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Auteur (up) Lagarde, F.; Fiandrino, A.; Ubertini, M.; d'Orbcastel, E.R.; Mortreux, S.; Chiantella, C.; Bec, B.; Bonnet, D.; Roques, C.; Bernard, I.; Richard, M.; Guyondet, T.; Pouvreau, S.; Lett, C.
Titre Duality of trophic supply and hydrodynamic connectivity drives spatial patterns of Pacific oyster recruitment Type Article scientifique
Année 2019 Publication Revue Abrégée Marine Ecology Progress Series
Volume 632 Numéro Pages 81-100
Mots-Clés Coastal lagoon; Connectivity; Crassostrea gigas; Larval ecology; Oligotrophication; Recruitment; Settlement; Spatial patterns
Résumé The recent discovery of Pacific oyster Crassostrea gigas (also known as Magallana gigas) spatfields in a Mediterranean lagoon intensely exploited for shellfish farming (Thau lagoon) revealed significant contrasts in spatial patterns of recruitment. We evaluated the processes that drive spatial patterns in oyster recruitment by comparing observed recruitment, simulated hydrodynamic connectivity and ecological variables. We hypothesized that spatial variability of recruitment depends on (1) hydrodynamic connectivity and (2) the ecology of the larval supply, settlement, metamorphosis, survival and biotic environmental parameters. We assessed recruitment at 6-8 experimental sites by larval sampling and spat collection inside and outside oyster farming areas and on an east-west gradient, from 2012-2014. Hydrodynamic connectivity was simulated using a numerical 3D transport model assessed with a Eulerian indicator. The supply of large umbo larvae did not differ significantly inside and outside oyster farming areas, whereas the supply of pediveligers to sites outside shellfish farms was structured by hydrodynamic connectivity. Inside shellfish farming zones, unfavorable conditions due to trophic competition with filter-feeders jeopardized their settlement. In this case, our results suggest loss of settlement competence by oyster larvae. This confirms our hypothesis of top-down trophic control by the oysters inside farming zones of Thau lagoon in summer that fails to meet the ecological requirements of these areas as oyster nurseries. Knowledge of oyster dispersal, connectivity and recruitment in coastal lagoons will help local development of sustainable natural spat collection. On a global scale, our method could be transposed to other basins or used for other species such as mussels, clams or scallops, to better understand the spatial patterns of bivalve recruitment. Management of the oyster industry based on natural spat collection will help develop a sustainable activity, based on locally adapted oyster strains but also by reducing the risks of transferring pathogens between basins and the global carbon footprint of this industry.
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Volume de collection Numéro de collection Edition
ISSN 0171-8630, 1616-1599 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2673
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Auteur (up) Lagarde, F.; Richard, M.; Bec, B.; Roques, C.; Mortreux, S.; Bernard, I.; Chiantella, C.; Messiaen, G.; Nadalini, J.-B.; Hori, M.; Hamaguchi, M.; Pouvreau, S.; ROQUE D'ORBCASTEL, E.; Tremblay, R.
Titre Trophic environments influence size at metamorphosis and recruitment performance of Pacific oysters Type Article scientifique
Année 2018 Publication Revue Abrégée Marine Ecology Progress Series
Volume 602 Numéro Pages 135-153
Mots-Clés Crassostrea gigas; Cryptophytes; Larval ecology; Oligotrophication; Prodissoconch II; Recruitment; Thau lagoon
Résumé Reproduction and recruitment of benthic invertebrates are influenced by the climate and by the ecological structure of marine ecosystems, along with local anthropogenic pressures such as eutrophication or oligotrophication. Using the Pacific oyster Crassostrea gigas as a biological model, we tested the hypothesis that the variability in prodissoconch II (PII) size (i.e. size at metamorphosis) depends on ecological functioning. Settlement and recruitment were assessed at 5 sampling sites on the French Mediterranean shellfish farmed Thau lagoon during the main summer recruitment events in 3 consecutive years (2012-2014). Hydrobiological and planktonic analyses were conducted at 3 sampling sites. Our results showed that recruitment was extremely heterogeneous, ranging from 0 to 260 ± 27 SE ind. dm-2 throughout the ecosystem and was linked with variability in PII size, which ranged from 180 to 296 µm. The annual temporal pattern of PII sizes appeared to be controlled by temperature during the settlement period, whereas the spatial pattern depended on phytoplankton biomass and on the trophic functioning of the ecosystem. Smaller PII sizes were significantly correlated with the highest phytoplankton biomass, while larger PII sizes were positively correlated with mixotrophic cryptophyte abundance. We found an inverse relationship between PII size and survival after metamorphosis, showing that recruitment success was associated with smaller PII sizes. Regional climate conditions and local trophic functioning appear to be key factors in metamorphosis and consequently contribute to recruitment heterogeneity. Further studies should be performed in other ecosystems following an oligotrophication trajectory to generalize this result.
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Editeur Lieu de Publication Éditeur
Langue en Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0171-8630, 1616-1599 ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2398
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Auteur (up) Richard, M.; Bourreau, J.; Montagnani, C.; Ouisse, V.; Le Gall, P.; Fortune, M.; Munaron, D.; Messiaen, G.; Callier, M.D.; Roque d'Orbcastel, E.
Titre Influence of OSHV-1 oyster mortality episode on dissolved inorganic fluxes: An ex situ experiment at the individual scale Type Article scientifique
Année 2017 Publication Revue Abrégée Aquaculture
Volume 475 Numéro Pages 40-51
Mots-Clés carrying-capacity; Crassostrea gigas; crassostrea-gigas spat; eastern oyster; juvenile; la-madeleine quebec; mediterranean thau lagoon; Mineralisation; mortality; mussel mytilus-edulis; mu-var; Nutrient fluxes; Ostreid herpesvirus 1; ostreid herpesvirus-1 infection; oxygen consumption; oxygen-consumption rates; pacific oysters; Spat
Résumé Ostreid herpesvirus 1 (OsHV-1 mu var) infection has caused significant mortalities in juvenile oysters (Crassostrea gigas). In contrast to the practices of other animal production industries, sick and dead oysters are not separated from live ones and are left to decay in the surrounding environment, with unknown consequences on fluxes of dissolved materials. A laboratory approach was used in this study to test the influence of oyster mortality episode on dissolved inorganic fluxes at the oyster interface, dissociating (i) the effect of viral infection on metabolism of juvenile oysters and (ii) the effect of flesh decomposition on oxygen consumption and nutrient releases at the individual scale. Nine batches of juvenile oysters (Individual Total wet weight 1 g) were infected via injection of OsHV-1 enriched inoculums at different viral loads (108 and 109 OsHV-1 DNA copies per oyster) to explore infection thresholds. Oysters injected with filtered seawater were used as controls (C). Oysters were maintained under standard conditions to avoid stress linked to hypoxia, starvation, or ammonia excess. Before, after the injection and during the mortality episode, i.e. at days 1, 3, 7, 10 and 14, nine oysters per treatment were incubated in individual metabolic chambers to quantify oxygen, ammonium and phosphate fluxes at the seawater-oyster interface. Nine empty chambers served as a reference. Injections of the two viral loads of OsHV-1 induced similar mortality rates (38%), beginning at day 3 and lasting until day 14. The observed mortality kinetics were slower than those reported in previous experimental pathology studies, but comparable to those observed in the field (Thau lagoon, France). This study highlights that oxygen and nutrient fluxes significantly varied during mortality episode. Indeed (i) OsHV-1 infection firstly modifies oyster metabolism, with significant decreases in oxygen consumption and ammonium excretion, and (ii) dead oysters lead to a strong increase of ammonium (6 fold) and phosphate (41 fold) fluxes and a decrease in the N/P ratio due to mineralisation of their flesh. The latter may modify the structure of the planktonic community in the field during mortality episode. This study is a first step of the MORTAFLUX program. The second step was to in situ confirm this abnormal nutrient loading during a mortality episode and show its impact on bacterio-, phyto-and protozoo-plankton. (C) 2017 Elsevier B.V. All rights reserved.
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Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0044-8486 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2149
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Auteur (up) Suquet, M.; Malo, F.; Queau, I.; Ratiskol, D.; Quere, C.; Le Grand, J.; Fauvel, C.
Titre Seasonal variation of sperm quality in Pacific oyster (Crassostrea gigas) Type Article scientifique
Année 2016 Publication Revue Abrégée Aquaculture
Volume 464 Numéro Pages 638-641
Mots-Clés age; Crassostrea gigas; cryopreservation; fish; gamete quality; Motility; Season; spawning season; Sperm ageing; Sperm quality; time
Résumé Seasonal changes of sperm quality which can affect sperm biological parameters throughout the breeding period, have been little studied in mollusc species. Controlling gamete quality would aid the management of gametes in hatcheries and the development of selection programs. The aim of the present study was to describe the changes in sperm quality of wild Pacific oysters through the spawning season by comparing sperm parameters al the beginning (May), middle (July) and end (October) of this period using a panel of bio-descriptors. These parameters were studied over the 2014 breeding season based on shed sperm collected after serotonin injection of wild breeders. A significantly higher percentage of motile sperm was observed al the end of the spawning season (+78% relative to the value observed al the beginning) althought a lower total number of spermatozoa was collected (-59%). The mean condition index of oysters, however, was no different between the three sampling dates. For intratesticular sperm, the increase of the percentage of motile sperm and Velocity of the Average Path (VAP) in relation to time post activation was not significantly different among sperm sampling periods, suggesting that the kinetic of the sperm 'maturation process was similar. Furthermore, the mean VAP observed on shed sperm did not change through the spawning season. The sub-continuous gametogenesis of Pacific oyster can help to explain why only limited consequences of sperm ageing are observed in this species. Furthermore, the effects of sperm ageing may depend on the annual reproductive pattern of Pacific oyster. Statement of relevance: This study showed the effect of sperm ageing on sperm quality parameters. This knowledge is useful for aquaculture and would support the recent trends of mollusc farming, allowing a better management of the gametes in hatchery. (C) 2016 Elsevier B.V. All rights reserved.
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Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0044-8486 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 1687
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