Departamento de Biología Evolutiva y Biodiversidad
Museo Nacional de Ciencias Naturales, CSIC
c/ José Gutierrez Abascal 2
28006 Madrid
SPAIN
Phone: 34-91-4111328, ext. 1202
Fax: 34-91-5645078
email: bosch@mncn.csic.es

During summers 1997, 1998 and 1999 mass mortality episodes of post-metamorphic common midwife toads Alytes obstetricans were detected in the Peñalara Natural Park, an alpine area in central Spain very close to Madrid (Fig. 1).

The population had suffered a sharp decline, disappearing from 91% of the ponds where they were known to reproduce some years ago (Fig. 2). In the skin of ill (Fig. 3) and dead toads (Fig. 4) scanning electron microscopy and histological techniques (Fig. 5) revealed the presence of chytridiomycosis infection. This evidence supports chytridiomycosis as the most plausible cause of the decline of the species in the area. This is the first report in Europe of an amphibian decline caused by the amphibian chytrid, Batrachochytrium dendrobatidis.

Figure 1. The Peñalara Natural Park, a boggy area located at 2000 meters of altitude. The Park holds more that 250 ponds and ten species of amphibians.

Figure 2. Healthy individual of Alytes obstetricans some years ago.

Fig. 3. Living post-metamorphic toad showing metallic-green spots on the skin.

Fig. 4. Post-metamorphic midwife toad found dead in Peñalara Natural Park.

Fig. 5 Histology of skin from infected toads showing several sections with zoosporangia of Batrachochytrium dendrobatidis.