Endangered Frogs Get Helping Hand

Endangered amphibians such as the limosa harlequin frog (Atelopus limosus) now have a tiny bit of hope to cling to thanks to a captive breeding program run by a collaboration between conservation groups, including the Panama Amphibian Rescue and Conservation Project and the Smithsonian Conservation Biology Institute.

For the first time, researchers with the captive breeding project have managed to raise nine limosa harlequin frogs from one mating pair, and they have hundreds of tadpoles on hand from a second breeding pair.

The diminutive amphibians—whose young are small enough to perch atop George Washington's face on the U.S. quarter—are of the chevron-patterned variety of limosa harlequin frog.

"These frogs represent the last hope for their species," said biologist Brian Gratwicke, of the Smithsonian Conservation Biology Institute, in a statement.

They are part of a project aimed at saving populations of several priority frog species in Panama, including the crowned treefrog (Anotheca spinosa) and the horned marsupial frog (Gastrotheca cornuta).

Skin-deep

Deforestation, water pollution, and stream sedimentation are the main threats to the harlequin species, according to International Union for Conservation of Nature assessments. But the amphibian chytrid fungus is also a concern.

The virulent sickness, caused by the fungus Batrachochytrium dendrobatidis (Bd), attacks the keratin contained in an amphibian's skin. Researchers aren't sure exactly how the fungus kills, but some studies have shown that Bd can affect a frog's ability to transport molecules across its skin.

Frogs take in water and oxygen through their skin, so a disease that affects that ability is cause for concern. Some studies have implicated the disease in about one-third of possible extinctions in the Atelopus genus of harlequin frogs in Latin America.

But there may be some hope for amphibians, including the limosa harlequin frogs.

New research published March 21 in the journal Scientific Reports found that increased body temperatures in three species of Australian frogs (Litoria lesueuri, Litoria serrata, and Litoria nannotis) reduced the chances of infection by the chytrid fungus.

This relationship with body temperature may explain the pattern of infection seen around the world, the study authors wrote. And manipulating habitats to increase opportunities to achieve warmer temperatures may help amphibians combat the disease.

Insurance

The project's husbandry operations, like the one near the town of Gamboa in central Panama (map), are key to building up populations of endangered frog species as a kind of insurance against extinction.

Conservation biologist Jorge Guerrel, with the Smithsonian Tropical Research Institute, built small underwater caves in which female limosa harlequin frogs could lay their eggs.

Gently flowing, well-oxygenated water between 72° and 75°F (22° and 24°C) was also essential.

The Panama Amphibian Rescue and Conservation Project currently cares for 55 adult limosa harlequin frogs of the chevron-patterned variety and ten of the plain-color variety.