eDNA Study Turns New York City's East River into Urban Biodiversity Monitor

Scientists collecting one litre of water weekly from New York City's East River over a full year have used vertebrate environmental DNA metabarcoding to detect 71 local marine fish species, more than 60 terrestrial animals, and genetic traces of human food consumption patterns aligned with national US dietary statistics. The findings suggest that urban waterways can function as continuous biosensors for real-time biodiversity tracking and public health monitoring.

The study, conducted between May 2024 and May 2025 by researchers at Rockefeller University and collaborators, found that 16 species — representing 23 per cent of detected types — accounted for 95 per cent of fish eDNA in samples. A ten-fold increase in marine fish eDNA occurred during summer, closely paralleling seasonal water temperature changes. Comparison with a 2016 survey revealed that two species — skilletfish and feather blenny — have become newly abundant at the site, likely due to local oyster reef restoration. Human eDNA was the most abundant vertebrate category detected, with levels of domestic animal, wildlife and dietary fish eDNA directly correlated with human eDNA, indicating a shared wastewater source.

New York City's combined sewer overflow outfalls currently discharge about 18 billion gallons of untreated wastewater into the estuary annually. The study found that food animal DNA — including chicken, beef, pork, turkey, lamb, goat and commonly consumed fish such as salmon and European sea bass — appeared in proportions closely matching national US consumption statistics, demonstrating that wastewater eDNA can serve as an indicator of local dietary patterns. Lead author Mark Stoeckle at Rockefeller University said the DNA traces provide a unique window into eating patterns and public health trends rather than obscuring ecological data.

The researchers said municipal authorities could use eDNA monitoring to assess whether rat control programmes are working by tracking changes in rodent DNA concentrations in waterways. The findings support the hypothesis that eDNA accurately indexes local fish populations, with top species results broadly overlapping with traditional mechanical gear-based surveys conducted over 35 years. The study argues that urban waterways worldwide could become distributed observatories of ecological change, enabling cities to track ecosystem health and human impacts continuously and in near real-time — a particularly relevant tool for cities managing combined sewer infrastructure.

Key figure — 18 billion gallons of untreated wastewater annually