A team of scientists from around the world, including UC Berkeley researchers, released a study mapping the effects of a pathogenic fungus on global frog populations Monday.

Erica Bree Rosenblum — an associate professor in the Department of Environmental Science, Policy and Management — collaborated with campus graduate student Allison Byrne and former UC Berkeley postdoctoral researcher and head of the Voyles Lab at the University of Nevada, Reno, Jamie Voyles. Together, they worked with international researchers to document the effects of the pathogenic chytrid fungus Batrachochytrium dendrobatidis, or Bd, and its different strains.

Synthesizing their findings, the researchers developed a map that shows all of the different strains of the fungus and where they have been found worldwide. The map is the most complete record of the chytrid fungus to date, according to Berkeley News.

Human expansion and development can alter ecosystems, resulting in a loss of biodiversity. Much of the loss can be attributed to the transport of disease-causing agents to remote areas, as was the case with the chytrid fungus, according to the study, published in the Proceedings of the National Academy of Sciences of the United States of America. 

Amphibians are particularly susceptible to emerging infectious diseases and have been “hit particularly hard” by Bd, according to the study.

Some amphibians use their skin, which contains keratin, for respiration. Bd can affect the keratin in frogs’ skin, leading to breathing issues and difficulty maintaining osmotic pressure and electrolyte levels.

In 2017, Rosenblum and Byrne created a “custom genotyping method” that uses noninvasive skin swabs to obtain pathogen data. The researchers have been able to expand the sample size in Asia, Europe, Africa and the Americas and investigate sites where hybrid lineages of the pathogen interact and become more harmful.

Their work can be used to “further explore the history — and predict the future impacts — of this devastating pathogen,” according to the study.

The researchers used the data gathered to create a map that identifies amphibian communities that experienced Bd outbreaks. Affected populations are beginning to repopulate in small sizes but are eminently vulnerable to both Bd tolerant species and additional outbreaks, according to the study. It is uncertain how amphibians respond to different strains of Bd.

According to the study, much of the field is still uncharted and the team addressed the need to expand the sample size and develop a potential action plan to “halt Bd lineage spread and secondary contact.”

N. Louise Glass — a campus professor of plant and microbial biology — stressed the importance of studying the “epidemiology of frog infections.”

“This knowledge will be important regarding quarantine measures and understanding mechanisms of resistance to infection,” Glass said.