Assessing the impacts of the invasive frog, Xenopus laevis, on amphibians in western France

International audienceAs invasive species are one of the principal threats on global biodiversity, assessing their impact is a crucial element of conservation biology. Quantifying the possible impacts of an invasive population represents the first step in the establishment of efficient management plans. In this study, we applied a method of site-occupancy modeling to estimate the influence of an invasive frog, Xenopus laevis, on the amphibian species richness in western France. In our analyses we took into account habitat characteristics (i.e. the size and general shape of the ponds), the structure of the aquatic vegetation, the presence of other vertebrates, and the physicochemical parameters of the pond. Richness was negatively related to the abundance of X. laevis and to the time since colonization as estimated by the distance of the pond to the site of introduction. Habitat niche breadth of native amphibians did not differ between invaded and non-invaded areas. This might be a consequence of the homogeneity of the habitats selected for our study. The lack of heterogeneity in the abiotic factors, the absence of a correlation between species richness and these abiotic factors, and the correlation of the abundance and time since colonization by X. laevis with species richness suggest a negative effect of this species on local amphibians. This result highlights the importance of conservation and management plans aiming to limit the expansion of this invasive species

SUR QUELQUES CURIOSITÉS D'HISTOIRE NATURELLE DANS LES PERTUIS CHARENTAIS : FAUNE DES INVERTÉBRÉS MARINS

Eight invertebrate species, rediscovered, demographically expanding or newly observed are reported from the Pertuis Charentais Sea. They were sampled from intertidal rocky shores (Alpheus macrocheles, Aslia lefevrei, Epitonium clathrulatum and Haliotis tuberculata), intertidal sand flats (Africorchestia spinifera and Arcuatula senhousia) and subtidal bottoms (Aslia lefevrei and Rapana venosa). One species is pelagic (Lepas anatifera). Most of them are within their natural range. However, R. venosa, native to Southeast Asia, has been introduced in the Pertuis Charentais since the 2010s and its populations are currently expanding. The new northern limit of Africorchestia spinifera along the Atlantic coast is defined as the Ré Island. Phoresis of Crepidula fornicata on Carcinus maenas is noted but was already described in European waters whereas it is a hitherto undescribed and unexpected association with the gastropod R. venosa

SUR QUELQUES CURIOSITÉS D'HISTOIRE NATURELLE DANS LES PERTUIS CHARENTAIS : FAUNE DES INVERTÉBRÉS MARINS

Eight invertebrate species, rediscovered, demographically expanding or newly observed are reported from the Pertuis Charentais Sea. They were sampled from intertidal rocky shores (Alpheus macrocheles, Aslia lefevrei, Epitonium clathrulatum and Haliotis tuberculata), intertidal sand flats (Africorchestia spinifera and Arcuatula senhousia) and subtidal bottoms (Aslia lefevrei and Rapana venosa). One species is pelagic (Lepas anatifera). Most of them are within their natural range. However, R. venosa, native to Southeast Asia, has been introduced in the Pertuis Charentais since the 2010s and its populations are currently expanding. The new northern limit of Africorchestia spinifera along the Atlantic coast is defined as the Ré Island. Phoresis of Crepidula fornicata on Carcinus maenas is noted but was already described in European waters whereas it is a hitherto undescribed and unexpected association with the gastropod R. venosa