- 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
- Ishii Midori Murase Hiroto Fukuda Yoshiaki Sawada Kouichi Sasakura Toyoki Tamura Tsutomu Bando Takeharu Matsuoka Koji Shinohara Akira Nakatsuka Sayaka Katsumata Nobuhiro Okazaki Makoto Miyashita Kazushi Mitani Yoko
- 出版者
- The Mammal Society of Japan
- 雑誌
- Mammal study (ISSN:13434152)
- 巻号頁・発行日
- vol.42, no.4, pp.191-199, 2017-12
- 被引用文献数
- 12
In this study, we investigated the diving behavior of sei whales relative to the vertical -distribution of their potential prey in the western North Pacific during the summer of 2013. Acoustic time-depth transmitters were attached to two sei whales for 10.2 and 32.0 h, respectively. The vertical distribution and density (expressed as the volume backscattering strength, SV) of their potential prey were recorded by an echosounder. Diving behavior was classified into two shapes: U-shaped and V-shaped. For both individuals, U-shaped diving was associated with higher SV values than V-shaped diving and the frequency of U-shaped diving increased from late afternoon until sunset. During the daytime, dense scattering layers (presumably zooplankton) were distributed at approximately 40 m and they then migrated toward the surface around sunset. The diving depth of the whales followed the diel migration of the scattering layers and the diving was concentrated in these layers when the density became high. The results of this study indicate that sei whales change their diving depth and shapes in response to the diel vertical migration of their potential prey.