Optimisation de l'élevage larvaire expérimental d'huîtres creuses, Magallana (ex Crassostrea) gigas, en vue de limiter le développement de communautés bactériennes pathogènes

In commercial and experimental Pacific oysters, Magallana gigas, hatcheries, recurring mortalities have been observed, which can be caused by various factors. Therefore, Ifremer has created the project ALADIN, “Amélioration des performances en élevages larvaires d’invertébrés marins”, of which this publication is a part. The main goal of this study, which took place at the PMMLT, “Plateforme Mollusques Marins de La Tremblade”, is to reduce pathogenic bacterial communities by optimizing zootechny rather than routinely using antibiotics. To assess the impact of rearing practices, such as water changes, larval densities and antibiotic use, on larval performances, a static larval rearing of M.gigas was conducted. Bacterial communities in seawater, larvae and phytoplankton compartments were identified with metabarcoding 16S. The results suggest that antibiotics don’t have any effect on larval performances, whereas daily water changes improve larval growth and fixation and reduced larval densities improve larval survival, growth and fixation. Furthermore, pathogenic bacteria from Vibrio genus were identified, despite the use of antibiotics. To conclude, optimizing zootechny and using antibiotics only as a curative measure, could improve larval performances