Can protected mountain areas serve as refuges for declining amphibians? Potential threats of climate change and amphibian chytridiomycosis in an alpine amphibian population

Abstract

In June 2004 and June 2005, we checked 40 and 134 ponds respectively for alive and dead alpine newts, common toads, common frogs, and their clutches on the “Kirchfeld” plateau in the Northern Limestone Alps of Austria. We found several hundred dead common frogs and alpine newts in the two consecutive years and also observed an unusually high number of heterospecific matings between common toads and common frogs in 2004. In order to test whether the observed mortalities were caused by disease, we screened 98 individuals of the three species for chytridiomycosis, a highly infective fungal disease, in 2008. All samples proved to be negative. We therefore assume that the high losses for the common frog population (26 % in 2004 and 9 % in 2005) during the spring migration, as well as the breakdown of the temporal premating isolation between the common frog and common toad, were caused by temperature anomalies alone, i.e. sudden low temperatures after a warm spring period. The high number of dead alpine newts found in 2005 was negatively correlated to the oxygen saturation of the ponds, frequently covered by ice during the early breeding season. We discuss the possible effects of climate change on phenological timing, breeding isolation and chytridiomycosis in alpine amphibian populations. 19