Biol Invasions (2009) 11:1989–2008 DOI 10.1007/s10530-009-9491-7 ORIGINAL PAPER The river Rhine: a global highway for dispersal of aquatic invasive species Rob S. E. W. Leuven Æ Gerard van der Velde Æ Iris Baijens Æ Janneke Snijders Æ Christien van der Zwart Æ H. J. Rob Lenders Æ Abraham bij de Vaate Received: 15 February 2008 / Accepted: 19 February 2009 / Published online: 25 June 2009 Ó The Author(s) 2009. This article is published with open access at Springerlink.com Abstract The river Rhine is heavily influenced by changing communities, affecting the food webs and human activities and suffers from a series of forming new constraints on the recovery of the native environmental constraints which hamper a complete biodiversity. From the eighteenth century onward, in recovery of biodiversity. These constraints comprise the freshwater sections of the river Rhine, a total of intensive navigation and habitat modification by 45 non-indigenous macroinvertebrate species have hydraulic engineering. Improving water quality while been recorded. The average number of invasions per these constraints remain in place has led to increased decade shows a sharp increase from\1 to 13 species. colonization by aquatic invasive species. This ten- Currently, the contribution of non-indigenous species dency has been accelerated by the construction of to the total species richness of macroinvertebrates in canals connecting river basins. Over the last two the river Rhine is 11.3%. The Delta Rhine and Upper centuries, the total surface area of river catchments Rhine exhibit higher numbers of non-indigenous connected to the river Rhine via inland waterways species than other river sections, because the sea has been increased by a factor 21.6. Six principal ports in the Delta Rhine and the Main-Danube canal invasion corridors for aquatic species to the river function as invasion gateways. Important donor areas Rhine are discerned. The extensive network of inland are the Ponto-Caspian area and North America (44.4 waterways has allowed macroinvertebrate species and 26.7% of the non-indigenous macroinvertebrate from different bio-geographical regions to mix, species, respectively). Transport via shipping and R. S. E. W. Leuven (&) Á I. Baijens Á J. Snijders Á G. van der Velde C. van der Zwart Á H. J. R. Lenders National Natural History Museum Naturalis, P.O. Box Department of Environmental Science, Institute for 9517, 2300 RA Leiden, The Netherlands Wetland and Water Research (Partner institute of the Netherlands Centre for River Studies), Radboud A. bij de Vaate University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, Ministry of Transport and Public Works, Institute for The Netherlands Inland Water Management and Waste Water Treatment e-mail: [email protected] (Partner institute of the Netherlands Centre for River Studies), P.O. Box 17, 8200 AA Lelystad, G. van der Velde The Netherlands Department of Animal Ecology and Ecophysiology, Institute for Wetland and Water Research (Partner Present Address: institute of the Netherlands Centre for River Studies), A. bij de Vaate Radboud University Nijmegen, P.O. Box 9010, 6500 GL Waterfauna Hydrobiologisch Adviesbureau, Oostrandpark Nijmegen, The Netherlands 30, 8212 AP Lelystad, The Netherlands 123 1990 R. S. E. W. Leuven et al. dispersal via man made waterways are the most flowing through the rift valley of the Rhine Graben important dispersal vectors. Intentional and uninten- that extends from Basel to Bingen with the rivers tional introductions are highest for the period 1950– Neckar and Main as major tributaries; (4) the Middle 1992. The cumulative number of non-indigenous Rhine, flowing through a narrow valley deeply species in time is significantly correlated with the incised in the Rhenish Slate Mountains and picking increase in total surface area of other river catchments up waters of the river Mosel at Koblenz; (5) the connected to the river Rhine by means of networks Lower Rhine, extending from Bonn to Lobith with of canals. The species richness of non-indigenous the rivers Ruhr, Emscher and Lippe as major macroinvertebrates is strongly dominated by crusta- tributaries; (6) the Delta Rhine in the Netherlands, ceans and molluscs. Invasive species often tolerate where the river divides into three major distributaries higher salt content, temperature, organic pollution called the Waal, Nederrijn, and IJssel (Fig. 1). The and current flow than native species. Spatiotemporal river provides services for transportation, power analyses of distribution patterns reveal that average generation, industrial production, urban sanitation, and maximum dispersal rates of six invasive spe- drinking water, agriculture and tourism, and is a cies vary between 44–112 and 137–461 km year-1, classic example of a multipurpose waterway (Van der respectively. Species arriving in upstream sections Velde and Van den Brink 1994; Cioc 2002; Uehlinger first show a shorter time lag between colonisation of et al. 2009). However, its biodiversity and ecological the Delta and Upper Rhine than species initially integrity are severely affected by these human arriving in downstream areas. Temporal analyses of activities (Van den Brink et al. 1990; Nienhuis macroinvertebrate assemblages in the littoral zones et al. 2002; Bij de Vaate et al. 2006; Leuven et al. indicate that native species are displaced by non- 2006; Nienhuis 2008; Uehlinger et al. 2009). indigenous species. However, established non-indig- In spite of ambitious and successful rehabilitation enous species are also displaced by more recent mass programmes aiming at improvement of water quality, invaders. restoration of riverine ecosystems and enhancement of habitat connectivity, the river still suffers from a Keywords Dispersal rate Á Invasion corridor Á series of environmental constraints which hamper a Macroinvertebrates Á Non-indigenous species Á complete recovery of biodiversity (Leuven and Shipping Á Species replacement Á Waterways Poudevigne 2002; Nienhuis et al. 2002; Bij de Vaate et al. 2006; Van der Velde et al. 2006a, b; Van der Velde and Bij de Vaate 2008). Examples of these constraints are intensive navigation and irreversible Introduction habitat modification by hydraulic engineering (e.g., canalisation and construction of groynes and stony The river Rhine is the primary artery of one of the banks). Improving water quality while these con- most important economic regions of Europe. The straints remain in place has led to increased coloni- river has a total length of about 1,250 km, a drainage zation of the river Rhine by non-indigenous species area of circa 185,260 km2 and an average discharge that spread their geographic distribution and caused of about 2,300 m3 s-1 (Uehlinger et al. 2009). Nine significant changes in composition, structure and states are in part or entirely situated within its ecosystem processes (Den Hartog et al. 1992; Bij de catchment (Austria, Belgium, France, Germany, Vaate et al. 2002; Haas et al. 2002; Van der Velde Italy, Liechtenstein, Luxemburg, the Netherlands et al. 2006a, b; Bernauer and Jansen 2006; Baur and and Switzerland). Six morphologically and ecologi- Schmidlin 2007; Van Riel et al. 2006b; Panov et al. cally distinct river sections are distinguished (Van der 2009). Velde and Van den Brink 1994; IKSR 2002; Uehlin- The introduction of non-indigenous species in the ger et al. 2009): (1) the Alpine Rhine and its river Rhine has occurred both intentionally and tributaries, i.e., the reach between the source (Lake unintentionally (Van der Velde et al. 2002). In the Toma) and Lake Constance; (2) the High Rhine that past, several species have been introduced for flows from lower Lake Constance to Basel, there aquaculture, fisheries or ornamental purposes. Exam- merging with the river Aare; (3) the Upper Rhine, ples of unintentional introductions are the release of 123 The river Rhine: a global highway for dispersal 1991 Fig. 1 Geographical location of various river Port of a Amsterdam b sections in the Rhine basin The Netherlands (a) and the river distributaries in the Delta North Sea Rhine (b) Port of Rotterdam Lobith Delta Rhine Lippe Meuse Ruhr Lower Rhine 50 km Belgium Scheldt Middle Rhine Germany Mosel Main Lux. Upper Rhine Neckar France Lake Constance High Rhine Borders Aare Austria Rhine basin Switzerland Alpine Rhine Italy species via ballast water or via transport on ship hulls This paper describes the development of invasion (Ricciardi and MacIsaac 2000). The ports in the corridors and the distribution of non-indigenous Rhine delta are important gateways for non-indige- macroinvertebrate species in freshwater sections of nous species (Bij de Vaate et al. 2002). Moreover, the river Rhine. The study is restricted to aquatic the wish to expand navigation routes across river macroinvertebrates that live in the main channel or basin boundaries has led to the construction of connected bodies of water in its floodplains. The navigation canals that connect the river Rhine with analysis of invasion pathways, vectors, dispersal previously isolated catchments of the Caspian Sea, rates, taxonomic richness and abundances in local the southern European seas (Azov, Black and Med- communities is undertaken. The following research iterranean Sea), the northern European seas (Baltic, questions are addressed: North and White Sea) and the Atlantic ocean (Galil et al. 2007; Panov et al. 2009). This network of 1. Which spatiotemporal developments in the Euro- waterways opened long distance dispersal routes for pean inland waterways and sea shipping routes aquatic species from several bio-geographic areas lifted barriers for dispersal of non-indigenous (Bij de Vaate et al. 2002; Van der Velde et al. 2002; species to the river Rhine? Arbacˇiauskas et al. 2008; Karatayev et al. 2008; 2. Which non-indigenous species have established Panov et al. 2009). in various sections of the river and what are 123 1992 R. S. E. W. Leuven et al. temporal patterns in their arrival, donor areas, species were collected: taxonomic group, species pathways and dispersal vectors? name, donor area, dispersal vector, pathway (invasion 3.