Bird squawk or frog croak? When forest officer C.R. Naik played a call on his phone to ecologists K.S. Seshadri and K.V. Gururaja, they were convinced it was a white-breasted kingfisher. “We even teased him, saying that he neither knew his birds nor his frogs,” says Seshadri, a faculty at ATREE, Bengaluru. But Naik insisted it was that of a frog, sending supporting videos that led the two scientists to confirm Naik was right. And so, a new species — the Karaavali skittering frog — was unearthed.
Kottigehara dancing frog. | Photo Credit: Gururaja K.V.
The Karaavali skittering frog is among over the 200-odd new amphibian species discovered over the past few decades, many of which are in the biodiversity hotspots of the Western Ghats and the Indo-Burma region. Some of the other more recent amphibian discoveries include a new cascade frog, Amolops siju, found living deep inside a cave in Meghalaya; a new green tree frog, Gracixalus patkaiensis, spotted in the Namdapha Tiger Reserve in Arunachal Pradesh, and the very rare Mahabharat Torrent frog, Amolops mahabharatensis, discovered for the first time in India.
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According to Gururaja, we are discovering many new amphibians because of a molecular revolution in DNA sequencing techniques along with bioacoustics, in recent years. “We now have around 465 species of amphibians,” says Gururaja, a faculty at the Srishti Manipal Institute of Art, Design and Technology. “When I wrote my thesis in 2002, India had 220 species, and I’d say there are 100-150 more to be discovered.”
Manoharan’s bush frog | Photo Credit: Seshadri K.S.
Even as biologists celebrate the discovery of new species, they are aware of the grim reality facing amphibians, the most threatened vertebrate class in the world. The just-released second Global Amphibian Assessment, published in the latest edition of Nature, reveals that nearly 40.7% of amphibian species are globally threatened by habitat loss, disease and climate change.
“It feels like a complete paradox. We are not still fully aware of what is out there. But we are losing things at a fast rate,” says Karthikeyan Vasudevan, an ecologist associated with the Centre for Cellular and Molecular Biology, Hyderabad, who, like Gururaja, was part of this recent study. He points out that India ranks sixth globally for the diversity of frogs with 70% of them endemic or restricted to a specific geographic area. “41% of all the species in India are threatened,” he adds.
Ochlandrae reed frog | Photo Credit: Seshadri K.S.
At high risk
Amphibians evolved some 360 million years ago, when sarcopterygian fish with lungs and bony-limbed fins ventured onto land, making amphibians the first terrestrial vertebrates. Besides frogs, which comprise the majority of amphibians, the group also includes toads, salamanders and caecilians.
While amphibians, like many other plants and animals, face huge threats due to human activities, they are even more vulnerable because of their high degree of endemism. Preeti Hebbar, an assistant professor at the department of biology and humanities, MIT Bengaluru, Manipal Academy of Higher Education, Manipal, says the high habitat specificity makes endemic, range-restricted species of amphibians especially sensitive to even the slightest changes in their microhabitat. “If you put them in another one, they may not survive.”
Also, unlike birds and mammals, amphibians cannot regulate their body temperature, making them particularly vulnerable to intense climate fluctuations. Additionally, chytridiomycosis, a fungal disease that has been sweeping the world, has killed scores of them. “The fungal disease is an outcome of global trade,” says Vasudevan, who has researched the disease for nearly a decade. While India, once a major exporter of frog legs, banned their trade in 1987, this had already led to the pathogen spreading worldwide. “A lot of extinctions would have happened this way,” he believes.
Why amphibians matter
In August this year, the NatureFirst Eco-Village (NRC), an ecotourism spot in Dharwad, Karnataka, announced that it was opening a frog park on its campus. Frogs are an indicator of ecosystem health, says Harshavardhan Sheelavant, the planning head of the CSR wing of NRC. When they set up the eco-village, much of the local ecology had been lost, and the water table had diminished. He firmly believes that NRC’s attempt to rejuvenate local ecology and water systems was vital in bringing back the frogs. “Where there are frogs, it is safe for human beings to live,” he says.
Amphibians also play a vital role in keeping a check on insect populations. “If amphibians go extinct, we are going to have an explosion of insects,” says Vasudevan, adding that the rise in vector-borne diseases such as malaria in Panama and Central America after the devastation of amphibian species proves this.
Ecosystems, after all, are incredibly complex; one can never predict how the extinction of a single species can impact the entire natural world. “At some point, there will be one critical link that will collapse, and the whole ecosystem will see a downfall,” says Seshadri. The current conservation narrative, which focuses on larger, charismatic species such as the tiger and elephant, is askew with smaller, less-popular animals often getting neglected. Butterflies, frogs and ants also provide deep insights into ecological parameters, such as microhabitat or stream quality, and must be protected. “If you put together all the frogs in the world and weigh them, the biomass is likely to be more than all the tigers put together,” points out Seshadri.
The Global Amphibian Assessment states that “scaled-up investment is urgently needed to reverse the current trends.” Vasudevan agrees. “Zoos have a big role to play,” he says, pointing out that currently, we have only one zoo in India — the Padmaja Naidu Zoo in Darjeeling — that breeds the Himalayan salamander.
Not only are zoos a great way to raise awareness about amphibians, but captive breeding programmes can help repopulate species in decline, something that is happening in the Bronx Zoo with the Panamanian golden frog, which is almost extinct in the wild. “Amphibians have seen 250 million years of evolution, seen so many events, including several mass extinctions,” says Vasudevan, adding that the fact that they are now facing threats is a reminder of how big the human footprint is. “We have to step in and start doing something.”
preeti.z@thehindu.co.in
