The mix of animals is shifting
Watch Between 2005–2009 and 2020–2024, damselflies and common net-spinning caddisflies became rarer while dobsonflies and aquatic worms became regulars.
65% → 15%damselflies, share of surveys
47% → 92%aquatic worms, share of surveys
The total score hides a change in which animals live in the riffles.
Stoneflies (41% → 31%), damselflies (65% → 15%) and common net-spinning caddisflies (65% → 38%) were found less often, while aquatic worms (47% → 92%) and dobsonflies (24% → 100%) became regulars.
Each site's surveys now share fewer groups with its first five years (average similarity before and since 2013: Site 1 0.48 → 0.39, Site 2 0.57 → 0.45).
Some of this may come from changes in who sorts and identifies the animals, which the survey records cannot show.