The Invasive Amphipod Gammarus tigrinus Sexton, 1939, in Puck Bay

Rapidly expanding human activities in the Baltic Sea area in the last 100 yr has created environmental conditions conducive to invasions of benthic invertebrate species, including Gammarus tigrinus, which first appeared in the Szczecin Lagoon of the Baltic Sea in 1975 and by summer 2001 was found in Puck Bay. Native Gammarus species appear to have been displaced by invasive species such as G. tigrinus. Individuals from the Hel Peninsula coastal zone were larger than those from the inner and southern part of Puck Bay. In the southern and western parts of the bay, native species currently coexist withG. tigrinus but displacement is expected here as well because G. tigrinus reproduces prolifically and is resistant to pollution and changing environmental conditions.