Amphibian Biodiversity: Let's save it before it's too late!

Debananda S Ningthoujam *

Prelude

Many of us would fondly remember the sleep-inducing sounds of frogs croaking in rainy nights in our childhoods. Those of us who had our schooling some 40, 30, 20 or even 10 years ago would have played happily with alluring tadpoles in household ponds. But times are changing now.

Maybe the current generation of children would prefer playing with mobile handsets and other electronic gadgets. And even if some of the present or future generations of children wish to play with tadpoles, maybe soon frogs would have disappeared from the face of earth.

As Wangari Maathaai said in her Nobel speech, we need to "restore the home of the tadpoles and give back to our children a world of beauty and wonder".

What are amphibians?

Amphibians are a group of animals that consist of 3 orders:

• Anura: frogs and toads
• Caudata: newts and salamanders
• Gymnophiona: caecilians or amphibians that look like giant earthworms.

Amphibians were the first terrestrial vertebrates that evolved about 350 million years ago.

Habitats

Their distribution is near universal, thriving in various habitats globally except the Antarctica. Amphibians are found in rainforests, wetlands, deserts, alpine environments and many other niche habitats.

Salient features of amphibians

• 3 groups of amphibians are anurans, caudate and caecilians
• About 6000 species of amphibians are known
• Evolved around 350 million years ago
• First 4-limbed vertebrates
• Simple body structure
• Delicate and permeable skin
• Some types of salamanders have no lungs
• 3-stage life cycle-egg, larva and adult
• Chinese giant salamander is largest amphibian growing up to 6 feet in length
• Amphibian populations are declining all over the world

Threatened species

About 1895 species of amphibians out of 6,285 species recognized so far are threatened with extinction, according to the Red List of IUCN. 165 species have become extinct in recent years. 500 more may get extinct very soon if appropriate conservation steps are not taken up urgently. The number of threatened amphibian species is much more than that of birds and mammals.

Threats to amphibian diversity

• Habitat loss
• Pollution
• Overharvesting
• Climate change
• Infections

Some of the major threats to amphibians are habitat loss or fragmentation due to deforestation, wetland drainage, construction of roads and other developmental projects. This is compounded by pollution due to agricultural chemicals such as atrazine, DDT, PCBs, and dioxins which cause cancer, limb deformities and endocrine disruption leading to feminization of male frogs and other amphibians.

UV-B radiation due to ozone depletion is also having adverse effects on amphibians esp. young ones or tadpoles and this effect is more serious at higher altitudes. Introduced alien species such as fishes and non-native frogs also create havoc, e.g. Cuban tree-frog that came to US ate up many of the native frogs.

The export of frogs as pets or for food has aggravated the worsening situation of the frogs. In addition to all these factors, some emergent fungal infections such as chytrid fungal diseases have targeted some amphibian populations in past few years.

Why conserve amphibians?

Amphibians play crucial roles as predators and preys helping maintain the balance of nature. They also act as bioindicators that help us monitor the health of the ecosystems. They are also cultural and religious symbols as harbingers of rain, life and good luck.

There are myriad benefits from amphibians. Major ones include:

• Basic science: amphibians can yield many secrets through basic scientific research
• Ecosystem health: they help maintain ecosystem health
• Bioindicators: they can act as bioindicators of ecosystem health
• Medicines: many of them give wonderful medicines, e.g. Australian red-eyed tree-frog(Litoria chloris) produce an anti-AIDS compound
• Biocontrol: as they eat insects they help check agricultural insect pests and diseases such as malaria
• Aesthetic: they are beautiful animals and have their own right to exist
• Cultural: amphibians are cultural symbols used as harbingers of rain, good luck and happy life.

How to conserve amphibian diversity?

Action plans must depend on:

1. Understanding the causes of amphibian declines and extinctions
2. Documenting the diversity of amphibians
3. Working out long-term conservation programs
4. Undertaking of emergency crises solutions

Some of the short-term programs may include:

• Captive breeding
• Reintroductions
• Removal of invasive alien species (IAS).

Coda

We need to conserve amphibians for our own survival even if we do not want to protect these beautiful animals for altruistic reasons. Let's listen to the anguished calls of these ancient creatures. Their survival is at stake due to anthropogenic activities.

Let's save them before it's too late. Because if all amphibians become extinct, it will not he long before Homo sapiens go extinct!

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* Debananda S Ningthoujam wrote this article for The Huieyen Lanpao (English Edition)
The author teaches biochemistry in Manipur University and researches on biodiversity and biotechnology areas especially microbial biodiversity and biotechnology. He also writes popular science articles on scientific biography and science, environment & biodiversity issues. This article was webcasted on July 13, 2010.

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