Invasive Mollusc, Crustacean, Fish And Reptile Species Along The Hungarian Stretch Of The River Danube And Some Connected Waters

Abstract

The River Danube, connected to the Rhine catchment via the Rhine–Main–Danube Canal, is part of a significant aquatic invasion corridor in Europe between the North Sea and the Black Sea. Among its aquatic fauna molluscs, crustaceans and fishes represent the most prominent groups of invaders in terms of species number and biomass. The listed reptile species is in the list of the 100 worst invasive species in the world. This paper reviews available information about the arrival time, way of introduction, distribution area, dominance in communities, ecosystem functions, and impact on the native fauna along the Hungarian stretch of the Danube of 43 non-indigenous species having arrived from several continents as Africa, Asia, Europe, North America, or New Zealand. Transport vectors that contribute to the introduction and the rapid spread of alien species are river shipping, deliberate crayfish and fish stocking, pet trade, release from aquaria, and food consumption. The invasions of the studied species have a potential to alter the structure and the function of Danubian ecosystems and create new biodiversity and economic problems. Due to the international importance of the River Danube, efforts should be made to prevent new invasions and manage the existing invaders along the whole river.