Publications (10)27.16 Total impact
-
Article: Effects of oceanic salinity on body condition in sea snakes.
[show abstract] [hide abstract]
ABSTRACT: Since the transition from terrestrial to marine environments poses strong osmoregulatory and energetic challenges, temporal and spatial fluctuations in oceanic salinity might influence salt and water balance (and hence, body condition) in marine tetrapods. We assessed the effects of salinity on three species of sea snakes studied by mark-recapture in coral-reef habitats in the Neo-Caledonian Lagoon. These three species include one fully aquatic hydrophiine (Emydocephalus annulatus), one primarily aquatic laticaudine (Laticauda laticaudata), and one frequently terrestrial laticaudine (Laticauda saintgironsi). We explored how oceanic salinity affected the snakes' body condition across various temporal and spatial scales relevant to each species' ecology, using linear mixed models and multimodel inference. Mean annual salinity exerted a consistent and negative effect on the body condition of all three snake species. The most terrestrial taxon (L. saintgironsi) was sensitive to salinity over a short temporal scale, corresponding to the duration of a typical marine foraging trip for this species. In contrast, links between oceanic salinity and body condition in the fully aquatic E. annulatus and the highly aquatic L. laticaudata were strongest at a long-term (annual) scale. The sophisticated salt-excreting systems of sea snakes allow them to exploit marine environments, but do not completely overcome the osmoregulatory challenges posed by oceanic conditions. Future studies could usefully explore such effects in other secondarily marine taxa such as seabirds, turtles, and marine mammals.Integrative and Comparative Biology 06/2012; 52(2):235-44. · 2.45 Impact Factor -
Article: Highly venomous sea kraits must fight to get their prey
[show abstract] [hide abstract]
ABSTRACT: A long-term recapture study in New Caledonia has shown sea kraits (Laticauda laticaudata and L. saintgironsi) have a strong predator prey relationship with anguilliform fish (Brischoux et al. 2007; Ineich et al. 2007). Considering krait versus prey body size (sometimes almost of the same size), many conger eels (e.g., Conger cinereus) and moray eels captured by the sea kraits have the potential to retaliate. We observed typical ‘‘V-shaped'' injuries on many snakes: 29.7% L. laticaudata had scars and 11.4% recent injuries (N = 2,797 individually marked snakes); 33.2% L. saintgironsi had scars and 9.5% recent injuries (N = 3,582). Deep cuts sometimes resulted in very large and deep wounds (N > 100). Because anguilliform fish are indeed capable of inflicting dangerous bites, the trophic relationships between these two predators are more complex than assumed: the benefit of maximising the amount of energy per foraging trip associated with the capture of large prey trades off against the injury risk that increases with prey size. Prey selection, searching effort, killing tactics, and venom efficiency selection can all be affected. Figure 1a (20 m depth, island of Taveuni, Fiji, November 2004) clearly illustrates the ability of moray eels to bite sea kraits (see Fig. 1b) during predation as a defence mechanism. We regularly observed sea kraits with recent deep ‘‘V-shaped'' bites coming on shore without prey in the stomach, possibly to rest and recover (Fig. 1c). Perhaps capturing fish is more difficult than previously assumed, even for the highly venomous sea kraits.Coral Reefs 05/2012; 29(2):379-379. · 3.88 Impact Factor -
Article: Morphological adaptations to marine life in snakes.
[show abstract] [hide abstract]
ABSTRACT: We investigated morphological adaptations to aquatic life within animals that exhibit a structurally simple, elongate body form, i.e., snakes. This linear body plan should impose different biomechanical constraints than the classical streamlined body shape associated with propulsion by fins, feet, or wings. Our measurements of general body shape of terrestrial, amphibious, and marine snakes (all from the same phylogenetic lineage, the Elapidae) show that seasnakes display specialized morphological attributes for life in water. Most notably, the cross-sectional body shape is circular in terrestrial snakes but dorso-ventrally elongated in seasnakes (due to a prominent ventral keel); amphibious species (sea kraits) exhibit an intermediate shape. The tail of amphibious and marine species (a major propulsive structure during swimming) is higher and thinner than in terrestrial snakes (i.e., paddle-shaped) but shorter relative to body length. The evolution of a laterally compressed shape has been achieved by an increase in body height rather than a decrease in body width, possibly reflecting selection for more effective propulsive thrust, and for an ability to maintain hydrodynamic efficiency despite the minor bodily distension inevitably caused by prey items and developing offspring.Journal of Morphology 02/2011; 272(5):566-72. · 1.54 Impact Factor -
Article: Is aquatic life correlated with an increased hematocrit in snakes?
[show abstract] [hide abstract]
ABSTRACT: Physiological adaptations that allow air-breathing vertebrates to remain underwater for long periods mainly involve modifications of the respiratory system, essentially through increased oxygen reserves. Physiological constraints on dive duration tend to be less critical for ectotherms than for endotherms because the former have lower mass-specific metabolic rates. Moreover, comparative studies between marine and terrestrial ectotherms have yet to show overall distinct physiological differences specifically associated with oxygen reserves. We used phylogenetically informed statistical models to test if habitat affects hematocrit (an indicator of blood oxygen stores) in snakes, a lineage that varies widely in habitat use. Our results indicate that both phylogenetic position (clade) and especially habitat are significant predictors of hematocrit. Our analysis also confirms the peculiar respiratory physiology of the marine Acrochordus granulatus. Contrary to previous findings, marine snakes have significantly-albeit slightly-elevated hematocrit, which should facilitate increased aerobic dive times. Longer dives could have consequences for foraging, mate searching, and predation risks. Alternatively, but not exclusively, increased Hct in marine species might also help to fuel other oxygen-demanding physiological adaptations, such as those involved in osmoregulation.PLoS ONE 01/2011; 6(2):e17077. · 4.09 Impact Factor -
Article: Children prioritize virtual exotic biodiversity over local biodiversity.
[show abstract] [hide abstract]
ABSTRACT: Environmental education is essential to stem current dramatic biodiversity loss, and childhood is considered as the key period for developing awareness and positive attitudes toward nature. Children are strongly influenced by the media, notably the internet, about biodiversity and conservation issues. However, most media focus on a few iconic, appealing, and usually exotic species. In addition, virtual activities are replacing field experiences. This situation may curb children knowledge and concerns about local biodiversity. Focusing our analyses on local versus exotic species, we examined the level of knowledge and the level of diversity of the animals that French schoolchildren are willing to protect, and whether these perceptions are mainly guided by information available in the internet. For that, we collected and compared two complementary data sets: 1) a questionnaire was administered to schoolchildren to assess their knowledge and consideration to protect animals, 2) an internet content analysis (i.e. Google searching sessions using keywords) was performed to assess which animals are the most often represented. Our results suggest that the knowledge of children and their consideration to protect animal are mainly limited to internet contents, represented by a few exotic and charismatic species. The identification rate of local animals by schoolchildren was meager, suggesting a worrying disconnection from their local environment. Schoolchildren were more prone to protect "virtual" (unseen, exotic) rather than local animal species. Our results reinforce the message that environmental education must also focus on outdoor activities to develop conservation consciousness and concerns about local biodiversity.PLoS ONE 01/2011; 6(8):e23152. · 4.09 Impact Factor -
Article: Kleptothermy: an additional category of thermoregulation, and a possible example in sea kraits (Laticauda laticaudata, Serpentes).
[show abstract] [hide abstract]
ABSTRACT: Lacking the capacity for thermogenesis, most ectotherms inhabiting thermally heterogeneous environments rely instead upon exploiting that ambient heterogeneity. In many cases they maintain body temperatures within a narrow range despite massive spatial and temporal variation in ambient conditions. Reliance on diverse thermal opportunities is reflected in specific terms for organisms that bask in sunlight to regulate their temperature (heliotherms), or that press their bodies against warm substrates to facilitate heat flow (thigmotherms), or that rely on large body mass to maintain thermal constancy (gigantothermy). We propose an additional category of thermoregulators: kleptotherms, which regulate their own temperature by 'stealing' heat from other organisms. This concept involves two major conditions: the thermal heterogeneity created by the presence of a warm organism in a cool environment and the selective use of that heterogeneity by another animal to maintain body temperatures at higher (and more stable) levels than would be possible elsewhere in the local area. Kleptothermy occurs in endotherms also, but is usually reciprocal (rather than unilateral as in ectotherms). Thermal monitoring on a small tropical island documents a possible example of kleptothermy, based on high stable temperatures of a sea snake (Laticauda laticaudata) inside a burrow occupied by seabirds.Biology letters 09/2009; 5(6):729-31. · 3.76 Impact Factor -
Article: Thirsty sea snakes forsake refuge during rainfall
[show abstract] [hide abstract]
ABSTRACT: Abstract Vertebrates living in dry or salty habitats spend significant amounts of time and energy maintaining their hydro-mineral balance; any opportunity to drink fresh water should reduce such expenses. However, to find fresh water, individuals are generally forced to leave the safe and buffered conditions that prevail in their refuges. Therefore, they must face harsh environmental conditions and increased predation risks. We examined this trade-off in the field, using a very large dataset gathered on amphibious sea snakes that confront periodic droughts. The study was carried out on different islets in the lagoon of New Caledonia. As expected, sea kraits remain concealed most of the time under rocks or within burrows during dry weather. They select precise time windows to move rapidly between the sea and the land, thereby minimizing the time spent in the open. Rainfall triggered massive disruptions of this rhythm: many snakes quickly forsook their shelter to drink in the open, and remained almost motionless until satiety. Interestingly, they adopted specific and unusual postures to drink. They perched on the top of rocks that were benefiting from running and less salty water during downpours. They also drank the droplets attached to vegetation during drizzle.Austral Ecology 10/2008; 33(7):911 - 921. · 1.82 Impact Factor -
Article: Is melanism adaptive in sea kraits?
[show abstract] [hide abstract]
ABSTRACT: Ontogenic melanism (progressive darkening of the skin) has been documented in snakes. Black coloration of the skin often compromises the cryptic effects associated with other patterns (e.g. zigzags) and exposes individuals to predation; however, the mortality risk can be balanced, for example by a thermoregulatory advantage during sun basking. Such adaptive context has been proposed to explain the appearance and the maintenance of melanism within snake populations. Based on a very large captures and re-captures sample (>8000 observations) gathered on two species of sea-kraits (Laticauda saintgironsi and L. laticaudata in New Caledonia), we observed that melanism occurred in only one species (L. laticaudata), was infrequent and concerned adult snakes solely. None of three adaptive hypotheses respectively linked to thermoregulation, predation, or protection against sun radiations, provided a satisfactory account for the occurrence of melanism in our study populations. Therefore, we suggest that melanism was a fortuitous phenomenon.Amphibia-Reptilia 01/2008; 29:1-5. · 1.06 Impact Factor -
Article: A method to reconstruct anguilliform fishes from partially digested items
[show abstract] [hide abstract]
ABSTRACT: Estimating the amounts of resources consumed by individuals is important in many studies. For predators, allometric relationships can be used to extrapolate the size of preys from undigested remains found in the stomach and in the faeces. However, such equations are available for a limited number of species. Based on a large sample size gathered in New Caledonia on both predators (sea kraits) and their preys (anguilliform fishes), we provide the first allometric relationships that allow estimating accurately the mass and the size of various anguilliform fish species.Marine Biology 05/2007; 151(5):1893-1897. · 2.28 Impact Factor -
Article: Adaptive maternal cannibalism in snakes (Epicrates cenchria maurus, Boidae)
[show abstract] [hide abstract]
ABSTRACT: In many animal species, mothers that produce stillborn offspring or undeveloped ova immediately ingest them. This cannibalism has been interpreted in two ways: (1) as a form of parental care (to prevent disease spreading to healthy littermates, and eliminate predator-attracting scent cues); or (2) to recycle otherwise wasted energy, thus facilitating maternal recovery. Our experimental study on captive Colombian rainbow boas (Epicrates cenchria maurus) provides the first quantitative support for this latter hypothesis. We show that by eating their non-viable offspring and undeveloped eggs, female boas can rapidly recycle a significant component of their otherwise wasted reproductive investment. Female boas that ingested non-viable progeny equivalent to half their litter mass exhibited rapid recovery of dorsal musculature and hence were able to constrict prey items more forcefully than were unfed females when tested 2 weeks after parturition. The consequent enhancement of constricting ability may influence maternal survival and foraging success. Thus, maternal cannibalism may be an effective tactic to avoid wasting reproductive resources, and to shorten the period required for recovery from pregnancy. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 84, 767–774.Biological Journal of the Linnean Society 03/2005; 84(4):767 - 774. · 2.19 Impact Factor
Top co-authors
Top Journals
- PLoS ONE (2)
- Marine Biology (1)
- Coral Reefs (1)
- Biological Journal of the Linnean Society (1)
- Journal of Morphology (1)
Institutions
-
2009–2012
-
University of Sydney
- School of Biological Sciences
Sydney, New South Wales, Australia
-
-
2011
-
University of Florida
Lake Alfred, FL, USA
-
-
2007–2008
-
Université François Rabelais
Tours, Centre, France
-
-
2005
-
French National Centre for Scientific Research
Lyon, Rhone-Alpes, France
-
