Abstract
When we decide only the first and second taxa in their relative abundance in an attached diatom assemblage, we can obtain the DAlpo (diatom assemblage index to organic water pollution)approximate value and the saprobic level in a saprobic system of the investigated site from proposed tables. We think the method will receive wide application as a simple biological simulating method for organic water pollution, and also for paleolimnology.
The diatom assemblages in which the predominating taxo n belongs to Achnanthes are usually representative ones in clean water such as xenosaprobic and oligosaprobic area with over 50 in DAlpo value. However, Achnanthes exigua and A. minutissima var. saprophila occurred respectively in polluted waters from a-mesosaprobic to polysaprobic as the most dominant taxon. The assemblage in which the predominating taxon belongs to Anomoeoneis appeared in α-oligosaprobic standing waters, to Aulacoseira in both δ-mesosaprobic flowing and standing waters, and to Melosira in oligosaprobic flowing waters.
