The influence of environmental factors on microbial community composition in a mountain river

Microbial communities are known to be sensitive indicators for water pollution and biomonitoring assessment. In this study, we aimed at observation of microbial abundance and community composition in the mountain river Morávka. The results showed temporal and spatial changes in total cell abundance (TCA). TCA reached 10⁵–10⁶ cells/ml, increasing values were detected towards the mouth with maxima in summer and autumn months. Out of Eubacteria Betaproteobacteria and Cytophaga-Flavobacterium were found to predominate, while Archaea represented only 4.8 % of TCA. Along the flow three distinct patterns of phylogenetic groups' share were revealed related to increasing pollution. Microbial community composition was found to be most significantly dependent on the elevation and the sampling date. Moreover, environmental variables like O₂ saturation, water temperature, trophic potential and pH influenced microbial community as well. Statistical analyses showed significant seasonal (23.5 %) and spatial (4.7 %) changes in microbial community composition.