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 many 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 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.

Many studies have put a great emphasis at understanding, mainly in laboratory conditions, 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 situ and in metamorphosing larval fishes has received very little attention.
Through my research on coral-reef fishes, I have developed an Eco/Physio/Devo framework that permits to better understand how climate change and EDC could affect the proceedings of metamorphosis and settlement. As settlement and metamorphosis are critical for fish populations’ stock sustainability, I seek to uncover the levels and the effects of current and predicted anthropogenic pertubations on fish metamorphosis proceedings, to better understand their potential outcomes on nursery ecology and fish population replenishment processes.


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 proceedings underlying reef fish life-history transitions (e.g. settlement) 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 the development/maturation of sensory organs and the acquisition of sensory abilities. This involves various histological (e.g. dissection, tissue fixation, paraffin embedding, microtome sectioning, staining, electronic microscopy, SEM) and behavioral analyzes (e.g. choice experiments, task performances).

Fish Eco-Toxicology

I look at how water pollution (chemicals, plastics, noises), temperature rise, and oceanic acidification can impact fish ecology and physiology. To do so, I perform in situ and ex situ experiments to assess contamination/stress levels and decipher how they could disrupt fish endocrine systems and impair their development, behavior and survival.



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

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    Importance of metamorphosis in coral-reef fish larval recruitment

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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

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    Fish Eco-physio Eco-toxico and Sensory-ecology in nursery Habitats

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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

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

Consistency in the supply of larval fishes among coral reefs in French Polynesia

1st authorResearch Article
Besson M., Gache C., Brooker R.M., Madi Moussa K., Waqalevu V.P., LeRohellec M., Jaouen V., Peyrusse K., Berthe C., Bertucci F., Jacob H., Brié C., Wan B., Galzin R., Lecchini D.
PLoS ONE 12(6): e0178795
Publication year: 2017