… a blog written by Sarah Hawkes, Buglife’s Natur am Byth! Scarce Yellow Sally Conservation Officer
Surveyors: John Davy-Bowker and Olly Davy Bowker
The survey of the riverbed is now complete for 2024, despite the atrocious conditions early on which delayed us by almost three weeks whilst the rain kept falling and the River Dee remained high. So high in fact, that John Davy-Bowker, our surveyor in the river, would have been over his head had he gone in; that’s if he’d been able to keep his feet on the bottom in the fast-flowing waters!
Even with the delays and waits for the levels to subside, the safety lines were well used, the dry suit was a permanently worn piece of John’s kit and many sites had to be visited multiple times to review levels. The work was slowed, too, by the difficult fast flow conditions. However, for the last couple of sites the sun came out and the weather was glorious, if chilly.
On shore, apart from manning the safety lines, Olly Davy-Bowker kept things going with identifications and ensuring the equipment was all to hand. The Chester Zoo Team (Hannah Thomas, Joe Hutchins and Jamie Keith) not only helped get the survey work done but carried out detailed water sampling at each site.
The substrate at each site varied quite a lot, from small sandy gravels to large blocks, (the latter making kick sampling pretty unpromising, though once the samples had come ashore, we found a good deal of life).
We found good numbers of a major food species for Isogenus at many sites, Olive Uprights (Rhithrogena semicolorata). Some interesting additional species came to shore in the sample nets, including a few leech species, Brook Lampreys, Bullheads, and some lovely caseless caddis larvae.
Star of the non target species, however, was a good sized find of Yellow Mayfly larvae (Potomanthus luteus), at 2 sites which confirmed the establishment of this Endangered species in the Dee.
Best of all though, we found our target, the Scarce Yellow Sally (Isogenus nubecula) at three sites, (including at one new site) in good numbers. This is the best of news – we had wondered how anything could have held on in those endless months of heavy rain and raging river flows! Clearly, however, Sally and her riverbed associates are made of stern stuff.
All Image Credits: Sarah Hawkes. From left to right: Pic 1 – Scarce Yellow Sally (Isogenus nebucula) taking a look; Pic 2 – Team Overton Weir; Pic 3 – Caseless caddis Rhyacophila sp.; Pic 4 – JDB and Olly DB surverying for Isogenus at Erbistock; Pic 5 – Olive Uprights (Rithrogena sp.) larvae; Pic 6 – Kick sampling at Froncysyllte; Pic 7 – Yellow Mayfly larva (Potomanthus luteus) in a teaspoon
