Invasion of the Baltic Sea basin by the Ponto-Caspian amphipod Pontogammarus robustoides and its ecological impact

Range extensions of amphipods and other aquatic macroinvertebrates in the inland waters of Europe have been mainly facilitated by the interconnection of river basins through artificial canals, intentional introductions, and shipping. Among the most successful and ecologically aggressive aquatic immigrants are Ponto-Caspian amphipods from the family Pontogammaridae. The southern and central water corridors connecting the Black Sea with the North and Baltic seas were used for active westward migration by Dikerogammarus haemobaphes (Eichwald) and Dikerogammarus villosus (Sowinsky) (see Bij de Vaate et al. 2002, Jazdzewski and Konopacka 2002), whereas the expansion across European inland waters outside native ranges by two other pontogammarid species, Pontogammarus robustoides (G. O. Sars) and Obesogammarus crassus (G. O. Sars) started from the point of their first intentional introduction in the Baltic Sea basin.