Monday, 10 December 2012

Outbreak of chytrid fungus threatens Portugal’s Midwife toads

Toads have disappeared from 2/3rds of known habitats
December 2012. The emergence of chytridiomycosis is now widely recognized as a major cause of amphibian declines and biodiversity loss on local and global scales. Amphibian mortalities caused by the pathogenic chytrid fungus (Batrachochytrium dendrobatidis (Bd)) were first recorded in Iberia, Europe over a decade ago.

In August 2009, hundreds of post-metamorphic common Midwife toads (Alytes obstetricans) were found dead in the water and margins of a pond in the Serra da Estrela Natural Park, north-central Portugal, and analyses confirmed their infection with Bd. Given the likelihood of a new outbreak of chytridiomycosis, staff from Durrell Institute of Conservation and Ecology, School of Anthropology and Conservation, evaluated the possible impacts of this disease on populations of Midwife toads within the Park by conducting field surveys during 2010 and 2011.

They compared the present distribution and abundance of Midwife toads with historical records, and quantified the present prevalence and intensity of infection by Bd. Results showed that Midwife toads had disappeared from 67% of the 1 x 1 km squares where it had been recorded previously. Results also showed that breeding is currently limited to just 16% of the confirmed known breeding sites and that larvae are now less abundant. There is also a high incidence of Bd in the remaining sites.

These effects were most pronounced at altitudes above 1200 m. The findings suggest that an outbreak of chytridiomycosis is responsible for the rapid decline of Midwife toads in Serra da Estrela, and it is believed that urgent conservation measures are needed to prevent local extinction of the species.

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