Sunday, October 10, 2010

Declines in Amphibian Populations

El Cope National Park has already felt the effects of population loss, losing over thirty species of amphibians.

One species from Panama, known as the golden frog (Atelopus zeteki), that has lately been struggling against Batrachochytrium dendrobatidis.

A Nature article from July 19, 2010 showed that species of amphibians have died off over the past ten years, giving biologists no clue to their existence. This might be one reason why Richard Lehtinen referred to cricket frogs as an "annual" species. A technique known as DNA barcoding has been used to identify amphibian species that were previously unknown. A park in Panama recently gave rise to eleven species, but only six of these are still extant. The cause seems to be due to the fungus Batrachochytrium dendrobatidis (same fungus that Lehtinen's cricket frog paper talked about). B. dendrobatidis affects almost 3,000 amphibian species across the globe, and it causes them to have difficulty breathing because of overly thick skin. The fungal disease has been studied using toe clippings and liver samples. Researchers have compared the effects of the epidemic before and after it struck back in 2004. El Cope, Panama was home to sixty-three species before the decline, but is now only home to thirty-three (five of these were previously unknown). Researchers are saying that things are being lost before they can be found and that there has been confusion regarding species of amphibians on whether certain ones are one species or two. Biologist Van Vredenburg stated that, "Up until now, we've only had a very crude estimate of what is lost."
Amphibians are being removed from their natural habitats by herpetologists for conservation purposes. Anti-fungal solutions are necessary to preserve these animals. Two of the three types of amphibians (frogs and and salamanders) are already capable of defending themselves against the fungus because of symbiotic bacteria growing on their skin. The bacteria is currently being swiped from healthy populations and taken to labs for culturing in order to then immunize amphibian populations with large amounts of this advantageous bacteria. It should be in everyone's best interest to insure that the oldest class of four-legged vertebrates continues to flourish worldwide.
Paper reference: doi: 10.1038/news.2010.360


  1. Is the sybiotic relationship with the good bacteria possible only in certain species, or has it just not spread to other populations? The physiological differences between the species (mainly the toxins that some of them produce) may make it impossible for the bacteria to grow in some of the frog species. Of course, the toxins may make it impossible for the fungus to grow on them anyway, so the toxic species may not need the bacteria. I wonder if there are any studies out there about this...

  2. In the actual article, nothing was mentioned about precisely what types of frogs or salamanders, but that's a good question to be addressed in a future paper if one pertaining to that hasn't been published yet.

  3. The bacterial ecology of frog skin will probably turn out to be quite complex. And it is interesting that this fungal infection seems to be hitting the tropical species hardest.

  4. Since the fungus does well in tropical climates and works slower in climates closer to ours... could that be used to stop the disease?

  5. Actually, the fungus is more lethal at high-altitude, cold areas in the tropics. This fungal species grows better in cooler areas. So the sensitivity of tropical species may be due more to biogeography and lack of previous exposure to the fungus than the warm temperature.