Report on Harmonisation of freshwater biological methods

21. Some countries like France, Estonia and Sweden use the OMNIDIA software fortaxonomic identification (Lecointe et al., 1993), which allows the calculation of agreat number of diatom indices and contains a systematic and an ecological database.Consultation of other literature is also recommended for the algal identification, likefloras, identification guides and iconographs appropriated to the habitats andgeographic region under consideration.22. The recording of abundance is usually expressed as the number of cells per taxonper sample on occasions using abundance classes. Relative coverage of the river bedis also mentioned by Norway.23. With respect to the non-diatom group, Austria estimates abundance in microscopepreparations and estimates coverage of channel bed by macroalgae. Germany is alsodeveloping a method which includes an abundance specification in 5 classes based ina verbal descriptions.24. Three different categories of assessment methods were identified in this review:biotic indices, assemblage/community assessment and multimetric indices.25. For phytobenthos, biotic indices are the most common assessment methodincluding 5 different approaches all based in diatom assemblages, applied to 9countries. Only one country is using assemblage/community assessment (Austria) andtwo are using multimetric indices (Estonia and Germany).26. The Biological Diatom Index’ (IBD- Indice Biologique Diatomées; AFNOR,2000) is the only standardized method applied on a national level. This has been usedin France as part of a monitoring program since 1999. Other countries, like Spain andEstonia are also using IBD as their assessment method, while Sweden use “TheGeneric Diatom Index” (Bourrelly, 1981) and the “Specific Pollution SensitivityIndex” (Cemagref, 1982). Both are diatom indices of French origin, and assess thegeneral quality of the watercourses. The IBD is used to assess different pressures likeorganic pollution, eutrophication, acidification and toxic substances.27. Another index commonly used is the British Trophic Diatom Index (TDI - Kellyand Whitton, 1995; Kelly et al., 1998). This index is based on diatoms and provides amonitoring tool that separates the influence of nutrients from that of other constituentsof sewage discharges. Its application comprises both an indication of eutrophication72