Riverfly Monitoring

We are part of the Riverfly Partnership and run monthly Riverfly Monitoring at 2 LOHP sites - Hinderclay Fen in the east and Scarfe Meadows in the west. Volunteers don their chest waders and come rain or shine, wade into the Little Ouse to carry out a 3-minute kick sample followed by a hand search. They then spend at least 2 hours per site counting the catch.

Volunteer_undertaking_a_Riverfly_Survey_

Volunteer undertaking a Riverfly Survey on the Little Ouse at Scarfe Meadows

What are we looking for?

Invertebrates which can help to show the health of a river. Declines in water quality can be reflected by declines in invertebrate diversity and abundance. Nationally 8 invertebrate target groups are identified and counted, and so far in LOHP surveys we have identified 6 - namely Cased Caddis, Caseless Caddis, Mayfly (Ephemeridae), Olives (Baetidae), Stoneflies and Freshwater Shrimps (Gammarus).

Riverfly Surveying Hinderclay Fen.JPG

Sorting through the catch at Hinderclay Fen

Scoring

As you can imagine this involves a lot of counting and some estimating. Each species gets a score, which are totaled up at the end of the survey to reveal the overall score for that site.

1 to 9 of each species = 1 point

10 to 99 = 2 points

100 to 999 = 3 points

1000+ = 4 points.

 

The Environment Agency (EA) sets trigger levels for each site. If a survey breaches its trigger level, then it is reported to the EA immediately as it may be related to a more serious pollution incident.

 

What else do we find?

This monthly survey has also given us the opportunity to observe other interesting species. For example, for the first time since LOHP was founded, an eel was spotted swimming downstream at Hinderclay Fen. American Signal crayfish have also been caught in the sample at Scarfe Meadows which necessitated a visit from the EA to confirm. Other species seen are many bullhead of all sizes, sticklebacks, water hoglouse, damselfly nymphs, pea mussels, water mites, pond snails, ramshorn snails, leeches, alderfly, diving beetle, midge larvae and water boatmen.

 

All our results are logged and can be viewed on Riverfly Partnership website - just choose Little Ouse as your river and you can click between the 2 sites.

 

Want to get involved?

To come and see what we do and get involved contact us.