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: The remote South Sandwich arc is an archipelago of small volcanic islands and seamounts entirely surrounded by deep water and about 600 km away from the closest island, South Georgia. As some of the youngest islands (〈 5 m.y.) in the Southern Ocean they are ideal for studying colonization processes of the seabed by benthic fauna, but are rarely investigated because of remoteness and extreme weather. The current study attempted to quantify the richness and abundance of the epibenthic macrofauna around the Southern Thule group by taking five epibenthic sledge samples along a depth transect including three shelf (one at 300 m and two at 500 m) and two slope stations (1000 and 1500 m). Our aim was to investigate higher taxon richness and community composition in an isolated Antarctic locality, since recent volcanic eruptions between 1964 and 1997. We examined patterns across all epibenthic macrofauna at phylum and class levels, and investigated trends in some model groups of crustaceans to order and family level. We found that abundance was highest in the shallowest sample and decreased with depth. Shelf samples (300 and 500 m) were dominated by molluscs and malacostracans while at the deeper stations (1000 and 1500 m) nematodes were the most abundant taxon. Surprisingly, the shallow shelf was dominated by animals with restricted dispersal abilities, such as direct developing brooders (malacostracans) or those with lecithotrophic larvae (bivalves of the genus Yoldiella, most bryozoan species). Despite Southern Thule's geological youth, recent eruptions, and its remoteness the shallow shelf was rich in higher taxa (phyla/classes) as well as orders and families of our model groups. Future work at higher taxonomic resolution (species level) should greatly increase understanding of how life has reached and established on these young and highly disturbed seabeds.