Geographical variation in egg dormancy in coastal copepods: an approach from inter-population comparison

• Project/Area Number: 18K05779
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: The University of Tokyo
• Principal Investigator: Nishibe Yuichiro 東京大学, 大気海洋研究所, 准教授 (50403861)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2020: ¥130,000 (Direct Cost: ¥100,000、Indirect Cost: ¥30,000); Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2018: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
• Keywords: 動物プランクトン / カイアシ類 / 休眠 / 地理的変異 / 沿岸域 / 生活史

Outline of Final Research Achievements

Geographical variation in egg diapause in the coastal copepod Acartia hudsonica was investigated in the two populations from different temperature regimes (Otsuchi Bay and Maizuru Bay). This study showed that A. hudsonica females switched abruptly from subitaneous to resting egg production just before disappearing in early summer in Maizuru Bay, while in Otsuchi Bay active A. hudsonica populations were present year-round and females produced both subitaneous and resting eggs simultaneously during spring-early summer. The inter-population difference was also found in the duration of egg diapause and its relation to temperature.

Academic Significance and Societal Importance of the Research Achievements

沿岸性カイアシ類における卵休眠の地理的変異についてはこれまで数例しか報告されておらず、特に休眠卵の生理学的特性においても個体群間で変異が存在することはほとんど知られていなかった。そのため、本研究の結果は、変動の激しい沿岸環境に生息する動物プランクトンの環境適応や生活史の進化を理解する上で重要な知見となる。また、これらの結果は、同種であっても個体群によって環境応答性が異なることを示しており、海洋の温暖化による沿岸生物の季節性や分布の将来変化を予測する上でも重要な情報を提供する。

Research Products

• [Journal Article] Higher ingestion rates and importance of ciliates in the diet of a large, subarctic copepod revealed by larger volume incubations (2023)
  • Author(s): Takahashi Kazutaka、Ichinomiya Mutsuo、Okazaki Yuji、Nishibe Yuichiro
  • Journal Title: Limnology and Oceanography Volume: 68 Issue: 4 Pages: 790-802
  • DOI: 10.1002/lno.12310
  • Peer Reviewed / Open Access
• [Journal Article] Species-specific patterns in spatio-temporal dynamics of juvenile chum salmon and their zooplankton prey in Otsuchi Bay, Japan, revealed by simultaneous eDNA quantification of diverse taxa from the same water samples. (2023)
  • Author(s): Yuki Minegishi, Marty Kwok-Shing Wong, Mako Nakao, Yuichiro Nishibe, Aiko Tachibana, Yoo-Jun Kim, Susumu Hyodo
  • Journal Title: Fisheries Oceanography Volume: 32 Issue: 3 Pages: 255-326
  • DOI: 10.1111/fog.12631
  • Peer Reviewed / Open Access
• [Journal Article] Dead heat: copepod carcass occurrence along the Japanese coasts and implications for a warming ocean (2019)
  • Author(s): Tang K W、Ivory J A、Shimode S、Nishibe Y、Takahashi K
  • Journal Title: ICES Journal of Marine Science Volume: 印刷中 Issue: 6 Pages: 1825-1835
  • DOI: 10.1093/icesjms/fsz017
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Factors controlling reproduction of copepods in the Kuroshio region (2022)
  • Author(s): Hiroaki Saito, Nao Nakagiri, Siyu Jiang and Yuichiro Nishibe
  • Organizer: International Symposium on Small Pelagic Fish: New Frontiers in Science for Sustainable Management
  • Int'l Joint Research
• [Presentation] 沿岸性カイアシ類の緩発性休眠卵: その生理学的特性と生活史における役割 (2019)
  • Author(s): 西部裕一郎
  • Organizer: 2019年日本ベントス学会・日本プランクトン学会合同大会