An Ocean in a Drop of Water

National Museum of Natural History

“Do you have to see a skunk to know there’s a skunk?” This is one of several analogies Chris Meyer, research zoologist and chair of the Department of Invertebrate Zoology at the National Museum of Natural History, uses to describe environmental DNA (eDNA)—a powerful tool that combines sampling and DNA mapping technology to survey the ocean’s biodiversity.

“With net trawls or visual surveys fish can slip away, ship crews can’t navigate certain waters, or you miss the nightlife if you’re only sampling during daylight hours,” Meyer said. “With eDNA, you can do it in the dark, in unclear water or over hard bottoms—it’s nondestructive, noninvasive. And, you can trust it,” the same way you trust your nose to tell you that a skunk is nearby.

Watch Meyer give an in-depth lecture on eDNA, recorded in September 2022.

Proven. Simple. Efficient. Accurate.

A clear picture of biodiversity across oceans is an essential starting point to track and understand when and how oceans change—and how everything people do, from fishing to building dams, impacts marine life.

Most living organisms shed DNA constantly, regenerating cells and leaving traces behind—like a skunk’s signature scent, lingering in the air. A single liter of ocean water can contain traces of DNA from hundreds of creatures. With eDNA, scientists only need one liter of water to extract and organize each strand of DNA in the sample and match those traces to DNA sequences of known species. This provides a detailed, accurate snapshot of what’s living below the surface.

It can also illuminate the gaps—pinpointing unknown DNA sequences that suggest something mysterious is present, which might merit investigation.

Environmental DNA is a proven technology: simple, efficient and extraordinarily precise. The Smithsonian has used it to track fish species in Florida and the Chesapeake Bay; the U.S. Geological Survey is using it to track rare and invasive species.

What’s missing? A centralized, coordinated effort to bring stakeholders together and harness the power of eDNA on a grand scale.

A Library of Life

Man at a microscope in a lab setting. Photo Stephen Voss
Scientists in Meyer’s laboratory run samples collected from ocean expeditions—such as this basket star from the Gulf of Mexico—through a machine that sequences its DNA. That sequence is then available to reference in an accessible eDNA library.

The Smithsonian has an unrivaled collection of marine specimens—millions of DNA samples from fish, mammals, mollusks, coral and more, digitized and available online.

“We can provide a trusted reference library,” said Meyer, a database to help identify species from eDNA samples taken across the country and beyond. “And we have experts across the Smithsonian working on pathogens, invasive species, corals—we provide the full ecological picture.”

The institution also has the capacity to lead and draw people together: federal agencies, conservation organizations, communities that rely on fishing to make their living, and many more. These groups can work together to create standardized metrics to 

measure biodiversity: a common language to compare ecosystems across oceans and across decades to discover what keeps them healthy and protect those in danger of harm.

Meyer is working with agencies and partners to make a common eDNA reference library a reality. “We want to be able to ‘smell’ all the species, not just the skunk,” he said. “We should be the trusted broker of biodiversity knowledge—and encourage more people to innovate, go further, see what comes next.”

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Published Summer 2023 in IMPACT Vol. 9. No 2

Click here to read more about the Smithsonian's work to build, maintain and protect resilient ecosystems. 

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