びわ湖北西部に流入する河川の水生昆虫群集およびbiotic index
概要
KOMATSU, Tsukasa (Nara Women's Univ., Nara) Aquatic insect communities and the biotic index of the rivers which flow into the northwestern part of the Lake Biwa. Jap. J. Ecol. 14,119-125 (1964). The present paper deals with the ecological studies of aquatic insect communities of Chinai River, Ishida River and Ado River which flow into the northwestern part of the Lake Biwa. The biotic index of the same rivers was determined based on the BECK-TSUDA method, the simplified method which was proposed by BECK (1955) and later revised by TSUDA (1960,1961) for reporting on the biological investigations in connection with stream quality surveys. The field study was made in the summer of 1963. The results are summarized as follows : 1. These rivers have a fauna, characteristic to mountain streams throughout their courses. Especially the Chinai River and Ishida River have a torrential fauna even at their mouth. 2. The standing crops of aquatic insects of the three rivers are shown in Tables 2,3,4. 3. In uppper parts of the three rivers, the standing crops of creepers were more than those of the other life forms. In the middle and lower parts, net-spinners and case-bearers exceeded the creepers in member. 4. The biotic index of the three rivers are shown in Fig. 4. The Chinai River and Ishida River had clear water and the biotic index was large throughout the course. In the middle part of the Ado River, where the bottom sand digging was going on, the biotic index was smaller, the value 15.