Dear EarthTalk

Are the world’s amphibians still in decline and what’s being done to help them?

Chris W.

Stamford, CT

Unfortunately yes, amphibians are

still in serious trouble around the world. A recently updated worldwide population assessment by the non-profit International Union for the Conservation of Nature (IUCN) found that 32 percent of the 6,000-plus amphibian species left on the planet have declined to dangerously low levels — and qualify for vulnerable, endangered or critically endangered status on the group’s “Red List” of at-risk wildlife.

Perhaps even more disturbing is that upwards of 160 amphibian species — some of which have been around for hundreds of millions of years — have gone extinct just in the last 25 years. Since amphibian species are particularly sensitive to environmental change, they are often the first animals to decline in areas just beginning to experience environmental degradation, and as such are considered to be important indicators of the health of the wider ecosystems surrounding them.

Scientists are hard-pressed to pick one major cause for such dramatic declines, but at least one key culprit is a fungal pathogen called “frog chytid” (Batrachochytrium dendrobatidis). According to the non-profit Amphibian Ark, frog chytid causes changes to amphibians’ sensitive outer skin layer, making vital life processes — such as the absorption of water, oxygen and electrolytes — difficult or impossible. Prior to 1999 researchers hadn’t yet identified this variant of the chytid fungus, let alone the role it was playing in decimating amphibian populations. It is particularly dangerous because none of the world’s amphibians seem to be immune — even those species that survive an infestation still carry and transmit the parasite.

Frog chytid isn’t the only factor in amphibians’ recent troubles. According to the AmphibiaWeb website, habitat destruction, alteration and fragmentation (with the forest goes the frogs), as well as predatory introduced species, increased exposure to UV-B radiation (likely caused by erosion of the Earth’s protective ozone layer), various forms of air and water pollution, and poaching all combine to stack the odds against amphibians. Human-induced climate change is likely playing a role in the decline as well, with rising global temperatures creating optimal conditions for the growth and spread of the frog chytid pathogen while also displacing amphibians from formerly hospitable habitat zones.

IUCN and its partners Conservation International and NatureServe have released an Amphibian Action Conservation Plan, which outlines ways that international institutions, national governments, corporations and even everyday people can take part in helping to save our frogs and their relatives. According to the plan, reducing pollution and lowering our carbon footprint is an important first step. Likewise, preserving more amphibian habitat — especially in Latin America, which has the largest number of threatened amphibian species, and the Caribbean, where upwards of 80 percent of amphibians are at risk — will be key to the survival of our frogs, toads, salamanders and caecilians. Captive breeding programs in various zoos and labs around the world, reintroductions of species into formerly abandoned habitats, and the removal of harmful non-native species also need to play a role in preserving these many species that, once gone, will never reappear.

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