Modeling based on dynamic energy budget theory (DEB) of the kinetic of paralytic shellfish toxins (PST) bioaccumulation in the Pacific oyster Crassostrea gigas

• Main Author: Pousse, Emilien
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne occidentale - Brest, Frédéric Jean
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2017
• Subjects: Dynamic Energy Budget; Paralytic Shellfish Toxins; Pacific oyster; Accumulation kinetics; Ecotoxicology; Budgets d’Énergie Dynamiques; Toxines paralysantes; Cinétiques d’accumulation; Écotoxicologie; [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology; Pacific; Crassostrea gigas
• Online Access: https://theses.hal.science/tel-03670390; https://theses.hal.science/tel-03670390/document; https://theses.hal.science/tel-03670390/file/These-2017-SML-Ecologie_marine-POUSSE_Emilien.pdf

The oyster Crassostrea gigas is one of the most commercialized molluscs in the world. It is a very cosmopolitan species that has been disseminated by humans and is susceptible to various agents such as pathogens (bacteria, viruses), parasites,xenobiotics and/or toxic micro-algae. As a filter-feeder, it may accumulate phycotoxinswhile feeding on harmful algal blooms (HAB), including paralytic shellfishtoxins (PST). To protect human health shellfisheries harvesting are closed duringHAB, impacting the aquaculture industry. This PhD work aims to develop a Dynamic Energy Budget (DEB) based model to describe kinetics of PST accumulationand detoxification in C. gigas. Interest of coupling bio-accumulation to DEBmodel lies in the inclusion of physiological (e.g. body size, tissue composition)and environmental (food quantity and quality) variables to simulate accurately the dynamics of contaminants in marine organisms. Two experiments consisting in exposing C. gigas to the toxic dinoflagellate Alexandrium minutum were performed.Toxin intake was calibrated in a first short-term experiment where clearance rates and assimilation efficiency were individually measured during an exposure to toxic and non-toxic micro-algae. Metabolic rates (respiration, cardiac activity) were also assessed. This study brings new insights concerning the important inter-individualvariability of PST accumulation reported in C. gigas by identifying three phenotypes characterized by different clearance rates. Then a long-term exposure to a mixture of toxic and non-toxic micro-algae was carried out to calibrate (1)toxin elimination process, (2) PST effects on oyster bioenergetic and (3) validatea mathematical representation of particles selection. A DEB model simulating the evolution of toxin concentration via two compartments (unassimilated and assimilatedtoxins) is proposed which was validated using a laboratory dataset and field surveys. In a last part, the numerical model is then used to investigate the differences in toxification and depuration ...