This “double-header” of pond and river dipping in the last week of September is now becoming well-established, well-attended and very popular, for all ages!
They found mostly invertebrates: pond skaters, greater and lesser waterboatmen, damselfly nymphs and mayfly nymphs, racing round the trays at high speed; also the transparent and eerie ghost / phantom midge larvae, waterlice, freshwater shrimps, water fleas and lots of big wandering pond snails. Stars of the show were the few menacing dragonfly nymphs - fierce carnivores with a fearsome reputation, and several handsome “newtpoles”, or efts, larval smooth newts (vertebrates, amphibians of course), hatched from eggs laid by their mothers in the spring, already with 4 strong legs but still having external gills, which disappear when they finally metamorphose into adults.
River dipping the following day held a special significance for chairman Dave Sage, recently qualified as BART (Bristol Avon Rivers Trust) River fly monitor for the Chew at Dapps Hill bridge, charged with the task of taking a monthly sample of 8 river flies (stonefly nymphs, 4 mayfly nymph species, 2 caddisfly larvae species, and freshwater shrimps), and reporting results to the Trust. This was carried out before the main event, producing a biotic index score of 6, a good score for this stretch of river.
The river dipping later carried out by the over 7’s and their parents supported these results: Stonefly nymphs & burrowing mayfly nymphs were present in most samples, comparable with last years good results. Some samples contained good numbers of cased & uncased caddis fly larvae (including Hydropsyche species), more evidence of well-oxygenated water. Bloodworms, sludgeworms, leeches and other polluted water indicators were present in low numbers, reflecting a continuing healthy river ecosystem here. A few samples even contained fish - bullheads and minnows - which swam into the nets of their own accord! It’s no wonder this stretch of river has herons & kingfishers!
A big thanks to Rita, Liz and Julia from the committee for their superb support with both events, as well as to Anna, Rosie, Isla and Aoife from Wellsway School Green Team (and bronze D of E) for helping the younger participants with sampling and identification.
Dave Sage
Keynsham Group
Avon Wildlife Trust
Registered charity 280422
Email: keynshamawt@gmail.com
