Use of Kohonen Self Organizing Maps (SOM) for the characterization of benthic diatom associations of the River Danube and its tributaries

Abstract

Benthic diatom flora of the River Danube was investigated along the river from the source streams to the end of the Hungarian stretch during a four-year period. Characteristic diatom community assemblages were established using KOHONEN Self-Organizing Map (SOM) algorithm. We found five sample clusters, arranged according to the location. The first three groups are located in the German-Austrian stretch, while the fourth and fifth groups are located in the Slovakian-Hungarian stretch. Characteristic species of the clusters 1 and 2 are Achnanthidium minutisimum (KUTZ.) CZARNECKI, Denticula tenuis KUTZ., Nitzschia fonticola GRUN., Psammothidium bioretii (GERMAIN) BUKHT. & ROUND, Melosira varians AG., Planothidium subatomoides (HUST.) BUKHT. & ROUND, character species of cluster 3 is Amphora pediculus (KUTZ.) GRUN., while character species of the clusters 4 and 5 are Nitzschia dissipata (KUTZ.) GRUN., Navicula cryptotenella LANGE-BERT., Cocconeis placentula var. euglypta (EHR.) GRUN., Rhoicosphenia abbreviata (AG.) LANGE-BERT., Nitzschia inconspicua GRUN. This arrangement is also well in agreement with the poorer water quality of the lower, and the better water quality of the upper stretch.