Dominique Ratiskol, Bruno Petton, Philippe Soudant, Marc Suquet, Nelly Le Goïc, Justine Castrec, Isabelle Queau, Hélène Hégaret, Myrina Boulais, Maïlys Picard, Valentin Foulon, Marianne Alunno-Bruscia, Caroline Fabioux, 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), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), University of North Carolina [Wilmington] (UNC), University of North Carolina System (UNC), Laboratoire de Physiologie des Invertébrés (LPI), Physiologie Fonctionnelle des Organismes Marins (PFOM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), This project was supported by the National Research Agency ANR CESA, which founded the ACCUTOX project ANR-13-CESA-0019 (2013–2017). This work was also co-funded by grants from the Regional Council of the Région Bretagne and Brest Métropole, ANR-13-CESA-0019,ACCUTOX,De la caractérisation des déterminants de l'accumulation des toxines paralysantes (PST) chez l'huître (Crassostrea gigas) au risque sanitaire pour l'homme dans son contexte sociétal(2013), and 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 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)
International audience; Harmful algal blooms are a threat to aquatic organisms and coastal ecosystems. Among harmful species, the widespread distributed genus Alexandrium is of global importance. This genus is well-known for the synthesis of paralytic shellfish toxins which are toxic for humans through the consumption of contaminated shellfish. While the effects of Alexandrium species upon the physiology of bivalves are now well documented, consequences on reproduction remain poorly studied. In France, Alexandrium minutum blooms have been recurrent for the last decades, generally appearing during the reproduction season of most bivalves including the oyster Crassostrea gigas. These blooms could not only affect gametogenesis but also spawning, larval development or juvenile recruitment. This study assesses the effect of toxic A. minutum blooms on C gigas reproduction. Adult oysters were experimentally exposed to A. minutum, at environmentally realistic concentrations (10(2) to 10(3) cells mL(-1)) for two months during their gametogenesis and a control group, not exposed to A. minutum was fed with a non-toxic dinoflagellate. To determine both consequences to next generation and direct effects of A. minutum exposure on larvae, the embryo-larval development of subsequent offspring was conducted with and without A. minutum exposure at 10(2) cells mL(-1). Effects at each stage of the reproduction were investigated on ecophysiological parameters, cellular responses, and offspring development. Broodstock exposed to A. minutum produced spermatozoa with decreased motility and larvae of smaller size which showed higher mortalities during settlement. Embryo-larval exposure to A. minutum significantly reduced growth and settlement of larvae compared to non-exposed offspring. This detrimental consequence on larval growth was stronger in larvae derived from control parents compared to offspring from exposed parents. This study provides evidence that A. minutum blooms, whether they occur during gametogenesis, spawning or larval development, can either affect gamete quality and/or larval development of C gigas, thus potentially impacting oyster recruitment.