北海道大学水産科学研究彙報 = Bulletin of Fisheries Sciences, Hokkaido University;第70巻 第1号

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Vertical Distribution, Community Structure, and Active Carbon Flux of Two Macrozooplankton Taxa : Amphipods and Euphausiids in the Summer of the Western North Pacific

Hanamiya, Yurika;Murase, Hiroto;Matsuno, Kohei;Yamaguchi, Atsushi

Permalink : http://hdl.handle.net/2115/79118
JaLCDOI : 10.14943/bull.fish.70.1.77
KEYWORDS : Active carbon flux;Biological pump;Phronima spp.;Themisto pacifica;Primno abyssalis;Vibilia gibbosa;Euphausia spp.;Nematoscelis spp.;Thysanoessa spp.;Stylocheiron spp.

Abstract

This study conducted diel vertical migration and active migration flux estimation of macrozooplanktonic amphipods and euphausiids at 0-250 m water column of the three stations in the western North Pacific during summer. For amphipods, 25 species belonging to 17 genera were identified. Their standing stock was 60-574 ind. m−2 during the daytime and 35-5,228 ind. m−2 at night-time. For euphausiids, 19 species belonging to 7 genera were identified. The standing stock of euphausiids was 80-382 ind. m−2 and 286-2,156 ind. m−2 during the day and at night, respectively. Feeding impacts during the night were estimated to be 0.19-11.76 mg C m−2 day−1 (amphipods) and 5.12-16.42 mg C m−2 day−1 (euphausiids). Respiration during the daytime accounted for 0.08-6.38 mg C m−2 day−1 (amphipods) and 2.33-7.70 mg C m−2 day−1 (euphausiids). The feeding impact and respiratory flux by active migration of macrozooplankton taxa were estimated as 8.34-28.18 mg C m−2 day−1 and 3.15-14.08 mg C m−2 day−1, respectively. These values corresponded to 3.7-12.4% of primary production (feeding impact) and 2.4-10.7% of sinking passive flux from the euphotic zone (respiratory flux). Thus, this study emphasizes the importance of active flux by macrozooplankton for vertical material flux in the western North Pacific.

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