Wednesday July 8, 2026
DWR —
Finding the Delta’s most elusive residents means digging deep down into the microscopic traces they leave behind.
DWR scientists are doing just that by tapping into DNA, the cellular material that contains the building blocks of life and is found in all organisms. Every living organism sheds environmental DNA (eDNA) into its surroundings through skin cells, waste, mucus, or other biological material.
Using a process known as metabarcoding, DWR scientists analyze tiny traces of genetic material left behind by plants and animals to generate a detailed snapshot of an ecosystem and the species that inhabit it. Researchers collect environmental DNA (eDNA) samples from air, soil, and water, then use advanced genetic techniques to identify the organisms present.
Because eDNA can reveal a species’ presence without the need to physically capture, handle, or even observe it, metabarcoding provides a powerful, non-invasive tool for monitoring biodiversity and tracking ecosystem health. DWR scientists analyze those genetic traces to create an instant snapshot of the ecosystem and the species living within it.
Metabarcoding analyzes small genetic sequences in eDNA samples and compares them to reference databases to determine which species are present in a sample. In an environment as varied as the Delta, a single water sample can determine the presence of a host of species, big and small.
“The barcode is one small genetic sequence, often a ‘housekeeping gene’ common to all organisms,” said Daphne Gille, environmental program manager with DWR. “By comparing the barcode sequences we get in our sample to genetic reference databases, we can tell which species, from plankton all the way up to fish, were present at a particular time.”