New records Southern Baltic

New records of Cercopagis pengoi (Cladocera, Crustacea) are reported for the first time from the central and western part of the Polish zone of the Baltic Sea. About 100 exotic species have been recorded in the Baltic Sea (Leppäko-ski et al. 2002). One of the most recent non-indigenous species in the Baltic Sea is the fishhook water-flea Cercopagis pengoi, a predatory cladoceran native to the Ponto-Caspian region (Mordukhai-Boltovskoi & Rivier 1987). The invasion history of C. pengoi dates back to the early 1990s. Recorded for the first time in the Baltic Sea in the Gulf of Riga and in the open Gulf of Finland in 1992 (Ojaveer & Lumberg 1995, Krylov et al. 1999), the fishhook water-flea subsequently expanded its distribution to other areas of the Baltic Sea (Avinski 1997, Gorokhova et al. 2000). In 1999 it was found in Polish waters: the Vistula Lagoon (Hornatkiewicz-Żbik 1999) and th