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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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Auteur institutionnel Thèse
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 0079-6611 ISBN Médium
Région Expédition Conférence
Notes WOS:000582696800013 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2887
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Auteur Putman, N.F.; Abreu-Grobois, F.A.; Broderick, A.C.; Ciofi, C.; Formia, A.; Godley, B.J.; Stroud, S.; Pelembe, T.; Verley, P.; Williams, N.
Titre Numerical dispersal simulations and genetics help explain the origin of hawksbill sea turtles in Ascension Island Type Article scientifique
Année 2014 Publication Revue Abrégée Journal of Experimental Marine Biology and Ecology
Volume 450 Numéro Special Issue Pages 98-108
Mots-Clés dispersal; mtDNA; ocean circulation model; Sea turtle
Résumé Long-distance dispersal and ontogenetic shifts in habitat use are characteristic of numerous marine species and have important ecological, evolutionary, and management implications. These processes, however, are often challenging to study due to the vast areas involved. We used genetic markers and simulations of physical transport within an ocean circulation model to gain understanding into the origin ofjuvenile hawksbill sea turtles (Eretmochelys imbricata) found at Ascension Island, a foraging ground that is thousands of kilometers from known nesting beaches. Regional origin of genetic markers suggests that turtles are from Western Atlantic (86%) and Eastern Atlantic (14%) rookeries. In contrast, numerical simulations of transport by ocean currents suggest that passive dispersal from the western sources would be negligible and instead would primarily be from the East, involving rookeries along Western Africa (i.e., Principe Island) and, potentially, from as far as the Indian Ocean (e.g., Mayotte and the Seychelles). Given that genetic analysis identified the presence of a haplotype endemic to Brazilian hawksbill rookeries at Ascension, we examined the possible role of swimming behavior by juvenile hawksbills from NE Brazil on their current-borne transport to Ascension Island by performing numerical experiments in which swimming behavior was simulated for virtual particles (simulated turtles). We found that oriented swimming substantially influenced the distribution of particles, greatly altering the proportion of particles dispersing into the North Atlantic and South Atlantic. Assigning location-dependent orientation behavior to particles allowed them to reach Ascension Island, remain in favorable temperatures, encounter productive foraging areas, and return to the vicinity of their natal site. The age at first arrival to Ascension (4.5-5.5 years) of these particles corresponded well to estimates of hawksbill age based on their size. Our findings suggest that ocean currents and swimming behavior play an important role in the oceanic ecology of sea turtles and other marine animals.
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Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0022-0981 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 333
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Auteur Putman, N.F.; Verley, P.; Endres, C.S.; Lohmann, K.J.
Titre Magnetic navigation behavior and the oceanic ecology of young loggerhead sea turtles Type Article scientifique
Année 2015 Publication Revue Abrégée J Exp Biol
Volume 218 Numéro 7 Pages 1044-1050
Mots-Clés Caretta caretta; Magnetic orientation; Magnetoreception; Navigation; ocean circulation model
Résumé During long-distance migrations, animals navigate using a variety of sensory cues, mechanisms and strategies. Although guidance mechanisms are usually studied under controlled laboratory conditions, such methods seldom allow for navigation behavior to be examined in an environmental context. Similarly, although realistic environmental models are often used to investigate the ecological implications of animal movement, explicit consideration of navigation mechanisms in such models is rare. Here, we used an interdisciplinary approach in which we first conducted lab-based experiments to determine how hatchling loggerhead sea turtles (Caretta caretta) respond to magnetic fields that exist at five widely separated locations along their migratory route, and then studied the consequences of the observed behavior by simulating it within an ocean circulation model. Magnetic fields associated with two geographic regions that pose risks to young turtles (due to cold wintertime temperatures or potential displacement from the migratory route) elicited oriented swimming, whereas fields from three locations where surface currents and temperature pose no such risk did not. Additionally, at locations with fields that elicited oriented swimming, simulations indicate that the observed behavior greatly increases the likelihood of turtles advancing along the migratory pathway. Our findings suggest that the magnetic navigation behavior of sea turtles is intimately tied to their oceanic ecology and is shaped by a complex interplay between ocean circulation and geomagnetic dynamics.
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Auteur institutionnel Thèse
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 0022-0949, 1477-9145 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1265
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Auteur Putman, N.F.; Verley, P.; Shay, T.J.; Lohmann, K.J.
Titre Simulating transoceanic migrations of young loggerhead sea turtles : merging magnetic navigation behavior with an ocean circulation model Type Article scientifique
Année 2012 Publication Revue Abrégée Journal of Experimental Biology
Volume 215 Numéro 11 Pages 1863-1870
Mots-Clés dispersal; Distribution; loggerhead sea turtle; magnetic map; magnetorecpetion; ocean circulation model
Résumé Young loggerhead sea turtles (Caretta caretta) from eastern Florida, USA, undertake a transoceanic migration in which they gradually circle the Sargasso Sea before returning to the North American coast. Loggerheads possess a. magnetic map' in which regional magnetic fields elicit changes in swimming direction along the migratory pathway. In some geographic areas, however, ocean currents move more rapidly than young turtles can swim. Thus, the degree to which turtles can control their migratory movements has remained unclear. In this study, the movements of young turtles were simulated within a high-resolution ocean circulation model using several different behavioral scenarios, including one in which turtles drifted passively and others in which turtles swam briefly in accordance with experimentally derived data on magnetic navigation. Results revealed that small amounts of oriented swimming in response to regional magnetic fields profoundly affected migratory routes and endpoints. Turtles that engaged in directed swimming for as little as 1-3 h per day were 43-187% more likely than passive drifters to reach the Azores, a productive foraging area frequented by Florida loggerheads. They were also more likely to remain within warm-water currents favorable for growth and survival, avoid areas on the perimeter of the migratory route where predation risk and thermal conditions pose threats, and successfully return to the open-sea migratory route if carried into coastal areas. These findings imply that even weakly swimming marine animals may be able to exert strong effects on their migratory trajectories and open-sea distributions through simple navigation responses and minimal swimming.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0022-0949 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 215
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