- 著者
- Hanamiya Yurika Murase Hiroto Matsuno Kohei Yamaguchi Atsushi
- 出版者
- 北海道大学大学院水産科学研究院
- 雑誌
- 北海道大学水産科学研究彙報 (ISSN:24353353)
- 巻号頁・発行日
- vol.70, no.1, pp.77-89, 2020-08-24
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.
- 著者
- Abe Yoshiyuki Hildebrandt Nicole Matsuno Kohei Niehoff Barbara Yamaguchi Atsushi
- 出版者
- 北海道大学大学院水産科学研究院
- 雑誌
- 北海道大学水産科学研究彙報 (ISSN:24353353)
- 巻号頁・発行日
- vol.70, no.1, pp.91-102, 2020-08-24
We compared copepod abundance, biomass and community structure in the Atlantic sector (Fram Strait) and Pacific sector (Canada Basin) of the Arctic Ocean by using vertical stratified zooplankton samples collected from 0-1,000 m or 0-1,500 m during daytime in summer. Abundance and biomass were high at the surface layer and decreased with increasing depth in both regions. Abundance and biomass in the surface layer in the Fram Strait were 6-18 times higher than those in the Canada Basin. According to cluster analysis, the copepod communities were separated into three groups that varied vertically and included both locations. Regional differences were marked for Calanus finmarchicus, which was distributed only in the Fram Strait. In the Canada Basin, Spinocalanidae composed 56.1% of calanoid copepod abundance for the bathypelagic groups and also contributed 7.5% of abundance throughout the water column. The dominance of Spinocalanidae may reflect the oligotrophic environment in the Pacific sector of the Arctic Ocean.
- 著者
- Sato Kaede Matsuno Kohei Arima Daichi Abe Yoshiyuki Yamaguchi Atsushi
- 出版者
- SpringerOpen
- 雑誌
- Zoological Studies (ISSN:1810522X)
- 巻号頁・発行日
- vol.54, no.1, 2015-01-16
- 被引用文献数
- 18 1
Background An optical plankton counter (OPC) was used to examine spatial and temporal changes in the zooplankton size spectra in the neighboring waters of Japan from May to August 2011. Results Based on the zooplankton biovolume of equivalent spherical diameter (ESD) in 45 bins for every 0.1 mm between 0.5 and 5.0 mm, a Bray-Curtis cluster analysis classified the zooplankton communities into six groups. The geographical distribution of each group varied from each of the others. Groups with a dominance of 4 to 5 mm ESD were observed in northern marginal seas (northern Japan Sea and Okhotsk Sea), while the least biovolume with a dominance of a small-size class (0.5 to 1 mm) was observed for the Kuroshio extension. Temporal changes were observed along the 155° E line, i.e., a high biovolume group dominated by 2 to 3 mm ESD during May shifted to other size spectra groups during July to August. These temporal changes were caused by the seasonal vertical descent of dominant large Neocalanus copepods during July to August. As a specific characteristic of the normalized biomass size spectra (NBSS), the slope of NBSS was moderate (−0.90) for the Neocalanus dominant spring group but was at −1.11 to −1.24 for the other groups. Theoretically, the slope of the NBSS of the stable marine ecosystem is known to settle at approximately −1. Conclusions Based on the analysis by OPC, zooplankton size spectra in the neighboring waters of Japan were separated into six groups. Most groups had −1.11 to −1.24 NBSS slopes, which were slightly higher than the theoretical value (−1). However, one group had a moderate slope of NBSS (−0.90) caused by the dominance of large Neocalanus copepods.
- 著者
- Sugioka Rikuto Matsuno Kohei Takahashi Keigo D. Makabe Ryosuke Takahashi Kunio T. Moteki Masato Odate Tsuneo Yamaguchi Atsushi
- 出版者
- 北海道大学大学院水産科学研究院
- 雑誌
- 北海道大学水産科学研究彙報 (ISSN:24353353)
- 巻号頁・発行日
- vol.71, no.1, pp.39-50, 2021-08-03
Various zooplankton studies have been conducted in the Indian sector of the Southern Ocean, but studies investigating spatial changes in both meso- and macro-zooplankton populations are limited. To reveal the north-south change of the mesoand macro-zooplankton community structure and the population structure of large copepods, we investigated zooplankton communities collected by the Ocean Research Institute (ORI) net along the 110°E transect in the Indian sector of the Southern Ocean during the austral summer. The zooplankton abundance and biomass were high at the stations north of 60°S and was dominated by large copepods, especially Calanoides acutus. A cluster analysis identified four zooplankton community groups. The distribution pattern of the community groups is likely to be related to the frontal system. The population structure of the dominant species of C. acutus, Calanus propinquus and Rhincalanus gigas had a similar tendency ; early copepodite stages were abundant in the northern region, while late copepodite stages dominated in the southern region. The meridional changes in the population structure are explained by different reproduction periods in each region related to sea-ice melt timing.