Amphibians in jeopardy
Research from Honduras has indicated that the spread of the catastrophic Chytrid fungus, which has already pushed countless amphibian species to the brink of extinction, may be even harder to control than previously thought.
Chytrid fungus (Batrachochytrium dendrobatidis, or ‘Bd’) is an ancient species of fungi which attacks amphibians indiscriminately. All kinds of amphibians are vulnerable to this pathogen, including frogs, salamanders and caecilians, which causes a fatal illness in many species known as chytridiomycosis.
Data collected over a four year period from Cusuco National Park in Honduras has revealed infected amphibians living in arboreal bromeliads, sometimes very high up in trees and far from any body of water
Bd is believed to be waterborne and its flagellated infectious zoospores rely heavily upon the movement of water to drive dispersal and carry it to the next amphibian host. However data collected over a four year period from Cusuco National Park in Honduras has revealed infected amphibians living in arboreal bromeliads, sometimes very high up in trees and far from any body of water.
The research team, led by Jonathan Kolby from The Conservation Agency (Rhode Island, US), hoped to observe conditions within some bromeliads that could pose environmental barriers to Bd, protecting the amphibians within. “But to our dismay,” says Kolby, “we found amphibians showing signs of infection and illness even within bromeliads containing water as acidic as that which caused harm to Bd within laboratory experiments.”
Research sheds light
But the work may yet shed some light on the Bd problem. During the summer of 2010, they ambitiously attempted to create the best illustration of how this pathogen may be spreading throughout Cusuco as well as through other regions of Central America. This meant radiotracking endemic and endangered treefrogs, climbing trees to collect large bromeliads to sample water and dissect for insects and amphibians, swabbing amphibians for Bd infection detection, and water filtering to detect the presence of Bd in rivers and bromeliads.
In addition, they constructed experimental equipment suspended from trees to investigate the possibility of Bd being blown by the wind. The project was an amazing success and the team was able to collect hundreds of samples. These samples are currently being processed by molecular analysis at the US Geological Survey and at Washington State University, in order to determine the presence of Bd DNA.
Kolby and his team hope that these results will be a step forward in formulating the most effective strategy to protect amphibian populations from Bd. “Once we have obtained all of these results, we will begin to interpret how likely it is that Bd may be spread by the action of infected amphibians, by insects and arthropods, by people wearing contaminated footwear, and by the wind.”