Investigation of benthic algal communities, especially diatoms of some Hungarian streams in connection with reference conditions of the water framework directives

Benthic diatom investigations of some Hungarian streams have been carried out in order to find reference sites in assistance to the ecological quality analysis of the different river types according to the Hungarian river typology. On the basis of the coevaluation of biological and chemical parameters, among the investigated streams, some part of Kemence stream seems to be the appropriate reference site for the classification of the highland, siliceous rivers of Hungary. However, further invastigations are needed for the selection of reference sites for the other types of Hungarian river typology. This is the most difficult in the case of lowland rivers, which are exposed to more severe anthropogenic impacts. Important is the question which biological parameters should be investigated and considered when assessing the ecological condition of our waters. In the United States, e.g. the assessment of the relative abundance of Achnanthidium minutissimum is quite widespread (Stevenson and Bahls 1999), the exte...