Ecological benefits of creating messy rivers

This study explores the ecological effects of a woody bank revetment in an upper reach of the River Manifold, Staffordshire, UK. Significantly higher abundances of macroinvertebrates were recorded immediately downstream of the deciduous bank revetment compared with a reference site, in 3 out of 4 months surveyed. The watercourse at the revetment also had significantly higher species richness of aquatic fauna than the reference site in some months. While there was no evidence of spatial or temporal variation in aquatic species richness within the reference site during the study period, the species biodiversity of the sub-sample collected from the deciduous revetment zone was more varied: there was significantly higher Ephemeroptera/Plecoptera/Trichoptera (EPT) richness close to the woody bank. Additionally, three relatively rare mayfly species were exclusively associated with the woody revetment (Baetis niger, Ameletus inopinatus and Siphlonorus alternatus). Water temperatures were also found to be lower in close proximity to the revetment. These micro-scale effects suggest that revetments could deliver a range of conservation benefits, not least habitat creation and mitigation of rising river temperatures under climate change.