ON THE DISTRIBUTION AND ECOLOGY OF HOLOTHURIANS IN THE WEDDELL SEA (ANTARCTICA)

Species composition and ecology of holothurians on 52 stations in the Weddell Sea are described. A total of 26,833 specimens, belonging to 32 species, 22 genera, 7 families and 5 orders were collected during the Polarstern cruises ANT I, ANT II and ANT III. Two distinct groups showing different distributions, were identified by cluster analysis. In the first group, the majority of species belongs to the Aspidochirotacea and Elasipodida. They are adapted to soft bottoms and found at the base of the Antarctic Peninsula, in the Gould Bay area and in the Filchner Depression. The other group consists mainly of species belonging to the Dendrochirotida and individual representatives of the remaining orders. Substrates are sand, hard bottom and biogenic structures. This group maintains a higher species diversity, has a preference for shallower depths and has more species than the soft bottom group. A description of different spatial niches for several holothurians was possible using morphological features together with information obtained from under-water photographs. A comparison of the Weddell Sea species with those from East Antarctica and the area around the Antarctic Peninsula revealed close similarities for the depth range between 160 and 700 m.