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Auteur Amemou, H.; Kone, V.; Aman, A.; Lett, C.
Titre Assessment of a Lagrangian model using trajectories of oceanographic drifters and fishing devices in the Tropical Atlantic Ocean Type Article scientifique
Année 2020 Publication Revue Abrégée Prog. Oceanogr.
Volume 188 Numéro Pages 102426
Mots-Clés circulation model; coastal regions; Drifter; equatorial atlantic; Fish aggregating device; Model performance; northern gulf; Particle; performance; resolution; statistics; surface currents; Trajectory; transport; variability; Velocity
Résumé In the Tropical Atlantic Ocean, we assessed the accuracy of a Lagrangian model (Ichthyop) forced with velocity fields from a hydrodynamical model (CROCO) and two different remote sensing products (GlobCurrent and OSCAR) using trajectories of oceanographic drifters. Additionally, we evaluated the possibility to expand the drifters data using trajectories of GPS-buoy equipped drifting Fish Aggregating Devices (FADs). The observed and simulated trajectories were compared in terms of spatial distribution, velocity distribution and a nondimensional skill score. For the drifters and FADs, the GlobCurrent and OSCAR products lead to similar performances as the CROCO model-ouputs in the broad studied domain. In the Gulf of Guinea, however, the CROCO model performed significantly better than the other two because the parent solution of CROCO benefited from its communication with a child grid of finer resolution in this region. On average, the simulations lead to an underestimation of the drifter and FAD velocities, likely because the spatial resolutions of the forcing products were insufficient and the time frequency at which they were produced were too low to resolve the relevant oceanic processes properly. We found a low skill for all models to simulate FAD trajectories, possibly because of the devices vertical structure that prevent FADs from drifting like water parcels. Our results therefore suggest that in the Tropical Atlantic the FAD dataset may not be appropriate to use for corroborating Lagrangian simulations.
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ISSN 0079-6611 ISBN Médium
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Notes WOS:000582696800013 Approuvé pas de
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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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ISSN 0272-7714 ISBN Médium
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Notes WOS:000539292700013 Approuvé pas de
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Auteur Walker, T.R.; Grant, J.; Weise, A.M.; McKindsey, C.W.; Callier, M.D.; Richard, M.
Titre Influence of suspended mussel lines on sediment erosion and resuspension in Lagune de la Grande Entree, Iles-de-la-Madeleine, Quebec, Canada Type Article scientifique
Année 2014 Publication Revue Abrégée Aquaculture
Volume 433 Numéro Pages 450-457
Mots-Clés Aquaculture; Biodeposits; biogeochemical fluxes; culture; dynamics; intertidal cohesive sediments; lagoon; Mytilus; Mytilus edulis; Particle; rates; Resuspension; Sediment erosion; Shear velocity; size; stability
Résumé Downward fluxes of organically rich biodeposits under suspended mussel lines can cause benthic impacts such as changes in benthic community structure or microbial mat production. Quantifying sediment erosion in these coastal ecosystems is important for understanding how fluxes of organic matter and mussel biodeposits contribute to benthic pelagic coupling. Critical shear velocity (u(crit)*(t)), erosion rates and particle size distributions of resuspended sediment were measured at four stations distributed along a transect perpendicular to a mussel farm in Lagune de la Grande Entree, Iles-de-la-Madeleine (Quebec, Canada). Stations were selected underneath the outer-most mussel line (0 m) and at distances of 15,30 m and at a reference station (500 m) further along the transect. Shear velocity was measured using a calibrated portable Particle Erosion Simulator, also referred to as the BEAST (Benthic Environmental Assessment Sediment Tool). Undisturbed sediment cores obtained by divers were exposed to shear stress to compare differences between stations. Erosion sequences indicated no significant differences in u(crit)* between stations, but there were significant differences in erosion rates beneath mussel lines compared to other stations. Erosion rates were the highest in cores from beneath mussel lines, but paradoxically had the lowest u(crit)* Mean erosion rates at u*crit varied between 25 and 47 g m(-2) min(-1) and critical erosion thresholds varied between 1.58 and 1.73 cm s(-1), which compare with intensive mussel culture sites elsewhere in eastern Canada. Significant differences existed in biotic and abiotic properties of sediments which could explain variation in maximum erosion rates within and between stations. Particle sizes measured by videography of resuspended sediment at different shear velocities ranged from 02 to 3.0 mm. Quantifying sediment erosion from intact marine sediments helps to improve our mechanistic understanding of these processes, and the BEAST further contributes to predictive capability in benthic pelagic coupling modeling. (C) 2014 Elsevier B.V. All rights reserved.
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ISSN 0044-8486 ISBN Médium
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Notes <p>ISI Document Delivery No.: AQ1GH<br/>Times Cited: 0<br/>Cited Reference Count: 39<br/>Walker, Tony R. Grant, Jon Weise, Andrea M. McKindsey, Christopher W. Callier, Myriam D. Richard, Marion<br/>Natural Sciences and Engineering Research Council of Canada (NSERC); Aquaculture Collaborative Research and Development Program (ACRDP); Societe de Development de l'Industrie Maricole (SODIM); Fisheries and Oceans Canada<br/>We thank MAPAQ and B. Hargrave for the collaboration and C. Eloquin and associates for the permission to use their site. Funding was provided by the Aquaculture Collaborative Research and Development Program (ACRDP), the Societe de Development de l'Industrie Maricole (SODIM) and the Fisheries and Oceans Canada. We thank B. Schofield and M. Merrimen for the fabrication of the BEAST which formed part of the equipment necessary for the Canadian Arctic Shelves Exchange Study (CASES), a Research Network funded by the Natural Sciences and Engineering Research Council of Canada (NSERC).<br/>Elsevier science bv<br/>Amsterdam</p> Approuvé pas de
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