During the KuramBio expedition in 2012, macrobenthos samples were collected with an epibenthic sledge from 12 sites on the abyssal plain of the Northwest Pacific Basin adjacent to the Kuril-Kamchatka Trench (KKT) and on the western slope of the KKT, at depths between 4830 and 5780 m. In terms of the peracarid fauna, the NW Pacific abyss was found to be one of the richest and densely populated deep-sea regions of theWorld Ocean.With 482 species, 168 genera, 61 families and 5 orders, the superorder Peracarida was found to be the most diverse and one of the most abundant macrobenthic taxa in the collection. Of the taxa found, 3 genera and 386 (80%) species were apparently new to science, 30 genera and the family Dendrotionidae (Isopoda) being recorded for the first time in theNWPacific. The peracarid fauna composition at the abyssal depths of the KKT region was typical of the open, non-isolated abyssal plain. The Isopoda proved the most diverse and abundant peracarid order (245 species, 61.3% of the individuals), followed by the Amphipoda (79 species, 19.6%), Tanaidacea (77 species, 9.1%), the Cumacea (70 species, 9.7%), and the Mysida (11 species, 0.23%). The highest peracarid abundance (up to 1047 ind./1000 m2) was recorded on the western slope of the trench, abundances at the abyssal plain being lower (125–639 ind./1000 m2). The peracarid distribution in the area studied was affected by a complex of various factors, the food availability reflected in the Particular Organic Matter (POM) flux belonging to the most important ones. Specifically, increases in the peracarid abundance and species richness corresponded in most cases with a high sediment organic carbon content or the high surface productivity level in the area. As indicated by the sediment composition, the food input to the deep-sea system apparently differed between the sites sampled. On the trench slope, accumulation of organic debris, transported down the slope from shallower regions, played an apparently major role. The abyss in the northern and in the southern parts of the area sampled is influenced by the high surface productivity,resulting from the regional hydrography. The area east of the Middle Kuril Islands is likely influenced by the organic materialtransported from the Sea of Okhotsk through the Kuril Straits.
2019. V. 49(3). P. 1343-1360