Mayflies (Insecta : Ephemeroptera) and the assessment of ecological integrity: a methodological approach

Mayflies (Ephemeroptera) play an important role in almost all undisturbed f reshwater communities and their larvae frequently form a considerable part of the material sampled during biomonitoring procedures. Mayfly taxa are wi dely accepted as bioindicators for water quality and form an integral part of standardized systems for the saprobic evaluation of running waters. Neve rtheless, successful interpretation of data depends heavily on sampling str ategies and the technical concepts adopted therein. The following paper dis cusses current problems affecting the correct assessment of mayfly communit y structure and proposes basic requirements to improve the meaningfulness o f limnological routine sampling with regard to Ephemeroptera. The topics co vered include: mayfly diversity in different types of freshwater communitie s in Europe; natural habitats and sampling sites/sampling strategies; life cycles and minimum sampling frequency; level of identification and interpre tation of data.