Invasive species often tolerate higher salt content, temperature, organic pollution and current flow than native species. The species richness of non-indigenous macroinvertebrates is strongly dominated by crustaceans and molluscs. The cumulative number of non-indigenous species in time is significantly correlated with the increase in total surface area of other river catchments connected to the river Rhine by means of networks of canals. Intentional and unintentional introductions are highest for the period 1950–1992. Transport via shipping and dispersal via man made waterways are the most important dispersal vectors. Important donor areas are the Ponto-Caspian area and North America (44.4 and 26.7% of the non-indigenous macroinvertebrate species, respectively). The Delta Rhine and Upper Rhine exhibit higher numbers of non-indigenous species than other river sections, because the sea ports in the Delta Rhine and the Main-Danube canal function as invasion gateways. Currently, the contribution of non-indigenous species to the total species richness of macroinvertebrates in the river Rhine is 11.3%. The average number of invasions per decade shows a sharp increase from <1 to 13 species. From the eighteenth century onward, in the freshwater sections of the river Rhine, a total of 45 non-indigenous macroinvertebrate species have been recorded. The extensive network of inland waterways has allowed macroinvertebrate species from different bio-geographical regions to mix, changing communities, affecting the food webs and forming new constraints on the recovery of the native biodiversity. Six principal invasion corridors for aquatic species to the river Rhine are discerned. Over the last two centuries, the total surface area of river catchments connected to the river Rhine via inland waterways has been increased by a factor 21.6. This tendency has been accelerated by the construction of canals connecting river basins. Improving water quality while these constraints remain in place has led to increased colonization by aquatic invasive species. These constraints comprise intensive navigation and habitat modification by hydraulic engineering. Don’t hesitate! European summer is prime-time for cruising so make sure you grab our last-minute 2019 deals so you can spend your days cruising on tranquil waters.The river Rhine is heavily influenced by human activities and suffers from a series of environmental constraints which hamper a complete recovery of biodiversity. If you forget, the boat might have extras. They will help you zoom in on those fairytale castles scattered throughout the landscape. Make the most out of your river cruise by bringing some binoculars.Lueftner, Regina, or Nicko offer cheap and cheerful comfort cruises, or if you like living the life of luxury, AmaWaterways, Scenic and APT are for you! There is a wide range of cruises to choose from.It would be a crime not to sample the delicious flavours on your cruise ship! Indulge in a sweet stroopwafel in Amsterdam, a tasty trdelník in Prague, or a mouthwatering macaron in France.Get up at least once to watch the sunrise! Remember to wear warm clothes as it can be chilly as the mist rises up from the river and the sun peeks over the hills to wake up all the birds along the banks.Choose from the delightful Danube for cultural immersion, the relaxing Rhine for an enchanting adventure or the stunning Seine for an intimate tour of Paris, there are many possibilities to ensure that you have the best river cruise experience.
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