Frogs’ immune systems weakened by chemicals, study finds
Young frogs exposed to flame retardants have weakened immune systems, which could leave them more susceptible to diseases that are ravaging amphibians worldwide.
A new laboratory experiment is the first to link flame retardants to immune system problems in frogs, and adds to evidence that pollutants may contribute to global declines of their populations.
Tadpoles of northern leopard frogs were exposed to polybrominated diphenyl ethers in their food from the time they could swim until they turned into frogs. Then scientists injected the young frogs with a foreign protein and found that they produced up to 92 percent fewer antibodies than non-exposed frogs.
“Making antibodies to get rid of pathogens is vital to frogs’ ability to fend off disease,” said Tawnya Cary, a postdoctoral scholar at the Institute for Biology Education at the University of Wisconsin, Madison, and lead author of the study.
Nearly one-third of the world’s amphibians – more than 1,800 species of frogs, toads, salamanders and newts – are threatened with extinction or already extinct. Chytrid fungus is to blame for devastating many populations, although other threats include habitat destruction, UV radiation and parasites.
One theory for the spread of the deadly fungus is that “pollutants alter immune function of the animals, and then they’re not able to fend off disease pathogens properly,” Cary said.
The period when tadpoles are turning into frogs – called metamorphosis – is a “very vulnerable time,” said Louise Rollins-Smith, an associate professor of pathology, microbiology and immunology at Vanderbilt University who did not participate in the study.
Read the full story here.