The invertebrate fauna of a physically modified urban river

The typical urban river is affected by various factors relating to water qu ality problems, physical habitat modification (for flood prevention) and fl ashy flows. These restrict macroinvertebrate biodiversity such that a few t olerant taxa may dominate and more sensitive organisms may be completely ab sent. This paper presents the findings of a year long, macroinvertebrate su rvey of an urban river catchment and investigates the effects of physical h abitat modification on macroinvertebrates using various analytical tools. I t is demonstrated that considerable variation in invertebrate species, abun dance, diversity and tolerance exists between different urban rivers, sites on the same river and individual sites at different sampling times. Analys is of paired sites with similar water quality, but contrasting physical hab itat, indicates that less modified sites support a slightly higher quality macroinvertebrate fauna (defined by biotic score and beta diversity) than h eavily engineered sites. It is concluded that water quality is the primary limiting factor of invertebrate biodiversity in the heavily urbanized River Tame catchment. The removal of heavy engineering structures may facilitate improvements to invertebrate fauna in urban rivers only in conjunction wit h improvements to water quality.