SYDNEY, June 23 (Xinhua) -- Researchers from the Perth-based University of Western Australia (UWA) have found whale sharks are shedding their DNA into the seawater and leaving a trail of genetic clues in their wake.
The study published in Molecular Ecology Resources on June 19 found that even the smallest genetic signs in the seawater could help track individual whale sharks and monitor their populations.
Researchers from the UWA Oceans Institute and the Australian Institute of Marine Science (AIMS) collected eDNA, namely environmental DNA, by visiting known whale shark "hot spots" at Ningaloo Reef in Western Australia, where the team swam behind whale sharks and filled small bottles with seawater.
According to the researchers, whale sharks are notoriously challenging to track despite their large size. But like all marine species, whale sharks shed their unique DNA codes into the ocean, known as "eDNA", via skin, faeces, blood, mucus, sperm and other biological material.
The team then analyzed the seawater samples through a process called eDNA haplotyping.
Lead author Laurence Dugal from UWA's Oceans Institute said that they found out the method could detect the genetic signature of individual whale shark just by analyzing the seawater.
"We have moved beyond species detection and into the realm of pupulation genetics -- we've opened a new door in what is possible with eDNA," she said.
To confirm the signature of each shark, the team also collected tissue samples of 28 whale sharks and compared the results. It is also a logistically difficult and expensive method that requires invasive sampling techniques, according to Dugal.
"The results were incredibly accurate. The tissue biopsies successfully matched, with high accuracy, to all the individual whale shark's eDNA," he said.
Luke Thomas from the UWA Oceans Institute and AIMS said the research could go beyond whale sharks and be applied to other species at risk.
"This new method is faster, cheaper, highly accurate, easier to scale up and minimally invasive," Thomas said.
"It has the potential to radically change the way we monitor and track megafauna species." Enditem
