River Ching home to nearly 2,000 species, including eel and jellyfish

This March, volunteers collected water samples from six locations along the River Ching and found DNA belonging to 1,885 unique species

The River Ching has been found to be home to 1,885 unique species, including the critically endangered European eel and the unusual Peach Blossom jellyfish.

A survey funded by environmental charity Thames21 also highlights evidence of wastewater pollution and barriers that restrict fish movement in the River Ching, which flows for around 10km through Epping Forest, Highams Park and Chingford before joining the River Lea.

In March 2026, volunteers from the Ching Action Group collected water samples from six locations along the River Ching. Scientists at Trace Biomonitoring analysed the samples using environmental DNA (eDNA), a technique that identifies wildlife from traces of genetic material in water.

The survey identified 1,885 unique species, including twelve fish species, four native amphibian species, 22 bird species and 16 mammal species.

Among the most significant discoveries was the European eel (Anguilla anguilla). Eel DNA was detected more frequently in the lower reaches of the river, with detections falling sharply further upstream. The results suggest that Falmouth Avenue Weir may be restricting fish movement and access to suitable habitats.

The survey also detected DNA from Atlantic cod and tuna was found, raising questions about potential sources of food waste or wastewater entering the river. Further investigation is needed to establish the sources, the Ching Action Group says.

The findings also revealed differences in river health, with indicators of cleaner freshwater habitats in upper stretches and greater evidence of organic enrichment and wastewater-related pollution further downstream.

The results from the River Ching add to discoveries from a separate survey by the Stonebridge Lock Coalition, also funded by Thames21, which detected more than 2,000 unique species in the 5.5km River Lea Diversion, including 24 fish species and the rare pond water-crowfoot (Ranunculus peltatus).

Thames21’s EMPOWER Rivers Programme Manager, Sam Bentley-Toon, said: “The River Ching has a fantastic story to tell. The group’s eDNA survey has revealed a diverse freshwater ecosystem, including the critically endangered European eel and the unusual Peach Blossom jellyfish, while also highlighting the pressures facing urban rivers.

“The unexpected detection of Atlantic cod DNA raises important questions about wastewater and food waste entering the river. By working with local communities and scientific partners, we can use this evidence to identify problems, target restoration and give wildlife a better chance to thrive.”

Ching Action Group Co-Lead, Natasha Furlong, said: “It’s been really fascinating to see the wide range of species even a small urban river like the Ching can support. We, and the wider community, are particularly thrilled that eels are still present in the lower reaches and we’re looking forward to using this data to support our case for improvement projects across the river.”

Stonebridge Lock Coalition’s Mariam Turay added: “I was interested to see that the common toad, frogs and grass snake were not detected in the eDNA samples. These findings can help us identify which species may need greater support and guide efforts to restore the River Lea Diversion and improve wetland habitats on our marshes.”

Ching Action Group says the findings will help inform future monitoring and restoration, including investigating pollution sources, improving habitats and addressing barriers to fish migration.

You can read the full River Ching eDNa report here

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