Biomass of upper-interzonal copepod filter feeders in the Kurile-Kamchatka region

Vertical distribution of abundance and biomass of upper interzonal copepods Calanus cristatus, C. plumchrus, Eucalanus bungii, Metridia ochotensis and M. pacifica have been studied in the whole depth range of their occurrence. These species comprise 55 per cent of total plankton biomass in the 0-4000 m layer. The major part (90% of the population) of C. cristatus inhabit depths are above 3000 m, and of the other species - above 750-1000 m. Feeding of juveniles proceeds in the surface euphotic zone, and then adolescent animals descend to deep water. At depth 1000-2000 m they make up >40%, and at 2000-3000 m, about 20% of total biomass of plankton inhabiting these depths. Interzonal species serve as a food reserve for predatory deep-sea animals and as a close connection between the surface and deep-water communities that makes it possible to regard these communities as parts of a single biocoenosis.