SUBJECT :eDNA extraction has confirmed the presence of rare freshwater species in temple ponds in Assam 

Well-sheltered: Nilssonia nigricans.

By - Shiv Sahay Singh

Kolkata, June 12, 2018: It is not only humans who are blessed by the sacred waters of temple ponds across northeast India. These protected water bodies have emerged as safe havens for many threatened species of freshwater turtles, including the Nilssonia nigricans or Black Softshell turtle, declared extinct in the wild by the IUCN Red list.

However, given their ritual nature, scientists are denied complete access to these ponds and hence have used the technique of extracting environmental DNA (eDNA) to confirm the presence of specific varieties. In addition to N. nigricans, tests at the Nagshankar temple pond in Assam have confirmed the presence of two more species — Nilssonia gangetica or Indian softshell turtle, classified as Vulnerable, and Chitra indica or South Asian narrow-headed softshell turtle, listed as Endangered by the IUCN.

The research findings were recently published in the journal Herpetology Notes by scientists associated with the Zoological Survey of India (ZSI), Kolkata.

Chitra indica 

“Sighting of our target animals is very rare in nature. However, eDNA based specimen identification through DNA bar coding successfully detected the targeted taxa from environmental water samples,” said the paper, ‘Environmental DNA (eDNA) testing for detection of freshwater turtles in temple ponds.’

Shantanu Kundu, the corresponding author of the publication, said there are around 15 such old temple ponds in Assam alone, and a few more in other northeastern States. He added that similar studies could in future help in collating a database of the turtle species which these ponds hold. Vikas Kumar, Kaomud Tyagi, and Kailash Chandra are the other authors of the paper.

Kailash Chandra, Director of the ZSI, said eDNA testing is fast emerging as a tool for monitoring the biodiversity of an area without physically collecting specimens.

Nilssonia gangetica 

“At the ZSI we are expanding our database of DNA barcodes of various animal taxa, which are specific genetic signatures and are aiming to have a DNA database of all one lakh species found in India. This technology coupled with iodine will help us ascertain how climate change and other environmental factors are affecting the distribution of species in years to come, “ Dr. Chandra said.

Shailendra Singh, Director of Turtle Survival Alliance (TSA)-India, said once the process is standardised, similar samples could be collected not only from temple ponds, but larger water bodies including at various places in rivers like the Brahmaputra and other turtle habitats of the country.

Dr. Singh also suggested some kind of conservation be allowed in these temple ponds, which are host to many threatened freshwater turtles. On the global use of eDNA technology, he gave the example of the Yangtze Giant softshell turtle (Rafetus swinhoei) found in China and Vietnam and said scientists are using the technology to find out at least one male turtle in the wild so that the species of most threatened freshwater turtle can be saved.


Source: The Hindu