Similar local and landscape processes affect both a common and a rare newt species

in PLoS ONE (2013), 8(5), 62727

Although rare species are often the focus of conservation measures, more common species may experience similar decline and suffer from the same threatening processes. We tested this hypothesis by ... [more ▼]

Although rare species are often the focus of conservation measures, more common species may experience similar decline and suffer from the same threatening processes. We tested this hypothesis by examining, through an information-theoretic approach, the importance of ecological processes at multiple scales in the great crested newt Triturus cristatus, regionally endangered and protected in Europe, and the more common smooth newt, Lissotriton vulgaris. Both species were similarly affected by the same processes, i.e. suitability of aquatic and terrestrial components of their habitat at different scales, connectivity among breeding sites, and the presence of introduced fish. T. cristatus depended more on water depth and aquatic vegetation than L. vulgaris. The results show that environmental pressures threaten both common and rare species, and therefore the more widespread species should not be neglected in conservation programs. Because environmental trends are leading to a deterioration of aquatic and terrestrial habitat features required by newt populations, populations of the common species may follow the fate of the rarest species. This could have substantial conservation implications because of the numerical importance of common species in ecosystems and because commonness could be a transient state moving towards rarity. On the other hand, in agreement with the umbrella species concept, targeting conservation efforts on the most demanding species would also protect part of the populations of the most common species. [less ▲]

Behaviours Associated with Acoustic Communication in Nile Tilapia (Oreochromis niloticus)

in PLoS ONE (2013), 8(4), 61467

Endosulfan effects on Rana dalmatina tadpoles: Quantitative developmental and behavioural analysis

in Archives of Environmental Contamination & Toxicology (2013), 64(2), 253-262

Endosulfan is an organochlorine pesticide that was recently labeled as a persistent organic pollutant, but it is still widely employed, particularly in developing countries. The goal of this study is to ... [more ▼]

Endosulfan is an organochlorine pesticide that was recently labeled as a persistent organic pollutant, but it is still widely employed, particularly in developing countries. The goal of this study is to evaluate the acute (LC50) and chronic effects (developmental and behavioural traits) of this insecticide on Rana dalmatina tadpoles after exposure to ecologically relevant concentrations (0.005, 0.01, and 0.05 mg/L) by applying video-tracking techniques to evaluate the quantitative effect of endosulfan on amphibian behavioural patterns. The 96 h LC50 value was 0.074 mg endosulfan/L. Tadpoles chronically exposed to 0.01 and 0.05 mg endosulfan/L underwent high mortality rate, decreased larval growth, delayed development, and increased incidence of malformations, and they did not reach metamorphosis by the end of the experiment. Moreover, tadpoles exposed to these concentrations exhibited several abnormalities in swimming patterns, such as shorter distance moved, swirling, resting, and unusual use of space. The exposure to 0.005 mg endosulfan/L did not cause any significant effects on behaviour, larval growth, or development, but we observed a significant decrease in both survival and time to metamorphosis. We showed that developmental abnormalities are dose-dependent and that the pesticide effects could differ depending on the endosulfan concentration and the species tested. We also validated the hypothesis that behavioural analysis, along with the use of new analytical methods, could be a useful tool in amphibian ecotoxicological studies. [less ▲]

Conférence plénière. Le Triton alpestre : diversité, écologie, éthologie et conservation

Conference (2012, October 18)

La diversité biologique s’entend bien au-delà de la notion d’espèce. Elle englobe ainsi toutes les particularités du vivant, telles les adaptations locales, les voies de développement alternatives et les ... [more ▼]

La diversité biologique s’entend bien au-delà de la notion d’espèce. Elle englobe ainsi toutes les particularités du vivant, telles les adaptations locales, les voies de développement alternatives et les tactiques comportementales. Le Triton alpestre est une espèce d’amphibien largement répandue en Europe où il peut être rencontré dans une multitude d’habitats. Sa persistance dans un grand nombre de conditions environnementales lui confère le plus souvent un statut d’espèce apparemment non menacée. Mais au-delà de ce constat, cette espèce présente des spécialisations des plus intéressantes dont certaines pourraient être perdues suite aux pressions d’origine anthropique. Ainsi, le Triton alpestre requiert certaines compositions et configurations d’habitats, tant aquatiques que terrestres. Selon celles-ci, il peut montrer différents patrons de fidélité au site. Son régime alimentaire englobe une multitude de proies mais en fonction des opportunités présentes, il peut adopter des tactiques prédatrices ciblées. Au niveau des interactions sexuelles, les mâles adoptent des parades particulières en fonction des circonstances, telle une femelle peu réceptive par exemple. Dans la majorité des cas, les larves, issues d’œufs pondus dans le milieu aquatique, se métamorphosent en juvéniles qui mènent dès lors une vie terrestre. Mais dans diverses populations, en particulier au sud de l’Europe, il en est tout autrement. Ainsi, certaines larves continuent à grandir tout en conservant leurs branchies ; devenant dès lors aptes à la reproduction. Il en résulte une coexistence de deux formes alternatives : les métamorphes et les pédomorphes. Quoique d’une même espèce, ces deux formes présentent des différences qui sont d’une ampleur voisine voire supérieure à celles rencontrées entre espèces. Selon l’hétérogénéité spatiale et temporelle des habitats, les deux formes présentent des avantages particuliers pouvant expliquer le succès prépondérant de l’une sur l’autre. Les caractéristiques de développement sont aussi variées selon les environnements : acquisition précoce de la maturité sexuelle et métamorphose au stade adulte en fonction d’aléas environnementaux. Une menace particulière pèse cependant sur cette diversité intra-spécifique : l’introduction de poissons. Celle-ci pourrait amener à transformer ce polyphénisme en un monomorphisme où ne subsisterait que la forme métamorphosée, dispersante. En effet, les introductions répétées de poissons dans les environnements aquatiques, quels qu’ils soient, entrainent davantage la disparition des pédomorphes. Les métamorphes, quant à eux, sont également atteints mais peuvent subsister dans certaines conditions qu’il reste à déterminer. [less ▲]

Video multitracking to study the fish behaviour

Conference (2012, July 07)

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns and rhythms in fish (from individual to collective group) and ... [more ▼]

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns and rhythms in fish (from individual to collective group) and to track a very large number of individuals. These new technologies and methods provide valuable information to fundamental and applied science disciplines such as ethology, animal sociology, animal psychology, veterinary sciences, animal welfare sciences, statistical physics, pharmacology, as well as neuro- and ecotoxicology. Specifically in situations where a large number of individuals are involved, the use of video tracking data is essential, as manual analyses would be complicated, time-consuming and sometimes even impossible. Today, multitracking allows us to observe directly the behaviours of groups, and to determine the real interaction rules by sampling data collected in nature or in the laboratory, without any a posteriori rules as it was and is frequently the case in computer simulation of collective behaviours. With these technologies, the quantitative measures of collective behaviours is now easily accessible, and allow to define social behaviours with more accuracy than just qualitative criteria as is always the case for instance with the definition of shoaling and schooling behaviours. Firstly will be introduced a review of fish video multitracking techniques. This review describes the possibilities of tracking individuals and groups at different scales, but also outlines the advantages and limitations of the different detection methods. The problem of occlusions, during which errors of individual identifications are very frequent, will be discuss. Secondly, our recent contribution in colour-based multitracking will be introduced, notably the new application of fluorescent VIE (Visible Implant Elastomer) tags in automatic tracking technology to study the behaviour of transparent animals like glass eels (Anguilla anguilla) in dim light or in darkness. The method makes it possible to measure the activity (notably distance and speed) of four individuals as a function of tidal and nycthemeral rhythms in the same flume (circular aquarium simulating the river or estuarine conditions) across a wide time scale (from seconds to weeks) in the context of migration in estuary. [less ▲]

Newt decline in Western Europe: highlights from relative distribution changes within guilds

in Biodiversity & Conservation (2012), 21(11), 2887-2898

The recent increase in the number of monitoring schemes has formed the basis for high quality distribution atlases. This provides the opportunity of estimating global and specific decline patterns across ... [more ▼]

The recent increase in the number of monitoring schemes has formed the basis for high quality distribution atlases. This provides the opportunity of estimating global and specific decline patterns across regional and national borders. In this framework, this study focused on four sympatric newt species—including the great crested newt (Triturus cristatus), an Annex 2 European Habitats Directive species, over six geographic areas (five countries) in Western Europe. A relative comparison of distribution maps across time is used here and is based on more than twelve thousands occupied grid cells. It benefits from the definition of a guild, as these species are simultaneously detectable in wetlands. T. cristatus and the alpine newt (Mesotriton alpestris) were the most and the least threatened newt species, respectively, whereas the palmate (Lissotriton helveticus) and smooth newt (Lissotriton vulgaris) had an intermediate decline level at both coarse and fine grain resolutions. However, regional variations across Europe and scale effects were also found. On one hand, these results show that T. cristatus is not only regionally threatened but suffers from a global decline in Western Europe. On another hand, the results indicate that patterns of decline are not uniform within Europe and that species often considered as common and not threatened are, in fact, declining more than others. Finally, the proposed methodology, i.e. using guilds to assess relative decline, would be useful as a complement to other standardized methods in correctly advising conservation managers and policy makers, particularly for species with more subtle declines. [less ▲]

Using sets of behavioral biomarkers to assess short-term effects of pesticide: a study case with endosulfan on frog tadpoles

in Ecotoxicology (2012), 21(4), 1240-1250

Pesticides and other chemicals often have detrimental effects at environmental concentrations. Many amphibian species are particularly threatened because of their susceptibility but also because wetlands ... [more ▼]

Pesticides and other chemicals often have detrimental effects at environmental concentrations. Many amphibian species are particularly threatened because of their susceptibility but also because wetlands are often polluted. Behavioral assessments of toxicity have the advantage of showing sublethal effects but quantitative measures at varied scales of integrations are rarely considered together. In this study, we aimed at showing that these behavioral endpoints could be differently affected across time and concentrations, and be biomarkers of toxicity. To this end, we tested the effects of an organochlorine pesticide (endosulfan) on amphibians during a standard 96 h test. We evaluated possible lag effects in continuing the analyses after removal of the pesticide. The study was based on 240 tadpoles (4 pesticide treatments: 0.4, 3, 22, and 282 lg/l, 1 control and 1 solvent-control). Abnormal behaviors such as lying and swirling rapidly were exhibited only in the presence of the pesticide. Essential functions such as breathing and feeding were deeply affected by the pesticide: contaminated tadpoles breathed and fed less than control tadpoles. They also moved less and occupied a more central position in the aquariums in the presence of the pesticide. A higher mortality was only found at the highest concentration. These results suggest that endosulfan is toxic to amphibians at environmental concentrations. Behavioral markers showed potential as early warning systems. They should thus be used in complement to other markers to detect sublethal effects only a few days after application of the pesticide and at concentrations where mortality does not occur. [less ▲]

The impact of alien fish species on feeding behavior and shelter use in Alpine newt

Poster (2011, December 08)

Behavioural ecotoxicology in amphibians: development of biomarkers

Conference (2011, October 25)

Effeti comportamentali dell'endosulfan su girini di Rana dalmatina

Poster (2011, September)