<資料>京都大学北海道研究林標茶区における水生昆虫相と分類群同定キー

Abstract

京都大学北海道研究林・標茶区内を流れる南多和川の6本の支流において, 2013年6月から10月にかけて水生昆虫相を調査した. 期間を通して, 6目26科54属71分類群の水生昆虫分類群とその他の無脊椎動物5分類群が記録された. 水生昆虫の分類群組成は支流ごとに異なり, 上流部に位置する支流において観察される分類群数が多かった. 出現分類群は季節によって変化し, 6月に最も多かった. 出現機能群は粒状有機物食者と肉食者が多かった. また, 出現分類群の半分以上が粒状有機物食者と破砕食者といった腐植連鎖系の構成要素と考えられる分類群であり, 調査地の河川生態系が森林由来の有機物供給に強く依存度することが示唆された. さらに, 本研究では観察された分類群を対象に, 分類群同定キーをまとめた資料を添付した. この分類群同定キーの使用にあたっては, 本調査で観察されなかった分類群については, 誤同定を招く可能性があること, 京都大学北海道研究林・標茶区の河川以外(他地域や止水域)の水生昆虫の同定においては正確性が保証できないことに注意が必要である.

We identified aquatic insects captured at 6 tributaries in Minami-Tawa River that flows through the Hokkaido Research Forest, Kyoto University in Sibecha, Hokkaido, Japan from June to October 2013. Totally 71 taxa consisting of 54 genera, 26 families, and six orders of aquatic insects and five taxa of other macroinvertebrates were identified from the samples. The faunal structure varied among tributaries and the number of observed taxa was larger in tributaries located at an upper reach of Minami-Tawa River than these at a lower reach. The number of taxa observed was also changed among seasons and was largest in June. Particle organic material (POM) feeders and carnivores dominated in this ecosystem. More than half of the observed taxa was classified into POM feeders and shredder feeders, which are generally part of the members of the detritus food web. This pattern may indicate a high contribution of terrestrial organic materials, such as leaf litter and woody debris, as an energy source at the headwater ecosystems of Minami-Tawa River. In addition, we made an identification key to classify the samples obtained in this research, which will be useful for future studies and education in this research forest. Note that some species that were not observed in this study and that sampled from other than the Minami-Tawa River in the Hokkaido Research Forest might be misidentified in the usage of this key.