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| Roos, David; Pelletier, Dominique; Ciccione, Stéphane; Taquet, Marc; Hughes, George. |
| Monitoring the abundance of green turtles (Chelonia mydas) is necessary to assess population trends and risks of collapse. This note presents a study aimed at comparing three techniques for the direct estimation of green turtle numbers in their foraging habitats (seagrass beds and reef flats). The experiment was carried out at Mayotte Island, Western Indian Ocean. The techniques involved were surveys by snorkel, and aerial surveys using a microlight aircraft and a paramotor. Each technique had shortcomings and advantages. While each technique provided estimations of turtle numbers only surveys by snorkel permitted identification of species and sex, whenever visibility and turtle behaviour permitted. Along the shorelines, and over foraging areas, the... |
| Tipo: Text |
Palavras-chave: Foraging habitats; Snorkelling survey; Aerial survey; Abundance estimation; Chelonia mydas; Green turtle. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-432.pdf |
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| Jensen, Michael P.; Dalleau, Mayeul; Gaspar, Philippe; Lalire, Maxime; Jean, Claire; Ciccione, Stéphane; Mortimer, Jeanne A.; Quillard, Mireille; Taquet, Coralie; Wamukota, Andrew; Leroux, Géraud; Bourjea, Jerome. |
| Understanding how ocean currents impact the distribution and connectivity of marine species, provides vital information for the effective conservation management of migratory marine animals. Here, we used a combination of molecular genetics and ocean drift simulations to investigate the spatial ecology of juvenile green turtle (Chelonia mydas) developmental habitats, and assess the role of ocean currents in driving the dispersal of green turtle hatchlings. We analyzed mitochondrial (mt)DNA sequenced from 358 juvenile green turtles, and from eight developmental areas located throughout the Southwest Indian Ocean (SWIO). A mixed stock analysis (MSA) was applied to estimate the level of connectivity between developmental sites and published genetic data from... |
| Tipo: Text |
Palavras-chave: Chelonia mydas; Green turtle; Juvenile; MtDNA; Drifting simulation; Connectivity; Mixed stock analysis; Southwest Indian Ocean. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00612/72443/71398.pdf |
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| Luschi, Paolo; Benhamou, Simon; Girard, Charlotte; Ciccione, Stéphane; Roos, David; Sudre, Joël; Benvenuti, Silvano. |
| Marine turtles are renowned long-distance navigators, able to reach remote targets in the oceanic environment; yet the sensory cues and navigational mechanisms they employ remain unclear [1-3]. Recent arena experiments indicated an involvement of magnetic cues in juvenile turtles' homing ability after simulated displacements [4, 5], but the actual role of geomagnetic information in guiding turtles navigating in their natural environment has remained beyond the reach of experimental investigations. In the present experiment, twenty satellite-tracked green turtles (Chelonia mydas) were transported to four open-sea release sites 100-120 km from their nesting beach on Mayotte island in the Mozambique Channel; 13 of them had magnets attached to their head [6]... |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2407.pdf |
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| Mulochau, Thierry; Jean, Claire; Gogendeau, Pierre; Ciccione, Stéphane. |
| Young green turtles, Chelonia mydas, frequent the Syringodium isoetifolium seagrass beds on Reunion’s inner reef flats of fringing reefs, where they come to feed. Photographs of a green turtle looking for and eating the snake sea cucumber. Synapta maculata, were taken for the first time at Reunion Island. S. maculata is a sea cucumber species that was frequently observed on the inner reef flats and on the back-reef depression, but these abundances seem to be decreasing in recent years. Studies of S. maculata populations are needed to monitor changes in densities of this species, which has an important ecosystem role, as well as other observations to determine whether this case of green sea turtle predation is an isolated one or whether S. maculata may... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00685/79700/82486.pdf |
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| Chambault, Philippine; Dalleau, Mayeul; Nicet, Jean-benoit; Mouquet, Pascal; Ballorain, Katia; Jean, Claire; Ciccione, Stéphane; Bourjea, Jerome. |
| Background A strong behavioural plasticity is commonly evidenced in the movements of marine megafauna species, and it might be related to an adaptation to local conditions of the habitat. One way to investigate such behavioural plasticity is to satellite track a large number of individuals from contrasting foraging grounds, but despite recent advances in satellite telemetry techniques, such studies are still very limited in sea turtles. Methods From 2010 to 2018, 49 juvenile green turtles were satellite tracked from five contrasting feeding grounds located in the South-West Indian Ocean in order to (1) assess the diel patterns in their movements, (2) investigate the inter-individual and inter-site variability, and (3) explore the drivers of their daily... |
| Tipo: Text |
Palavras-chave: Chelonia mydas; Home range; Satellite tracking; Diel pattern; Tidal cycle. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00601/71269/69659.pdf |
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| Pelletier, Dominique; Roos, David; Ciccione, Stéphane. |
| The ability of captive-reared turtles to survive in the wild is not precisely known, nor are movements of immature turtles in the open ocean. To provide information on these issues, a satellite tracking experiment was conducted in the western Indian Ocean to monitor oceanic movements of immature green turtles. Two wild turtles and four captive-reared individuals were tracked. The latter had been displaced after birth from nesting sites to a distant rearing site. Wild turtles survived after release, but did not move far away from release site. We hypothesize that this resident behaviour may be explained by stage-specific habitat requirements. Captive-reared turtles survived after release and migrated over thousands of kilometres. Among these, the oldest... |
| Tipo: Text |
Palavras-chave: Indian Ocean; Captive reared; Migration pattern; Satellite telemetry; Chelonia mydas; Marine turtle. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-573.pdf |
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| Chambault, Philippine; Hattab, Tarek; Mouquet, Pascal; Bajjouk, Touria; Jean, Claire; Ballorain, Katia; Ciccione, Stéphane; Dalleau, Mayeul; Bourjea, Jerome. |
| Despite the large number of species distribution modelling (SDM) applications driven by tracking data, individual information is most of the time neglected and traditional SDM approaches commonly focus on predicting the potential distribution at the species or population‐level. By running classical SDMs (population approach) with mixed models including a random factor to account for the variability attributable to individual (individual approach), we propose an innovative five‐steps framework to predict the potential and individual‐level distributions of mobile species using GPS data collected from green turtles. Pseudo‐absences were randomly generated following an environmentally‐stratified procedure. A negative exponential dispersal kernel was... |
| Tipo: Text |
Palavras-chave: GPS tracking; Green turtles; Indian Ocean; Pseudo-absences; Shannon index; Spatial modelling. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00682/79412/81963.pdf |
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