Could zooplankton save frogs from deadly epidemic?

[Frog News]

Mongabay News (California, USA) August 26th, 2011 02:10 PM: Could zooplankton save frogs from deadly epidemic?

Scientists find a possible cure to a disease that has been devastating frogs, toads, salamanders, newts, and caecilians worldwide.

Scientists have discovered that a species of zooplankton will eat a fungal pathogen that is killing amphibians around the world.

Researchers at Oregon State University found that Daphnia magna, a freshwater microorganism, will consume the zoopore or the free-swimming stage of the "chytrid" fungus. The discovery opens the door for a possible biological solution to a problem that has confounded ecologists.

"We feel that biological control offers the best chance to control this fungal disease, and now we have a good candidate for that," said Julia Buck, a doctoral student in zoology at and Oregon State University lead author of the study, which is published in Biodiversity and Conservation. "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."

Buck and colleagues suggest that Daphnia magna could reduce the density of B. dendrobatidis, the chytrid fungus, enough to enable amphibians to fight off infection.

Chytrid has been moving across key habitats like a plague. While scientists have been unsure what is driving its spread, some suspect accidental introduction by researchers, tourists, and forest workers. Chytrid is blamed for the extinction of dozens of species of frogs and toads over the past 20 years. Its presence has been linked to declines in other amphibians as well.

"About one third of the amphibians in the world are now threatened and many have gone extinct," said Andrew Blaustein, a professor of zoology and co-author. "It's clear there are multiple threats to amphibians, but disease seems to be a dominant cause."

Full Article

[John]

I'm an expert on water chemistry and I'm something of an authority on Daphnia - my work on these animals has been used by a bunch of researchers, labs, etc, over the past decade. I must admit to skepticism regarding this article published on Monga Bay. Firstly, Daphnia consume anything that's about 50 microns in diameter or less. They are well known for consuming bacteria, algae, and fungi that are suspended in water. So to say that they are eating Chytrid in the water is hardly surprising. Still, I'm always glad to see new research into the Chytrid menace.

Having said that, Daphnia are incredibly sensitive to water conditions/water chemistry. This is the primary reason why they are used by environmental monitoring companies and academic researchers across the world. It's also why Daphnia magna has a very patchy distribution, and why it can't live in water that lacks an alkaline pH and significant water hardness. I have no problem with the research paper about which Monga Bay/Jeremy Hance is writing, but he describes this research as if it can have some meaningful effect on the spread of Chytrid. This is unrealistic at best.