Recruitment of the Pacific oyster Crassostrea gigas in a shellfish-exploited Mediterranean lagoon: discovery, driving factors and a favorable environmental window

• Published in: Marine Ecology Progress Series
• Main Authors: Lagarde, Franck, Roque d’Orbcastel, Emmanuelle, Ubertini, Martin, Mortreux, Serge, Bernard, Ismael, Fiandrino, Annie, Chiantella, Claude, Bec, Beatrice, Roques, Cecile, Bonnet, Delphine, Miron, Gilles, Richard, Marion, Pouvreau, Stéphane, Lett, Christophe
• Other Authors: MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Université de Moncton, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), 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)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Unité de modélisation mathématique et informatique des systèmes complexes Bondy (UMMISCO), Institut de Recherche pour le Développement (IRD France-Nord )-Institut de la francophonie pour l'informatique-Université Cheikh Anta Diop Dakar, Sénégal (UCAD)-Université Gaston Bergé (Saint-Louis, Sénégal)-Université Cadi Ayyad Marrakech (UCA)-Université de Yaoundé I-Sorbonne Université (SU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: Crassostrea gigas; Oyster spat; Pediveliger; Metamorphosis; Recruitment; Oligo trophication; Larval ecology; ACL; envir; socio; Pacific; Pacific oyster
• Online Access: https://doi.org/10.3354/meps12265; https://hal.umontpellier.fr/hal-01928210/file/Lagarde_etal_MEPS_2017.pdf; https://hal.umontpellier.fr/hal-01928210

International audience In the context of increasing demand for environmental recovery, aquatic systems may face the challenge of evolving under oligotrophication. This is the case in Mediterranean lagoons, in particular the shellfish-farmed Thau lagoon in France, where we studied recruitment of the Pacific oyster Crassostrea gigas. Oyster spat and environmental parameters were monitored at several sampling sites for 3 yr (2012 to 2014) using an original method with a temporal overlap deployment of collectors to study pre- and post-settlement processes and to identify the best conditions for recruitment. Contrary to the ‘no Pacific oyster reproduction’ paradigm in Mediterranean lagoons, our study showed that recruitment of this introduced species is possible in the Thau lagoon at levels comparable to those in other traditional French breeding basins. We identified a favorable environmental window for recruitment characterized by high water temperature (>26.5°C) and high nanophytoplankton and Chaetoceros spp. abundances (>4.3 × 106 and 345 × 103 cells l-1, respectively). In these favorable conditions, we hypothesize that the ecosystem functions as an autotrophic system, in contrast to the heterotrophic system that characterizes unfavorable conditions. Under heterotrophic conditions, high abundances of mixotrophic and heterotrophic organisms (ciliates and dinoflagellates) limited the metamorphosis of C. gigas larvae, leading to poor recruitment. This study provides new knowledge on the reproduction of the Pacific oyster in a Mediterranean lagoon under warming and oligotrophication. The shellfish industry will profit from the discovery of spatfields to develop new nursery practices that are eco-friendly and limit risks of transfers with other spatfall areas.