ECHINOGAMMARUS TRICHIATUS (MARTYNOV, 1932) - A NEW PONTO-CASPIAN AMPHIPOD INVADER IN POLAND WITH REMARKS ON OTHER ALIEN AMPHIPODS FROM THE ODER RIVER

Echinogammarus trichiatus (Martynov, 1932), was recorded for the first time in Poland, in the lower Oder River, in September 2012. The species has most probably reached the Oder through the Havel-Oder Canal, being a part of the German inland canal system in which it has been already present since 2006. We found individuals of both sexes, including ovigerous females and juveniles. The structure of its population and its abundance (second dominant gammarid species on the site) suggests that it is well established and, thus, we may expect further invasion of the species into Polish waters. Six other invasive species of amphipods were recorded along the course of the Oder. Four of them, Dikerogammarus villosus, D. haemobaphes, Gammarus tigrinus and Chelicorophium curvispinum, occurred in the entire studied section of the river. Two, Pontogammarus robustoides and Obesogammarus crassus, were found only in the lowest part of the Oder.