Estimation of food source partitioning in riverine fishes considering on inter- and intra-specific individual difference

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K07549
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Aquatic bioproduction science
• Research Institution: Mie University
• Principal Investigator: YODO Taiga 三重大学, 生物資源学研究科, 准教授 (00378324)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 炭素・窒素安定同位体比分析 / 外来魚 / 食物網 / 河川中流域

Outline of Final Research Achievements

Food web structure of fish community at middle reach of a stream was analyzed by carbon and nitrogen stable isotope analysis (SIA). We success to estimate food web structures based on fish individuals. However, contrary to expectations, food resource partitioning with species-mixed groups was not observed. Stable isotope signatures were related within each species. It seems that the period which inter-individual relationships keep may too short to detect by SIA. In two of three study stations, carbon SI signatures were lower in water-column-dwelling fishes than bottom-dwelling fishes. It can be explained by the results of digestive tract contents analysis that water-column-dwelling fishes feed terrestrial insects but bottom-dwelling fishes do not. In the last station, the result was different because carbon SI signatures of producers were closer than those of the other two stations. In all stations, competitive relationships between a native goby and an alien congener were observed.

Free Research Field

魚類生態学

Academic Significance and Societal Importance of the Research Achievements

これまで主として目視観察によって，渓流域や飼育実験下の限られた条件下で行われてきた，魚種でなく個体に着目した餌利用研究について，安定同位体比分析を用いることで，多数の魚種が生息し，規模や透明度から目視観察が難しく研究が進んでこなかった河川中流域での解析に成功した。本邦では河川中流域の同位体比分析による食物網構造自体知見に乏しく，学術的意義は大きい。また，国内外来魚の餌の競合による影響について，視覚的にわかりやすく提示することができ，理解の得られにくい国内外来魚問題の啓発手法として有効と考えられる。