1. World Wildlife Magazine
  2. Summer 2022

How scientists use eDNA to monitor biodiversity

What can we learn about an ecosystem by analyzing its water? More than you might expect. Water—like soil, air, and snow—contains DNA naturally shed by animals through their hair, feces, saliva, and skin. Studying this environmental DNA, or eDNA, can give us a snapshot of the health of an ecosystem and its species. And while it might sound like a tool from your favorite true crime podcast, eDNA has enabled big strides in wildlife monitoring.

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Graphic showing process of eDNA collection© MATT TWOMBLY/WWF-US
  1. TAPPING THE SOURCE
    When wild animals move through their habitats, they leave behind genetic markers, traces of which are washed into lakes, streams, and rivers. Researchers collect samples of that water, which they pass through a filter to capture organic materials containing eDNA that are then sent to a lab for processing.
  2. WHAT’S INSIDE
    Each sample can hold the genetic codes of dozens or even hundreds of animals, offering vital clues about the overall well-being of terrestrial and aquatic ecosystems. Through eDNA, scientists can track the impacts of climate change or detect endangered species or harmful pathogens in a landscape.
  3. UNRAVELING THE CODE
    In the lab, DNA amplification and sequencing helps researchers pinpoint which species are present in the samples—in some cases, the process can even single out individual animals.
  4. THE BOTTOM LINE
    eDNA can’t determine an animal’s age or a species’ population size. But when combined with other tools, it can improve our ability to assess the status of wildlife populations and habitats, empowering scientists to design more timely and effective conservation strategies.

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Graphic showing process of eDNA collection© MATT TWOMBLY/WWF-US

TRACKING TIGERS

WWF scientists will soon use eDNA alongside camera traps to conduct a survey of tigers and their prey in Bhutan’s Royal Manas National Park. If the methods yield similar results, eDNA sampling could complement camera traps in future national tiger surveys, substantially reducing survey costs.

25%

eDNA sampling is faster and, in some cases, more comprehensive than other monitoring methods: In a WWF study in British Columbia between 2018 and 2019, eDNA sampling of stream water detected 25% more terrestrial mammals than camera trapping did, because many—including several bat species—were too small to trigger cameras.

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World Wildlife magazine provides an inspiring, in-depth look at the connections between animals, people and our planet. Published quarterly by WWF, the magazine helps make you a part of our efforts to solve some of the most pressing issues facing the natural world.

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