Wax And Wane Of Macrophytes

From 1993 to 2014 extensive investigations of the macrophyte vegetation in the Alte Donau were carried out. They included a yearly detailed mapping of water vegetation as well as periodical surveys of the submerged plant biomass. At the beginning of the investigations, an enormous decrease of the macrophyte vegetation could be registered compared to previous studies. The breakdown of the macrophyte vegetation was caused by the poor water quality at that time and reached its climax in 1995 when the Alte Donau was nearly free from macrophytes. To improve the situation a set of management measures was realized by order of the city of Vienna. This study shows the response of the macrophyte vegetation with regards to the development of the submerged biomass as well as to the observed changes in species composition.