Aquatic Organisms, Ecosystems, and Stressors


Freshwater and marine ecosystems are facing increasingly frequent and severe anthropogenic perturbations.

These stressors can be very diverse (e.g. heat waves, chemical and plastic pollution, habitat changes) and can independently and/or synergistically affect the the biology of aquatic organisms and functioning of aquatic ecosystems.

I am particularly interested in the effects of stressors on key ecological processes, e.g. predator-prey dynamics and resilience loss, and on critical life-history transitions, e.g. bottlenecks and important developmental steps such as metamorphosis. I use a variety of aquatic study systems, but I tend to use reef fishes and freshwater ciliates as my model organisms.

I like to use experimental and integrative approaches, from the molecule to the ecosystem, and automated and reproducible methods to investigate the inner biological mechanisms explaining how broader ecological processes can be affected by multiple stressors.


I am currently a Lecturer at Sorbonne Université (France), where my research and teaching activities are primarily focused on marine ecotoxicology using integrative, experimental and automated approaches.

From 2020 to 2022, I was a Research Associate at the School of Biological Sciences, University of Bristol, where I investigated the impacts of multiple stressors on the resilience of aquatic ecosystems using laboratory systems, gantries, AI, and experimental arenas.

From 2018 to 2020, I was a Postdoctoral Research Fellow at the IAEA Environment Laboratories (Monaco), where I studied the effects of microplastics on fish ecophysiology, behavior and histology, using radio-nuclear techniques.

In 2018, I was awarded the Young Research Prize from the Bettencourt-Schueller Foundation, for my work and research project examining the impacts of anthropogenic stressors on larval fish sensory development and survival via endocrine disruption.

I did my PhD (2014 – 2017) at CRIOBE, PSL Research University (French Polynesia) on the metamorphosis of coral reef fishes, its inner molecular mechanisms, sensorial and ecological importance, and sensitivity to stressors. My PhD was also conducted within the Institut de Génomique Fonctionnelle (Lyon, France) and the OOB (Banyuls-sur-Mer, France), with a fellowship from the ENSL (Lyon, France).


Experimental Ecology

I seek to uncover the effects of stressors on the biology and ecology of aquatic organisms using laboratory systems. To do so, I like to build arenas, mesocosms, and to use automated measurements and functional treatments to investigate how specific biological and ecological processes respond to stressors.


I aim at understanding the inner mechanisms underlying the effects of stressors on aquatic ecosystems functioning. For this, I use integrative approaches, from the molecule to the behavior and species interactions, to examine how the biology of aquatic organisms can explain their ecological response to stressors.

Multiple Stressors

I look at how multiple stressors such as habitat/temperature changes and pollutants can impact the biology and ecology of aquatic systems. I perform in situ and laboratory experiments to assess stress levels in the environment & organisms, and to scrutinize how they can disrupt key biological and ecological processes.



    Effects of multiple stressors on the resilience of protist communities

    This project aims at understanding the effects of multiple stressors and the resilience of ecological communities, using protist microcosms, automated gantries and AI.

    This project is part of my Research Associate position within the School of Biological Sciences, at the University of Bristol, in collaboration with Dr. Chris Clements (University of Bristol) and the University of Sheffield.


    Effects of microplastic pollution on aquatic organisms

    This project examines the effects and toxicology of microplastics on the physiology of aquatic organisms, using radio-nuclear techniques.

    This project was part of my postdoctoral work at the IAEA in Monaco (2018-2020), and continues since then in collaboration with Dr. Marc Metian and Dr. Peter Swarzenski (IAEA).


    Fish Ecophysio Ecotoxico and Sensory-ecology in nursery Habitats

    This project investigates the importance of thyroid hormones in reef fish metamorphic and recruitment processes, as well as the sensitivity of the thyroid signaling to anthropogenic stressors.

    This project was part of my PhD (2014-2017) and first postdoc (2018) within the CRIOBE, and continues since then in collaboration with Dr. David Lecchini (CRIOBE) and Dr. Vincent Laudet (OIST).


    Effects of acidification on coral reef fish metamorphic processes

    This project explores the effects of acidification on a key life history transition transition in reef fish life cycle.

    This project started during my postdoc at the IAEA (2018-2020) and continues since then in collaboration with Dr. Marc Metian (IAEA), and Dr. Laetitia Hedouin and Dr. Dvid Lecchini (CRIOBE).


    Sea turtle populations, migrations, and nesting sites in French Polynesia

    This project is part of the monitoring of sea turtles migrations, populations and nesting sites in French Polynesia operated by Te mana o te moana association, led by Dr. Cécile Gaspar.


Towards the fully automated monitoring of ecological communities

1st authorOpinion/PerpectivesReview/Synthesis
Besson M., Alison J., Bjerge K., Gorochowski T.E., Høye T.T., Jucker T., Mann H.M.R., Clements C.F.
Ecology Letters
Publication year: 2022

Anthropogenic stressors impact fish sensory development and survival via thyroid disruption

1st authorResearch Article
Besson M., Feeney W.E., Moniz I., François L., Brooker R.M., Holzer G., Metian M., Roux N., Laudet V., Lecchini D.
Nature Communications
Publication year: 2020

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

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

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.
Publication year: 2017