Distribution of the Macrophyte Communities in the Danube Reflects River Serial Discontinuity

The Danube is the second-longest river in Europe that subjected to various man-made alterations, including those related hydro-power plants. We surveyed and analyzed presence abundance of macrophytes main channel from 2582 kilometers (rkm) 171 rkm. also assessed selected habitat parameters sampled stretches. Sixty-eight different plant species were recorded along entire course. Among neophytes, we found Elodea nuttallii, E. canadensis, Vallisneriaspiralis Azolla filiculoides. Based on similarity analysis, distinguished 15 communities, most which defined as associations, classified into 5 alliances represented three vegetation classes, namely rooted hydrophytes Potamogetonetea, pleustophytes Lemnetea marshes Phragmitetea. number species, well communities single stretches, varied Canonical correspondence analysis (CCA) revealed environmental explained 21% composition. CCA runs with neophytes 41% variance, current velocity, water transparency, bank structure significant variables. present study free-running sections are poor whereas impounded reaches mainly show an opposite result.