CORVALLIS, Ore. -- Zoologists at Oregon State University have discovered that a freshwater species of zooplankton will eat a fungal pathogen which is devastating amphibian populations around the world.
This tiny zooplankton, called Daphnia magna, could provide a desperately needed tool for biological control of this deadly fungus, the scientists said, if field studies confirm its efficacy in a natural setting.
The fungus, B. dendrobatidis, is referred to as a "chytrid" fungus, and when it reaches high levels can disrupt electrolyte balance and lead to death from cardiac arrest in its amphibian hosts. One researcher has called its impact on amphibians "the most spectacular loss of vertebrate biodiversity due to disease in recorded history."
The research, reported today in the journal Biodiversity and Conservation, was supported by the National Science Foundation.
"There was evidence that zooplankton would eat some other types of fungi, so we wanted to find out if Daphnia would consume the chytrid fungus," said Julia Buck, an OSU doctoral student in zoology and lead author on the study. "Our laboratory experiments and DNA analysis confirmed that it would eat the zoospore, the free-swimming stage of the fungus."
"We feel that biological control offers the best chance to control this fungal disease, and now we have a good candidate for that," she said. "Efforts to eradicate this disease have been unsuccessful, but so far no one has attempted biocontrol of the chytrid fungus. That may be the way to go."
The chytrid fungus, which was only identified in 1998, is not always deadly at low levels of infestation, Buck said. It may not be necessary to completely eliminate it, but rather just reduce its density in order to prevent mortality. Biological controls can work well in that type of situation.
Amphibians have been one of the great survival stories in Earth's history, evolving about 4
|Contact: Andrew Blaustein|
Oregon State University