|
|
|
| Registros recuperados: 13 | |
|
|
| 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 |
| |
|
|
| Bourjea, Jerome; Dalleau, Mayeul; Derville, S.; Beudard, F.; Marmoex, C.; M'Soili, A.; Roos, David; Ciccione, S.; Frazier, J.. |
| Nesting green turtles Chelonia mydas were studied at Moheli Island, Union of Comoros, southwestern Indian Ocean (SWIO). Five contiguous beaches near Itsamia village, in the southeastern part of the island, were monitored daily for nesting activity from January 1999 to June 2007 and irregularly between August 2009 and December 2014; nesting success was recorded from 2000 to 2006. Nesting occurred year-round and peaked in the austral winter, from March through August, with the highest values in May. During the 7 yr period when nesting success was recorded, 63164 successful nestings were reported, and the total was 69630 when estimates of missing data were included. The average rate of nesting success was 0.49 (SD = 0.04, n = 7). Using the estimate of 3.03... |
| Tipo: Text |
|
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00266/37733/35745.pdf |
| |
|
|
| 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 |
| |
|
|
| Dalleau, Mayeul; Benhamou, Simon; Sudre, Joel; Ciccione, Stephane; Bourjea, Jerome. |
| While our understanding of the early oceanic developmental stage of sea turtles has improved markedly over recent decades, the spatial context for this life history stage remains unknown for Indian Ocean loggerhead turtle populations. To address this gap in our knowledge, 18 juvenile loggerheads were satellite tracked from Reunion Island (21.2A degrees S, 55.3A degrees E) between 2007 and 2011. Nine turtles swam north toward Oman (20.5A degrees N, 58.8A degrees E), where one of the world's largest rookeries of loggerheads is located. Three individuals traveled south toward South Africa and Madagascar, countries that also host loggerhead nesting grounds. Fourteen of the transmitters relayed diving profiles. A dichotomy between diurnal and nocturnal diving... |
| Tipo: Text |
|
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00210/32173/32178.pdf |
| |
|
|
| 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 |
| |
|
|
| Bourjea, Jerome; Dalleau, Mayeul. |
| Cette mission scientifique s’est déroulée dans le cadre du projet DYMITILE II (Dynamique Migratoire des Tortues marines nidifiant dans les Iles françaises de l’océan Indien) en vue de la rédaction des recommandations scientifiques pour la mise en place d’un plan national d’action pour la conservation de ces espèces dans les territoires français de l’océan Indien. Cette mission avait 3 objectifs principaux : - contribuer à la meilleure compréhension des voies migratoires des tortues vertes femelles en migration post reproductive dans les principaux sites de ponte du sud-ouest de l’océan Indien. Compte tenu du succès des précédents déploiements de balises, nous avons décidé de focaliser la mission sur les tortues dans la mangrove. - Contribuer à mieux... |
| Tipo: Text |
|
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00244/35515/34019.pdf |
| |
|
|
| Bourjea, Jerome; Dalleau, Mayeul; Jean, Claire; Ciccione, Stephane. |
| Dans la suite de la mission à Europa en 2011, des missions menées depuis 2005 par les équipes d’Ifremer et de Kélonia, et dans le cadre de l’Action 4.2.3 du Plan National d’Action (PNA) tortues marines dans les îles Eparses, l’objectif de cette mission à Glorieuses et à Juan de Nova a été de continuer à acquérir des données sur la dynamique spatio-temporelle des immatures de tortues vertes présentes dans les îles Eparses. Plus précisément, cette mission a eu pour objectif de : 1- continuer la série longue de marquage –relecture de tortues vertes juvéniles présentes dans le lagon des Glorieuses et de Juan de Nova ainsi que les suivis de croissance des individus recapturés, 2- déterminer le comportement spatial à fine échelle des tortues vertes juvéniles... |
| Tipo: Text |
|
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00260/37095/35605.pdf |
| |
|
| |
|
|
| Dalleau, Mayeul; Ciccione, Stephane; Mortimer, Jeanne A.; Garnier, Julie; Benhamou, Simon; Bourjea, Jerome. |
| Changes in phenology, the timing of seasonal activities, are among the most frequently observed responses to environmental disturbances and in marine species are known to occur in response to climate changes that directly affects ocean temperature, biogeochemical composition and sea level. We examined nesting seasonality data from long-term studies at 8 green turtle (Chelonia mydas) rookeries that include 21 specific nesting sites in the South-West Indian Ocean (SWIO). We demonstrated that temperature drives patterns of nesting seasonality at the regional scale. We found a significant correlation between mean annual Sea Surface Temperature (SST) and dates of peak nesting with rookeries exposed to higher SST having a delayed nesting peak. This supports the... |
| Tipo: Text |
|
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00098/20940/18558.pdf |
| |
|
| |
|
|
| Derville, Solene; Jean, Claire; Dalleau, Mayeul; Le Gal, Jean-yves; Ciccione, Stephane; Bourjea, Jerome. |
| Situated about 500 km off the Malagasy east coast, the island of Tromelin is a key nesting site for the endangered green turtle, Chelonia mydas, in the south Western Indian Ocean. Nesting turtles found in this isolated island have been closely monitored since the 1970s, but the most recent estimates of nesting parameters date from 1986. Using mark-recapture data, track counts, and nests monitoring data collected over the 2009/2010 nesting peak, reproductive characteristics, population size, and offspring production were updated and discussed in the light of the track survey undertaken from 1986 to 2010. Females showed a consistent reproductive behaviour compared with previous studies in terms of clutch frequency (2.75 +/- 1.46) and nesting success (0.65).... |
| Tipo: Text |
Palavras-chave: Reptilia Testudines: Cheloniidae Chelonia mydas; Green turtle nesting activity population assessment Indian Ocean Tromelin Island. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00273/38424/36794.pdf |
| |
|
|
| Bourjea, Jerome; Mortimer, Jeanne A.; Garnier, Julie; Okemwa, Gladys; Godley, Brendan J.; Hughes, George; Dalleau, Mayeul; Jean, Claire; Ciccione, Stephane; Muths, Delphine. |
| To refine our understanding of the spatial structure of the green turtle (Chelonia mydas) populations in the South West Indian Ocean (SWIO), we analysed patterns of mitochondrial DNA (396 base pairs control region fragment) variation among 171 samples collected at five distinct locations (Kenya, Northern Mozambique, and three locations in the Republic of Seychelles: the Granitic, Amirantes, and Farquhar groups) and compared them to genetic data (n = 288), previously collected from 10 southern locations in the SWIO. We also analysed post-nesting satellite tracks (n = 4) from green turtles nesting in the Amirantes group. Pairwise comparisons of haplotype frequencies showed significant genetic differentiation amongst rookeries and suggest that the SWIO hosts... |
| Tipo: Text |
Palavras-chave: Indian Ocean; MtDNA; Satellite tracking; Phylogeography; Management unit; Chelonia mydas. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00266/37732/36062.pdf |
| |
|
|
| Dalleau, Mayeul; Kramer‐schadt, Stephanie; Gangat, Yassine; Bourjea, Jerome; Lajoie, Gilles; Grimm, Volker. |
| Environmental factors shape the spatial distribution and dynamics of populations. Understanding how these factors interact with movement behavior is critical for efficient conservation, in particular for migratory species. Adult female green sea turtles, Chelonia mydas, migrate between foraging and nesting sites that are generally separated by thousands of kilometers. As an emblematic endangered species, green turtles have been intensively studied, with a focus on nesting, migration, and foraging. Nevertheless, few attempts integrated these behaviors and their trade‐offs by considering the spatial configurations of foraging and nesting grounds as well as environmental heterogeneity like oceanic currents and food distribution. We developed an... |
| Tipo: Text |
Palavras-chave: Connectivity; Corridors; Individual-based model; Migration; Movement; Sea turtle. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00512/62337/66597.pdf |
| |
| Registros recuperados: 13 | |
|
|
|
