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Auteur Cozzoli, F.; da Conceicao, T.G.; Van Dalen, J.; Fang, X.; Gjoni, V.; Herman, P.M.J.; Hu, Z.; Soissons, L.M.; Walles, B.; Ysebaert, T.; Bouma, T.J.
Titre Biological and physical drivers of bio-mediated sediment resuspension: A flume study on Cerastoderma edule Type Article scientifique
Année 2020 Publication Revue Abrégée Estuar. Coast. Shelf Sci.
Volume 241 Numéro Pages 106824
Mots-Clés Allometry; benthic macroinvertebrates; Bioturbation; bivalves scrobicularia-plana; Body size; Cerastoderma edule; cohesive sediment; Cohesiveness; cross-community approach; current-velocity; ecosystem engineers; metabolic theory; mortality responses; noncohesive sediments; nutrient fluxes; Sediment resuspension
Résumé Predictive models accounting for the effect of bioturbation on sediment resuspension must be based on ecological theory as well as on empirical parametrization. The scaling trend of individual metabolic and activity rates with body mass may be a key to the mechanistic understanding of the observed patterns. With this study we tested if general size scaling rules in bio-mediated sediment resuspension may apply to a broad range of physical contexts for the endobenthic bivalve Cerastoderma edule. The effect on sediment resuspension of populations of C. edule differing by individual size was measured across physical gradients of current velocity and sediment composition in terms of fraction of fine particles. C. edule were able to enhance the resuspension of sediment containing silt, while they had scarce effect on the resuspension of coarse sediment. The effect of bioturbation was maximal at intermediate current velocity, when the hydrodynamic forcing is not strong enough to overcome the abiotic sediment resistance but it is able to suspend the bioturbated sediment. Although differences in sediment silt content and intensities of hydrodynamic stress have a relevant influence in determining the bioturbators individual contribution to sediment resuspension, the observed mass scaling trend is consistent across all treatments and close to theoretical expectation for size scaling of individual metabolic rates. This observation supports the hypothesis that the contribution of individual bioturbators to sediment resuspension is directly related to their energy use. Therefore, the proposed approach allows the formulation of expectations of biotic contribution to sediment resuspension based on the general size scaling laws of individual energy use.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0272-7714 ISBN Médium
Région Expédition Conférence
Notes WOS:000539292700013 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2819
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Auteur 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
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ISSN 0044-8486 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 2149
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