ON THE OCCURRENCE OF OCEANIC TINTINNINES WITH PARTICULAR CONSIDERATION OF THE SPECIES AMPHORIDES-LAACKMANNI (JORGENSEN, 1924), (CILIOPHORA,OLIGOTRICHIDA, TINTINNINA) IN THE NORTHERN ADRIATIC SEA

Investigations into the occurrence of oceanic tintinnines in the north ern Adriatic Sea were carried out during 62 cruises between November 1 979 and September 1995. A contribution to the knowledge of the ecologi cal conditions behind the occurrence of oceanic tintinnines, particula rly a consideration of the species Amphorides laackmanni (Tintinnina) in the northern Adriatic Sea, is presented in this paper. Oceanic tint innines are usually very rare organisms and their occurrence in the no rthern Adriatic is connected with the inflow of oligotrophic water mas ses from the southern Adriatic in autumn. After exceptionally high fre shwater discharge from the Po River caused an intensive diatom bloom ( October 1993), in early November, with an intrusion of water of high s alinity from the south, the mass occurrence of the rare species A. laa ckmanni in northern Adriatic open waters was noted, with a maximum of 890 indiv..l(-1). This numerical abundance is the highest ever registe red for oceanic tintinnines in the Adriatic Sea. Therefore it may be a ssumed that oceanic tintinnines occasionally play an important role in the food web in the northern Adriatic pelagic community.