Ecology of the reproduction of the Pacific oyster in Mediterranean lagoon

• Main Author: Lagarde, Franck
• Other Authors: MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Christophe Lett, Stéphane Pouvreau
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2018
• Subjects: Oyster; Larval ecology; Trophic resource; Connectivity; Recruitment; Coastal lagoon; Huître; Écologie larvaire; Ressource trophique; Connectivité; Recrutement; Lagune côtière; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV.EE.ECO]Life Sciences [q-bio]/Ecology; environment/Ecosystems; Pacific; Crassostrea gigas; Pacific oyster
• Online Access: https://theses.hal.science/tel-02924971; https://theses.hal.science/tel-02924971/document; https://theses.hal.science/tel-02924971/file/these_lagarde_franck_2018.pdf

The Mediterranean lagoons host many anthropogenic uses including shellfish aquaculture since the beginning of the 20th century. Imported in 1970, the cupped oyster, Crassostrea gigas, has adapted perfectly and has allowed an important development of oyster’s industry until 2008, the year of occurrence of spat outbreak related to the emergence of an Ostreid Herpes-virus µvar. The scarcity of spat and the speculation on this product changed regionally cultural practices and the supply of juveniles, with in particular the wish of developing a local activity of spat collection. However the cycle of reproduction of the species and the recruitment of juveniles were poorly known in lagoon environments. In this context, the objective of this thesis is to characterize the variability of the reproduction and the recruitment of the cupped oyster in Mediterranean lagoon. The lagoon configuration offers the advantages of productivity for the broodstock and hydrodynamic connectivity for the larvae. However, it appears that the ecological functioning of the system at the base of the primary production plays an essential role on the trophic resources for the success of oyster reproduction. This work takes place in the context of the ecological restoration under oligotrophication, which first effects we describe on the oyster's reproductive cycle. Les lagunes méditerranéennes hébergent de nombreux usages anthropiques dont la conchyliculture depuis le début du 20ème siècle. Importée en 1970, l’huître creuse, Crassostrea gigas, s’y est adaptée parfaitement et a permis un développement ostréicole important jusqu’en 2008, année d’apparition des surmortalités de naissain liées à l’émergence d’un variant du virus OsHv1. La raréfaction du naissain et la spéculation sur ce produit ont modifié régionalement les pratiques culturales et les modes d’approvisionnement en juvéniles, avec notamment la volonté de développer une activité locale de captage. Mais le cycle de reproduction de l’espèce et le recrutement de juvéniles étaient mal ...