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.