ORCID Profile
0000-0003-1161-2275
Current Organisations
Université de Strasbourg
,
Centre National de la Recherche Scientifique
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Public Library of Science (PLoS)
Date: 09-11-2010
Publisher: Wiley
Date: 18-10-2011
DOI: 10.1111/J.1365-2656.2011.01915.X
Abstract: 1. The assessment of species extinction risk has been well established for some time now. Assessing the potential for recovery in endangered species is however much more challenging, because complementary approaches are required to detect reliable signals of positive trends. 2. This study combines genetics, demography and behavioural data at three different time-scales to assess historical and recent population changes and evidence of reproductive synchrony in a small population of olive ridley sea turtle Lepidochelys olivacea. Lepidochelys is considered as the most extraordinary ex le of reproductive synchrony in reptiles, yet to date, it has only been reported in large populations. 3. Using Bayesian coalescent-based models on microsatellite nuclear DNA variability, we demonstrate that effective population size in olive ridleys nesting in French Guiana has dramatically declined by 99% over the last 20 centuries. This low current population size is further illustrated by the absence of genetic mitochondrial DNA ersity in the present nesting population. Yet, monitoring of nesting sites in French Guiana suggests a possible recovery of the population over the last decade. 4. Satellite telemetry shows that over the first 14 days of their 28-days inter-nesting interval, i.e. when eggs maturation is likely to occur, gravid females disperse over the continental shelf. They then gather together with a striking spatiotemporal consistency close to the nesting site, where they later emerge for their second nesting event. 5. Our results therefore suggest that reproductive synchrony also occurs in small populations. Olive ridleys may ensure this synchrony by adjusting the duration of the second half of their inter-nesting interval prior to landing, possibly through social mediation. 6. Such reproductive synchrony may be related to the maintenance of some species-specific strategy despite former collapse and may contribute to the present population recovery. The gregarious behaviour of reproductive in iduals close to shore where human-induced perturbations occur is however a cause for conservation concern for this still poorly known species.
Publisher: Elsevier BV
Date: 09-2009
Publisher: Public Library of Science (PLoS)
Date: 16-05-2012
Publisher: University of Chicago Press
Date: 07-2013
DOI: 10.1086/671127
Abstract: Organisms compensate for reproduction costs through two major strategies: capital breeders store body reserves before reproduction and do not feed during the breeding season, whereas income breeders adjust their food intake depending on concurrent reproductive needs. Sea turtles are commonly considered capital breeders. Yet recent biometric and behavioral studies have suggested that sea turtles may in fact feed during reproduction. We tested this hypothesis in the leatherback turtle Dermochelys coriacea, nesting in French Guiana. Our study is based on the innovative use of longitudinal monitoring for morphological (body size, body mass, and body condition) and physiological (plasma glucose, triacylglycerides, urea, calcium, and hematocrit) measurements in 35 females throughout the 2006 nesting season. During their 71-d nesting period, leatherbacks lost a mean (±SE) of [Formula: see text] kg (i.e., ∼11% of their initial body mass of [Formula: see text] kg). Simultaneously, a significant decrease in plasma concentrations of glucose, triacylglycerides, and urea was observed throughout the nesting season, following typical patterns reported in other long-fasting animals that rely on lipid body stores. At the end of the nesting season, the interin idual variability in plasma concentrations was very low, which may characterize some minimum thresholds associated with the end of reproduction. We also identified a minimum necessary threshold for female body condition at the onset of reproduction the body condition of any females beginning the nesting period below this threshold decreased dramatically. This study makes a compelling case that, in French Guiana, gravid leatherback females are anorexic during the nesting season (i.e., leatherback turtles are capital breeders). We further highlight the mechanisms that prevent this multiparous reptile from jeopardizing its own body condition while not feeding during reproduction.
Publisher: Inter-Research Science Center
Date: 30-05-2013
DOI: 10.3354/MEPS10301
Publisher: Wiley
Date: 22-01-2008
DOI: 10.1111/J.1365-2656.2007.01344.X
Abstract: 1. Investigating the foraging patterns of free-ranging species is essential to estimate energy/time budgets for assessing their real reproductive strategy. Leatherback turtles Dermochelys coriacea (Vandelli 1761), commonly considered as capital breeders, have been reported recently to prospect actively during the breeding season in French Guiana, Atlantic Ocean. In this study we investigate the possibility of this active behaviour being associated with foraging, by studying concurrently ing and beak movement patterns in gravid females equipped with IMASEN (Inter-MAndibular Angle SENsor). 2. Four turtles provided data for periods varying from 7.3 to 56.1 h while exhibiting continuous short and shallow benthic es. Beak movement ('b-m') events occurred in 34% of the es, on average 1.8 +/- 1.4 times per e. These b-m events lasted between 1.5 and 20 s and occurred as isolated or grouped (two to five consecutive beak movements) events in 96.0 +/- 4.0% of the recorded cases, and to a lesser extent in series (> five consecutive beak movements). 3. Most b-m events occurred during wiggles at the bottom of U- and W-shaped es and at the beginning and end of the bottom phase of the es. W-shaped es were associated most frequently with beak movements (65% of such es) and in particular with grouped beak movements. 4. Previous studies proposed wiggles to be indicator of predatory activity, U- and W-shaped es being putative foraging es. Beak movements recorded in leatherbacks during the first hours of their internesting interval in French Guiana may be related to feeding attempts. 5. In French Guiana, leatherbacks show different mouth-opening patterns for different e patterns, suggesting that they forage opportunistically on occasional prey, with up to 17% of the es appearing to be successful feeding es. 6. This study highlights the contrasted strategies adopted by gravid leatherbacks nesting on the Pacific coasts of Costa Rica, in the deep-water Caribbean Sea and in the French Guianan shallow continental shelf, and may be related to different local prey accessibility among sites. Our results may help to explain recently reported site-specific in idual body size and population dynamics.
Publisher: The Royal Society
Date: 25-07-2006
Abstract: Tracks of marine animals in the wild, now increasingly acquired by electronic tagging of in iduals, are of prime interest not only to identify habitats and high-risk areas, but also to gain detailed information about the behaviour of these animals. Using recent satellite-derived current estimates and leatherback turtle ( Dermochelys coriacea ) tracking data, we demonstrate that oceanic currents, usually neglected when analysing tracking data, can substantially distort the observed trajectories. Consequently, this will affect several important results deduced from the analysis of tracking data, such as the evaluation of the orientation skills and the energy budget of animals or the identification of foraging areas. We conclude that currents should be systematically taken into account to ensure the unbiased interpretation of tracking data, which now play a major role in marine conservation biology.
Publisher: Elsevier BV
Date: 05-2010
Location: No location found
No related grants have been discovered for Jean Yves GEORGES.