Great differences in peracarid crustacean density between the Arctic and Antarctic deep sea

Abstract

Density of peracarid crustaceans (Amphipoda, Cumacea, Isopoda, Mysidacea and Tanaidacea) from epibenthic sledge samples is presented from Weddell Sea stations (Yestkapp and Halley Bay ANT XV-3). These data from both the supranet (1–1.3 m above the ground) and epinet (27–60 cm above the ground) of the epibenthic sledge are compared with samples taken at comparable depths in the Arctic Ocean (ARK X-l and ARK XI-2) using the same gear. The latter showed 1 magnitude higher density values in similar depth zones in the Arctic Ocean, possibly reflecting the age of the environment and maturity of the benthic communities. Densities of Peracarida increased slightly with increasing depth in the Arctic, whereas they decreased with in-creasing depth in the Weddell Sea, especially at around 1,000 m in the epinet samples. Species richness of Peracarida is presented from the supranet samples for the first time in the Weddell Sea. In the Antarctic samples, Mysidacea with their hyperbenthic mode of life were generally collected more frequently in the supranet than in the epinet, while the other taxa were more abundant in the epinet, even at deeper stations at the shelf break.