Source of the Danube
As early as 1847 the following definition can already be found in the "Universallexikon des Großherzogtums Baden" (Universal Lexicon of the Grand Duchy of Baden): “Danube, the biggest river of Germany, rises at the Martinskapelle in a wild and lonely area of the Black Forest, is called Brege at its origin and forms the river Danube in Donaueschingen where it is unified with the Brigach." (German original: „Donau, der größte Fluß Deutschlands, entspringt bei der Martinskapelle in einer wilden und einsamen Gegend des Schwarzwaldes, heißt am Anfang Brege… und bildet erst in Donaueschingen, wo sie sich mit der Brigach vereinigt, die Donau.“)
Dikerogammarus villosus
"D. villosus" was originally found in the lower courses of large rivers in the Black Sea and Caspian Sea drainage basins. It has become an invasive species across central and western Europe, using the Danube river and its tributaries in its expansion. It is thought to have first escaped from the Danube in 1992 when the Rhine–Main–Danube Canal was opened and has since spread to nearly all the major rivers in western Europe, including the Rhône, Loire, Seine, Moselle, Meuse, Rhine and Main, as well as the Baltic Sea. It is unknown how the species is dispersed but it is probably related to shipping activity. It spread quickly through western Europe; found in the Rhine at the German–Dutch border (1995), the canals and rivers of northern Germany (1998), the Baltic Szczecin Lagoon (2001), the Moselle (2001), the Netherlands (2002), Lake Constance (2003), Lake Leman, the Rhine in France (2003), the (2003) and Lake Garda (2003). Its spread is thought to be related to the previous introduction of the zebra mussel, "Dreissena polymorpha" which it has evolved alongside. In September 2010, it was found in Grafham Water in Cambridgeshire, the first report of the species in the United Kingdom and it was found in Wales in November 2010.