Alongside regular water quality testing for phosphates, nitrates, other chemicals and E. coli, there's a new initiative coming to Bedfordshire looking at invertebrates in local brooks and streams. My wife and I recently took part in a training day where we learnt how to sample, sort and identify eight key invertebrates to help study the health of these local water bodies.
Citizen science for river health
The data collected is part of the Riverfly Monitoring Initiative, a nationwide citizen science programme. Through regular surveys long-term data on riverfly populations is collected, providing valuable information on the health of our rivers.
Riverflies are invertebrates that spend most of their life cycle living in freshwater. They are highly sensitive to changes in water quality, which makes them useful indicators of river health.
Local water bodies
Here in Shortstown our local water bodies include both parts of Elstow Brook (upstream and downstream) and Harrowden Brook. To look at them you might not think of them as teeming with life, but scratch the surface and the story might be quite different.
How the survey works
The survey involves sampling the water for 3 minutes, moving across and along the stream bed for 10m. The samples are taken in a way that reflects the composition of the stream, sampling shallow and deep (below knee high), fast and slow moving, and along the banks. Another 1 minute is spent collecting rocks and brushing any invertebrates off into the sampling net. The samples are then collected in a bucket, rinsed to clear silt and debris before being placed in a tray and sorted into types. Once the sorting and counting is completed the sample is returned to the water.
Eight different invertebrates are counted: caddisflies (cased and caseless), shrimp, stoneflies, mayflies, olives, blue winged olives, and flat bodied Heptageniidae. The number of each riverfly form the basis of a score that reflects the overall health of the water and over time a picture can be built about the stream or brook from which a trigger level can be set. If the score falls below the trigger level the appropriate agency can be informed and action taken.
The survey also looks for invasive species with names like the demon shrimp or the signal crayfish.
Get involved
You can read more about the survey and how to get involved on the website: The Riverfly Partnership
