Several chinese mitten crab (Eriocheir sinensis), invasive species, neozoon, crabs, juveniles move next to and in the shiny water of the Elbe and on stones, hide in the cracks of the rocks and the concrete bank stabilisation, mass migration upstream, flowing, moving water washes around stones and animals, river, water body, barrage of the Elbe in Geesthacht, Lower Saxony, Schleswig-Holstein, Germany