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New PhD student · July 2025 Welcome to Célia Caillibot, PhD student within MaHeWa studying ciguatera in New Caledonia |
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Since July, Célia Caillibot has joined us at the Ifremer representation office in New Caledonia. Under the supervision of Thierry Jauffrais (IFREMER), Nicolas Lebouvier (UNC), and Philipp Hess (IFREMER), she will be working as part of Work Package 2: Ecological Vulnerability and Biological Impacts.
A rich background before the PhD After completing her initial training in Bordeaux in Chemistry — specialising in Ecotoxicology and Environmental Chemistry — she undertook her first internship during her Master 1 at the Ifremer representation in Concarneau, focusing on the effects of ichthyotoxic dinoflagellates from the genus Karlodinium on oyster gametes. She then completed a second internship during her Master 2 at ISEA (Institute of Exact and Applied Sciences) on reference values for several metals in streams flowing through peridotite massifs. With these two initial experiences and her degree in hand, she continued her path with a VSC at the New Caledonia Laboratory (LNC, DAVAR), where she implemented a multi-residue pesticide analysis method in plants using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). Eager to deepen her understanding of the environmental specificities of the New Caledonian context, she successfully obtained a PhD contract along with an Ifremer scholarship, in partnership with Ifremer (LEAD-NC and PHYTOX teams), the University of New Caledonia (ISEA), and the MaHeWa project. PhD subject: better understanding ciguatera risk in New Caledonia Célia’s thesis aims to better understand the risk associated with ciguatera in New Caledonia — a foodborne illness caused by consuming fish contaminated with ciguatoxins produced by the microalga Gambierdiscus. Common in tropical regions, this phenomenon is a major public health issue, with 10,000 to 50,000 cases reported annually, further exacerbated by climate change. Given the absence of curative treatment and the variety of symptoms (gastrointestinal, neurological, and cardiovascular), her research adopts a multidisciplinary approach combining ecophysiology, chemistry, molecular biology, and marine resource management to improve the understanding of this risk and help prevent poisoning in the New Caledonian context. Methodology Célia’s methodology is based on an integrated approach combining fieldwork with laboratory analysis. Field campaigns will be conducted at three study sites (Lifou, the Southern Lagoon, and potentially Ouvéa) to assess the impact of seasonal changes and marine heatwaves on microalgal diversity, using SPATT and WS devices to collect microalgae and characterise the toxins present, particularly ciguatoxins. Fish (both herbivorous and carnivorous) and giant clams will also be sampled four times a year at these sites to analyse the toxicity of commonly consumed species. In the lab, isolated Gambierdiscus strains will be identified using molecular biology, morphological analysis, and chemotaxonomy techniques, with the goal of building an algal strain library. These strains will then be exposed to different temperature conditions to study their growth, thermal tolerance, toxic potential, and cellular organisation, in order to predict how the ciguatera risk might evolve in a warming ocean and to better understand the toxin profiles of local marine species.
We look forward to sharing Célia’s first research results with the MaHeWa community as this very promising project moves forward! |
