Benthic diatom communities in Estonian rivers

Epilithic, epiphytic and epipelic (soft bottom) diatom communities were studied in three rivers (Ahja, Selja and Valgejõgi). Although the total number of recorded diatom taxa was 165, the studied diatom assemblages consisted of 32, 26, or 28 constant taxa in the three studied rivers, respectively. The dominating diatoms were Achnanthidium minutissimum, Cocconeis placentula, Amphora pediculus, Staurosirella pinnata, Planothidium lanceolatum, and Diatoma moniliformis. The cluster analysis of three different diatom communities yielded different results. The clustering of the composition and structure of the epilithic diatom community brought out three principal groups of river reaches differing in the trophic status of water. Hence the epilithic community of diatoms can be recommended for the monitoring of Estonian running waters.