by Jes Burns
Biologist Shaun Clements stands in the winter mist in a coastal Oregon forest, holding a small vial of clear liquid.
“We should be safe mixing it now, right?” he asks his colleague, Kevin Weitemier, above the sound of a rushing stream a few feet away.
Weitemier brings a second vial, full of stream water. In deliberate, seemingly choreographed movements, they pour the liquid back and forth between the small containers, mixing two, then three times — never spilling a drop.
The two move out into the cold stream with the vials. Clements is in the main stream, while Weitemier stays closer to shore. At the same moment, they tip the containers on end. Two trillion particles of lab-created DNA fall into the rushing water. It’s an experiment to figure out how far and how quickly environmental DNA – or “eDNA” – travels in different kinds of streams.
Occasionally a big idea comes along that promises to revolutionize the world – think about things like self-driving cars. For biologists – especially those who work with fish and other aquatic plants and animals – eDNA is one of those big ideas. The technology is starting to revolutionize how we protect native animals and ensure invasive species don’t take hold.
The easiest way to understand eDNA is to imagine yourself relaxing in a steamy hot tub. As you’re soaking, a bubble splashes water into your mouth and you spit it out. A day’s worth of dead skin sloughs off. Finally, toasty warm, you get out of the tub.
The you-flavored broth left behind is full of your DNA. It has become part of the larger environment. And long after you’re gone, that DNA could be detected — if someone knew what to look for.
The same holds true for any organism in any body of water.
“All these little critters out there, they’re shedding DNA from their skin cells, urine, feces,” Clements explains.
Clements works for the Oregon Department of Fish and Wildlife. He says Oregon has a lot of waterways and the state doesn’t have the resources to fully monitor endangered fish, look for invasive plants or check in on all the other native species, potentially including mammals like river otters, beavers and bats.
With eDNA, doing all of this could get much cheaper and easier.
“Just by taking a water sample, you can tell somewhere in basin above you, there was this range of species and something about their relative abundance,” he says.
And this potential has fisheries biologU.ists excited for what lies ahead.
“Environmental DNA sampling really can be a game changer,” says U.S. Forest Service fisheries biologist Mike Young.
So Many Variables
Young says biologists and fisheries managers in the West are already really good at using eDNA to find the threatened species bull trout in small streams. That’s because he and other scientists have been working for years to figure out exactly what it means to find bull trout DNA in a water sample. They know what a positive detection indicates about bull trout presence and relative population numbers…
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