Gelatinous invertebrate zooplankton of the South Adriatic: species composition and vertical distribution

The species composition and vertical distribution of gelatinous invertebrate zooplankton were investigated from April 1993 to June 1994 in the 0-1000 m water column at a deep-sea station in the northern part of the South Adriatic Pit. Fifty-seven species were identified: 11 hydromedusae, 13 calycophores, 3 ctenophores, 3 heteropods, 10 pteropods, 8 polychaetes and 9 chaetognaths. The pteropod Desmopterus papilio and the heteropod Protatlanta mediterranea were recorded for the first time in the Adriatic Sea. Data from this study differed from those of previous investigations in the South Adriatic as regards the numerically dominant polychaete and pteropod species. All investigated groups generally were more abundant in the upper 100 m and decreased with depth. Different vertical distributions of life stages were observed for those species that occupy a wide depth range: Persa incolorata, Solmissus albescens, Limacina inflata, Cymbulia peroni, Pelagobia longicirrata, Sagitta lyra and Sagitta decipiens.