Gammarus tigrinus Sexton, 1939 continues its invasion in the Baltic Sea: first record from Bornholm (Denmark).
The paper provides a new record of the North-American invasive amphipod Gammarus tigrinus from the Bornholm island (Denmark), accompanied by DNA barcodes. We found this species in two locations 9 km apart: 1. Baltic Sea in Svaneke, 2. Østersøen stream, Nexø. Our finding shows further range expansion of this species in the Baltic Sea. Earlier findings of this invader from Germany (1985), Poland (1988), Lithuania (2004), Latvia (2011), Estonia (2003), Finland (2003) and Russia (2005). However, taking into account, the current locality, spreading directions and speed it is only a matter of time, before the species colonizes coastal waters all around the Baltic Sea and its islands.