Community structure, life history, and feeding habit of the planktonic amphipod Themisto spp. off Sanriku area, western North Pacific

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K06194
• 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: Kitasato University
• Principal Investigator: Yamada Yuichiro 北里大学, 海洋生命科学部, 講師 (80458744)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 動物プランクトン / 端脚類 / Themisto japonica / Themisto pacifica / 三陸

Outline of Final Research Achievements

The occurrence, geographical distribution, population dynamics and feeding habits of the planktonic amphipods Themisto japonica and T. pacifica were analyzed using samples collected nearshore and offshore of the Sanriku area of Iwate Prefecture, western North Pacific. Both species were abundant in January, June and October. T. japonica appeared more frequently along the coast, while the percentage of T. pacifica increased offshore. Mature females of T. japonica appeared in almost all months, but were not abundant. Mature males and females of T. pacifica appeared year-round, with particularly abundant in January, March, May-July, and October. It was considered to have three generations per year in T. japonica and four generations per year in T. pacifica.

Free Research Field

浮遊生物学

Academic Significance and Societal Importance of the Research Achievements

三陸海域ではThemisto属端脚類はかなり高頻度で出現し、特に当海域で漁獲されるツノナシオキアミの集群中に多く混在し、さらにごく沿岸においても濃密な群れを形成することがあるので、漁業者からも本端脚類の出現動向について強い関心を寄せていた。本端脚類は沖合海域において有用魚種に多く捕食されているだけでなく、ごく沿岸域においてもサケ稚魚の最も重要な餌料となっている。これらのことから、三陸海域における本属端脚類の生態を解明することは、生物学、海洋学的側面のみならず東北地方における水産振興の面においても重要である。