Reading a Creek’s DNA: An Aquatic Inventory at Point Reyes and Golden Gate

Animals living in a stream shed genetic material into the water around them. Sampling that environmental DNA (eDNA) can show which species use a creek.

In summer 2023, the San Francisco Bay Area Network's coho and steelhead monitoring team began a two-year inventory of aquatic species in streams across Point Reyes National Seashore and Golden Gate National Recreation Area, using eDNA. The account comes from Lizzie Bear, a Watershed Stewards Program corpsmember with the network's salmonid monitoring program.

Scientists in Parks intern Tim Smoot and Mosaics in Science intern Maya Scanlon take a water sample at Schooner Creek, Point Reyes, for genetic analysis. NPS / Watershed Stewards Program corpsmember Lizzie Bear.

What they are looking for

The crew wants to know whether particular species are using particular streams on Park Service land. Those of most conservation concern:

• steelhead trout;
• California red-legged frog;
• foothill yellow-legged frog;
• western pond turtle.

Knowing exactly where these sensitive animals live will help guide how the parks manage their resources.

How it works

1. Filter the water. A battery-powered vacuum pump draws creek water through self-preserving filters that catch the particles carrying DNA.
2. Send it to the lab. A partner organization analyzes the filters to identify which species' DNA they hold.
3. Check in person. After sampling, the crew electrofishes or seines the same site, catching animals to record their age, length and weight — details eDNA alone cannot give.

Watershed Stewards corpsmember Lizzie Bear and PRNSA fisheries field assistant Tara Blake scout sampling sites along Kehoe Creek. NPS / Watershed Stewards Program corpsmember Catherine Masatani.

Where

As the first year of sampling wrapped up, the crew was waiting on the lab results. More is on the network's salmonid monitoring page and the Pacific Coast Science & Learning Center's coho and steelhead page.

Sources

Based on "Fisheries Crew Begins Aquatic Inventory Project," by Watershed Stewards Program corpsmember Lizzie Bear, San Francisco Bay Area Network, published by the National Park Service; rewritten in hubnx's own words.