Reef-Fish Metamorphosis, Recruitment, and Nursery-Ecology in a Changing World


Increasingly frequent and severe anthropogenic perturbations have modified the ecological functions of coastal water areas, such as their nursery role for most teleost fish species.
In these species, settlement in nurseries (e.g. seagrass beds, coral-reefs, mangroves) coincides with major transformations as larval fishes (initially pelagic) metamorphose in benthic/demersal juveniles. Through this thyroid-hormone-mediated metamorphosis, fish develop morphological features, sensory abilities, and physiological functions adapted to their new coastal environment, therefore enhancing their growth and survival and promoting their recruitment in the adult populations.

Recruitment is a critical step in most teleost fish life cycle, as it determines population replenishment, resilience and stock sustainability. Many studies have put a great emphasis at understanding the impacts of climate change scenarios and waterborne endocrine disrupting chemicals (EDC) on the the reproductive functions and the early larval development in fishes. However, the impact of such perturbations in recruiting larval fishes has received little attention. Indeed, while recent studies start to elucidate the defects caused by anthropogenic stressors on the behavioral ecology and survival of reef fishes at recruitment, we still lack a comprehensive understanding of the inner physiological and developmental mechanisms behind such sensory & survival issues.

Through my research, I have developed a framework that integrates physiological, developmental and behavioral approaches to better understand how anthropogenic stressors can affect the proceedings of metamorphosis and recruitment. I seek to uncover the levels and the effects of current and predicted anthropogenic pertubations on fish metamorphosis proceedings to better understand their outcomes on fish recruitment processes and  nursery ecology.


I am currently a postdoctoral research fellow at the IAEA Environment Laboratories (Monaco), working on the impacts of nano- and micro-plastics on marine organisms. In 2018, I also worked as a postdoc at CRIOBE (Moorea, French Polynesia) on endocrine disruptors of coral-reef fish metamorphosis. I obtained my PhD from PSL Research University and the EPHE (Paris, France) in 2017, after my research on the triggering and proceedings of coral-reef fish metamorphosis under anthropogenic stressors. My PhD was performed within the CRIOBE, the Institut de Génomique Fonctionnelle (Lyon, France) and the OOB (Banyuls-sur-Mer, France), with a fellowship from the ENSL (Lyon, France).


Fish Eco-Physiology

I seek to uncover the hormonal triggering and proceedings underlying fish life-history transitions (e.g. settlement & recruitment) and their importance in the organism physiology (e.g. diet shift, microbiome shift, digestive tract remodeling, metabolic rates, swimming performance) and ecology (e.g. feeding behavior, schooling, survival).

Fish Neuro-Ecology

I aim at understanding the link between sensory organs development/maturation and sensory abilities acquisition. This involves various histological techniques (embedding/sectionning/staining, SEM, LSM, MRI) and behavioral analyzes (choice experiments, task performances, personality, behavioral lateralization).

Fish Eco-Toxicology

I look at how chemicals, plastics, noises, increased temperature and acidification can impact fish ecology and physiology. To do so, I perform in situ and laboratory experiments to assess contamination & stress levels in the environment & organisms, to then decipher how disrupted endocrine systems can lead to impaired development, behavior and survival.



    Deciphering the impact of nano- and macro-plastic pollution on marine organisms

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    Fish Ecophysio Ecotoxico and Sensory-ecology in nursery Habitats

    Deciphering the importance of metamorphosis in teleost fish recruitment processes.

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    Coral-reef fish settlement patterns

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    Monitoring of sea turtles populations, migrations, and nesting sites in French Polynesia

    Page under construction


Effects of Virgin Micro- and Nanoplastics on Fish - Trends, Meta-Analysis, and Perspectives

1st authorReview
Jacob H., Besson M., Swarzenski P., Lecchini D., Metian M.
Environmental Science & Technology
Publication year: 2020

Predation drives recurrent convergence of an interspecies mutualism

Research Article
Feeney W.E., Brooker R.M., Johnson L.N., Gilbert J.D., Besson M., Lecchini D., Dixson D.L., Cowman P.F., Manica A.
Ecology Letters
Publication year: 2019

Exposure to agricultural pesticide impairs visual lateralization in a larval coral reef fish

1st authorResearch Article
Besson M., Gache C., Bertucci F., Brooker R.M., Roux N., Jacob H., Berthe C., Sovrano V.A., Dixson D.L., Lecchini D.
Scientific Reports 7: 9165
Publication year: 2017

Fish larval recruitment to reefs is a thyroid hormone-mediated metamorphosis sensitive to the pesticide chlorpyrifos

1st authorResearch Article
Holzer G., Besson M., Lambert A., François L., Barth P., Gillet B., Hughes S., Piganeau G., Leulier F., Viriot L., Lecchini D., Laudet V.
eLife, 6. doi:10.7554/elife.27595
Publication year: 2017