‘A little bit creepy’

For Mark Stoeckle, fishing for freefloating genetic material in the East River every week for the past couple of years has changed his outlook.

“It’s a little bit creepy, the idea that you’re swimming with the DNA of all these organisms,” he said. “Now I’m aware that when I go in the water I’m really going in someone else’s environment.” and many different plants that lived hundreds of thousands of years ago. He also found the preserved DNA of mammoths.

Environmental DNA “helps us reach the inaccessible,” said Willerslev from the Natural History Museum of Denmark, adding that this approach will play a key role in scientists’ quest to understand nature.

When Colleen Kamoroff spent the summer collecting water in 2015 from the lakes in California’s Sierra Nevada, she saw a healthy group of native mountain yellow-legged frogs hopping around.

One month later, they were all dying. The culprit: a microorganism that has caused the decline of about 200 amphibian species around the world, called chytrid fungus.

Kamoroff, a wildlife biologist who works for Yosemite National Park in California, started looking for chytrid fungus DNA in the water she had sampled. She was surprised to find it.

“Maybe if we knew they were infected at that point, we could have been more prepared. We could have started treating them” with medication, she said.

Marine biologist Ramon Bonfil has spent more than three years looking for the last sawfish of Mexico. The last specimen was accidentally caught in 2016. Other than that, no one has seen a live sawfish for almost a decade.

Gill nets, drones and fishermen have all failed to spot the elusive and strange-looking rays.

Bonfil, however, discovered sawfish DNA in three water samples he took two years ago in the state of Veracruz.

“The key is knowing where they are,” Bonfil said.