Invasive mysids (Crustacea: Malacostraca: Mysida) in Hungary: distributions and dispersal mechanisms

By now three invasive Ponto-Caspian mysid species have established self-sustaining populations in Hungary: Limnomysis benedeni, Hemimysis anomala, and Katamysis warpachowskyi. At present, L. benedeni has the widest distribution of the three species in the country; it occurs in all of the three major rivers (Danube, Tisa, Drava) as well as in the Lake Balaton and other rather isolated waters, while H. anomala and K. warpachowskyi currently occur only in the water system of the Danube (sensu stricto). The occurrences in the recently revised samples date back the arrival of H. anomala to 1997, almost seven years earlier than the first previously known occurrence. Based on their habitat preferences, it is probable that the two recently appeared species have not exploited their potential; their distribution is limited by geographical and hydrological barriers. On the other hand, it is probable that H. anomala and K. warpachowskyi will never have a distribution as wide as L. benedeni already has in this area. Our records of L. benedeni in numerous isolated recreational fishing ponds (reservoirs and gravel-pit lakes) imply the functioning of an effective dispersal mechanism independent of navigation, which in our opinion could only be fish stocking. We can assume that this dispersal vector is available for the two recently appeared species as well, enabling them to colonize otherwise inaccessible parts of the drainage basin. As a preventive measure, we recommend the filtering of the water pumped into fish transporting tanks.