Danube-Auen National Park on both land and water, and other invertebrates, the total number of species in Donau-Auen National Park is estimated to be at least 5,000. Danube-Auen National Park Donau-Auen National Park () covers 93 square kilometres in Vienna and Lower Austria and is one of the largest remaining floodplains of the Danube in Middle Europe. The German word Aue (variant Au) means "river island, wetland, floodplain, riparian woodland", i.e. a cultivated landscape in a riparian zone. The words Aue and Au occur in a large number of German place names—including Donau, the German word for the Danube River—and refer to forests,
Commissions of the Danube River times, Two Light Vessels at the Mouths of the Danube." What resulted was the establishment of the CED as "an international financial agent with considerable independence . . . the novel prerogative was that it could go into the money market and contract loans." In 1866, the commission found itself in financial trouble because of the just-ended Austro-Prussian War. But it secured money by issuing bonds, offering the river tolls as security. "To be sure, the rate of 10 per cent was high, but the significant fact is that the joint agent of the nations was developing a real identity