall objectives?
1) To document variation in sub-lethal tolerance of hypoxia and acute warming in a population of juveniles, and reveal cross-tolerance
2) To demonstrate that relative tolerance depends upon each individual’s intrinsic respiratory physiology
3) To investigate how tolerance relates to underlying mitochondrial respiration
4) To evaluate whether tolerance trades-off against important individual traits such as growth efficiency
5) To evaluate the genomic links between maintenance metabolism and hypoxia tolerance and to estimate the heritability for these two traits
From October 2019-March 2020: I collected individual metabolic rate and hypoxia tolerance data on 934 individuals.
In September 2020: I measured mitochondrial respiration in 95 fish in liver and heart tissues.
From October 2020-March 2021: I collected oxygen consumption and thermal tolerance data in 95 fish.
I am currently analysing the data.
During the fellowship, I have been able to reach a wider public by using social media (Twitter, Linkedin).
All the international conferences have been postponed due to the current pandemic situation. So far, I am currently analysing the data. The outcoming results from the fellowship will be presented in 2022 at two international conferences.
I am a co-author on one review paper published in Journal of Fish Biology in 2020. One manuscript is in preparation for submission in Biology Letters and will be published this year 2021. Another manuscript is currently in progress of writing up and will be submitted this year as well in 2021 in Aquaculture. The expected 6-7 manuscripts are planned to be submitted by 2022-2023 in diverse high-ranking journals (Biology Letters).
As mentioned above, the results obtained during this fellowship will provide information on the environmental robustness of a given fish population while facing challenging conditions. This can be informative for the sustained aquaculture industry. They can integrate this trait of robustness in their selection management and process to actively favour more tolerant strains. Additionally, by identifying the specific physiological phenotypes for tolerance of two important concurrent environmental stressors, we can predict the future structure or dynamic of wild fish populations.