Riverfly Monitoring Initiative

Alongside regular water quality testing for phosphates and nitrates, we are going to start surveying Riverfly populations in the local brook.  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. 

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.  To look at it you might not think your local stream is teeming with life, but scratch the surface and the story might be quite different. 

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 eight types 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. 

Check out The Riverfly Partnership at https://www.riverflies.org/