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| Ballorain, Katia; Ciccione, Stephane; Bourjea, Jerome; Grizel, Henri; Enstipp, Manfred; Georges, Jean-yves. |
| We investigated the habitat use in green turtles exploiting a 13-ha multispecific seagrass meadow at Mayotte Island, south-western Indian Ocean. A phytoecological survey shows the occurrence of eight seagrass species, dominated by Halodule uninervis and Syringodium isoetifolium, distributed according to four distinct seagrass communities along the depth gradient. Direct underwater censuses show that green turtles occurred all over the meadow. Yet when community relative surface area was taken into account green turtles preferentially frequented the most seaward, biomass-richer S. isoetifolium-dominated community, suggesting that green turtles compensate for their intrinsically nutrient-poor herbivorous diet. Additionally, smaller (\80 cm standard curved... |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00018/12918/10201.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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| 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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| Jean, Claire; Ciccione, Stephane; Ballorain, Katia; Georges, Jean-yves; Bourjea, Jerome. |
| Reunion Island in the south-west Indian Ocean once had significant nesting populations of marine turtles but they declined rapidly after human colonization. In 1996, after regular sightings of turtles offshore, an aerial survey programme was initiated to monitor the occurrence of marine turtles and their distribution along the west coast of the island Between 1998 and 2008, along a 30-km coastline transect between Saint Leu and Saint Paul, a total of 1,845 marine turtle sightings were recorded during 146 flights with an ultralight aircraft The mean number of turtle sightings per survey increased significantly between 1998 and 2008, and a variety of sizes were recorded throughout the year Marine turtles were found over coral reef zones and on the outer reef... |
| Tipo: Text |
Palavras-chave: Abundance; Aerial survey; Conservation; Indian Ocean; Marine turtles; Reunion Island. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00005/11588/9280.pdf |
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