My research investigates the biology, ecology and life history of populations of marine top predators and their links to changes occurring in their environments. It not only uses marine animals as indicators - or sentinels - of fast occurring environmental changes in oceans all over the world, but also as invaluable samplers to monitor biochemical oceanographic changes in remote areas where collecting in-sit data is otherwise very difficult. My approach integrates field-based biological data collection with cutting-edge biologging / biotelemetry technologies and advanced statistical and mathematical modeling tools to broaden our understanding of impacts of the current climate crisis on our oceans and the species that inhabit them. Ultimately, my work aims at developing mechanistic knowledge to better assist global conservation efforts of our marine ecosystems. My research mainly focuses on three research broad themes articulated around an integrative approach:
(1) FORAGING ECOLOGY AND ONTOGENY
Foraging is the process by which animals acquire the food they need to survive and reproduce in the wild. My research investigates foraging ecology of marine animals, the movement (vertical and horizontal), behavioural or physiological adjustments they can make when facing changes in availability, distribution or accessibility of their prey, as well as what makes them successful or not in different environmental conditions. I am also interested in how young marine animals learn to forage in the oceans given their limited experience and physiological capacities, and how oceanographic changes might impact their foraging success and thus survival during their first years at sea. This ultimately affect fitness of animals, health of their populations and dynamics of their ecosystem.
Bioenergetics is the study of energy transfer and transformation in biological systems based on thermodynamics laws. I am interested in characterizing and understanding the cascade of energy transfers throughout marine food webs at the individual or population levels, and how this can be affected by environmental changes in our oceans. I am also interested in understanding how predators energy input / expenditure balance defines allocation to physiological functions and activities and ultimately the capacity of individuals to survive and successfully reproduce in the wild, with consequences on their population trends. Bioenergetics studies integrate field- and lab-based data with advances statistical and mathematical modelling methods. Ultimately, bioenergetics models can help predicting how marine food webs, animal populations or individual organisms might be affected by different environmental change scenarios.
(3) BIOLOGGING & BIOTELEMETRY
Direct observation of marine animals is nearly impossible and yet, detailed scientific data on the movement, behaviour, physiology and surrounding habitat of free-ranging animals is essential to effective wildlife conservation. Biologging and biotelemetry use miniature animal-attached electronic devices that allow to record such diverse data - from dive depth to tri-axial acceleration or water salinity - related to the life of animals and their ecosystems. I collaborate with engineers and technicians to design marine mammal-adapted new sensors, test new tags, as well as develop on-board processing algorithms for transmission of summarized data via satellites. These cutting-edge technological advancements bring an unprecedented understanding of interactions between animals and their environments - which my research themes (1) and (2) widely depend upon - and is a major contributor to significantly advancing global wildlife protection efforts.
I work on marine species located at the top of their food webs such as marine mammals and seabirds. If I worked on species all over the world, my main research interest is on (sub)-Arctic and (sub)-Antarctic pinnipeds, whether phocid seals or otariids (fur seals and sea lions). Below is a non-exhaustive gallery of my study animals and their location: northern fur seals (Callorhinus ursinus), hooded seals (Cystophora cristata) and grey seals (Halichoerus grypus) for the northern hemisphere; and Southern elephant seals (Mirounga leonina) and Antarctic fur seals (Arctocephallus gazella) for the southern hemisphere.
Northern fur seals
Antarctic fur seals
Southern elephant seals
Impact of environmental changes on ice seal ecology
Over the past decades, the Arctic has experienced some of the most rapid global warming, resulting in structural changes in sea-ice as well as in oceanographic physico-chemical parameters. This changes will impact organisms at every level of the Arctic food web from phytoplankton to top predators. Because of their position at the top of the marine food web and their close association with sea-ice, ice seals are considered bio-indicators of the ecosystem health. The sensitivity to the impacts of climate change on ice seals is expected to be species-specific. Hooded seals (Cystophora cristata) are considered highly sensitive to changes in sea ice conditions due to a high dependence to stable ice floes for whelping, lactation, and moulting (thermoregulation), and as foraging habitat. Hooded seals are listed as ‘Vulnerable’ by the International Union for Conservation of Nature (IUCN). The scarcity of Arctic ice seal demographic and movement data via biotelemetry (due to their remote habitat and logistical and financial difficulties to set up large scale field sessions) limits our ability to clearly understand the impacts of climate-induced changes on ice seal dynamics and distribution, and consequently limits our capacity to forecast the future viability of ice seals to adapt to climate and habitat change. This project seeks to first investigate the movement and foraging ecology hooded seals at different life stages to provide a better understanding of the mechanistic links between environmental changes and seals’ behavioural and ecological responses. Ultimately, understanding these links will allow us to forecast the impacts of projected climate scenarios on marine Arctic ecosystem functioning.
Funding and partners:
BNP Paribas foundation, Department of Fisheries and Oceans Canada, French Ministry of Higher Education and Research, CNRS, La Rochelle Uiversity, France-Canada Research Funds, ECOMM chaire
Impacts of oceanic changes on energetics, behaviours & life-history strategies of fur seals
The current impacts of climate changes on oceans are not homogenous worldwide: in sub-polar and temperate regions, marine ecosystems tend to experience a directional linear increase towards hotter environments, while tropical regions decrease in climate stability and predictability along with an increase in frequency of extreme climate events such as ENSOs and marine heatwaves. These rapid physical forcings will have a different impact on the structure and dynamics of food webs, right up to top predators, which as integrators of ecosystem changes from geochemical parameters to preyscape dynamics, are considered indicators of marine ecosystem health. The consequences of warming for long-lived top predators depends on their ability to respond to and survive changing in environmental patterns they are exposed to. As long-lived species are unlikely to show evolutionary responses at the rate to keep pace with climate change, behavioral plasticity is key for understanding these responses to environmental changes. In turn, these behavioural changes will impact diet and movements of individuals, their energetic cost/benefit ratios, and result in expressions of phenotypic and life history-trait plasticity. The main objective of this project is to determine how changes in physical and biological/trophic environments impact the behaviours, energetics and life history traits of fur seals in various locations. Specifically, how environmental variability and predictability shape individual strategies of fur seals given their acclimation and adaptive capacities, the consequences on fitness traits, and ultimately on population trajectories.
Funding and partners:
French Polar Institute IPEV, CNRS, La Rochelle University
Newly-developed microsonars and AI methods to analyze the underwater data they collect
Marine ecosystems are undergoing drastic and rapid changes due to anthropogenic pressures from intensive fishing, pollution, habitat loss, or global warming. The consequences of these changes on ecosystem functioning often remain poorly assessed, with only 5% addressing the overall question of the ecological consequences of these physical changes due to a persisting deficit of in situ-collected biological data. These gaps are primarily due to a lack of tools suitable for sampling intermediate trophic levels (i.e. nekton: zooplankton, gelatinous, fish and squid ...) simultaneously with the measurement of physical and biogeochemical oceanographic parameters at fine scales. In the last 20 years, animal-borne bio-logging devices, have revolutionized the study of animal behavior in their natural environments, and allowed to start bridging these data gaps. To that end, new underwater micro-cameras and a newly-developed micro-sonar that mimics the echolocation system of whales and dolphins, have been deployed on diving marine animals to record the presence of mid-trophic level organisms along the trajectory of diving marine predators . Moreover, the large and growing datasets generated by these loggers prohibit manual analysis in their entirety and as such require the development of accurate and relevant data processing methods based on machine learning to automatically extract relevant information from raw data.
Funding and partners:
CNRS, La Rochelle University, ECOMM chaire, CNES, French Polar Institute IPEV
Role of marine mammals in ocean nutrient cycling, and in sea-to land nutrient transfers
Nutrient cycling are a major component of ecosystem functioning. Essential nutrients accumulated in the ecosystem are released during the mineralization of organic matter by decomposers, making these elements available to plants. Thus, the nature of the accumulated organic matter and microbial diversity will direct the quality and quantity of mineral nutrients available to plants, governing more generally the structuring of the food web. Animals facilitate these transfers to primary producers by digesting essential elements stored in an unavailable form (slow-decomposing living organic matter) and releasing them in a more available form via the production of feces and urine. Their role in these biogeochemical fluxes, although poorly documented, is identified as significant and even structuring. Top predators in the oceans, such as cetaceans, have a significant role in these nutrient fluxes, which they collect via their food in the oceans, and recycle via their waste, enriching these same ecosystems. Seabirds, seals or sea lions on the other hand make regular trips back and forth between the marine environment where they feed and the land where they rest and reproduce. These journeys promote the transfer of nutrients from the sea to the land and contribute to the enrichment of terrestrial food chains.
Funding and partners:
CNRS, La Rochelle University, PELAGIS Observatory, University of Rennes
In addition to my research projects, I engage in scientific committees, both nationally and internationally. I am also active in advancing equality, equity, diversity and inclusion in the workplace, and I co-created a not-for-profit organization to promote ocean conservation.
I am a member of the Ethics Committee of AniBOS, an international network part of the Global Ocean Observing System (GOOS). It provides freely available oceanographic data collected through biologging, and biotelemetry devices deployed on marine animals. By collecting oceanographic data from the most inaccessible regions of the global seas from diving animals around the globe and making them freely available to the scientific community, AniBOS aims at enhancing our observing capabilities and our understanding of changing oceans. AniBOS has been endorsed by UNESCO's UN Ocean Decade as a Decade Project 2021 – 2030.
I am a member of the French Commission specialized in Innovative and Transverse Instrumentation initiatied by the National Institute of Universe Sciences (INSU) of Centre National For French Scientific Research (CNRS). Our aim is to promote the development of innovative instruments for the observation and analysis of our environment, and to facilitate the transfer, application and valorization of these tools from one domain to others when possible and relevant.
I am a co-leader, along with Dr Muriel Visani a Computing Scientist at La Rochelle University France, of the 'Biologging, Remote Sensing and AI Applications in Environmental Sciences' team of EU-CONEXUS, a collective of European universities that came together to create the European University for Smart Urban Coastal Sustainability.
Equality, Diversity, Inclusion and Well-Being Committee
I created an Equality, Diversity, Inclusion and Well-Being committee at my institute, in which the 20 members actively engage in actions to promote a better, more equal, diverse, inclusive and well-balanced work environment. We are also closely associated with the Equality department of our associated university.
I am the co-founder of Wings & Dives, a not-for profit international collective of academic marine biologists, ecologists and biostatisticians who work together to promote ocean conservation. This goal of this marine ecology research initiative is to promote conservation of our oceans' health, biodiversity and sustainability. To do so, we lead science-based projects on environmental issues that marine ecosystems and species currently face.