Doc Maarten leads the survey.

Photo Kevan Martin


Doc Maarten' recalls:

"On the chilly day that was the 4th of March 2023, a hardy group of bug enthusiasts gathered at the Long Mead Barn with the mission to identify the invertebrates living in the Chil Brook, Limb Brook, Fish Pond and Wharf Stream.

This event was follow-up of the hugely successful 'Bugs in Brooks' Workshop led by Dr. Maarten ('Doc Maarten') van Hardenbroek van Amerstol of Newcastle University. Doc  Maarten is a local Eynsham resident (Ed: don't ask!). The plan is to make regular quarterly surveys of Eynsham's ponds and streams for invertebrates, which are important indicators of how polluted our water is.


bugs4Doc Maarten shows how to use a key to identify the species.
Photo Kevan Martin


All samples were collected with a standardised “kick sampling” method, which involves kicking the stream bed in front of a standard net for 3 minutes to expose and catch any animals hiding there. The group separated out different species and then counted how many different species were present (biodiversity). From our data we calculated the Walley Hawkes Paisley Trigg Index (WHPT Index), a water quality index that is used across the UK. The graph below shows some of the results where we compare our new data (collected in 2022 and 2023) with earlier data collected by the Environment Agency.

Analysis of NRN's 'Bugs in Brooks' samples of 2022 and 2023
compared to historic Environment Agency data.


The sad conclusion is that biodiversity seems to be in decline in several of the smaller brooks in and around Eynsham. Quite likely this is the result of the high amount of sewage spills in recent years. We will continue monitoring our streams and have planned two more ‘bugs in brooks’ identification sessions this year on Sat 10th June and Sat 9th Sept. If you are interested in water boatmen, lacewing larvae, or ramshorn snails - or just fancy a bit of pond dipping, please come along."


bugs5Hard at work
Photo Kevan Martin