ABUNDANCE OF GELATINOUS CARNIVORES IN THE NEKTON COMMUNITY OF THE ANTARCTIC POLAR FRONTAL ZONE IN SUMMER 1994

The species composition, abundance, vertical distribution, biovolume a nd carbon content of gelatinous nekton in the Antarctic Polar Frontal Zone are described from a series of RMT25 hauls collected from a serie s of 200 m depth layers between 0 and 1000 m. In total, 13 species of medusa, 6 species of siphonophore, 3 species of ctenophore and 1 speci es of salp and nemertean were identified. On average gelatinous organi sms contributed 69.3% to the biovolume and 30.3% to the carbon content of the samples, although the ranges were high (0 to 98.9% and 0 to 62 .6% respectively). The most important contributor to the biovolume and carbon content was the scyphomedusan Periphylla periphylla. Some spec ific associations and restricted vertical distributions were related t o trophic interactions among ostracods, amphipods and cnidarians. Obse rvations made near South Georgia showed that medusae and ctenophores w ere preyed upon by albatrosses and notothenioid fish respectively. The results support the premise that gelatinous organisms are a major and , at times, are the main component of the oceanic macroplankton/nekton community in the Southern Ocean.