Are fishing ports in the inner bay incubators for harmful/toxic Phytoplankton?

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K15592
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Research Institute of Environment, Agriculture and Fisheries, Osaka Prefecture
• Principal Investigator: YAMAMOTO Keigo 地方独立行政法人大阪府立環境農林水産総合研究所(環境研究部、食と農の研究部及び水産研究部), その他部局等, 総括研究員 (80503937)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: Alexandrium catenella / 個体群形成 / シスト / 発芽 / 流動 / 海水交換

Outline of Final Research Achievements

In order to clarify the contribution of fishing ports to the proliferation of toxic and harmful plankton in the inner bay, a study was conducted at the Sakai-Dejima fishing port located in the inner part of Osaka Bay. We compared the occurrence of the toxic dinofragellate Alexandrium catenella and environment inside and outside the fishing port, and confirmed its potential for earlier proliferation inside the port than outside. On the other hand, cyst accumulation levels were lower than in the main bay, and analysis of ADCP data revealed outflow/inflow patterns in wind direction/velocity and tides, which were applied to cell dynamics to explain diurnal increases and decreases in cell density in the fishing port. These results indicate that the inflow from the main bay and the environment in the port are more important than the amount of cysts for the growth of plankton in the port, and that groups of plankton that proliferate on a large scale in the port may re-flow into the main bay.

Free Research Field

プランクトン生態学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果により、漁港での有害・有毒プランクトンの大規模な増殖が漁港内に蓄積したシストを起源としたものではなく、本湾から流入したシードポピュレーションが漁港内の公定な環境下で大規模に増殖し、さらに本湾に再流出することが明らかになった。すなわち、漁港の初期増殖域としての役割が解明されたことで、漁港の環境を有害・有毒プランクトンの増殖に不適な環境に改善することより、有害・有毒プランクトンへの集中的な対応と防除対策の可能性が広がる。