Contributions of fish to the instream dispersal of drift algae

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05745
• 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: Ibaraki University
• Principal Investigator: Abe Shin-ichiro 茨城大学, 教育学部, 教授 (40371869)
• Co-Investigator(Kenkyū-buntansha): 棗田 孝晴 茨城大学, 教育学部, 教授 (00468993)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 付着藻類 / 淡水魚類 / 両側回遊魚 / 移動・分散 / 移動・分散 / 河川生態系

Outline of Final Research Achievements

This study assessed fish endozoochory for riverine microalgae dispersal. We confirmed that microalgae composed of cyanobacteria, diatoms and green algae, survived in feces egested by four fish taxa which differ from food habit (Plecoglossus altivelis altivelis, P. altivelis ryukyuensis, Rhinogobius nagoyae, Cottus sp.). Furthermore, some microalgal taxa egested by the fish, such as the diatom (Melosira varians) and conjugating green algae (Cosmarium spp., Closterium spp., Senedesmus spp.), retained proliferative capacity. This result indicated that riverine microalgae can be dispersed via ingestion by freshwater fish in streams. The result of fish fauna survey in tributaries of Naka River showed that travel rage of benthic fish was determined by the height of drop structure constructed upstream. The spatiotemporal variabilities in biotic (e.g., the amount of food) and abiotic factors (e.g., water depth and flow) of environments would affect the distribution pattern of riverine fish.

Free Research Field

生態学

Academic Significance and Societal Importance of the Research Achievements

本研究は、河川付着藻類の分散過程の一つとして、淡水魚類による被食散布が生じ得ることを明らかにした。世界各地の河川で在来・外来の有害藻の分布拡大が顕在化している。本研究の成果は、それら有害藻の河川内分布の予測およびその対策を講じるうえで新たな視点を加えるものである。