ABSTRACT
The North Atlantic Oscillation (NAO) is a large-scale climatic pattern that strongly influences the atmospheric circulation in the northern Hemisphere and by consequence the long-term variability of marine and terrestrial ecosystem over great part of northern Europe and western Mediterranean. In the Mediterranean, the effects of the NAO on vertebrates has been studied mainly on bird populations but was rarely analysed in ectothermic animals, and in particular in amphibians. In this study, we investigated the relationships between winter, spring and summer NAO indexes and the long-term population dynamics of the plethodontid salamander Speleomantes strinatii. This terrestrial salamander was monitored inside an artificial cave in NW Italy for 24 consecutive years. The relationships between seasonal NAO indexes and the salamander dynamics were assessed by cross-correlation function (CCF) analysis, after prewhitening the time series by autoregressive moving average statistical modelling. Results of CCF analyses indicated that the salamander abundance varied in relation to the one-year ahead winter NAO (P = 0.018), while no relationships were found with spring and summer indexes. These results strengthen some previous findings that suggested a high sensitivity of temperate terrestrial amphibians to wintertime climatic conditions.
Subject(s)
Climate , Urodela , Animals , Italy , Population Density , Population DynamicsABSTRACT
North America and the neotropics harbor nearly all species of plethodontid salamanders. In contrast, this family of caudate amphibians is represented in Europe and Asia by two genera, Speleomantes and Karsenia, which are confined to small geographic ranges. Compared to neotropical and North American plethodontids, mortality attributed to chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) has not been reported for European plethodontids, despite the established presence of Bd in their geographic distribution. We determined the extent to which Bd is present in populations of all eight species of European Speleomantes and show that Bd was undetectable in 921 skin swabs. We then compared the susceptibility of one of these species, Speleomantes strinatii, to experimental infection with a highly virulent isolate of Bd (BdGPL), and compared this to the susceptible species Alytes muletensis. Whereas the inoculated A. muletensis developed increasing Bd-loads over a 4-week period, none of five exposed S. strinatii were colonized by Bd beyond 2 weeks post inoculation. Finally, we determined the extent to which skin secretions of Speleomantes species are capable of killing Bd. Skin secretions of seven Speleomantes species showed pronounced killing activity against Bd over 24 hours. In conclusion, the absence of Bd in Speleomantes combined with resistance to experimental chytridiomycosis and highly efficient skin defenses indicate that the genus Speleomantes is a taxon unlikely to decline due to Bd.
