抄録
Ecological chracteristics of the diatom assemblage in which the predominating taxon belongs to Nitzschia, Pinnularia, Surirellaand Synedra are the following.
Nitzschia: Thirteen taxa belong to Nitzschia occurr ed as the predominating taxon in 391 sites (30%) among 1287 sampling sites. Almost all the taxa occur in oligosaprobic and β-mesosaprobic waters with 30-84 in DAIpo marks, however, Nitzschia palea is one of the few saprophilous taxa among them and occur frequently in polluted waters with less than 29 in DAlpo marks.
Pinnularia: Pinnularia brauniivar. amphicephala is generally known as an acido biontict axon, moreover, this is a typical saprophilous taxon.
Surirella: Two taxa belong to Surirella occurred as the predominating taxon in slightly polluted flowing sites with 30-51 in DAIpo marks.
Synedra: The diatom assemblage in which the predominating taxon belongs to Synedra has a tendency of occurring in clean waters. Among the seven taxa appeared as the predominating taxon, Synedra inaequalis and S. ulna var. ulna occurred in xenosaprobic and β-mesosaprobic flowing waters respectively, S. acus, S. delicatissima var. deticatissima, S. rumpens var. familiaris, S. rumpens var. fragilarioides and S. amphicephala in oligosaprobic standing waters.
