New York City’s East River has made quite the comeback since its days as a sewage dumping ground—and sequencing the waterway’s DNA may illuminate its regained biodiversity.
Researchers from The Rockefeller University collected liter-quantity water samples from the East River over the course of a year and analyzed the environmental DNA (eDNA) they contained (PLOS One 2026, DOI: 10.1371/journal.pone.0332676). By using a technique known as metabarcoding, which allows the identification of multiple vertebrate species in one sample, researchers were able to describe fish populations and detect what New Yorkers—rat and human—were having for dinner.
According to researcher Mark Stoeckle, the primary motivation of the study was to monitor fish activity and test the feasibility of using eDNA as a complement to traditional monitoring methods like catch and release. While such approaches are still needed to determine factors like the health of individual fish, eDNA data are “showing a detailed picture that’s as good or better than what we can get with nets or traps,” Stoeckle says.
The East River is particularly vulnerable to wastewater contamination; as most New Yorkers know, even a little bit of rain can overwhelm drainage systems, which then release overflow into the waterway. Because that overflow contaminates the river with DNA from other sources, it poses a problem in eDNA collection.
For that reason, the secondary impetus for the study was to test if the analytical methods that the researchers used could cut through the wastewater noise. The methods were able to identify endemic vertebrates, despite wastewater presence, and the eDNA from the wastewater itself provided insight into the diets of New Yorkers. For example, the researchers found chicken DNA in the wastewater.
Stoeckle says he hopes this work inspires others to look to eDNA for biomonitoring, especially given its cost-effectiveness. “The materials are about $15,000 for a year,” he says. “If you put a boat in the water to survey fish, it’s $15,000 a day. So there’s an opportunity for not just government agencies but potentially conservation-minded groups to look at their own environment. Doesn’t have to be an urban estuary, but you’re certain to learn something.”
2026 American Chemical Society
