Fred Jean

Deep sequencing of the mantle transcriptome of the great scallop Pecten maximus.

RNA-Seq transcriptome data were generated from mantle tissue of the great scallop, Pecten maximus. The consensus data were produced from a time course series of animals subjected to a 56-day thermal challenge at 3 different temperatures. A total of 26,064 contigs were assembled de novo, providing a useful resource for both the aquaculture community and researchers with an interest in mollusc shell production.

Handling enhances the development of brown ring disease signs in Ruditapes philippinarum

ABSTRACT Brown ring disease (BRD) in the Manila clam is characterized by the formation of a brown deposit of conchiolin on the inner surface of the shell that gives the disease its name. The development of the signs of BRD may be favored by the entry of bacteria in the extrapallial compartments via mechanical disruptions of the periostracal lamina and/or chipping of the shell margin. To test this hypothesis, we conducted an experiment simulating clam handling under aquaculture conditions and we checked for prevalence of BRD signs. Our results assess that rough handling of Ruditapes philippinarum in presence of the bacterium Vibrio tapetis significantly increase the prevalence of BRD signs. As a consequence, our results show that minimizing manipulation and transfer of clams during culture is beneficial to avoid the development of BRD signs.

Sources of paralytic shellfish toxin accumulation variability in the Pacific oyster Crassostrea gigas

&NA; This study was designed to assess the contribution of feeding behavior to inter‐individual variability of paralytic shellfish toxin (PST) accumulation in the Pacific oyster Crassostrea gigas. For this purpose 42 oysters were exposed for 2 days to non‐toxic algae and then for 2 other days to the PST producer Alexandrium minutum. Individual clearance rate (CR) of oysters was continuously monitored over the 4 days using an ecophysiological measurement system. Comparison of CR values when exposed to toxic and non toxic algae allowed to estimate a clearance rate inhibition index (CRII). Toxin concentration of oysters was quantified at the end of the experiment. These data allowed to estimate the toxin accumulation efficiency (TAE) as the ratio of toxin accumulated on toxin consumed. Changes of clearance rate during the experiment indicated that all individuals stopped feeding immediately after being exposed to A. minutum for at least 7 h. This fast response likely corresponded to a behavioral mechanism of avoidance rather to a toxin‐induced response. Individuals also showed high inter‐variability in their recovery of filtration after this period. Most of the inter‐individual variability (78%) in PST accumulation in C. gigas could be explained by the consumption of A. minutum cells, thus emphasizing the importance of the feeding behavior in accumulation. Based on the toxin concentration in their tissues, oysters were clustered in 3 groups showing contrasted patterns of PST accumulation: the high accumulation group was characterized by high feeding rates both on non‐toxic and toxic diet and subsequently a low CRII and high TAE. Inversely, the low accumulation group was characterized by low filtration rates, high CRII and low TAE. Both filtration capacity and sensitivity of oysters to toxins may account for the differences in their accumulation. The contribution of TAE in PST accumulation is discussed and might result from differences in assimilation and detoxification abilities among individuals. HighlightsFacing exposure to A. minutum, individual clearance rates of oysters were measured.Algal consumption explains variability in paralytic shellfish toxin accumulation.Three phenotypes were identified on the basis of their accumulation potential.Phenotypes differed in their feeding rates.Phenotypes also differed in their sensitivity to toxins and accumulation efficiency.

DEBSe@: an e-learning platform to introduce the Dynamic Energy Budget (DEB) theory for marine ecology, fisheries sciences and aquaculture applications

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. DEBSe@: an e-learning platform to introduce the Dynamic Energy Budget (DEB) theory for marine ecology, fisheries sciences and aquaculture applications Yoann Thomas, Fred Jean, Laure Pecquerie, Gonçalo Marques, Sébastien Hervé, Valérie Dantec, Jonathan Flye-Sainte-Marie