Macroinvertebrate functional feeding group methods in ecological assessment

Six functional feeding group (FFG) indices applied in ecological assessment were tested for their accuracy in detecting impairment in 12 cases of disturbance on 11 streams in south-western Germany. Three metrics — percentage of predators, percentage of shredders and Rhithron-Ernahrungstypen-Index RETI — performed well in small highland streams up to five m width. The FFG metrics were compared to the taxonomic measures ‘percentage of Chironomidae’ and ‘percentage of ephemeropteran, plecopteran and trichopteran taxa’ (EPT) used the USA, and to a metric based on locomotion type (percentage of sessile taxa). As the implementation of such metrics implies the use of ecological data tables, some aspects of the pro and contra of European ecological lists published in recent years were critically assessed.