Description: Shallow marine benthic communities around Antarctica show high levels of endemism, gigantism, slow growth, longevity and late maturity, as well as adaptive radiations that have generated considerable biodiversity in some taxa1. The deeper parts of the Southern Ocean exhibit some unique environmental features, including a very deep continental shelf2 and a weakly stratified water column, and are the source for much of the deep water in the world ocean. These features suggest that deep-sea faunas around the Antarctic may be related both to adjacent shelf communities and to those in other oceans. Unlike shallow-water Antarctic benthic communities, however, little is known about life in this vast deep-sea region2, 3. Here, we report new data from recent sampling expeditions in the deep Weddell Sea and adjacent areas (748-6,348 m water depth) that reveal high levels of new biodiversity; for example, 674 isopods species, of which 585 were new to science. Bathymetric and biogeographic trends varied between taxa. In groups such as the isopods and polychaetes, slope assemblages included species that have invaded from the shelf. In other taxa, the shelf and slope assemblages were more distinct. Abyssal faunas tended to have stronger links to other oceans, particularly the Atlantic, but mainly in taxa with good dispersal capabilities, such as the Foraminifera. The isopods, ostracods and nematodes, which are poor dispersers, include many species currently known only from the Southern Ocean. Our findings challenge suggestions that deep-sea diversity is depressed in the Southern Ocean and provide a basis for exploring the evolutionary significance of the varied biogeographic patterns observed in this remote environment.

Description: Three expeditions were performed in the framework of ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) in order to understand the Southern Ocean (SO) biodiversity of the Isopoda and to investigate faunal connections with other deep-sea areas in the world oceans. We sampled mainly in the Atlantic sector of the SO (Drake Passage along the Shackleton Fracture Zone, off Elephant Island, in the South Shetland Islands area, in the northwestern Weddell Sea, and at the South Sandwich Islands), but also took two stations in each Bellingshausen Sea and Cape Basin. In total, three expeditions yielded 13,046 specimens of Isopoda. During ANDEEP I-II 5525 specimens and 317 species of Isopoda were sampled, and 7521 specimens and 496 species were discriminated from the ANDEEP III material. Overall, Isopoda comprised 35% of all Peracarida sampled, and we identified 674 isopod species from the 40 deep SO stations. Eighty-nine of these species (13%) were known, the others (585 species) were new to the area, and most of these were new to science, 43 genera being recorded for the first time. Asellota comprised 97% of all ANDEEP Isopoda, and Munnopsidae were the most dominant family, followed by the Desmosomatidae, Haploniscidae, and Ischnomesidae. To our present knowledge 87% of the SO deep-sea Isopoda are apparently "endemic". Most species did not occur frequently in the samples. Abundance was higher at the shallower ANDEEP stations and highest in the Powell Basin at station 133, and generally decreased with increasing depth. Species richness was highest with 92 species at the bathyal station 80-9 in 3100 m off Kapp Norvegia, in general, species richness was highest at around 3000 m depth with 216 species found at all ANDEEP stations, and 92 species sampled at a single station in 3100 m depth. The cluster analysis of the isopod composition from ANDEEP revealed in general terms that the abyssal Weddell-Sea stations build one cluster. Depth turned out to be the most important abiotic factor for the species composition reported. Most of the species frequently occurring at the abyssal stations are Munnopsidae, which can swim. The SO deep sea differs in faunal composition from the shelf, and few isopod species occur at many stations, while most species only occur at few. The reasons for these findings are unknown. Future studies should focus on the functional role of the frequent species of the SO deep-sea ecosystem and food-web.

Description: In this study isopod species of the Ross Sea were investigated. Literature until May 2008 was checked to provide an overview of all known and described species in the Ross Sea. This species checklist was then enlarged through material of the 19th Italica expedition in 2004. During this expedition for the first time a small mesh net (500 µm) was used. Nine thousand four hundred and eighty one isopod specimens were collected during this expedition. Through this material the number of isopod species in the Ross Sea increased from 42 to 117 species, which belong to 20 families and 49 genera. Fifty-six percentage of the isopods species collected during the Italica expedition are new to science. The zoogeography of the 117 species was investigated. A non-transformed binary presence-absence data matrix was constructed using the Bray-Curtis coefficient. The results were displayed in a cluster analysis and by nonmetric multidimensional scaling (MDS). This paper gives a first insight into the occurrence and distribution of the isopod species of the Ross Sea.