Determination and quantification of mesopelagic micronekton predation by coastal seabirds

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K06192
• 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: Toyo University
• Principal Investigator: Motohiro Ito 東洋大学, 生命科学部, 准教授 (80612332)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 沿岸性海鳥 / 中深層性マイクロネクトン / ウミネコ / 沿岸生態系 / ハダカイワシ / 夜間採餌 / 食性分析 / GPSロガー

Outline of Final Research Achievements

The coastal related seabirds, especially diurnal surface-fishing gulls known to foraged mainly on pelagic fishes. However, we found the substantial and continuous usage of the deep-sea living mesopelagic micronekton species by Black-tailed gulls.
We conducted field works at islands in the Nisaijim Island, Iwate, Bentenjima and Taishima Island, Aomori, and Matsumae kojima Island, Hokkaido, Japan. We conducted stomach content and DNA analysis for detailed species identification for the samples. We also obtained GPS tracks from breeding seabirds, simultaneously. In this study, mesopelagic micronekton species such as lanternfish, barracudina Deep-sea Shrimp etc. appeared substantially and continuously from Black tailed gulls in the Nisaijima and Benten Island, where the deep pelagic ocean is close to their breeding colonies. GPS tracks reviled that those gulls often use pelagic area (>800-3000 m) during night. Those might be closely involved to their mesopelagic micronekton use.

Free Research Field

海洋生態学

Academic Significance and Societal Importance of the Research Achievements

中深層性マイクロネクトンは外洋に生息し、数千m程度の深い水深帯と極表層を能動的に移動するとが古くから知られており、外洋域の深海から表層への栄養ポンプとして機能する鍵種とであると考えられている。
本研究では世界に先駆けて、沿岸性海鳥類が中深層性マイクロネクトンを継続的かつ一定量を利用していくことを発見し定量的に明らかにした。また、これらを利用する種や個体群の特徴や採餌場所を明らかにした。これにより、外洋の深海から沿岸生態系へという栄養的なつがりを明らかにできた。
本発見は、深海から沿岸・陸域への栄養供給と物質循環に新たなシナリオを提供し、今後当該分野の研究に大きく寄与すると期待される。