Permalink : http://hdl.handle.net/2115/48638

KEYWORDS : Bathypelagic;Mesopelagic;Oxygen minimum zone;Species diversity;Vertical flux

To evaluate vertical changes in the abundance, biomass, and community structure of copepods and their effect on material flux, stratified samples were collected at 15 discrete depths between 0 and 3,000 m with a fine mesh size (60 μm) Vertical Multiple Plankton Sampler in the southern Bering Sea and northern North Pacific on 14 and 16 June 2006. Both copepod abundance and biomass decreased with increasing depth, and both decreases were described well with a power model. A total of 72 calanoid copepod species belonging to 34 genera and 15 families were identified in the Bering Sea and 63 species belonging to 32 genera and 13 families were identified in the northern North Pacific. At both stations, the copepod communities comprised five groups that had distinct vertical distribution patterns. The groups at 500-1,500 m were adapted to the oxygen minimum zone, and copepod carcasses outnumbered living specimens at 500-750 m in the northern North Pacific and at 750-1,000 m in the Bering Sea. Oxygen levels were very low in the minimum zone in both regions, so the occurrence of a specialized community and the abundance of carcasses are considered to be a special characteristics at these depth. Based on metabolic rates estimated from an empirical equation, copepods were estimated to consume 20±13% (mean±sd) of the particle organic carbon flux throughout the water column in the Bering Sea and 32±19% of the flux in the northern North Pacific. The feeding impact of copepods was estimated to be greatest at 0-100 m. As the fate of POC flux, heterotrophic bacteria was estimated to be important at 100-1,000 m, while most of them were considered to be directly sinking a t1,000-3,000 m.