Abstract (eng)
Among other biota aquatic macrophytes are indicator elements of water quality, applied for the assessment of the ecological status of a waterbody in EU-Member States (Water-Framework-Directive 2000/60/EC, European Commission). In this study, the macrophyte communities of two fundamentally different waterbodies in Lower Austria are compared: the near-natural River Fischa and the artificial Wiener Neustädter Canal (Wiener Neustädter Kanal/ further onwards: WNC). Of special interest is their largely parallel course, crossing the landscape of the ‘Viennese Basin’ towards River Danube. Based on data from earlier surveys, a historical outline is also included. The applied method of mapping macrophytes is compliant with the European Standard (EN 14184:2014) for surveying macrophytes in running waters, following the concept of Kohler et al. 1971 and Kohler & Janauer 1995. By subsequent application of several approaches in multivariate statistics, the differences between the two water bodies are demonstrated. The results confirm the expectation that the aquatic macrophyte communities of the two waterbodies are significantly different concerning diversity and individual indicator species. Overall, River Fischa showed a greater species inventory, which is most probably caused by its more diversified environmental background, in contrast to the predominantly homogenous conditions in the artificial Wiener Neustädter Canal (WNC). The aquatic plant community composition of each running water varied over the documented surveys, spanning a time of 39 years. This periodical monitoring of macrophyte communities of whole river courses enables the detection of significant alterations and may be used to explain the consequences of past environmental changes on species composition.