Evidence of a chytrid fungus infection involved in the decline of the common midwife toad ( Alytes obstetricans) in protected areas of central Spain

Abstract

During the summers of 1997, 1998 and 1999 mass mortality episodes of post-metamorphic common midwife toads ( Alytes obstetricans) occurred in a protected area in central Spain. The population suffered a sharp decline, disappearing from 86% of the ponds where they were known to reproduce some years ago. Scanning electron microscopy and histological techniques revealed the presence of a chytridiomycosis infection in the skin of the toads. This evidence supports chytridiomycosis as the most plausible cause of the decline of the species in the area. This is the first report of an apparent chytridium-caused amphibian decline in Europe.