OCCURRENCE OF A NEW PONTO-CASPIAN INVASIVE SPECIES, CORDYLOPHORA CASPIA (PALLAS, 1771)

Cordylophora caspia, a new Ponto-Caspian invasive species was found in Lake Balaton in August 2001. The aim of this study was to survey the distribution, abundance and life cycle of this species in Lake Balaton and to investigate its possible route of invasion. In Lake Balaton different substrata (stones, water lilies, reeds) were examined at several stations. Life cycle studies of C. caspia were done on specimens sampled at Tihany peninsula station. Colonies of C. caspia occurred at most sampling stations in Lake Balaton together with other invasive Ponto-Caspian invertebrates (e.g. the mussel Dreissena polymorpha and the amphipod Chelicorophium curvispinum). Colonies of C. caspia form menont stadia from December through April. Reproduction starts in May and lasts until November, the density ranged be-tween 6.44 to 25.78 ind. cm–2 of stone substrata. Lake Balaton is connected to Danube River via the Sió canal. Stones from the littoral zone of the Danube River were sampled in 2003, from Dunaföldvár to Mohács, to ascertain whether this waterway might be the source of the introduction of C. caspia to Lake Balaton. No individuals of C. caspia were found at any of the Danube stations. Key words: Cordylophora caspia, life cycle, stony littoral zone, Lake Balaton, invasive specie