Action: Remove the chytrid fungus from ponds
- One before-and-after study in Mallorca found that pond drying and fungicidal treatment of resident midwife toads reduced levels of infection but did not eradicate chytridiomycosis.
The chytrid fungus Batrachochytrium dendrobatidis has been found to survive in lake water for seven weeks after introduction (Johnson & Speare 2003). Treatment of the aquatic environment may help to reduce the effect of the disease on amphibians. One potential method is completely drying ponds, as a study found that complete drying of the chytrid fungus resulted in 100% mortality (Johnson et al. 2003).
Johnson M.L., Berger L., Philips L. & Speare R. (2003) Fungicidal effects of chemical disinfectants, UV light, desiccation and heat on the amphibian chytrid Batrachochytrium dendrobatidis. Diseases of Aquatic Organisms, 57, 255–260.
Johnson M. & Speare R. (2003) Survival of Batrachochytrium dendrobatidis in water: quarantine and disease control implications. Emerging Infectious Diseases, 9, 922–925.
Supporting evidence from individual studies
A before-and-after study in 2009–2010 of a pond in Mallorca (Lubick 2010) found that drying out the pond and treating resident Mallorcan midwife toads Alytes muletensis with a fungicide reduced the prevalence but did not eradicate chytridiomycosis. All samples from tadpoles came back positive for the chytrid fungus the spring after pond drying and treatment. However, the number of spores detected on each swab was lower than the previous year, suggesting a lower level of infection. Healthy-looking toads were seen breeding in the pond following pond drying and treatment. Over 2,000 toad tadpoles were removed from the pond in March–August 2009. The pond was emptied and left to dry over the summer. Tadpoles were taken to a laboratory and given daily five minute baths in the fungicide itraconazole for one week. They were held in captivity for up to seven months. Once the pond refilled in autumn, tadpoles were released. The following spring tadpoles were swabbed to test for chytridiomycosis.