Amphipods of the Nemunas River and the Curonian Lagoon, the Baltic Sea Basin: where and which Native Freshwater Amphipods Persist?

Abstract

Native freshwater amphipods have recently been absent from the Curonian Lagoon. The only native amphipod species persisting in the Nemunas River is Gammarus varsoviensis. It occurs in the Lithuanian part of the river upstream from the Kaunas Water Reservoir, and must also live further upstream, in its Belarusian part. G. varsoviensis has also been recorded in two tributaries of the lower section of the Nemunas River, which is currently inhabited only by Ponto-Caspian invaders. The comparison of historical data and the current distribution of native amphipods in the Nemunas River and its tributaries suggests that G. varsoviensis must have been the dominant native freshwater amphipod species in the lower reaches of the Nemunas River and the Curonian Lagoon before the mass invasion of Ponto-Caspian amphipods. Another native amphipod Gammarus pulex could have also been present at some sites in the lower section of the Nemunas River. The discovery of G. varsoviensis in the Daugava River, Latvia, suggests that ...