VIEWPOINT Helen Meredith

It is a time of crisis for the world’s amphibians, says Helen Meredith. In this week’s Green Room she says we may be facing our last chance to save this important group of animals.

They consume huge quantities of invertebrates, including humanity’s most vilified pests and their crucial role in global ecosystems helps maintain healthy functioning environments

A third of all species of amphibian are threatened with extinction; nearly half are in decline, and they are the most threatened of all the vertebrate groups.

If allowed to continue, the projected losses would constitute the largest mass extinction since the disappearance of the dinosaurs.

But first things first; what are amphibians and why should we care about their decline?

Amphibians are one of nature’s less familiar groups – an issue that presents major challenges to establishing the conservation action they so urgently require.

They have been around on the planet for about 360 million years, arising over 100 million years before the first mammal and 200 million years before the first bird.

Great survivors

Modern amphibians comprise frogs, toads, salamanders, newts and caecilians (limbless amphibians), and number in excess of 6,000 species to date.

More than 20% are not understood well enough to be assigned any conservation status and it is estimated that up to 10,000 species may exist in total.

WHAT ARE AMPHIBIANS? First true amphibians evolved about 250m years ago There are three orders: frogs (including toads), salamanders (including newts) and caecilians, which are limbless Adapted to many different aquatic and terrestrial habitats Present today on every continent except Antarctica Many undergo metamorphosis, from larvae to adults

They are found on every continent except Antarctica, ranging from the Arctic Circle to the tropical deserts.

Of all the vertebrates, amphibians lead some of the strangest lives. Various species can survive partial freezing, 10 years without food, long droughts and temperatures of up to 40C (104F).

They are among life’s great survivors, enduring mass extinction events that have wiped out the dinosaurs and whole swathes of mammals and birds. In this light, their current extinction crisis seems all the more troubling.

Although they may not seem to have an impact upon the daily lives of many cultures, they provide numerous essential services to mankind.

They consume huge quantities of invertebrates, including humanity’s most vilified pests.

Their crucial role in global ecosystems, both as predator and prey, helps maintain healthy functioning environments. Frogs are an important protein source in many subsistence cultures and are traded in their millions as food and pets.

The skin secretions that protect amphibians against predation and infection have been found to contain important pharmaceutical compounds that show potential in treating a variety of illnesses from HIV to cancer.

The most famous case is that of the phantasmal poison frog (Epipedobates tricolor). Skin secretions from this frog yielded the compound epibatidine, which is a painkiller 200 times more effective than morphine.

The fight to save the world’s amphibians shouts into a howling gale of climate change, war, overpopulation, economic crises, and countless other global disasters

Amphibians are repositories of potentially life-saving chemicals and are key model organisms in scientific research.

Witnessing the precipitous decline of the amphibians is sobering. Why now, after hundreds of millions of years of survival, are they bowing out?

As always, the reasons are diverse and complex. The usual suspects of habitat destruction, climate change, invasive species, environmental contaminants and overexploitation represent key interrelated factors.

Additionally, a disease called chytridiomycosis or “chytrid” (caused by the fungus Batrachochytrium dendrobatidis) infects a wide range of amphibians globally and is capable of driving species to extinction.

Exacerbated by the other issues impacting amphibians, chytrid has emerged as one of the major threats to their survival. This disease can kill amphibians in otherwise pristine habitats or provide the final nail in the coffin for species already pushed to the brink of extinction.

The fight to save the world’s amphibians shouts into a howling gale of climate change, war, overpopulation, economic crises, and countless other global disasters, rendering their plight (just like many other aspects of biodiversity) somewhat low on the agenda of global priorities; they are slipping away almost unnoticed.