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the GiGLer

The newsletter of Greenspace Information of Greater London CIC

River Citizen Scientists

Joe Pecorelli, Zoological Society of London

Riverfly-training | © ZSL

I’m pleased to write that my article on ZSL’s European eel monitoring project for the GiGLer in December 2012 successfully attracted new partners and volunteers to the project. I’m hopeful this article might do the same for another citizen science project ZSL are initiating. But first, let me bring you up to date with the latest news from our eel monitoring in the Thames region.

Last year, we moved to a new phase of the project – working with our citizen science partners to make physical improvements to London’s rivers to facilitate the upstream migration of eels. Two eel passes were installed, one on the River Darent and one on the River Hogsmill. We were delighted to trap elvers upstream of the new pass on the Hogsmill for the first time, soon after it was installed. We plan to continue work to open up more freshwater habitat to eels in the future.

ZSL’s new “London’s Rivers” project builds on the partnership and network of volunteers developed over three years of citizen science eel monitoring. With agreement from the Riverfly Partnership we will act as a regional hub to roll out and support the implementation of a river monitoring initiative on London’s rivers. In spring this year, volunteers were offered river monitoring training on the first two rivers to join the programme; the Crane and the Hogsmill.

The sampling method taught during the one-day training session is based on long established principles of water quality monitoring. Families of river invertebrates are allocated scores according to their sensitivity to pollution. When pollution enters a river, the highest scoring taxa are the first to be lost and the average score for the river falls. The riverfly scoring system is a simplified version of the technique that the Environment Agency use, based on only eight families of invertebrates.

Currently, the Riverfly Partnership’s River Monitoring Initiative is in use on over eighty rivers across the UK. In London, the initiative will bring together ZSL, citizen science volunteers and the Environment Agency to work in partnership. The sites to be monitored are agreed in advance with the Environment Agency and trigger levels; the minimum acceptable score for a sample; are set for each site. A sample that scores below the trigger level is first checked by ZSL freshwater ecologists before it is reported to the Environment Agency for further investigation. By sampling their local river every month, volunteers will build up an in-depth knowledge of its health and will be able to detect and record pollution events that might otherwise go undetected. Once a pollution event is detected and reported, the Environment Agency can further investigate its source and take appropriate action against the polluters.

There has never been a more important time to recruit more community volunteers into river management and train them in robust citizen science methods. There are an estimated 600km of rivers and streams lacing through Greater London, many of which are degraded both physically and chemically. Evidence from rivers such as the Wandle show that London’s rivers can be improved when members of the local community work in partnership with statutory agencies. Collectively, the capital’s rivers have the potential to provide one of the most significant spaces for wildlife in London and to allow Londoners to connect with nature. However, we need more people to work with us and help make this happen.

How to Get Involved

If you would like to volunteer to become a ZSL citizen scientist, or are interested in setting up the river monitoring initiative on your local river, we would be very interested to hear from you. Please contact

We would like to thank all our project partners and, of course, our dedicated band of citizen scientists.

Project partners

The Riverfly Partnership, Kingston University, The South East Rivers Trust, Medway Valley Countryside Partnership, North West Kent Countryside Partnership, Ham United, The Thames Rivers Trust, London Wildlife Trust, Friends of The River Crane Environment, Thames 21, The Wildfowl and Wetland Trust, The River Chess Association, Historic Royal Palaces, The Spelthorne Natural History Society, The Thames Anglers Conservancy and the Environment Agency

The ZSL Citizen Science programme is funded by the Crane Valley Partnership and the People’s Postcode Lottery.

Joe Pecorelli’s commitment to nature conservation was inspired by Sir David Attenborough and by spending much of his childhood in wellies standing in Fleet Pond, a Local Nature Reserve in Hampshire. Having previously travelled Europe setting up and curating public aquaria, Joe now manages citizen science projects for ZSL. He says it’s a fantastic job, and feels privileged to work alongside a wonderful, eclectic group of partnership organisations and dedicated volunteers.

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