Ponto-Caspian Amphipods and Mysids in the Inland Waters of Lithuania: History of Introduction, Current Distribution and Relations with Native Malacostracans

Abstract

Ponto-Caspian amphipods Pontogammarus robustoides, Obesogammarus crassus and Chaetogammarus warpachowskyi, and mysids Paramysis lacustris, Limnomysis benedeni and Hemimysis anomala were introduced into the Kaunas Water Reservoir located on River Nemunas, during 1960–1961. The crustaceans established sustainable populations there. Later transplanting of non-native species to over 100 lakes and two other water reservoirs was tried. Recently, sustainable populations of Ponto-Caspian amphipods and mysids inhabit these two water reservoirs. Non-native amphipods and mysids were also found in 6 and 8 lakes, correspondingly. Current distribution suggests that Ponto-Caspian amphipods can establish sustainable populations only in large mesotrophic lakes, while mysids can also survive in large and open eutrophic lakes. Both groups of these crustaceans can also live in well-drained lakes. In the habitats suitable for Ponto-Caspian amphipod P. robustoides, this amphipod excludes the native species Gammarus lacustris and G. pulex. There are also indicators suggesting that Ponto-Caspian mysid P. lacustris could have a negative effect on the native glacial relict mysid Mysis relicta.