The gelatinous zooplankton in the pelagic system of the southern ocean: A review

The classic view of the Antarctic planktonic system has suggested that food web dynamics are dominated by the phytoplankton-krill food web link. Recent observations, however, have indicated that this is an oversimplification and that the Antarctic food web is much more complicated. In contrast to crustaceans, gelatinous zooplankton (hydroidomedusae, siphonophores, scyphomedusae, ctenophores, gymnosomatous pteropods and tunicates such as salps, doliolids, pyrosomes and appendicularians) have received little attention among zooplanktologists in spite of the high biovolume that they contribute to the zooplankton communities. Gelatinous zooplankton comprises a quarter of the planktonic species number collected in the Southern Ocean although many additional species remain undescribed. This review considers the published information on spatial distribution, abundance, wet biomass, carbon and lipid content, feeding ecology and biological associations. The sparse but significant information collected suggests that the ecological role of gelatinous zooplankton is underestimated in the Antarctic pelagic system. Sampling methods and investigations that correctly evaluate the impact of gelatinous organisms are extremely necessary for properly placing this group in the Antarctic trophic web.