Declining central American frog species are bouncing back

Date:  April 11, 2018

Source:  Vanderbilt University Medical Center

Summary:

For more than 40 years, frog populations around the world have been declining. Now, a new study reports that some Central American frog species are recovering, perhaps because they have better defenses against a deadly fungal pathogen.

For more than 40 years, frog populations around the world have been declining. Now, a new study reports that some Central American frog species are recovering, perhaps because they have better defenses against a deadly fungal pathogen.

"It's a hopeful, optimistic chapter," said Louise Rollins-Smith, PhD, associate professor of Pathology, Microbiology and Immunology, and a co-author of a study recently published in the journal Science.

A collaborative group of investigators at multiple institutions showed that the fungal pathogen Batrachochytrium dendrobatidis continues to be as lethal now as it was more than 10 years ago. The antimicrobial defenses produced by frog skin, however, appear to be more effective than they were before the fungal epidemic began.

Rollins-Smith and her colleagues began studying how frogs combat B. dendrobatidis in Panama in 2004. For several years, Douglas Woodhams, PhD, a postdoctoral fellow on her team, and laboratory manager Laura Reinert made multiple trips to Central America to collect samples of frog skin secretions.

Continued 

Fingerprint' technique spots frog populations at risk from pollution

March 24, 2017


Researchers at Lancaster University have found a way to detect subtle early warning signs that reveal a frog population is at risk from pollution.

Worldwide, amphibian populations are declining due to habitat loss, disease and pollution which is cited as a major threat to their survival.

Scientists publishing in Scientific Report, have found evidence of stress in tadpoles taken from ponds most impacted by pollution caused by nutrients and pesticides. They say the technique they used to spot these changes could offer an early warning system for populations at risk.

Working over a three-year period they looked at common frog populations in urban and rural ponds subject to varying degrees of pollution. Using a special kind of biochemical 'fingerprinting' detected via infrared spectroscopy, the team looked at tissues taken from tadpoles as well as frogspawn to examine their biochemical makeup - searching for markers such as glycogen which can vary as the organism responds to stress. The team found strong evidence of higher levels of stress in tadpoles living in those ponds most impacted by pollution, more so than frogspawn embryos, which are protected to some degree by their jelly coat.

These subtle detrimental effects are otherwise very hard to detect using conventional biological toxicity tests and analytical chemistry but the new technique of biospectroscopy can act as an early warning before a local population becomes extinct. The test could potentially help scientists carrying out environmental monitoring on frog and amphibian populations to indicate which freshwater systems are at risk from pollution, before it's too late.

Dr Crispin Halsall, an environmental chemist at Lancaster University, said: "Amphibians are particularly vulnerable to contamination due to their sensitive life-stages, particularly tadpoles. Agricultural pesticides and nutrients from fertilisers are a threat to frogs during their breeding season.

Researchers at Lancaster University have found a way to detect subtle early warning signs that reveal a frog population is at risk from pollution.

 

Credit: Lancaster University

 

 

 

 

 

 

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